| In millions, except per share items | Sep-30-17 | Jun-30-17 | Mar-31-17 | Dec-31-16 | Sep-30-16 | Jun-30-16 | Mar-31-16 | Dec-31-15 |
| | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K |
| Cash Flows from Operating Activities | | | | | | | | |
| Net loss | -13.7 | -16.3 | -18.3 | -17.3 | -19.6 | -22.0 | -25.5 | -29.2 |
| |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
| Depreciation | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Noncash stock-based compensation | 1.1 | 1.5 | 1.8 | 1.9 | 2.3 | 2.7 | 3.2 | 3.7 |
| Change in fair value of warrant liability | -0.1 | 0.2 | | | | | | |
| Increase in prepaid expenses and other current assets | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | 0.2 | 0.3 | 0.1 |
| Increase (decrease) in accounts payable and accrued expenses | 1.0 | 1.4 | 1.6 | -0.3 | -0.2 | -0.6 | 0.2 | 0.0 |
| Net cash used in operating activities | -11.6 | -13.3 | -14.9 | -15.6 | -17.3 | -19.6 | -21.8 | -25.3 |
| |
| Cash Flows from Investing Activities | | | | | | | | |
| |
| Cash Flows from Financing Activities | | | | | | | | |
| Proceeds from exercise of stock warrants | | 0.0 | | | | | | |
| Net cash provided by financing activities | | 6.4 | 3.9 | 2.9 | 1.6 | | | |
| Net decrease in cash, cash equivalents and restricted cash | -6.9 | -6.9 | -11.0 | -12.7 | -15.7 | -19.6 | -21.8 | -25.2 |
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| Noncash transactions: | | | | | | | | |
| Settlement of warrant liability due to cashless warrant exercises | -0.6 | | | | | | | |