Unaudited Quarterly Financial Information (Tables)

12 Months Ended

Apr. 30, 2020

Quarterly Financial Information Disclosure [Abstract]

Summary of Unaudited Quarterly Financial Information

Fiscal year 2020	Quarter ended July 31, 2019			Quarter ended October 31, 2019			Quarter ended January 31, 2020			Quarter ended April 30, 2020
Revenue	$	3,369		$	3,920		$	1,577		$	3,824
Operating expenses		12,933			13,209			14,301			12,781
Net loss		(7,338	)		(5,903	)		(9,291	)		(6,585	)
Net loss per share	$	(0.42	)	$	(0.33	)	$	(0.52	)	$	(0.37	)
Fiscal year 2019	Quarter ended July 31, 2018			Quarter ended October 31, 2018			Quarter ended January 31, 2019			Quarter ended April 30, 2019
Revenue	$	3,718		$	5,592		$	3,890		$	2,926
Operating expenses		10,727			10,485			10,550			14,186
Net loss		(5,030	)		(3,304	)		(3,956	)		(8,526	)
Net loss per share	$	(0.47	)	$	(0.22	)	$	(0.23	)	$	(0.49	)