Condensed Statements of Cash Flows - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss		$ (10,134)	$ (9,948)
Adjustments to reconcile net loss to net cash used in by operating activities:
Depreciation and amortization		30	62
Stock-based compensation		702	414
Amortization of debt issuance cost		111	112
Net amortization on investments		(44)	42
Changes in operating lease liabilities		1	21
Changes in assets and liabilities:
Accounts receivable		(53)	606
Inventories		(91)	75
Prepaid expenses and other assets		(235)	(1,343)
Accounts payable		472	(29)
Accrued and other liabilities		(1,680)	(2,800)
Contract research liabilities		(161)	(537)
Deferred revenue		373	465
Total adjustments		(575)	(2,912)
Net cash used in by operating activities		(10,709)	(12,860)
Cash flows from investing activities
Purchases of property and equipment		(3)	(137)
Purchases of available-for-sale securities		(29,698)	(4,545)
Proceeds from maturities of available-for-sale securities		10,616	14,435
Net proceeds from sale of LACTEL product line		14,979
Net cash (used in) provided by investing activities		(4,106)	9,753
Cash flows from financing activities
Payments on equipment financing obligations		(1)	(1)
Net proceeds from issuances of common stock		51,049	761
Net cash provided by financing activities		51,048	760
Net increase (decrease) in cash, cash equivalents, and restricted cash		36,233	(2,347)
Cash, cash equivalents, and restricted cash, beginning of the period	[1]	21,462	35,074
Cash, cash equivalents, and restricted cash, end of the period	[1]	$ 57,695	$ 32,727

[1] Includes restricted cash of $150,000 (in long term restricted investments) included in the condensed balance sheets at March 31, 2021 and December 31, 2020.