14. Leases

The Company leases fill/finish, manufacturing, laboratory, warehouse and office facilities, office equipment and vehicles under various operating lease agreements. The Company leases a fill/finish space in Rockville, Maryland under an operating lease that contains no escalation clause, which expires in May 2027. The Company leases office and warehouse space in Baltimore, Maryland under an operating lease that contains a 2.75% escalation clause, which expires in July 2027. The Company leases office and warehouse space in Canton, Massachusetts, under an operating lease that contains a 3.0% escalation clause, which expires in April 2023. The Company leases office space in Washington, D.C. under an operating lease that contains a 2.5% escalation clause, which expires in March 2027. For the years ended December 31, 2017, 2016, and 2015, total lease expense was $1.6 million, $1.4 million and $1.3 million, respectively.

Future minimum lease payments under operating lease obligations as of December 31, 2017 were as follows:

(in thousands)
2017	$	1,626
2018		1,391
2019		1,339
2020		1,343
2021		1,346
2022 and beyond		3,685
Total minimum lease payments	$	10,730