CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Research and development	$ 27,016	$ 15,696	$ 75,636	$ 41,189
General and administrative	6,458	4,007	15,553	14,449
Increase in contingent consideration (inclusive of related party amounts of zero, $434, zero and $2,739, respectively)		1,060		6,683
Total operating expenses	33,474	20,763	91,189	62,321
Loss from operations	(33,474)	(20,763)	(91,189)	(62,321)
Other income (expense):
Interest expense	(848)	(935)	(2,654)	(2,633)
Other income (expense), net	(92)	744	216	2,040
Net loss before income tax	(34,414)	(20,954)	(93,627)	(62,914)
Net loss	(34,414)	(20,954)	(93,627)	(62,914)
Other comprehensive income (expense):
Other comprehensive expense (net of tax expense of zero for each of the periods ending September 30, 2020 and 2019)	(59)	(8)	(58)	(3)
Total other comprehensive expense	(59)	(8)	(58)	(3)
Comprehensive loss	$ (34,473)	$ (20,962)	$ (93,685)	$ (62,917)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.63)	$ (1.65)	$ (3.43)	$ (5.06)
Weighted-average shares of common stock, basic and diluted	54,973,788	12,665,834	27,324,297	12,427,367