Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenues:
Total revenues	$ 818	$ 890
Type of Revenue [Extensible List]	aptx:CollaborationRevenueMember		aptx:CollaborationRevenueMember
Operating expenses:
Research and development	$ 11,055	12,490
General and administrative	4,899	5,725
Total operating expenses	15,954	18,215
Loss from operations	(15,136)	(17,325)
Other income	426	614
Net loss and comprehensive loss	$ (14,710)	$ (16,711)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.34)	$ (0.50)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	43,835	33,390