Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (18,709)	$ (8,153)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	8	10
Amortization	82	71
Noncash stock-based compensation	1,460	969
Noncash interest	447
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(686)	429
Accounts payable and accrued expenses	2,839	(590)
Lease liability	(90)	(75)
Net cash used in operating activities	(14,649)	(7,339)
Cash flows from investing activities:
Purchases of marketable securities	(47,822)
Acquisition of property and equipment	(222)
Net cash used in investing activities	(48,044)
Cash flows from financing activities:
Proceeds from issuance of common stock in private placement, net of offering costs		7,810
Proceeds from exercise of stock options	285	15
Net cash provided by financing activities	67,660	10,074
Net increase in cash and cash equivalents	4,967	2,735
Cash and cash equivalents, beginning of period	34,479	7,851
Cash and cash equivalents, end of period	39,446	10,586
Supplemental disclosure of noncash financing activities
Warrants issued in connection with long-term debt	3,570
Supplemental cash flow information
Interest paid	896
At-the-market sales
Cash flows from financing activities:
Proceeds from issuance of common stock in public offering, net of offering costs		$ (2,249)
Proceeds from issuance of long-term debt	20,000
Public offering
Cash flows from financing activities:
Proceeds from issuance of common stock in public offering, net of offering costs	48,434
Debt financing costs paid	$ (1,059)