Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Operating activities:
Net loss	$ (7,484)	$ (11,341)
Items not involving cash:
Depreciation	104	79
Amortization of discount on term loan	137	125
Deferred income tax expense	52	33
Stock-based compensation	1,015	491
Unrealized foreign exchange (gain) loss	522	(23)
Unrealized gain on marketable securities	(281)	(29)
Changes in operating assets and liabilities:
Accounts receivable	(824)	20
Prepaid expenses and other current assets	113	389
Accounts payable and accrued expenses	(577)	1,560
Deferred revenue	(5,844)
Net cash used in operating activities	(13,067)	(8,696)
Investing activities:
Purchases of property, plant and equipment	(647)	(335)
Purchases of marketable securities	(107,482)	(34,325)
Proceeds from marketable securities	55,204	27,657
Net cash used in investing activities	(52,925)	(7,003)
Financing activities:
Issuance of common shares, net of issuance costs (note 10a)	102,456
Issuance of common shares pursuant to exercise of stock options	14	58
Net cash provided by financing activities	102,470	58
Effect of exchange rate changes on cash and cash equivalents	(725)	67
Increase (decrease) in cash and cash equivalents	35,753	(15,574)
Cash and cash equivalents, beginning of period	24,755	67,754	$ 67,754
Cash and cash equivalents, end of period	60,508	52,180	$ 24,755
Supplemental disclosures:
Interest paid	206	230
Interest received	1,172	709
Cash paid for operating lease	159	158
Supplemental disclosures of non-cash transactions:
Fair value of stock options exercised on a cashless basis	$ 583	$ 7