Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Total revenues	$ 490	$ 925	$ 1,308	$ 1,815
Type of Revenue [Extensible List]	aptx:CollaborationRevenueMember	aptx:CollaborationRevenueMember	aptx:CollaborationRevenueMember	aptx:CollaborationRevenueMember
Operating expenses:
Research and development	$ 8,365	$ 9,481	$ 19,420	$ 21,971
General and administrative	4,770	4,171	9,669	9,896
Total operating expenses	13,135	13,652	29,089	31,867
Loss from operations	(12,645)	(12,727)	(27,781)	(30,052)
Other income	128	596	554	1,210
Net loss and comprehensive loss	$ (12,517)	$ (12,131)	$ (27,227)	$ (28,842)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (0.36)	$ (0.61)	$ (0.86)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	45,680	33,493	44,757	33,442

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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