Prepaid Expenses

6 Months Ended

Jun. 30, 2018

Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]

Prepaid Expenses

7. Prepaid expenses

As of June 30, 2018, prepaid expenses were $5,615, consisting of $4,923 of prepaid R&D clinical costs, $479 of prepaid insurance and $213 of other prepaid costs. As of December 31, 2017, prepaid expenses were $1,635, consisting of $1,287 of prepaid R&D clinical costs, $124 of prepaid insurance, and $224 of other prepaid costs.