Supplemental Balance Sheet Information

9 Months Ended

12 Months Ended

Sep. 30, 2017

Dec. 31, 2016

Supplemental Balance Sheet Information [Abstract]

Property and equipment, net



	September 30, 2017			December 31, 2016
Scientific equipment	$	1,586		$	993
Leasehold improvements	192			57
Furniture and fixtures	31			27
Computers and software	26			26
Construction in process	—			17
Property and equipment, gross	1,835			1,120
Less: accumulated depreciation	(776		)	(617		)
Property and equipment, net	$	1,059		$	503

Depreciation and amortization expense was $70 and $46 for the three months ended September 30, 2017 and 2016, respectively, and $159 and $132 for the nine months ended September 30, 2017 and 2016, respectively.

Accrued expenses and other current liabilities



	September 30, 2017		December 31, 2016
Accrued Northwestern University License Agreements fee (Note 11)	$	—	$	1,500
Accrued legal expenses	1,004		123
Accrued payroll-related expenses	513		423
Other accrued expenses	979		114
Accrued expenses and other current liabilities	$	2,496	$	2,160

Property and Equipment

Components of property and equipment were as follows:



	December 31,
	2016			2015
Scientific equipment	$	993		$	627
Leasehold improvements	57			57
Furniture and fixtures	27			17
Computers and software	26			14
Construction in process	17			107
Property and equipment, gross	1,120			822
Less: accumulated depreciation	(617		)	(437		)
Property and equipment, net	$	503		$	385

Construction in process at December 31, 2015 represents the purchase of scientific equipment in December 2015 that was placed in service during the second quarter of 2016.