5. Accrued Expenses

Accrued expenses are as follows:

	December 31,
	2015		2014
	(in thousands)
Accrued clinical	$	4,536	$	2,132
Accrued bonus		2,178		1,286
Professional fees		647		328
Accrued payroll		518		213
Accrued vacation		310		177
Accrued severance	—			179
Other		1,366		549
Total accrued expenses	$	9,555	$	4,864

In February 2014, the Company entered into a separation agreement with an employee primarily as a result of the transition to the Company’s Cambridge, Massachusetts location. During the first quarter of 2014, the Company recorded severance expense in the amount of approximately $0.3 million, which was recorded to general and administrative expense. During the year ended December 31, 2014, approximately $0.3 million was paid out of the severance accrual and the remainder was paid during the first quarter of 2015. At December 31, 2015 and 2014, approximately $0 and $45,890, respectively, remained in accrued expenses in relation to the unpaid severance costs.

In August 2014, the Company entered into a separation agreement with an employee, which became effective on August 13, 2014. The Company will record the expense and liability associated with the separation agreement ratably over the period from August 5, 2014 through December 31, 2015 because the severance payments are subject to continued service and forfeiture until December 31, 2015. During the year ended 2015 and 2014, the Company recorded severance expense in the amount of approximately $0.3 million and $0.1 million respectively, which was recorded to research and development expense. At December 31, 2015 and 2014, approximately $0 and $0.1 million, respectively, remained in accrued expense in relation to the unpaid severance costs.