Stockholder's equity (deficit) (Tables)

3 Months Ended

Mar. 31, 2020

Stockholder’s equity (deficit)

Schedule of common stock reserved for issuance

	March 31, 2020	December 31, 2019
Options outstanding under the 2018 Stock Option and Grant Plan	2,193,592	2,296,029
Options outstanding under the 2019 Stock Option and Incentive Plan	901,858	800,526
Options available for future grant	2,812,364	1,771,931
2019 Employee Stock Purchase Plan	555,042	269,364
	6,462,856	5,137,850

Summary of restricted stock activity

		Grant-Date Fair
	Number of Shares	Value
Unvested restricted common stock as of December 31, 2019	155,149	$	0.52
Shares vesting	(61,617)		0.47
Unvested restricted common stock as of March 31, 2020	93,532	$	0.55