Income taxes (Tables)

12 Months Ended

Sep. 30, 2020

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities

The significant components of the Company’s deferred tax assets and liabilities are as follows:

	September 30,
(in thousands)	2020			2019
Net operating loss carryforwards	$	112,434		$	73,341
Research and development credit carryforwards		9,407			6,831
Operating lease liability		7,506			—
Other		5,639			4,553
Gross deferred tax assets		134,986			84,725
Less: Valuation allowance		(127,336	)		(84,598	)
Net deferred tax assets		7,650			127
Fixed assets		(105	)		(1	)
Operating lease right-of-use asset		(7,498	)		—
Intangible assets		(47	)		(126	)
Gross deferred tax liabilities		(7,650	)		(127	)
Total net deferred tax asset	$	—		$	—

Schedule of Effective Income Tax Rate Reconciliation

The following is a reconciliation of the statutory federal income tax rate to the Company’s effective tax rate:

	Year ended September 30,
	2020			2019			2018
Tax expense computed at the federal statutory rate		21	%		21	%		24	%
Change in valuation allowance		(25	)%		(22	)%		4	%
Research and development credit benefit		1	%		1	%		1	%
Change in federal tax rate		—			—			(28	)%
Stock-based compensation		3	%		—			—
Other expenses		—			—			(1	)%
Total income tax expense		—	%		—	%		—	%

Schedule of Unrecognized Tax Benefits Roll Forward

The aggregate changes in the balance of gross unrecognized tax benefits are as follows:

(in thousands)	Federal and state
Balance as of September 30, 2017	$	1,625
Increases related to tax positions taken during 2018		624
Balance as of September 30, 2018		2,249
Increases related to tax positions taken during 2019		1,042
Balance as of September 30, 2019		3,291
Increases related to tax positions taken during 2020		1,409
Balance as of September 30, 2020	$	4,700