| In millions, except per share items | Jun-30-23 | Jun-05-23 | Mar-31-23 | Mar-05-23 | Sep-30-22 | Sep-05-22 | Jun-30-22 | Jun-05-22 |
| | 10-Q | 8-K | 10-Q | 8-K | 10-Q | 8-K | 10-Q | 8-K |
| Operating expenses: | | | | | | | | |
| Research and development expense | 13.5 | | 12.0 | | 7.4 | | 6.7 | |
| General and administrative | 3.1 | 3.1 | 4.1 | 4.1 | 3.3 | 3.3 | 3.6 | 3.6 |
| Total operating expenses | 16.6 | 16.6 | 16.0 | 4.1 | 11.8 | 11.8 | 10.3 | 10.3 |
| Loss from operations | -16.6 | -16.6 | -16.0 | -16.0 | -11.8 | -11.8 | -10.3 | -10.3 |
| Other income, net | 0.8 | 0.8 | 0.7 | 0.7 | 0.0 | 0.0 | 0.2 | 0.2 |
| Net loss | -15.8 | -15.8 | -15.3 | | -11.3 | -11.3 | -10.1 | -10.1 |
| Accretion to redemption value and cumulative dividends on preferred stock | | | | | | | | |
| Net loss attributable to common stockholders | -15.8 | 0.0 | -15.3 | -15.3 | -11.3 | 0.0 | -10.1 | 0.0 |
| |
| Net loss per share attributable to common stockholders, basic | ($0.81) | ($0.81) | ($0.79) | ($0.79) | ($0.59) | ($0.59) | ($0.53) | ($0.53) |
| Net loss per share attributable to common stockholders, diluted | ($0.81) | ($0.81) | ($0.79) | ($0.79) | ($0.59) | ($0.59) | ($0.53) | ($0.53) |
| |
| Weighted-average number of shares used in computing net loss per share, basic | 19.5 | 0.0 | 19.4 | 19.4 | 19.3 | 0.0 | 19.3 | 0.0 |
| Weighted-average number of shares used in computing net loss per share, diluted | 19.5 | 0.0 | 19.4 | 19.4 | 19.3 | 0.0 | 19.3 | 0.0 |
| |
| Other comprehensive loss: | | | | | | | | |
| Unrealized gain (loss) on investments | 0.1 | 0.1 | 0.2 | | | | -0.2 | -0.2 |
| Comprehensive loss | -15.7 | -15.7 | -15.1 | | -11.5 | -11.5 | -10.3 | -10.3 |