Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (15,461)	$ (24,237)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	279	229
Amortization of premium/discount on investments	(58)	(185)
Non-cash interest expense	125	67
Stock-based compensation expense	2,218	1,436
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	632	(415)
Right-of-use asset	318	454
Accounts payable and accrued liabilities	(2,467)	1,829
Deferred revenue	58,721	2,108
Lease liabilities	518	(386)
Net cash provided by (used in) operating activities	44,825	(19,100)
Investing activities
Purchases of property and equipment	(254)	(200)
Purchase of short-term investments	(4,871)	(39,804)
Maturities of short-term investments	27,312	40,125
Proceeds from the sale of short-term investments	0	1,391
Net cash provided by investing activities	22,187	1,512
Financing activities
Proceeds from borrowings, net of issuance costs	5,000	0
Proceeds from sale of common stock, net of offering costs	0	23,598
Repayment of debt	0	(1,000)
Proceeds from exercise of stock options	2	11
Net cash provided by financing activities	5,002	22,609
Effect of exchange rate on cash, cash equivalents and restricted cash	(49)	(10)
Net increase in cash and cash equivalents and restricted cash	71,965	5,011
Cash and cash equivalents and restricted cash, beginning of period	16,509	10,843
Cash and cash equivalents and restricted cash, end of period	88,474	15,854
Supplemental Information
Discount in connection with issuance of debt	335	0
Cash paid for interest	198	67
Recognition of right-of-use asset	$ 0	$ 11,757