Summary of significant accounting policies (Tables)

3 Months Ended

Mar. 31, 2018

New Accounting Pronouncements or Change in Accounting Principle [Line Items]

Schedule of impact of adoption of financial statement line items shows comparative balances under ASC 606 and ASC 605

The following financial statement line items have been shown to reflect comparative balances under ASC 606 and ASC 605 for the period ended March 31, 2018, for both of the collaborations with Sanofi Genzyme Collaboration and AbbVie.

Condensed Consolidated Statements of Operations and Comprehensive Loss


	Three months ended March 31, 2018
	Under ASC 606		Under ASC 605		Effect of change
	(in thousands, except per share data)
Collaboration revenue	$	942	$	1,305	$	(363)
Loss from operations		(20,106)		(19,743)		(363)
Net loss		(19,926)		(19,563)		(363)
Net loss per share, basic and diluted	$	(0.63)	$	(0.62)	$	(0.01)

Condensed Consolidated Balance Sheets


	As of March 31, 2018
	Under ASC 606		Under ASC 605		Effect of change
	(in thousands)
Deferred revenue, current	$	20,217	$	18,967	$	1,250
Deferred revenue, non-current		99,506		80,463		19,043
Accumulated deficit	$	(200,689)	$	(180,396)	$	(20,293)

Condensed Consolidated Statements of Cash Flows


	Three months ended March 31, 2018
	Under ASC 606		Under ASC 605		Effect of change
	(in thousands)
Net loss	$	(19,926)	$	(19,563)	$	(363)
Adjustments to reconcile net loss to net cash provided by operating activities:
Deferred revenue		68,057		67,694		363