| In millions, except per share items | Jun-30-23 | Mar-31-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Operating activities | | | | | | | | |
| Net loss | -12.6 | -11.2 | -13.3 | -12.0 | -11.3 | -15.3 | -9.5 | -7.9 |
| |
| Reconciliation of net loss to net cash used in operating activities: | | | | | | | | |
| Stock-based compensation expense | 1.3 | 1.2 | 1.1 | 1.2 | 1.1 | 1.2 | 1.0 | 1.0 |
| Net gain on warrants inherited in acquisition of Quellis | | | | | | 1.5 | | |
| Right-of-use asset - operating lease | 0.1 | 0.1 | | | | | | |
| Other non-cash items | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | -0.1 | 0.0 | 0.0 |
| Changes in assets and liabilities: | | | | | | | | |
| Prepaid expenses and other assets | 0.7 | -0.9 | -1.1 | -0.7 | 0.1 | 0.2 | 1.2 | -2.1 |
| Lease liability - operating lease | -0.2 | -0.1 | | | 0.0 | 0.0 | -0.7 | |
| Accounts payable | -0.1 | 0.1 | | -0.2 | 0.1 | -0.6 | 1.0 | 0.0 |
| Accrued expenses | 0.0 | -2.5 | 2.6 | 1.4 | -0.2 | 0.6 | -0.3 | 0.9 |
| Net cash used in operating activities | -10.7 | -13.3 | -10.7 | -10.2 | -10.1 | -12.6 | -6.3 | -7.7 |
| |
| Investing activities | | | | | | | | |
| Purchases of short-term investments | -207.0 | -95.9 | -178.5 | -52.7 | -83.2 | -81.7 | -78.0 | |
| Sales and maturities of short-term investments | 149.1 | 290.9 | 43.4 | 54.7 | 76.4 | 54.6 | 39.0 | |
| Purchases of property and equipment | | 0.0 | 0.0 | -0.1 | 0.0 | | | |
| Net cash provided by (used in) investing activities | -57.9 | 195.0 | -135.2 | 2.0 | -6.8 | -27.1 | -39.0 | |
| |
| Financing activities | | | | | | | | |
| Proceeds from exercise of stock options | 0.3 | 0.0 | 0.1 | 0.0 | | | 0.0 | 0.0 |
| Net cash provided by financing activities | 0.3 | 0.0 | 120.4 | 24.3 | | | 0.0 | 0.0 |
| Net increase (decrease) in cash, cash equivalents and restricted cash | -68.3 | 181.8 | | | -16.9 | -39.7 | | |
| |
| Supplemental disclosure of non-cash transactions: | | | | | | | | |
| Conversion of Series X Preferred Stock into common stock | | 1.1 | | | | | | 3.4 |