This Annual Report on Form contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical fact, contained in this Annual Report on Form including statements regarding our strategy, future operations, future financial position, future revenue, projected costs, prospects, plans and objectives of management, are forward-looking statements. The words “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “would,” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words.

The forward-looking statements in this Annual Report on Form include, among other things, statements about:

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make. We have included important factors in the cautionary statements included in this Annual Report on Form particularly in the “Risk Factor Summary” below and in Part I, Item 1A “Risk Factors”, that we believe could cause actual results or events to differ materially from the forward-looking statements that we make. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make.

You should read this Annual Report on Form and the documents that we reference herein and have filed or incorporated by reference hereto completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements contained in this Annual Report on Form are made as of the date hereof, and we do not assume any obligation to update any forward-looking statements except as required by applicable law.

This Annual Report on Form includes certain statistical and other industry and market data that we obtained from industry publications and research, surveys and studies conducted by third parties as well as our own estimates of potential market opportunities. Industry publications and third-party research, surveys and studies generally indicate that their information has been obtained from sources believed to be reliable, although they do not guarantee the accuracy or completeness of such information. Our estimates of the potential market opportunities for our product candidates include several key assumptions based on our industry knowledge, industry publications, third-party research and other surveys, which may be based on a small sample size and may fail to accurately reflect market opportunities. While we believe that our internal assumptions are reasonable, no independent source has verified such assumptions.

Investment in our securities involves risk. You should carefully consider the following summary of what we believe to be the principal risks facing our business, in addition to the risks described more fully in Item 1A, “Risk Factors” of Part I of this Annual Report on Form and other information included in this report. The risks and uncertainties described below are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us or that we presently deem less significant may also impair our business operations.

The outbreak of and the resulting pandemic has presented a substantial public health and economic challenge around the world and continues to affect our employees, patients, communities and business operations, as well as economies and financial markets worldwide. In 2020, we progressed certain of our preclinical programs, specifically in therapeutics for pulmonary diseases and in vaccine development under our collaboration with Sanofi, as further discussed herein. However, as a consequence of the pandemic, we announced that enrollment and dosing in the ongoing Phase 1/2 clinical trial in patients with cystic fibrosis, or CF, was paused in April 2020 and then resumed in September 2020. The full extent to which the pandemic will directly or indirectly impact our business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning the actions taken in an effort to contain it or to potentially treat or vaccinate against and the economic impact on local, regional, national and international markets. Management actively monitors this situation and the possible effects on our financial condition, liquidity, operations, suppliers, industry and workforce. For additional information on risks posed by the pandemic, please see Part I, Item 1A—“Risk Factors—Risks Related to the Pandemic,” included elsewhere in this Annual Report on Form

We believe MRT5005 is the first clinical-stage mRNA product candidate designed to deliver mRNA encoding fully functional CFTR protein to the lung. We have designed MRT5005 to be inhaled via a handheld nebulizer. Once the inhaled MRT5005 has entered the epithelial cells lining the patient’s lungs, our therapeutic mRNA uses the cells’ own machinery for translation and expression of fully functional CFTR protein, thereby restoring this essential ion channel, which we believe will address the pathology of CF directly. Currently approved CFTR modulating therapies are limited to patients with specific genetic mutations; therefore, there remains a significant unmet medical need for patients with CF who have genetic mutations to currently approved CFTR modulating therapies. Additionally, patients treated with these current therapies still suffer from a long-term decline in lung function and exacerbations that require hospitalization. MRT5005 is

We are conducting a Phase 1/2 clinical trial to evaluate the safety and tolerability of single- and multiple-ascending doses of MRT5005. The clinical trial is investigating several groups receiving five once-weekly doses, as well as a group receiving five daily doses. Percent predicted forced expiratory volume in one second, or ppFEV, which is a well-defined and accepted endpoint measuring lung function, is also being measured at timepoints throughout the trial. In April 2019, we completed dosing of patients in the originally planned single-ascending dose, or SAD, portion of the Phase 1/2 clinical trial, which included 8, 16 and 24 mg SAD groups, and in July 2019, we reported interim data from the SAD portion of the clinical trial through follow up post dosing. MRT5005 was generally well-tolerated at low and levels with no serious adverse events reported at any dose level. Marked increases in ppFEVwere observed after a single dose of MRT5005, primarily at the level. Based on the analysis of the interim results, we amended the clinical trial protocol to evaluate additional dose levels. We added a 20 mg SAD group and 12 and 20 mg multiple-ascending dose, or MAD, groups; the MAD portion of the clinical trial includes 8, 12, 16 and 20 mg MAD groups. In January 2021, we announced that we completed enrollment and dosing in the dose cohorts comprising the second interim data analysis, including the 8, 12 and 16 mg MAD groups and the 20 mg SAD group. We anticipate reporting interim clinical data from these cohorts early in the second quarter of 2021. The clinical trial continues to enroll and dose in the remaining dose groups, which include a 20 mg MAD group and the daily dosing cohort.

Additionally, we are leveraging the broad applicability of our platform through a collaboration with Sanofi to develop infectious disease vaccines using our mRNA technology. In the case of vaccines, the mRNA instructs certain cells in the body to produce an antigen that will induce an immune response to an infectious pathogen. Under the collaboration with Sanofi, we are jointly conducting research and development activities to advance vaccines targeting up to seven infectious disease pathogens. As part of the ongoing vaccine development program, comprehensive studies have been conducted across several infectious disease targets. Multiple development candidates have been evaluated against distinct pathogens, all of which were well tolerated across all species tested. Multiple antigens have been tested with all demonstrating robust neutralization titers. Two of the target pathogens under development are and influenza. After evaluation of multiple vaccine candidates for immunogenicity and neutralizing antibody activity, MRT5500 was selected as the lead candidate for a vaccine against In October 2020, preclinical data was reported demonstrating that MRT5500 induced potent neutralizing antibodies against in mice and primates, or NHPs. Two doses of MRT5500 in NHPs induced neutralizing antibody levels significantly higher than those

observed in a panel of samples from patients. It was also demonstrated that MRT5500-immunized mice and NHPs exhibited a T cell response against Vaccine-associated enhanced respiratory disease, or VAERD, has generally not been reported to be associated with a T cell response and therefore these data suggest the potential for a reduced risk for VAERD. A Phase 1/2 clinical trial to evaluate MRT5500 is expected to begin in the first quarter of 2021. For information on risks related to our successful development of a vaccine against please see Part I, Item 1A—“Risk Factors—Risks Related to the Pandemic,” included elsewhere in this Annual Report on Form For the influenza vaccine program, lead LNP/mRNA formulations are being evaluated in preclinical studies to support a clinical proof of technology trial anticipated to begin 2021. Preclinical studies are ongoing for targets against additional viral and bacterial pathogens.

The successful development of our product candidates will require, among other things, our mRNA manufacturing capabilities. To date, we have established single-batch production with our clinical-stage mRNA therapeutics platform. of a dedicated manufacturing space through a contract manufacturing partner was completed during the third quarter of 2020 and has the potential to accommodate multiple batches per month upon continued investments and third-party supplier arrangements. As it relates to the development of a vaccine, depending on the final human vaccine dose and timing of activities, we estimate that we could have manufacturing capacity to produce doses annually. We plan to further expand our mRNA manufacturing capabilities to increase production capacity and will need to work with raw material and other third-party suppliers to achieve this goal.

Our vision is to build a leading mRNA product company, leveraging our extensive experience with proprietary mRNA product development, delivery, manufacturing and process development. Our proprietary MRT platform has enabled us to focus on direct therapeutic approaches to treat specific genetic diseases with significant unmet medical need. We are primarily focused on applying our MRT platform to treat pulmonary diseases where the production of proteins can modify disease. We are also leveraging our platform’s broad applicability to treat other diseases, including liver diseases, as well as to prevent disease through the development of infectious disease vaccines. To realize our vision, we plan to advance multiple programs to clinical stage, add new pipeline programs and continue to innovate on the mRNA platform. In order to achieve these goals, we plan to increase our research and development investments, add key capabilities, deepen our platform and delivery expertise as well as expand our infrastructure and facility size. We also plan to appropriately invest in manufacturing and commercial capabilities to support continued growth and advancement and our ultimate goal of delivering mRNA medicines to treat or prevent life-threatening or debilitating illnesses.

Gene editing seeks to permanently replace, delete or repair a defective gene sequence at the natural gene location in a patient’s genome. In contrast to gene therapy, an edited genetic sequence would be replicated in new cells following cell division, thereby reducing or eliminating the need for repeat dosing. However, current methods of gene editing face significant limitations, including unwanted and modifications to DNA, failure to make the intended modification, challenges in introducing the particular edit into the cell nucleus, and manufacturing complexities. There are currently no approved gene editing products and there is limited clinical experience with this approach.

In small molecule therapy, small molecules are designed to bind to disease-associated molecules and modulate their activity. Small molecule approaches to genetic disorders have limitations, including the inability to directly address specific gene defects and the potential to cause toxicities.

We believe that our MRT platform may be applied across a broad array of diseases and target tissues via multiple routes of administration where the production of a desired protein or the degradation of a protein can provide therapeutic benefit. In addition to the inhalation administration employed for our lead program for the treatment of CF, we have observed successful production of the desired proteins through other routes of administration in preclinical studies, which may allow us to develop MRT product candidates for the treatment of a wide range of rare and diseases, including diseases of the liver.

Vaccines work by mimicking disease-causing agents to stimulate the immune system, building up a defense mechanism that can be deployed to fight future infections. mRNA vaccines offer an innovative approach by delivering the nucleotide sequence encoding a protein associated with prevention or treatment of a pathogen. Because of their high potency, capacity for rapid development and potential for manufacture and safe administration, we believe that mRNA vaccines represent a potentially innovative alternative to conventional vaccine approaches. The same production process to manufacture mRNA designed to create desired protein for our product candidates can be used to manufacture different mRNA for vaccines, which we believe provides flexibility in development and potentially enables the development of vaccines for disease areas where vaccination is not yet a viable option. As part of the collaboration with Sanofi, we have advanced our development programs including screening, optimization and production of mRNA and LNP formulations across multiple infectious disease vaccine targets.

Currently approved CFTR modulating therapies are limited to patients with specific genetic mutations; therefore, there remains a significant unmet medical need for patients with CF who have genetic mutations to currently approved CFTR modulating therapies. Additionally, patients treated with these current therapies still suffer from long-term decline in lung function and exacerbations that require hospitalization. MRT5005 has the potential to treat the underlying cause of CF, regardless of the specific genetic mutation, including patients with limited or no CFTR protein. Our goal for MRT5005 is to provide patients with significant improvements in lung function, halt the progressive decline in lung function and substantially reduce the frequency of pulmonary exacerbations.

ppFEV, which is a well-defined and accepted endpoint measuring lung function, is also being measured at timepoints throughout the trial. In April 2019, we completed dosing of patients in the originally planned SAD portion of the Phase 1/2 clinical trial, which included 8, 16 and 24 mg SAD groups, and in July 2019, we reported interim data from the SAD portion of the clinical trial through follow up post dosing. MRT5005 was generally well-tolerated at low and levels with no serious adverse events reported at any dose level. Marked increases in ppFEVwere observed after a single dose of MRT5005, primarily at the level. Based on the analysis of the interim results, we amended the clinical trial protocol to evaluate additional dose levels. We added a 20 mg SAD group and 12 and 20 mg MAD groups; the MAD portion of the clinical trial includes 8, 12, 16 and 20 mg MAD groups. In January 2021, we announced that we completed enrollment and dosing in the dose cohorts comprising the second interim data analysis, including the 8, 12 and 16 mg MAD groups and the 20 mg SAD group. We anticipate reporting interim clinical data from these cohorts early in the second quarter of 2021. The clinical trial continues to enroll and dose in the remaining dose groups, which include a 20 mg MAD group and the daily dosing cohort.

CF is caused by dysfunctional or missing CFTR protein. The CFTR protein functions as a channel that regulates the movement of chloride ions in and out of the cells of organs such as the lungs, pancreas and the gastrointestinal tract. Through regulation of these ions, the amount of salts in the fluid both inside and outside of the cell remains balanced. When CFTR protein expels the ions, water is drawn out of cells and hydrates the cell surface. In patients with CF, the CFTR protein is defective and cannot perform its normal function of transporting ions across the cell membrane, resulting in an environment characterized by thick mucus on affected cellular surfaces. The deficiency in CFTR protein activity in patients with CF is particularly problematic in the lungs, where the of thick mucus obstructs air flow and provides a favorable environment for bacteria, which leads to chronic infection and persistent inflammation.

An mRNA therapy that results in the expression of the functional CFTR protein has the potential to significantly reduce the number of pulmonary exacerbations, halt the progressive decline in pulmonary function and provide significant improvements in lung function. We believe there is a significant unmet need and market opportunity for an mRNA therapy that can restore fully functional CFTR protein across all patients with CF regardless of the specific genetic mutation, including patients with CF considered to currently approved CFTR modulating therapies.

In our double-blind, placebo-controlled Phase 1/2 clinical trial of MRT5005, we plan to enroll up to 40 adult patients with CF who have two Class I and/or Class II mutations, across multiple sites in the United States. The primary endpoint of the trial is to assess the safety and tolerability of single- and multiple-ascending doses of MRT5005 administered by nebulization. In the MAD portion of the clinical trial, MRT5005 is administered once weekly for five weeks. There is also a daily dose cohort in which MRT5005 is administered once daily for five days. In this Phase 1/2 clinical trial, we are also performing measurements of ppFEVwhich represents the amount of air that can be exhaled from the lungs in one second. The rate of decline in ppFEV in patients with CF is considered a strong clinical predictor of mortality. In patients with CF, lung function is typically reported as a percentage of their ppFEV compared to that of a healthy individual of the same height, sex and race. We expect to design future clinical trials in which improvements in ppFEV or the reduction of pulmonary exacerbations will be the primary efficacy endpoint. The Phase 1/2 clinical trial of MRT5005 for the treatment of CF is being conducted in collaboration with the Cystic Fibrosis Foundation Therapeutics Development Network and the Emily’s Entourage Patient Registry.

In July 2019, we reported interim results from the SAD portion of our Phase 1/2 clinical trial of MRT5005 for the treatment of CF. The interim results summarize data from 12 adult patients with CF who received a single dose of either MRT5005 or placebo (3:1 randomization). Patients who received MRT5005 were assigned to one of

three dose groups (8, 16 or 24 mg). Of the 12 patients, 11 had at least one copy of the F508del mutation, and one patient did not have the F508del mutation and was considered to CFTR modulator treatment. Seven of the 12 patients were being treated with an approved CFTR modulator through screening, dosing and

The most common adverse events through Day 29 were cough and headache. There were no treatment-emergent serious adverse events. All treatment-emergent adverse events, or TEAEs, were considered mild to moderate. Five patients, three of whom were in the 24 mg dose group, experienced transient, mild to moderate febrile reactions deemed related to study drug. These events occurred approximately hours post-dosing, and were characterized by fever and symptoms such as headache, fatigue, chills or nausea, which were treated with medicines such as acetaminophen and nonsteroidal anti-inflammatory drugs or an anti-emetic. Symptoms resolved within 24 hours, and all patients were discharged from the study center on Day 2 as planned. In these five patients, low levels of human CFTR mRNA and/or lipid were detected in the blood.

A primary measure of lung function, ppFEV, was assessed at timepoints throughout the trial. Patients in the pooled placebo group and the 8 mg dose group did not show a marked improvement in ppFEV. In the period after dosing, the three patients in the 16 mg dose group demonstrated maximal ppFEV increases of 11.1%, 13.6% and 22.2%, for a mean maximum increase from baseline (+/- standard deviation) of 15.7% (5.8). Of the three patients in the 16 mg dose group, two were on a stable CFTR modulator treatment regimen for at least 28 days, while the third had a genotype that is considered to CFTR modulator treatments. Of the three patients in the 24 mg dose group, through Day 8, one patient experienced a maximum increase in ppFEV from baseline of 21.4%, while two patients did not show a marked increase in ppFEV.

Based on the first interim analysis of the SAD (Part A) data, we implemented certain protocol changes in this ongoing Phase 1/2 clinical trial. In the SAD portion of the trial, we amended the clinical trial protocol to include an additional 20 mg single dose group of four patients. In the MAD portion of the trial (Part B), we amended the clinical trial protocol to add 12 and 20 mg dose groups with four patients each, the latter dosing group contingent on successful completion of the 20 mg single dose

Human CFTR protein is a large, transmembrane protein that undergoes critical folding and extensive glycosylation prior to being trafficked to incorporate into the membrane of the cell within the lungs. By delivering mRNA encoding the CFTR protein to cells, we rely on the endogenous ribosomes to translate the proper CFTR protein and other endogenous cellular machinery to accurately fold, glycosylate and traffic the protein to its natural state and location within the cell.

Prior to the initiation of our Phase 1/2 clinical trial, our preclinical program included studies as well as studies in multiple species to establish the ability of our MRT platform for the treatment of CF. We conducted studies in which we observed that our CFTR mRNA drug substance successfully resulted in the production of human CFTR protein and we observed ion channel activity of the measured CFTR protein. We obtained substantial data through studies conducted in mice, rats and NHPs. In these studies, we observed successful mRNA delivery and subsequent human CFTR protein production within the lungs of all species tested. In addition, we generated ion channel activity, biodistribution, pharmacokinetic and safety data through evaluation of single- and multiple-dose regimens.

    We performed an study to evaluate the ability of our CFTR mRNA drug substance to produce human CFTR protein. In this study, we introduced the mRNA into cells and, after a given period of time, we analyzed the cells for human CFTR protein using standard laboratory methods. We observed a dose-dependent correlation with respect to both the amount of CFTR mRNA introduced into cells and the amount of full length human CFTR protein produced.

Once we established that our mRNA drug substance could produce the desired human CFTR protein, we used an Ussing Chamber assay to evaluate whether the mRNA-derived CFTR protein was active. An Ussing Chamber assay is commonly used to determine the function of CFTR protein by measuring ion transport across a cell membrane through CFTR. In this study, we evaluated the activity of the CFTR protein that was produced from three separate manufacturing lots of our CFTR mRNA drug substance. We evaluated each lot of our CFTR mRNA in polarized epithelial cells and conducted electrophysiological assays to measure ion flow across the cell membrane through our CFTR mRNA.

Three independent parameters confirmed that this ion flow was due to increased CFTR activity. First, the activity was stimulated by forskolin, a known activator of CFTR. The activity was further stimulated by ivacaftor, an potentiator of CFTR function, and it was selectively inhibited by a human-specific CFTR inhibitor. Based on these findings, we believe that the human CFTR protein produced from our mRNA drug substance was active and produced normal ion channel activity.

Additionally, in other studies, MRT5005 demonstrated active CFTR ion channel in human bronchial epithelial cells that were derived from human lung tissue.

    We investigated the ability of a single dose of MRT5005 to deliver CFTR mRNA to lungs in rats and NHPs. We observed CFTR mRNA levels of up to higher than normal in NHPs 24 hours after a single exposure to MRT5005. We also observed high levels of human CFTR mRNA deposition after a single administration in rats. While these levels in the rats decreased over time, CFTR mRNA deposition was still detectable at higher than normal levels 28 days after administration at the highest doses. Biodistribution analysis of multiple respiratory tract organs demonstrated that the large majority of our drug product deposited in the lungs of rats and NHPs. We believe that these results provide preclinical validation of the ability of MRT5005 to reach the lungs while protecting the delivered mRNA from rapid degradation by nuclease activity.

We conducted multiple-dose inhalation studies in both rats and NHPs. We administered five weekly treatments with a recovery period in each species. We monitored safety as well as pharmacodynamic parameters. We observed robust delivery of human CFTR mRNA upon treatment with MRT5005, resulting in higher than normal levels of CFTR mRNA, similar to what we observed in the single dose administration studies. We observed widespread distribution of the resulting human CFTR protein, with staining in both the bronchial epithelial cells as well as lower airway and alveolar regions. Upon multiple exposures, we observed the presence of human CFTR protein 28 days after the final treatment in rats and NHPs. More specifically, after five weekly doses of MRT5005, we observed a dose-dependent increase in human CFTR protein production.

For our CF discovery program, we are applying advances in mRNA science and LNP chemistry to design a next-generation CF mRNA therapeutic with the goal of building on the early encouraging data we have observed with our lead CF clinical candidate, MRT5005. We are utilizing novel LNPs, protein engineering and codon-optimization approaches, as well as manufacturing process enhancements with the potential to increase protein production, which may allow for low dose and/or short nebulization time. Preclinical studies are ongoing to evaluate safety, protein expression and duration of protein expression to support product candidate selection in this program. These data will inform the selection of the optimal mRNA sequence and LNP for a next-generation CF candidate, which we anticipate advancing into studies in the second half of 2021.

Our PCD discovery program is designed to deliver mRNA to the lung enabling the production of target proteins that would potentially restore ciliary function. We are performing studies to support the selection of our lead PCD candidate which we anticipate advancing into studies in the second half of 2021.

Through our collaboration with Sanofi, we continue to develop mRNA vaccine candidates for infectious diseases and we have advanced our preclinical development programs including screening, optimization and production of mRNA and LNP formulations across multiple targets. Two of the target pathogens under development are which causes and influenza.

After evaluation of multiple vaccine candidates for immunogenicity and neutralizing antibody activity, MRT5500 was selected as the lead candidate for a vaccine against In October 2020, preclinical data was reported demonstrating that MRT5500 induced potent neutralizing antibodies against in mice and NHPs. Two doses of MRT5500 in NHPs induced neutralizing antibody levels significantly higher than those observed in a panel of samples from patients. It was also demonstrated that MRT5500-immunized mice and NHPs exhibited a T cell response against VAERD has generally not been reported to be associated with a T cell response and therefore these data suggest the potential for a reduced risk for VAERD. A Phase 1/2 clinical trial to evaluate MRT5500 is expected to begin in the first quarter of 2021.

We have evaluated proprietary LNP/mRNA formulations for the development of a vaccine against influenza in preclinical studies, including immunogenicity assessments and neutralizing antibody (nAb) titer generation against key influenza antigens in both rodents and NHPs. We observed robust titers in NHPs administered at doses ranging from 15 micrograms to 250 micrograms. Further, activity was demonstrated upon immunization at a 400 nanogram dose of hemagglutinin mRNA/LNP vaccine when applied in an H1N1 lethal challenge influenza mouse model. These data are part of a broader preclinical package that we have generated supporting selection of lead LNP/mRNA formulations, and a clinical proof of technology trial is anticipated to begin 2021.

Large and established companies, such as Merck & Co., Inc., GlaxoSmithKline plc, Sanofi, Pfizer, Inc., Johnson & Johnson and AstraZeneca plc, among others, compete in the vaccine market. In addition, some of our mRNA competitors, Moderna, Inc. and BioNTech AG, have also developed vaccines using mRNA technology, and other mRNA competitors, such as CureVac AG and Arcturus Therapeutics Holdings, Inc., are developing vaccines. Currently, several of our competitors have developed vaccines that have received emergency use approval by the FDA or conditional marketing authorization from the European Medicines Agency, or EMA, and are being administered throughout the United States, Europe and other parts of the world.

In 2018, we entered into a collaboration and license agreement with Sanofi, or the Original Sanofi Agreement, to develop mRNA vaccines for up to five infectious disease pathogens, or the Licensed Fields. On March 26, 2020, we and Sanofi amended the Original Sanofi Agreement, or the First Sanofi Amendment, to include vaccines against as an additional Licensed Field, increasing the number of infectious disease pathogens to up to six. On June 22, 2020, we and Sanofi further amended the Original Sanofi Agreement to expand the scope of the collaboration and licenses granted to Sanofi, or the Second Sanofi Amendment. The Original Sanofi Agreement, as amended by the First Sanofi Amendment and the Second Sanofi Amendment, is referred to as the Amended Sanofi Agreement.

Under the terms of the Amended Sanofi Agreement, we have agreed to grant to Sanofi exclusive, worldwide licenses under applicable patents, patent applications, and materials, including those arising under the collaboration, to develop, commercialize and manufacture mRNA vaccines to prevent, treat or cure diseases, disorders or conditions in humans caused by any infectious disease pathogen, with certain specified exceptions.

Pursuant to the Amended Sanofi Agreement, we and Sanofi are jointly conducting research and development activities to advance mRNA vaccines targeting up to seven infectious disease pathogens. The term of the research collaboration, or the Collaboration Term, expires in June 2022, with an option for Sanofi to extend the Collaboration Term for one additional year, followed by a technology transfer to Sanofi. If Sanofi elects to extend the Collaboration Term, the collaboration may be further expanded to jointly conduct research and development activities to advance mRNA vaccines for up to an additional three infectious disease pathogens, bringing the total to up to ten pathogens. In addition to the research and development and technology transfer, we are responsible for manufacturing and supplying products, related materials and investigational products as required by the collaboration plan. Pursuant to the Amended Sanofi Agreement, we and Sanofi agreed to a governance structure to manage the activities under the collaboration. If we and Sanofi do not mutually agree on certain decisions, Sanofi will be able to break a deadlock without our consent under certain conditions. The collaboration includes an estimated budget. Sanofi is responsible for paying reimbursable development costs, including our employee costs, manufacturing costs, and costs paid to third parties, up to a specified amount for each Licensed Field.

We and Sanofi retain the rights to perform our respective obligations and exercise our respective rights under the Amended Sanofi Agreement. Sanofi also granted us sublicensable licenses under patent rights claiming certain improvements that Sanofi may make to the technology we had licensed to it or claiming certain technology arising from the collaboration and owned by Sanofi. We may exercise such licenses to develop, manufacture and commercialize products, other than products that use a vaccine to prevent, treat or cure a disease, disorder or condition in humans caused by an infectious disease pathogen. Sanofi may terminate these licenses to us if we materially breach the terms of the license and the breach remains uncured for a specified period, which may be extended in certain circumstances.

Pursuant to the Original Sanofi Agreement, Sanofi paid us an upfront payment of $45.0 million in 2018. Pursuant to the Second Sanofi Amendment, Sanofi paid us an additional upfront payment of $300.0 million in August 2020. If Sanofi chooses to exercise its option to extend the Collaboration Term for an additional year, Sanofi has agreed to pay us an additional payment of $75.0 million. The Amended Sanofi Agreement provides that we are eligible to receive aggregate potential payments of up to $1.9 billion upon the achievement of additional specified development, regulatory, manufacturing and commercialization milestones, inclusive of the fee to exercise the option to extend the Collaboration Term. In particular, we are entitled to receive development, regulatory and sales milestone payments of up to $148.0 million for each Licensed Field, other than the Licensed Field, development, regulatory and sales milestone payments of up to $250.0 million in the Licensed Field, and manufacturing milestone payments of up to $200.0 million. In addition, we are entitled to receive a $10.0 million milestone payment from Sanofi following completion of the technology and process transfer.

Under the terms of the Amended Sanofi Agreement, Sanofi has also agreed to pay us royalties on net sales of mRNA vaccines in the Licensed Field in accordance with the terms of and at the same high single digits to low teens percentages set forth in the Original Sanofi Agreement, except where such vaccines are provided as a donation or transferred to a third party without any profit margin, in which case we will be paid royalties sufficient to cover our royalty obligations.

Sanofi has sole responsibility for all commercialization activities for mRNA vaccines in the Licensed Fields and is obligated to bear all costs in connection with any commercialization in the Licensed Fields. We and Sanofi also entered into a separate supply agreement on June 22, 2020, with an effective date of December 20, 2019, governing the terms of the supply of products by us, or the Supply Agreement. Pursuant to the Supply Agreement, we have agreed to use commercially reasonable efforts to manufacture and supply Sanofi with and clinical supply of products and other research materials in certain Licensed Fields, as set forth in the Amended Sanofi Agreement. Sanofi will pay us for the and clinical supply at our cost to manufacture plus a specified markup. The Supply Agreement will remain in effect until terminated in accordance with its terms. However, under the Amended Sanofi Agreement, our obligation to manufacture and supply products is limited to a defined duration based on the Licensed Field of the applicable product. The Supply Agreement may be terminated by the mutual consent of the parties. Sanofi may terminate the Supply Agreement for convenience after a specified notice period, or in the event that we do not provide the supply in a timely manner. We may terminate the Supply Agreement in the event of a breach by Sanofi of its payment obligations and such breach remains uncured for a specified period. As part of the Second Sanofi Amendment, we and Sanofi agreed to negotiate in good faith and enter into a further supply agreement in respect of supply of products in the Licensed Field for use in Phase 3 clinical trials or commercial supply.

Under the Shire Agreement, we are obligated to use commercially reasonable efforts to develop and seek and obtain regulatory approval for products that include or are composed of MRT compounds covered by or derived from patent rights or acquired from Shire, or MRT Products, and to achieve specific developmental milestones. Pursuant to the amendment entered into in June 2018, an mRNA vaccine that is developed pursuant to our collaboration with Sanofi will be considered an MRT Product if it includes an MRT compound having an mRNA sequence that encodes a protein that is from, or that binds to, an infectious disease pathogen in a field that has been licensed by us to Sanofi. During the earnout period described below, with respect to any MRT Product in any country, we are obligated to use commercially reasonable efforts to market and sell such MRT Product in such country.

We are obligated to make milestone payments to Shire of up to $60.0 million in the aggregate upon the occurrence of specified commercial milestones, including upon the first commercial sale of an MRT Product for the treatment of CF and upon the achievement of a specified level of annual net sales with respect to an MRT Product. We are also obligated to make additional milestone payments of $10.0 million for each MRT Product upon the first commercial sale of a MRT Product; provided that such milestone payments will only be due once for any two MRT Products that contain the same MRT compounds or once per MRT Product that is a vaccine developed under our collaboration with Sanofi.

Under the Shire Agreement we are also obligated to pay a quarterly earnout payment of a percentage of net sales of each MRT Product. The earnout period, which is determined on a and basis, will begin on the date of the first commercial sale of such MRT Product in such country and will end on the later of (i) 10 years after such first commercial sale and (ii) the expiration of the last valid claim of the patent rights acquired from Shire or derived from patent rights or acquired from Shire covering such MRT Product in such country.

Prior to first dosing of the first patient with a CFTR MRT Product in a Phase 3 clinical trial, we are obligated to notify Shire if we receive a written notice from a third party seeking to (i) acquire, license or obtain rights to develop or sell a CFTR MRT Product or (ii) other than a transaction resulting in a change of control of our company, acquire all or a substantial portion of the assets we acquired from Shire or our other assets that are necessary for or related to the development and commercialization of CFTR MRT Products. Before we may enter into negotiations with any third party, Shire has 30 days to notify us of its interest in negotiating an agreement with respect to the rights or assets proposed to be acquired by the third party. If Shire provides such notice, we must negotiate exclusively with Shire for up to 90 days. If Shire does not notify us of its interest in such opportunity within such period, or if we and Shire do not enter into an agreement with respect to such opportunity within such period, then, for a period of 12 months, we may grant the rights or sell the assets to a third party on such terms as we may determine in our sole discretion without any further obligation to Shire with respect to the rights or assets subject to the proposal, but we may not enter into exclusive negotiations with any third party for a period longer than 90 days.

In September 2019, we entered into a suite retention and development agreement with Albany Molecular Research, Inc., or AMRI, under which a series of cleanroom suites, or the Suites, were built at AMRI’s manufacturing facility in accordance with our objectives, or the AMRI Agreement. The Suites are for the exclusive use by us and any of our collaboration partners for the manufacture of our product candidates during the term of the AMRI Agreement. The AMRI Agreement continues for five years after the completion date of August 31, 2020, or the Initial Term. We have the right to extend the Initial Term for an additional three-year term at prevailing commercially reasonable rates to be agreed between us and AMRI.

We have the right to terminate the AMRI Agreement for convenience after the date that is 36 months from the date of payment of the first monthly payment, which we refer to as the Initial Three-Year Period. In the event that we terminate the AMRI Agreement for convenience, we must pay AMRI of $6.0 million. If AMRI terminates the AMRI Agreement in the event of our material breach, AMRI is entitled to a lump sum payment from us equivalent to the Monthly Fee multiplied by the number of months remaining in the Initial Three-Year Period plus $6.0 million. In the event of a change of control applicable to us, the termination payment owed by our would be the Monthly Fee multiplied by the number of months remaining in the Initial Term plus $6.0 million.

We are a party an agreement with the Massachusetts Institute of Technology, or MIT, for a worldwide license for specified patent rights owned by MIT. This license grants us an exclusive license under the licensed patent rights to develop, manufacture and commercialize any product containing both (i) any RNA sequences, including mRNA, that encode a protein or peptide suitable for human therapeutic use, which may include operably linked sequences that facilitate translation of the coding portion of such RNA sequence, but such sequences do not include nucleic acids that function through an RNA interface mechanism or transcriptional activation mechanism, or the coding RNA component, and (ii) products covered by the licensed patent rights, or the lipid products. A product containing both a coding RNA component and a lipid product is referred to as a licensed product. Under the licensed patent rights, we are permitted to develop, manufacture and commercialize the licensed products for the delivery of coding RNA components to treat disease in humans. The license is subject to certain rights retained by MIT and other research institutions for research, teaching and educational purposes, rights retained under law by the federal government due to its funding the creation of the invention and rights granted to the sponsor of the research resulting in the inventions permitting internal research by the sponsor and its research collaborators.

We are also obligated to make milestone payments to MIT aggregating up to $1.375 million upon the achievement of specified clinical and regulatory milestones with respect to each licensed product and $1.250 million upon our first commercial sale of each licensed product, and to pay royalties of a low single-digit percentage to MIT based on our, and any of our affiliates’ and sublicensees’, net sales of licensed products. The royalties are payable on a and basis, and may be reduced in specified circumstances. Our obligation to make royalty payments extends with respect to a licensed product in a country until four years past the expiration of the patent or patent application licensed from MIT covering the licensed product in the country. In addition, we are obligated to pay MIT a low double-digit percentage of the portion of income from sublicensees that we ascribe to the patents, excluding royalties on net sales and research support payments. In 2019, pursuant to such provision, we paid $0.7 million to MIT as their share of sublicense income with respect to the upfront payment received under the Original Sanofi Agreement. We will be required to pay MIT a portion of the $300.0 million upfront payment from Sanofi and a portion of the premium

Our commercial success depends in part on our ability to obtain, maintain and enforce our proprietary and intellectual property rights relating to our programs and our core technologies for messenger RNA therapeutics, including discoveries, developments in improvements of mRNA compositions, manufacturing techniques and analytics, as well as LNP and other delivery vehicle compositions, manufacturing techniques and analytics. Our success also depends in part on our ability to develop and commercialize therapeutic products without infringing on the proprietary rights of others. Our policy is to seek to protect our proprietary and intellectual property positions by, among other methods, filing U.S. and foreign patent applications relating to technology important to the development and implementation of our business. We also rely on trade secrets, and continuing innovation to develop, maintain and expand our proprietary and intellectual property positions.

We file patent applications directed to our key programs, including MRT5005, in an effort to establish broad and dominant intellectual property positions regarding new compositions relating to these programs as well as uses of these and similar compositions in the treatment of relevant diseases. We also seek patent protection with respect to methods of making these compositions and to therapeutic biomarkers that may be useful in establishing or monitoring the efficacy of these compositions in patients. As of December 31, 2020, we owned or licensed 80 issued or allowed U.S. patents, 68 U.S. pending patent applications, 139 issued or allowed foreign patents, 250 foreign pending patent applications, and 55 pending Patent Cooperation Treaty, or PCT, or provisional patent applications relating to mRNA therapeutics. The foreign issued patents and patent applications are in a number of jurisdictions, including Europe, including Eastern Europe, North America including Canada and Mexico, Australia, Asia, India and South America.

The intellectual property portfolio for our MRT5005 program includes patents and applications directed to compositions for the mRNA component of MRT5005 as well as analogs thereof, to compositions for the delivery vehicle component of MRT5005 as well as analogs thereof, to compositions for the combination of the mRNA delivery vehicle components of MRT5005, as well as to methods for using and making these novel compositions. As of December 31, 2020, we owned or licensed 19 issued or allowed U.S. patents, 10 issued or allowed European patents, 15 pending U.S. patent applications, 10 pending European patent applications, at least 80 other foreign patents and patent applications in a number of jurisdictions, and two pending PCT or provisional patent applications relating to our MRT5005 program. The U.S. or issued patents or patents issuing from these pending applications for our MRT5005 program will have a statutory expiration date from 2030 to 2041. Patent term adjustments or patent term extensions could result in later expiration dates.

The term of individual patents depends upon the legal term for patents in the countries in which they are obtained. In most countries, including the United States, the patent term is 20 years from the earliest filing date of a patent application. In the United States, a patent’s term may be lengthened by patent term adjustment, which compensates a patentee for administrative delays by the USPTO in examining and granting a patent, or may be shortened if a patent is terminally disclaimed over an earlier filed patent. The term of a patent that covers a drug or biological product may also be eligible for patent term extension when FDA approval is granted, provided statutory and regulatory requirements are met. In the future, if and when our product candidates receive approval by the FDA or foreign regulatory authorities, we expect to apply for patent term extensions on issued patents covering those products, depending upon the length of the clinical trials for each medicine and other factors. There can be no assurance that any of our pending patent applications will issue or that we will benefit from any patent term extension or favorable adjustment to the term of any of our patents.

In addition to patents, we rely upon unpatented trade secrets and and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary information, in part, using confidentiality agreements with any future collaborators, scientific advisors, employees and consultants, and invention assignment agreements with our employees. We also have agreements requiring assignment of inventions with selected consultants, scientific advisors and collaborators. The confidentiality agreements are designed to protect our proprietary information and, in the case of agreements or clauses requiring invention assignment, to grant us ownership of technologies that are developed through a relationship with a third party.

With respect to our proprietary mRNA therapeutic technology platform, we consider trade secrets and to be an important component of our intellectual property. Trade secrets and can be difficult to protect. In particular, we anticipate that with respect to this technology platform, these trade secrets and will over time be disseminated within the industry through independent development, the publication of journal articles describing the methodology, and the movement of personnel skilled in the art from academic to industry scientific positions.

In the United States, our mRNA-based therapies would be licensed by the FDA as biological products, or biologics, under the Public Health Service Act, or PHSA, and regulated under the Federal Food, Drug and Cosmetic Act, or FDCA, and applicable implementing regulations and guidance. The failure of an applicant to comply with the applicable regulatory requirements at any time during the product development process, including testing, clinical testing, the approval process or post-approval process, may result in delays to the conduct of a study, regulatory review and approval and/or administrative or judicial sanctions. These sanctions may include, but are not limited to, the FDA’s refusal to allow an applicant to proceed with clinical trials, refusal to approve pending applications, license suspension or revocation, withdrawal of an approval, warning letters, adverse publicity, product recalls, product seizures, total or partial suspension of production or distribution, injunctions, fines and civil or criminal investigations and penalties brought by the FDA or Department of Justice, or DOJ, or other government entities, including state agencies.

An IND is an exemption from the FDCA that allows an unapproved product candidate to be shipped in interstate commerce for use in an investigational clinical trial and a request for FDA authorization to administer such investigational product to humans. Such authorization must be secured prior to interstate shipment and administration of any product candidate that is not the subject of an approved BLA. In support of a request for an IND, applicants must submit a protocol for each clinical trial and any subsequent protocol amendments must be submitted to the FDA as part of the IND. In addition, the results of the preclinical tests, together with manufacturing information, analytical data, any available clinical data or literature and plans for clinical trials, among other things, must be submitted to the FDA as part of an IND. The FDA requires a waiting period after the filing of each IND before clinical trials may begin. This waiting period is designed to allow the FDA to review the IND to determine whether human research subjects will be exposed to unreasonable health risks. At any time during this period, or thereafter, the FDA may raise concerns or questions about the conduct of the trials as outlined in the IND and impose a clinical hold or partial clinical hold. In this case, the IND sponsor and the FDA must resolve any outstanding concerns before clinical trials can begin.

requirements in the final rule encompass both ethical and data integrity standards for clinical studies. The FDA’s regulations are intended to help ensure the protection of human subjects enrolled in foreign clinical studies, as well as the quality and integrity of the resulting data. They further help ensure that foreign studies are conducted in a manner comparable to that required for IND studies.

Expanded access, sometimes called “compassionate use,” is the use of investigational products outside of clinical trials to treat patients with serious or immediately life-threatening diseases or conditions when there are no comparable or satisfactory alternative treatment options. The rules and regulations related to expanded access are intended to improve access to investigational products for patients who may benefit from investigational therapies. FDA regulations allow access to investigational products under an IND by the company or the treating physician for treatment purposes on a basis for: individual patients (single-patient IND applications for treatment in emergency settings and settings); patient populations; and larger populations for use of the investigational product under a treatment protocol or Treatment IND Application.

 clinical trials are initially conducted in a limited population to test the product candidate for safety, including adverse effects, dose tolerance, absorption, metabolism, distribution, excretion and pharmacodynamics in healthy humans or in patients. During Phase 1 clinical trials, information about the investigational biological product’s pharmacokinetics and pharmacological effects may be obtained to permit the design of well-controlled and scientifically valid Phase 2 clinical trials.

 clinical trials are generally conducted in a limited patient population to identify possible adverse effects and safety risks, evaluate the efficacy of the product candidate for specific targeted indications and determine dose tolerance and optimal dosage. Multiple Phase 2 clinical trials may be conducted by the sponsor to obtain information prior to beginning larger and more costly Phase 3 clinical trials. Phase 2 clinical trials are well controlled, closely monitored and conducted in a limited patient population.

 clinical trials proceed if the Phase 2 clinical trials demonstrate that a dose range of the product candidate is potentially effective and has an acceptable safety profile. Phase 3 clinical trials are undertaken within an expanded patient population to further evaluate dosage, provide substantial evidence of clinical efficacy and further test for safety in an expanded and diverse patient population at multiple, geographically dispersed clinical trial sites. A well-controlled, statistically robust Phase 3 clinical trial may be designed to deliver the data that regulatory authorities will use to decide whether or not to approve, and, if approved, how to appropriately label a biologic: such Phase 3 studies are referred to as “pivotal.”

any of the following: serious and unexpected suspected adverse reactions; findings from other studies or animal or testing that suggest a significant risk in humans exposed to the product; and any clinically important increase in the case of a serious suspected adverse reaction over that listed in the protocol or investigator brochure. Phase 1, Phase 2 and Phase 3 clinical trials may not be completed successfully within any specified period, or at all. Furthermore, the FDA or the sponsor may suspend or terminate a clinical trial at any time on various grounds, including a finding that the research subjects are being exposed to an unacceptable health risk. Similarly, an IRB can suspend or terminate approval of a clinical trial at its institution, or an institution it represents, if the clinical trial is not being conducted in accordance with the IRB’s requirements or if the product has been associated with unexpected serious harm to patients. The FDA will typically inspect one or more clinical sites to assure compliance with GCP and the integrity of the clinical data submitted.

Following submission of a BLA, the FDA conducts a preliminary review of the application generally within 60 calendar days of its receipt and strives to inform the sponsor by the 74 day after the FDA’s receipt of the submission whether the application is sufficiently complete to permit substantive review. The FDA may request additional information rather than accept the application for filing. In this event, the application must be resubmitted with the additional information. The resubmitted application is also subject to review before the FDA accepts it for filing. Once the submission is accepted for filing, the FDA begins an substantive review. The FDA has agreed to specified performance goals in the review process of BLAs. Under that agreement, 90% of applications seeking approval of New Molecular Entities, or NMEs, are meant to be reviewed within 10 months from the date on which the FDA accepts the application for filing, and 90% of applications for NMEs that have been designated for “priority review” are meant to be reviewed within six months of the filing date. For applications seeking approval of products that are not NMEs, the and review periods run from the date that the FDA receives the application. The review process and the Prescription Drug User Fee Act goal date may be extended by the FDA for three additional months to consider new information or clarification provided by the applicant to address an outstanding deficiency identified by the FDA following the original submission.

Before approving an application, the FDA typically will inspect the facility or facilities where the product is or will be manufactured. These inspections may cover all facilities associated with a BLA submission, including component manufacturing, finished product manufacturing and control testing laboratories. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications. Additionally, before approving a BLA, the FDA will typically inspect one or more clinical sites to assure compliance with GCP. Under the FDA Reauthorization Act of 2017, the FDA must implement a protocol to expedite review of responses to inspection reports pertaining to certain applications, including applications for products in shortage or those for which approval is dependent on remediation of conditions identified in the inspection report.

Third, the FDA may designate a product for priority review if it is a product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness. The FDA determines, on a basis, whether the proposed product represents a significant improvement when compared with other available therapies. Significant improvement may be illustrated by evidence of increased effectiveness in the treatment of a condition, elimination or substantial reduction of a treatment-limiting product reaction, documented enhancement of patient compliance that may lead to improvement in serious outcomes, and evidence of safety and effectiveness in a new subpopulation. A priority designation is intended to direct overall attention and resources to the evaluation of such applications, and to shorten the FDA’s goal for taking action on a marketing application from 10 months to 6 months.

The FDA strictly regulates the marketing, labeling, advertising and promotion of prescription drug products placed on the market. This regulation includes, among other things, standards and regulations for advertising, communications regarding unapproved uses, industry-sponsored scientific and educational activities, and promotional activities involving the Internet and social media. Promotional claims about a drug’s safety or effectiveness are prohibited before the drug is approved. After approval, a drug product generally may not be promoted for uses that are not approved by the FDA, as reflected in the product’s prescribing information. In the United States, health care professionals are generally permitted to prescribe drugs for such uses not described in the drug’s labeling, known as uses, because the FDA does not regulate the practice of medicine. However, FDA regulations impose rigorous restrictions on manufacturers’ communications, prohibiting the promotion of uses. It may be permissible, under very specific, narrow conditions, for a manufacturer to engage in nonpromotional, communication regarding information, such as distributing scientific or medical journal information.

If a company is found to have promoted uses, it may become subject to adverse public relations and administrative and judicial enforcement by the FDA, the Department of Justice, or the Office of the Inspector General of the Department of Health and Human Services, as well as state authorities. This could subject a

Pediatric exclusivity is another type of marketing exclusivity in the United States and, if granted, provides for the attachment of an additional six months of marketing protection to the term of any existing regulatory exclusivity, including the and orphan exclusivity. This exclusivity may be granted if a BLA sponsor submits pediatric data that fairly respond to a written request from the FDA for such data. The data do not need to show the product to be effective in the pediatric population studied; rather, if the clinical trial is deemed to fairly respond to the FDA’s request, the additional protection is granted. If reports of requested pediatric studies are submitted to and accepted by the FDA within the statutory time limits, whatever statutory or regulatory periods of exclusivity or patent protection cover the product are extended by six months. This is not a patent term extension, but it effectively extends the regulatory period during which the FDA cannot approve another application.

A patent claiming a new biologic product may be eligible for a limited patent term extension under the Hatch-Waxman Act, which permits a patent restoration of up to five years for patent term lost during product development and the FDA regulatory review. The restoration period granted on a patent covering a product is typically the time between the effective date of a clinical investigation involving human beings is begun and the submission date of an application, plus the time between the submission date of an application and the ultimate approval date. Patent term restoration cannot be used to extend the remaining term of a patent past a total of 14 years from the product’s approval date. Only one patent applicable to an approved product is eligible for the extension, and the application for the extension must be submitted prior to the expiration of the patent in question. A patent that covers multiple products for which approval is sought can only be extended in connection with one of the approvals. The USPTO reviews and approves the application for any patent term extension or restoration in consultation with the FDA.

Other legislative changes have been proposed and adopted since the ACA was enacted. These changes include the Budget Control Act of 2011, which, among other things, led to aggregate reductions to Medicare payments to providers of up to 2% per fiscal year that started in 2013 and due to subsequent legislative amendments to the statute, will stay in effect through 2029. The Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act, and other relief legislation suspended the 2% Medicare sequester from May 1, 2020 through March 3, 2021, and extended the sequester by one year, through 2030. The American Taxpayer Relief Act of 2012, which, among other things, reduced Medicare payments to several types of providers and increased the statute of limitations period for the government to recover overpayments to providers from three to five years. These new laws may result in additional reductions in Medicare and other health care funding and otherwise affect the prices we may obtain for any of our product candidates for which we may obtain regulatory approval or the frequency with which any such product candidate is prescribed or used.

Further, since enactment of the ACA, there have been, and continue to be, numerous legal challenges and Congressional actions to repeal and replace provisions of the law. For example, with enactment of the Tax Cuts and Jobs Act of 2017, which was signed by President Trump on December 22, 2017, Congress repealed the “individual mandate.” The repeal of this provision, which requires most Americans to carry a minimal level of health insurance, will become effective in 2019. Additionally, the 2020 federal spending package permanently eliminated, effective January 1, 2020, the “Cadillac” tax on high-cost employer-sponsored health coverage and medical device tax and, effective January 1, 2021, also eliminates the health insurer tax. Further, the Bipartisan Budget Act of 2018, among other things, amended the ACA, effective January 1, 2019, to increase from 50 percent to 70 percent the discount that is owed by pharmaceutical manufacturers who participate in Medicare Part D and to close the coverage gap in most Medicare drug plans, commonly referred to as the “donut hole.” The Congress may consider other legislation to replace elements of the ACA during the next Congressional session.

Further, there have been several recent U.S. Congressional inquiries and proposed federal and proposed and enacted state legislation designed to, among other things, bring more transparency to drug pricing, review the relationship between pricing and manufacturer patient programs, reduce the costs of drugs under Medicare and reform government program reimbursement methodologies for drug products. At the federal level, Congress and the Trump Administration have each indicated that they will continue to seek new legislative and/or administrative measures to control drug costs. For example, on May 11, 2018, the Trump Administration issued a plan to lower drug prices. The Trump Administration published a final rulemaking that will allow states or certain other government entities to submit importation program proposals to FDA for review and approval. Applicants would be required to demonstrate their importation plans pose no additional risk to public health and safety and will result in significant cost savings for consumers. At the same time, FDA issued draft guidance that would allow manufacturers to import their own drugs that are authorized for sale in other countries (multi-market approved products). In addition, President Trump issued five executive orders that are intended to lower the costs of prescription drug products. Several of these orders are reflected in recently promulgated regulations, and one of these regulations is currently subject to a nationwide preliminary injunction. It remains to be seen whether these orders and resulting regulations will remain in force during the Biden Administration.

In order to market any product outside of the United States, a company must also comply with numerous and varying regulatory requirements of other countries and jurisdictions regarding quality, safety and efficacy and governing, among other things, clinical trials, marketing authorization, commercial sales and distribution of products. Whether or not it obtains FDA approval for a product, an applicant will need to obtain the necessary approvals by the comparable regulatory authorities before it can commence clinical trials or marketing of the product in those countries or jurisdictions. Specifically, the process governing approval of medicinal products in the European Union, or EU, generally follows the same lines as in the United States. It entails satisfactory completion of preclinical studies and adequate and well-controlled clinical trials to establish the safety and efficacy of the product for each proposed indication. It also requires the submission to the relevant competent authorities of a marketing authorization application, or MAA, and granting of a marketing authorization by these authorities before the product can be marketed and sold in the EU. We anticipate that our mRNA-based therapies designed to treat diseases caused by protein or gene dysfunction will be regulated as advanced therapy medicinal products, or ATMPs, in the EU. Additionally, there may be local legislation in various EU Member States, which may be more restrictive than the EU legislation, and we would need to comply with such legislation to the extent it applies.

In April 2014, the new Clinical Trials Regulation, (EU) No 536/2014 (Clinical Trials Regulation) was adopted. The Clinical Trials Regulation will be directly applicable in all the EU Member States, repealing the current Clinical Trials Directive 2001/20/EC and replacing any national legislation that was put in place to implement the Directive. Conduct of all clinical trials performed in the EU will continue to be bound by currently applicable provisions until the new Clinical Trials Regulation becomes applicable. The extent to which clinical trials will be governed by the Clinical Trials Regulation will depend on when the Clinical Trials Regulation becomes applicable and on the duration of the individual clinical trial.

of products representing substantial innovation reviewed under the centralized procedure. Products from small- and enterprises may qualify for earlier entry into the PRIME scheme than larger companies. Many benefits accrue to sponsors of product candidates with PRIME designation, including but not limited to, early and proactive regulatory dialogue with the EMA, frequent discussions on clinical trial designs and other development program elements, and accelerated marketing authorization application assessment once a dossier has been submitted. Importantly, a dedicated Agency contact and rapporteur from the Committee for Human Medicinal Products (CHMP) or Committee for Advanced Therapies (CAT) are appointed early in PRIME scheme facilitating increased understanding of the product at EMA’s Committee level. A meeting initiates these relationships and includes a team of multidisciplinary experts at the EMA to provide guidance on the overall development and regulatory strategies.

To obtain a marketing authorization for a product under EU regulatory systems, an applicant must submit an MAA either under a centralized procedure administered by the EMA, or one of the procedures administered by competent authorities in the EU Member States (decentralized procedure, national procedure or mutual recognition procedure). A marketing authorization may be granted only to an applicant established in the EU. Regulation (EC) No 1901/2006 provides that prior to obtaining a marketing authorization in the EU, applicants have to demonstrate compliance with all measures included in an Paediatric Investigation Plan, or PIP, covering all subsets of the pediatric population, unless the EMA has granted (1) a product-specific waiver, (2) a class waiver or (3) a deferral for one or more of the measures included in the PIP.

by the applicant in response to questions of the CHMP. Accelerated evaluation might be granted by the CHMP in exceptional cases, when a medicinal product is of major interest from the point of view of public health and in particular from the viewpoint of therapeutic innovation. If the CHMP accepts such request, the time limit of 210 days will be reduced to 150 days but it is possible that the CHMP can revert to the standard time limit for the centralized procedure if it considers that it is no longer appropriate to conduct an accelerated assessment. At the end of this period, the CHMP provides a scientific opinion on whether or not a marketing authorization should be granted in relation to a medicinal product. Within 15 calendar days of receipt of a final opinion from the CHMP, the European Commission must prepare a draft decision concerning an application for marketing authorization. This draft decision must take the opinion and any relevant provisions of EU law into account. Before arriving at a final decision on an application for centralized authorization of a medicinal product the European Commission must consult the Standing Committee on Medicinal Products for Human Use. The Standing Committee is composed of representatives of the EU Member States and chaired by a European Commission representative. The European Parliament also has a related “droit de regard”. The European Parliament’s role is to ensure that the European Commission has not exceeded its powers in deciding to grant or refuse to grant a marketing authorization.

The European Commission may grant a “marketing authorization under exceptional circumstances.” Such authorization is intended for products for which the applicant can demonstrate that it is unable to provide comprehensive data on the efficacy and safety under normal conditions of use, because the indications for which the product in question is intended are encountered so rarely that the applicant cannot reasonably be expected to provide comprehensive evidence, or in the present state of scientific knowledge, comprehensive information cannot be provided, or it would be contrary to generally accepted principles of medical ethics to collect such information. Consequently, marketing authorization under exceptional circumstances may be granted subject to certain specific obligations, which may include the following:

The European Commission may also grant a “conditional marketing authorization” prior to obtaining the comprehensive clinical data required for an application for a full marketing authorization. Such conditional marketing authorizations may be granted for product candidates (including medicines designated as orphan medicinal products), if (i) the risk-benefit balance of the product candidate is positive, (ii) it is likely that the applicant will be in a position to provide the required comprehensive clinical trial data, (iii) the product fulfills an unmet medical need and (iv) the benefit to public health of the immediate availability on the market of the medicinal product concerned outweighs the risk inherent in the fact that additional data are still required. A conditional marketing authorization may contain specific obligations to be fulfilled by the marketing authorization holder, including obligations with respect to the completion of ongoing or new studies, and with

In the EU, innovative medicinal products approved on the basis of a complete independent data package qualify for eight years of data exclusivity upon marketing authorization and an additional two years of market exclusivity pursuant to Directive 2001/83/EC. Regulation (EC) No 726/2004 repeats this entitlement for medicinal products authorized in accordance the centralized authorization procedure. Data exclusivity prevents applicants for authorization of generics of these innovative products from referencing the innovator’s data to assess a generic (abridged) application for a period of eight years. During an additional period of market exclusivity, a generic marketing authorization application can be submitted and authorized, and the innovator’s data may be referenced, but no generic medicinal product can be placed on the EU market until the expiration of the market exclusivity. The overall period will be extended to a maximum of 11 years if, during the first eight years of those 10 years, the marketing authorization holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to their authorization, are held to bring a significant clinical benefit in comparison with existing therapies. Even if a compound is considered to be a new chemical entity so that the innovator gains the prescribed period of data exclusivity, another company nevertheless could also market another version of the product if such company obtained marketing authorization based on an MAA with a complete independent data package of pharmaceutical tests, preclinical tests and clinical trials.

A marketing authorization has an initial validity for five years in principle. The marketing authorization may be renewed after five years on the basis of a of the risk-benefit balance by the EMA or by the

competent authority of the EU Member State. To this end, the marketing authorization holder must provide the EMA or the competent authority with a consolidated version of the file in respect of quality, safety and efficacy, including all variations introduced since the marketing authorization was granted, at least six months before the marketing authorization ceases to be valid. The European Commission or the competent authorities of the EU Member States may decide, on justified grounds relating to pharmacovigilance, to proceed with one further five-year period of marketing authorization. Once subsequently definitively renewed, the marketing authorization shall be valid for an unlimited period. Any authorization which is not followed by the actual placing of the medicinal product on the EU market (in case of centralized procedure) or on the market of the authorizing EU Member State within three years after authorization ceases to be valid (the sunset clause).

Once authorized, orphan medicinal products are entitled to 10 years of market exclusivity in all EU Member States and in addition a range of other benefits during the development and regulatory review process including scientific assistance for study protocols, authorization through the centralized marketing authorization procedure covering all member countries and a reduction or elimination of registration and marketing authorization fees. However, marketing authorization may be granted to a similar medicinal product with the same orphan indication during the period with the consent of the marketing authorization holder for the original orphan medicinal product or if the manufacturer of the original orphan medicinal product is unable to supply sufficient quantities. Marketing authorization may also be granted to a similar medicinal product with the same orphan indication if this product is safer, more effective or otherwise clinically superior to the original orphan medicinal product. The period of market exclusivity may, in addition, be reduced to six years if it can be demonstrated on the basis of available evidence that the original orphan medicinal product is sufficiently profitable not to justify maintenance of market exclusivity

In the EU, pricing and reimbursement schemes vary widely from country to country. Some countries provide that products may be marketed only after a reimbursement price has been agreed. Some countries may require the completion of additional studies that compare the cost-effectiveness of a particular product candidate to currently available therapies or health technology assessments, in order to obtain reimbursement or pricing approval. For example, the EU provides options for its Member States to restrict the range of products for which their national health insurance systems provide reimbursement and to control the prices of medicinal products for human use. EU Member States may approve a specific price for a product or it may instead adopt a system of direct or indirect controls on the profitability of the company placing the product on the market. Other Member States allow companies to fix their own prices for products, but monitor and control prescription volumes and issue guidance to physicians to limit prescriptions. Recently, many countries in the EU have increased the amount of discounts required on pharmaceuticals and these efforts could continue as countries attempt to manage health care expenditures, especially in light of the severe fiscal and debt crises experienced by many countries in the EU. The downward pressure on health care costs in general, particularly prescription products, has become intense. As a result, increasingly high barriers are being erected to the entry of new products. Political, economic and regulatory developments may further complicate pricing negotiations, and pricing negotiations may continue after reimbursement has been obtained. Reference pricing used by various EU Member States, and parallel trade, i.e., arbitrage between and high-priced Member States, can further reduce prices. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for any products, if approved in those countries.

The safety of our employees is of utmost importance to us. In response to the pandemic, we have taken significant steps to protect our employees while simultaneously maintaining operations. We have restricted access to our facility to those individuals who perform critical research, translational medicine and laboratory support activities that must be completed on site, limited the number of such people that can be present at our facility at any one time and required that our personnel work remotely. For those individuals who must work we have taken significant steps to implement social distancing protocols consistent with guidelines issued by federal, state and local law. In addition, we have implemented weekly testing, provided antibody testing to all employees, and follow strict protocols to ensure on site safety.

Our principal executive office is located at 29 Hartwell Avenue, Lexington, Massachusetts 02421, and our telephone number is (617) Our internet website address is www.translate.bio. The information contained on, or that can be accessed through, our website is not a part of this Annual Report on Form

We have included our website address in this Annual Report on Form solely as an inactive textual reference. We make available free of charge through our website our Annual Report on Form Quarterly Reports on Form Current Reports on Form and amendments to those reports filed or furnished pursuant to Sections 13(a) and 15(d) of the Securities and Exchange Act of 1934, as amended, or the Exchange Act. We make these reports available through the “Financials and Flings” section of our website as soon as reasonably practicable after we electronically file such reports with, or furnish such reports to, the Securities and Exchange Commission, or the SEC. We also make available, free of charge on our website, the reports filed with the SEC by our executive officers, directors and 10% stockholders pursuant to Section 16 under the Exchange Act as soon as reasonably practicable after copies of those filings are provided to us by those persons. You can review our electronically filed reports and other information that we file with the SEC on the SEC’s website at

In December 2019, a novel strain of coronavirus named which causes was reported and in March 2020, the World Health Organization declared the outbreak of a global pandemic. The pandemic has continued to spread, and to date has led to the implementation of various responses, including government-imposed quarantines, travel restrictions and other public health safety measures. The extent to which the ongoing pandemic impacts our operations or those of the third parties on which we rely will depend on many factors, which are highly uncertain and cannot be predicted with confidence, including the duration of the pandemic, additional or modified government actions, new information that may emerge concerning the severity and impact of and the actions to contain or address its impact in the short and long term.

In April 2020, we announced that enrollment and dosing were paused in our ongoing Phase 1/2 clinical trial of MRT5005 in patients with cystic fibrosis, or CF, as a consequence of the pandemic. In September 2020, we announced that enrollment and dosing resumed and in January 2021, we announced that we completed enrollment and dosing in the dose cohorts comprising the second interim data analysis. The uncertain environment associated with the pandemic could result in additional disruptions in enrollment, affecting our timing to report data. For example, if a patient enrolled in the MRT5005 clinical trial chooses to receive a vaccine, it is possible that such patient may not be able to continue in our trial. Further, in response to the pandemic and in accordance with direction from state and local governmental authorities, we have restricted access to our facility to those individuals who perform critical research, translational medicine and laboratory support activities that must be completed on site, limited the number of such people that can be present at our facility at any one time and required that our personnel work remotely. We expect to continue experiencing these disruptions and possibly new disruptions in our operations and those of third parties for an unknown period of time, as the trajectory of the pandemic remains uncertain and continues to evolve in the United States and globally. The pandemic may further delay or otherwise adversely affect our clinical development activities as a result of many factors, including:

Any negative impact that the pandemic has on recruiting or retaining patients in our clinical trials for MRT5005, the ability of our suppliers to provide materials for our product candidates, or the regulatory review process could cause additional delays with respect to product development activities, which could materially and adversely affect our ability to obtain regulatory approval for and to commercialize our product candidates, increase our operating expenses, affect our ability to raise additional capital, and have a material adverse effect on our financial results.

The response to the pandemic may redirect resources with respect to regulatory and intellectual property matters in a way that would adversely impact our ability to progress regulatory approvals and protect our intellectual property. In addition, we may face impediments to regulatory meetings and approvals due to measures intended to limit interactions.

pandemic continues to rapidly evolve and its ultimate scope, duration and effects are unknown. The extent of the impact of the disruptions to our business, preclinical studies and clinical trials as a result of the pandemic will depend on future developments, which are highly uncertain and cannot be predicted with confidence, such as the ultimate geographic spread of the disease, the duration of the outbreak, travel restrictions and actions to contain the outbreak or treat its impact, such as social distancing and quarantines or lock-downs in the United States and other countries, business closures or business disruptions and the effectiveness of actions taken in the United States and other countries to contain and treat the disease.

The pandemic has already caused significant disruptions in the financial markets, and may continue to cause such disruptions, which could adversely impact any future plans to raise capital. The trading prices of our stock and that of other biopharmaceutical companies have been highly volatile as a result of the economic volatility. Moreover, it is possible the pandemic will significantly impact economies worldwide, which could result in adverse effects on our business and operations. We cannot be certain what the overall impact of the pandemic will be on our business and it has the potential to adversely affect our business, financial condition, results of operations, and prospects.

We have a collaboration with Sanofi to develop infectious disease vaccines using our messenger RNA, or mRNA, technology, including mRNA vaccines against the virus responsible for Pursuant to the collaboration, we are leveraging our mRNA platform and Sanofi’s vaccine expertise to develop mRNA vaccines for infectious diseases, which includes a goal of discovering, developing and advancing rapidly into the clinic a vaccine candidate.

Although MRT5500 has been selected as the lead vaccine candidate, and a Phase 1/2 clinical trial to evaluate MRT5500 is expected to begin in the first quarter of 2021, the development of a

vaccine candidate is still in its early stages. MRT5500 may not be safe and may not successfully prevent in a timely manner, if at all. In order to obtain regulatory approval to market a new biological product such as a vaccine, proof of safety, purity and potency must be demonstrated in humans. To satisfy these requirements, one or more adequate and well-controlled clinical trials will have to be conducted. We cannot predict if any applicable regulatory bodies will accept the proposed clinical program or if the outcome of the preclinical testing and studies will ultimately support the further development of MRT5500. As a result, we cannot be sure that MRT5500 will be able to be advanced into clinical trials on the expected timeline, if at all, and we cannot be sure that applicable regulatory authorities will allow clinical trials to begin. Moreover, even if clinical trials for MRT5500 are initiated, development efforts may not be successful, and clinical trials conducted may not demonstrate sufficient safety, purity and potency necessary to obtain the requisite regulatory approvals for MRT5500.

The timing and success of any clinical trials will also depend on our ability enroll subjects in the clinical trials. Vaccines for have been approved by the Food and Drug Administration, or FDA, and European Medicines Agency, or EMA, and are available on limited basis in the United States and Europe. In addition, several other companies are pursuing the development of a vaccine for and subject enrollment may be affected by availability of the authorized available vaccines and other clinical trials of competing vaccine candidates. Subject enrollment may also be affected by other factors, including variations in the incidence of at the time of the trial and the perceived risks and benefits of the clinical trial among potential subjects. Our inability to enroll a sufficient number of subjects for clinical trials would result in significant delays and could require us to abandon one or more clinical trials altogether. Even if we obtain positive results from preclinical studies or initial clinical trials, we may not achieve the same success in demonstrating safety and potency in later trials.

Further, while the FDA and other regulatory authorities have authority to expedite review and approval of various products, including vaccines, it is unclear how the FDA or such other authorities will exercise these powers with respect to our vaccine candidate, if at all. For example, while the FDA issued an Emergency Use Authorization, or EUA, for the first vaccine, it is unclear whether it will do so for future vaccine candidates. An EUA allows for the manufacture, research and distribution of drugs, biologics and medical devices that have not been approved or licensed by the agency under the standard requirements that typically govern the development of new medical products. The extent to which the FDA relies on the EUA process, or other expedited regulatory mechanisms for the study and review of vaccine candidates, remains unclear and will be subject to a number of different factors. As a result, even if our vaccine candidate shows promising results in preclinical and clinical studies, its approval under an EUA or expedited licensing processes is not assured and the need for authorization from the FDA may result in delays.

If the pandemic is effectively contained or the risk of infection is diminished or eliminated before we can successfully develop and manufacture an mRNA vaccine against Sanofi could its support for the joint development of such a vaccine. We are also committing financial resources and personnel to the development of MRT5500,which may cause delays in or otherwise negatively impact our other development programs, despite uncertainties surrounding the longevity and extent of coronavirus as a global health concern. Our business could be negatively impacted by our allocation of significant resources to a global health threat that is unpredictable and could rapidly dissipate or against which our vaccine, if developed, may not be partially or fully effective. In addition, other companies have developed an FDA approved a vaccine for and it is possible that could be effectively contained before or shortly after we are able to receive authorization for our vaccine candidate.

To date, we have produced multiple mRNA constructs and have established 100 gram single-batch production with our clinical-stage mRNA therapeutics platform. of a dedicated manufacturing space through a contract manufacturing partner was completed during the third quarter of 2020 and has the potential to accommodate multiple batches per month upon continued investments and third-party supplier arrangements. As it relates to development of MRT5500, depending on the final human dose and timing of activities, we estimate that we could have manufacturing capacity to produce doses annually. However, the manufacture of mRNA-based therapeutics is complex and requires significant expertise and capital investment, including the development of advanced manufacturing techniques and process controls. We may face difficulties in production of MRT5500, including scaling up and validating production, potential shortages of raw materials, a failure by our contract manufacturer to comply with guidelines, specifications and regulations necessary for the manufacture of any vaccine candidate we seek to manufacture, and other disruptions relating to the manufacture of any potential vaccine candidates.

Any additional fundraising efforts may divert our management from their activities, which may adversely affect our ability to develop and commercialize our product candidates. We cannot guarantee that future financing will be available in sufficient amounts or on terms acceptable to us, if at all. Our issuance of additional securities, whether equity or debt, or the possibility of such issuance, may cause the market price of our common stock to decline, and our stockholders may not agree with our financing plans or the terms of such financings.

In December 2016, we acquired the mRNA therapeutic platform, or MRT Program, pursuant to the Shire Agreement. Under the Shire Agreement, we are obligated to make milestone payments to Shire of up to $60.0 million in the aggregate upon the occurrence of specified commercial milestones, including upon the first commercial sale of a product that includes or is composed of MRT compounds acquired from Shire, or MRT Product, for the treatment of cystic fibrosis, or CF, and upon the achievement of a specified level of annual net sales with respect to MRT Products. We are also obligated to make additional milestone payments of $10.0 million for each MRT Product upon the first commercial sale of a MRT Product; provided that such milestone payments will only be due once for any two MRT Products that contain the same MRT compounds, or once for MRT Products that are mRNA vaccines in certain Licensed Fields under our collaboration and license agreement with Sanofi. Under the Shire Agreement, we are also obligated to pay a fixed, quarterly earnout payment of a percentage of net sales of each MRT Product. The earnout period will begin on the date of the first commercial sale of MRT Products and will end, on a and basis, on the later of (1) the expiration of the last valid claim of the assigned patents covering the manufacture, use or composition of such product in such country of the applicable MRT Product and (2) 10 years after the first commercial sale of the MRT Product in such country. If these payments become due under the terms of the Shire Agreement, we may not have sufficient funds available to meet our obligations and our development efforts may be materially harmed. If a combination MRT Product that is a vaccine is sold, in certain circumstances, we would be obligated to pay Shire a royalty on a minimum portion of net sales.

In addition, under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, and corresponding provisions of state law, if a corporation undergoes an “ownership change,” which is generally defined as a greater than 50% change, by value, in its equity ownership by certain stockholders over a three-year period, the corporation’s ability to use its net operating loss carryforwards and other tax attributes to offset its post-change income may be limited. We have determined that we have experienced multiple Sections 382 and 383 ownership changes in the past and if a portion of our net operating loss and tax credit carryforwards are subject to an annual limitation under Section 382. In addition, we may experience ownership changes in the future as a result of subsequent changes in our stock ownership, some of which may be outside of our control. If an ownership change has occurred or occurs in the future and our ability to use our historical net operating loss and tax credit carryforwards is materially limited, it would harm our future operating results by effectively increasing our future tax obligations.

We focus on delivering mRNA encoding functional versions of proteins into cells without altering the underlying DNA. Our future success depends on the successful development of this novel therapeutic approach. Relatively few mRNA-based therapeutic product candidates have been tested in animals or humans, and the data underlying the feasibility of developing mRNA-based therapeutic products is both preliminary and limited. While vaccines relying on mRNA have been approved by the FDA and EMA and are commercially available, to date, no product that utilizes mRNA as a therapeutic has been approved in the United States or Europe. We have not yet succeeded and may not succeed in demonstrating the efficacy and safety of any of our product candidates in clinical trials or in obtaining marketing approval thereafter. We have not yet completed a clinical trial of any product candidate and we have not yet assessed safety of any product candidate in humans. As such, there may be adverse effects from treatment with any of our current or future product candidates that we cannot predict at this time.

We do not currently have products approved for sale and are investing a significant portion of our efforts and financial resources in the development of MRT5005. As a consequence of the pandemic, we announced that enrollment and dosing in the ongoing Phase 1/2 clinical trial in patients with CF was paused in April 2020 and then resumed in September 2020. The uncertain environment associated with the pandemic could result in additional disruptions in enrollment, affecting our timing to report data. For example, if a patient enrolled in the MRT5005 clinical trial chooses to receive a vaccine, it is possible that such patient may not be able to continue in our trial. We expect that the pandemic will continue to impact our clinical trials as described above in “Risks Related to the Pandemic.” Our prospects are substantially dependent on our ability, or that of any future collaborator, to develop and obtain marketing approval for, and successfully commercialize, MRT5005.

Before obtaining marketing approval for our product candidates, we must complete preclinical development and then conduct extensive clinical trials to demonstrate the safety and efficacy of the product candidates. Clinical testing is expensive, time-consuming, difficult to design and implement and uncertain as to outcome. We cannot guarantee that our clinical trials, such as the planned Phase 1 trial for MRT5500 and our Phase 1/2 clinical trial of MRT5005 in patients with CF, will be conducted as planned, completed on schedule, if at all, or yield positive results. As a consequence of the pandemic, we announced that enrollment and dosing in the ongoing Phase 1/2 clinical trial in patients with CF was paused in April 2020 and then resumed in September 2020. The uncertain environment associated with the pandemic could result in additional disruptions in enrollment, affecting our timing to report data. For example, if a patient enrolled in the MRT5005 clinical trial chooses to receive a vaccine, it is possible that such patient may not be able to continue in our trial. We expect that the pandemic will continue to impact our clinical trials as described above in “Risks Related to the Pandemic.”

We have experienced delays in enrollment and dosing in our ongoing Phase 1/2 clinical trial in patients with CF as a consequence of the pandemic. We could also encounter delays if a clinical trial is suspended or terminated by us, by the institutional review boards of the institutions in which such trials are conducted or their ethics committees, by the Data Review Committee or Data Safety Monitoring Board for such trial or by the FDA or other foreign regulatory authorities. Such authorities may suspend or terminate a clinical trial due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA or other foreign regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, including those relating to the class of products to which our product candidates belong.

For example, our preclinical studies in animal models have been conducted using human mRNA, which differs from animal mRNA, making it difficult for us to use animal models to assess whether our product candidates are safe or effective in humans. Preclinical studies conducted in mice, rats and primates are not always indicative of clinical trial outcomes in humans.

Identifying, qualifying and enrolling patients to participate in clinical trials of our product candidates is critical to our success, and we may not be able to identify, recruit, enroll and dose a sufficient number of patients, or those with required or desired characteristics, to complete our clinical trials in a timely manner. The timing of our clinical trials depends on our ability to recruit patients to participate as well as to subsequently dose these patients and complete required periods. We depend on Sanofi to design and conduct clinical trials for our vaccine candidates. As a result, we may not control the manner or time schedule in which these clinical trials are conducted, which may negatively impact our business operations. In addition, we anticipate competition recruiting patients for the anticipated future clinical trials of MRT5500 as vaccines are available and many other companies are conducting or plan to conduct similar trials. In contrast, because our clinical trial of MRT5005 is focused on indications with relatively small patient populations, our ability to enroll eligible patients may be limited or may result in slower enrollment than we anticipate as a consequence to the pandemic or otherwise. Many CF clinical trial sites place importance on the review, ranking and sanctioning of CF patient advocacy groups. If CF patient advocacy groups do not timely sanction or highly rate our clinical trials, or prioritize trials of other sponsors over our trials, we may not be able to enroll sufficient patients to conduct our trials at their member sites, or it may take longer to conduct these trials.

As a consequence of the pandemic, we announced that enrollment and dosing had been paused in our ongoing Phase 1/2 clinical trial in patients with CF in April 2020. Even though we were able to resume and complete enrollment and dosing in this trial for the upcoming second interim data analysis as well as continue to enroll and dose in the remaining dose groups, we may encounter slower than expected enrollment or dosing delays due to the CF patient population, or CF advocacy groups may provide additional guidance for the safety of the CF population, which may delay the trial. The uncertain environment associated with the pandemic could result in additional disruptions in enrollment, affecting our timing to report data. For example, if a patient enrolled in the MRT5005 clinical trial chooses to receive a vaccine, it is possible that such patient may not be able to continue in our trial. We expect that the pandemic will continue to impact our clinical trial of MRT5005 as described above in “Risks Related to the Pandemic.” In addition, we may experience enrollment delays related to increased or unforeseen regulatory, legal and logistical requirements at certain clinical trial sites. For example, a delay in the manufacturing of clinical trial material for the Phase 1/2 clinical trial of MRT5500 resulted in a delay in the initiation of the trial. These delays could be caused by regulatory reviews by regulatory authorities and contractual discussions with individual clinical trial sites. Any delays in enrolling and/or dosing patients in our planned clinical trials could result in increased costs, delays in advancing our product candidates, delays in testing the effectiveness of our product candidates or termination of the clinical trials altogether.

Additionally, because we have limited financial and managerial resources, we may forego or delay pursuit of opportunities for certain programs or product candidates or for indications that later prove to have greater commercial potential. For example, we currently intend to focus our capital resources primarily on the clinical development of MRT5005 and the development of vaccines.However, the development of MRT5005 or MRT5500 may ultimately prove to be unsuccessful or less successful than another product candidate in our pipeline that we might have chosen to pursue on a more aggressive basis with our capital resources. Our estimates regarding the potential market for our product candidates could be inaccurate, and our spending on current and future research and development programs may not yield any commercially viable products. If we do not accurately evaluate the commercial potential for a particular product candidate, we may relinquish valuable rights to that product candidate through strategic collaboration, licensing or other arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights. Alternatively, we may allocate internal resources to a product candidate in a therapeutic area in which it would have been more advantageous to enter into a collaborative arrangement.

any product candidates we may develop. Because our initial focus is to identify and develop product candidates to treat diseases in which there is little clinical experience using new technologies, there is heightened risk that the FDA, the EMA or other regulatory authorities may not consider the clinical trial endpoints that we propose to provide clinically meaningful results. In addition, the resulting clinical data and results may be difficult to analyze. Even if the FDA determines that our success criteria is sufficiently validated and clinically meaningful, we may not achieve the endpoints to a degree of statistical significance.

This may be a particularly significant risk for many of the genetically defined diseases for which we plan to develop product candidates because many of these diseases have small patient populations, and designing and executing a rigorous clinical trial with appropriate statistical power is more difficult than with diseases that have larger patient populations. Further, even if we do achieve the criteria, the results may be unpredictable or inconsistent with the results of the endpoints or other relevant data. The FDA also weighs the benefits of a product against its risks, and the FDA may view the efficacy results in the context of safety as not being supportive of regulatory approval. The EMA and other regulatory authorities may make similar comments with respect to these endpoints and data. Any product candidate we may develop will be based on a novel technology that makes it difficult to predict the time and cost of development and of subsequently obtaining regulatory approval.

The manufacture of mRNA-based therapeutics is complex and requires significant expertise and capital investment, including the development of advanced manufacturing techniques and process controls. We and our third-party manufacturers must comply with current Good Manufacturing Practices, or cGMP, regulations and guidelines for the manufacturing of our product candidates used in preclinical studies and clinical trials and, if approved, marketed products. Manufacturers of biotechnology products often encounter difficulties in production, particularly in scaling up and validating initial production. Furthermore, if microbial, viral or other contaminations are discovered in our product candidates or in the manufacturing facilities where our product candidates are made, such manufacturing facilities may be closed for an extended period of time to investigate and remedy the contamination. In addition, the recent increase in large scale demand for the manufacture of mRNA vaccines may impact our ability to obtain the raw materials required to manufacture our mRNA products. Shortages of raw materials may also extend the period of time required to develop our product candidates.

Large and established companies, such as Merck & Co., Inc., GlaxoSmithKline plc, Sanofi, Pfizer, Inc., Johnson & Johnson and AstraZeneca plc, among others, compete in the vaccine market. In addition, some of our mRNA competitors, Moderna, Inc. and BioNTech AG, have also developed vaccines using mRNA technology and other mRNA competitors, such as CureVac AG and Arcturus Therapeutics Holdings, Inc., are developing vaccines. Currently, several of our competitors have developed vaccines that have received emergency use approval by the FDA or conditional marketing authorization from the EMA and are being administered throughout the United States, Europe and other parts of the world.

We currently have a collaboration and license agreement with Sanofi to develop mRNA vaccines for infectious disease pathogens, including MRT5500 has been selected as the lead candidate for a vaccine against Sanofi may not be successful in its efforts to develop or commercialize our vaccine candidates, which could adversely affect our business. In addition, Sanofi could decide not to pursue or prioritize our vaccine candidates, or disputes may arise over certain obligations, which could have an adverse effect on our ability to develop and commercialize any affected product candidate.

In addition, if Sanofi terminates its agreement with us, we may find it more difficult to attract new collaborators and our reputation among the business and financial communities could be adversely affected. All of the risks relating to product development, regulatory approval and commercialization described in this Annual Report on Form also apply to Sanofi’s activities.

As part of our strategy, we intend to seek to enter into collaborations with third parties for one or more of our programs or product candidates. Our likely collaborators for any other collaboration arrangements include large and pharmaceutical companies and biotechnology companies.

Collaborations are complex and time-consuming to negotiate, document and execute. In addition, consolidation among large pharmaceutical companies has reduced the number of potential future collaborators. Even if we are able to successfully enter into collaborations with third parties for one or more of our programs or product candidates, such collaborations may be subject to risks similar to those described above under the risk factor captioned “We have an existing collaboration with Sanofi and we are highly dependent on the efforts of Sanofi to advance our vaccine development program, including the vaccine against If our collaboration with Sanofi is not successful, our business could be adversely affected”

Under the Shire Agreement, prior to the first dosing of a patient with a CFTR MRT Product in a Phase 3 clinical trial, Shire has a right of first negotiation before we may grant rights or sell assets relating to our CFTR MRT Products to a third party. Shire may exercise the right of first negotiation for a period of 30 days following Shire’s receipt of written notice from us notifying Shire of the offer from a third party to acquire, license or commercialize grant rights or sell assets relating to our CF program.

We currently rely and expect to continue to rely on third parties, such as CROs, clinical data management organizations, medical institutions and clinical investigators, to conduct our clinical trials. In addition, we currently rely and expect to continue to rely on third parties to conduct some aspects of our research and preclinical studies. Any of these third parties may terminate their engagements with us, some in the event of an uncured material breach and some at any time for convenience. In addition, as a consequence of the pandemic, some of these parties may be unable to perform their engagements satisfactorily or at all. If any of our relationships with these third parties terminate, we may not be able to enter into alternative arrangements on commercially reasonable terms, if at all. Switching or including additional third parties involves increased cost and requires management’s time and focus. In addition, there is a natural transition period when a new third party commences work. As a result, delays may occur in our product development activities. Although we seek to carefully manage our relationships with our third parties, we could encounter similar challenges or delays in the future and these challenges or delays could have a material adverse impact on our business, financial condition and prospects. We expect that the pandemic will continue to impact our clinical trials as described above in “Risks Related to the Pandemic.”

Furthermore, third parties on whom we rely may also have relationships with other entities, some of which may be our competitors. In addition, these third parties are not our employees, and except for remedies available to us under our agreements with such third parties, we cannot control whether or not they devote sufficient time and resources to our ongoing clinical, and preclinical programs. If these third parties do not

In order to conduct clinical trials of our product candidates, we will need to have them manufactured in potentially large quantities. Our third-party manufacturers may be unable to meet this increased demand in a timely or cost-effective manner, or at all. In addition, as a consequence of the pandemic, our third-party manufacturers may experience delays or other interruptions with their manufacturing capabilities and may be unable to perform satisfactorily, or at all. In addition, quality issues may arise during activities and at any other time. For example, ongoing data on the stability of our products may shorten the expiry of our products and lead to clinical trial material supply shortages, and potentially clinical trial delays. If these third-party manufacturers are unable to successfully scale up the manufacture of our product candidates in sufficient quality and quantity, the development, testing and clinical trials of that product candidate may be delayed or infeasible, and regulatory approval or commercial launch of that product candidate may be delayed or not obtained, which could significantly harm our business.

Our results of operations could be adversely affected by general conditions in the U.S. and global economy and financial markets. A severe or prolonged economic downturn could result in a variety of risks to our business, including, weakened demand for our products, if any, and could adversely impact our ability to raise additional capital when needed on acceptable terms, if at all. A weak or declining economy could also strain our suppliers, possibly resulting in supply disruption, or cause our customers to delay making payments for any current or future approved products. Any of the foregoing could harm our business and we cannot anticipate all of the ways in which the current economic climate and financial market conditions could adversely impact our business. We expect that the pandemic will continue to disrupt the financial markets and may adversely impact economies worldwide as described above in “Risks Related to the Pandemic.”

We are highly dependent on members of our executive team. The loss of the services of any of them may adversely impact the achievement of our objectives. Any of our executive officers could leave our employment at any time, as all of our employees are employees.

turnover rate can be high. We may not be able to attract and retain personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies and academic institutions for skilled individuals. In addition, given the recent development of mRNA vaccines, there is an increased demand for employees with mRNA manufacturing skills. Furthermore, failure to succeed in preclinical studies, clinical trials or applications for marketing approval may make it more challenging to recruit and retain qualified personnel. The inability to recruit, or loss of services of certain executives, key employees, consultants or advisors, may impede the progress of our research, development and commercialization objectives and have a material adverse effect on our business, financial condition, results of operations and prospects.