| In millions, except per share items | Jun-30-23 | Mar-31-23 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 | Jun-30-21 |
| | 10-Q | 10-Q | 10-Q | 10-Q | 10-Q | 8-K | 10-Q | 10-Q |
| Cash flows from operating activities: | | | | | | | | |
| Net loss | | | -99.3 | -85.7 | -89.0 | | -65.6 | -47.5 |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
| Depreciation and amortization | | | 1.8 | 1.3 | 1.0 | | 0.7 | 0.4 |
| (Gain) loss on disposal of fixed assets | | | | 0.0 | | | | |
| Change in fair value of warrant liabilities | | | -5.1 | -12.0 | -6.1 | | -3.4 | 3.5 |
| Change in fair value of contingent consideration | | | 0.1 | 0.1 | 0.1 | | | |
| Stock-based compensation | | | 7.1 | 10.5 | 16.7 | | 17.8 | 10.4 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Prepaid expenses and other current assets | | | -0.9 | -1.4 | -0.8 | | -4.0 | -1.2 |
| Operating lease right-of-use assets | | | -9.1 | -15.8 | -14.9 | | -6.4 | |
| Other assets | | | 0.0 | | | | -0.1 | |
| Accounts payable | | | -0.4 | -0.4 | 1.5 | | 1.3 | 1.7 |
| Accrued expenses and other current liabilities | | | 2.2 | 1.5 | 1.8 | | 2.6 | 1.9 |
| Operating lease liabilities | | | 9.3 | 16.6 | 15.7 | | 7.5 | |
| Net cash used in operating activities | | | -71.0 | -67.6 | -60.8 | | -48.3 | -29.9 |
| |
| Cash flows from investing activities: | | | | | | | | |
| Purchases of property and equipment | | | -7.2 | -7.4 | -5.1 | | -3.1 | -1.2 |
| Purchases of marketable securities | | | -0.8 | -438.8 | -439.5 | | -438.7 | |
| Sales of marketable securities | | | 119.8 | 100.1 | 25.0 | | | |
| Net cash provided by investing activities | | | 111.7 | -346.1 | -419.7 | | -441.9 | -1.2 |
| |
| Cash flows from financing activities: | | | | | | | | |
| Proceeds from exercise of stock options | | | 2.6 | 1.7 | 4.1 | | 4.4 | 3.7 |
| Net cash provided by financing activities | | | 1.8 | -0.6 | 515.2 | | 515.4 | 516.1 |
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| Supplemental disclosure of non-cash investing and financing activities: | | | | | | | | |
| Property and equipment purchased but not paid | | | | 0.6 | | | | |