17. Related Party Transactions

The Company is party to a consulting agreement with a founder and a common stockholder of the Company who provides scientific advisory services. Total expenses under this agreement were $154, $164 and $169 for the years ended December 31, 2016, 2015 and 2014, respectively. Included in accounts payable and accrued expenses as of December 31, 2015 was $21 for amounts due to this stockholder.