PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details) - USD ($) $ in Thousands |
Mar. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| PREPAID EXPENSES AND OTHER CURRENT ASSETS | ||
| Deferred offering costs | $ 1,452 | $ 310 |
| Prepaid research and development expenses | 546 | 1,044 |
| Prepaid rent expense | 76 | 65 |
| Prepaid insurance expense | 26 | 1 |
| Other prepaid expenses and other current assets | 86 | 78 |
| Total prepaid expenses and other current assets | $ 2,186 | $ 1,498 |