15. Product Revenue

The Company’s product sales are derived from the sale of ABRAXANE®, REVLIMID®, and VIDAZA® in China under a distribution license from Celgene. The table below presents the Company’s net product sales for the three and six months ended June 30, 2018 and 2017.


	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2018	2017	2018	2017
	$	$	$	$
Product revenue – gross	31,670	—	55,155	—
Less: Rebate and sales return	(244)	—	(479)	—
Product revenue – net	31,426	—	54,676	—

The following table presents the rollforward of accrued sales rebates and returns for the six months ended June 30, 2018:


	Sales Rebates and Returns
	$
Balance as of December 31, 2017		3,997
Accrual		479
Payments		(3,789)
Balance as of June 30, 2018		687