CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 48,339,000	$ 10,316,000
Investments		73,065,000
Restricted cash	0	367,000
Prepaid expenses and other current assets	4,022,000	10,370,000
Total current assets	52,361,000	94,118,000
Property and equipment, net	31,544,000	17,626,000
Restricted cash, net of current portion	4,170,000	4,170,000
Operating lease right-of-use assets	22,226,000
Other non-current assets	50,000	48,000
Total assets	110,351,000	115,962,000
Current liabilities:
Accounts payable	2,488,000	2,381,000
Accrued expenses	23,858,000	15,818,000
Deferred revenue	6,268,000	742,000
Deferred rent		814,000
Operating lease liabilities	1,778,000
Total current liabilities	34,392,000	19,755,000
Long-term liabilities:
Deferred revenue, net of current portion	58,069,000	54,870,000
Note payable, net of discount	24,825,000	9,572,000
Deferred rent, net of current portion		9,814,000
Operating lease liabilities, net of current portion	37,102,000
Total liabilities	154,388,000	94,011,000
Commitments and contingencies (Note 10)
Redeemable convertible preferred stock	225,033,000	214,784,000
Stockholders’ deficit:
Additional paid-in capital	1,063,000	2,000
Accumulated other comprehensive income		43,000
Accumulated deficit	(270,133,000)	(192,878,000)
Total stockholders’ deficit	(269,070,000)	(192,833,000)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	110,351,000	115,962,000
Series A Redeemable Convertible Preferred Stock
Long-term liabilities:
Redeemable convertible preferred stock	46,162,000	44,169,000
Series B Redeemable Convertible Preferred Stock
Long-term liabilities:
Redeemable convertible preferred stock	84,769,000	81,108,000
Series C Redeemable Convertible Preferred Stock
Long-term liabilities:
Redeemable convertible preferred stock	$ 94,102,000	$ 89,507,000