8. Significant Agreements

Please refer to Note 12 for significant agreements with related parties and Note 6 for licenses granted to the Company.

Licenses Granted by the Company

The Company has granted a number of intellectual property licenses to other biotechnology and pharmaceutical companies. The terms of the licenses vary, however licenses may be exclusive or non-exclusive and may be sublicensable by the licensee. Licenses may grant intellectual property rights for purposes of internal and preclinical research and development only, or may include the rights, or options to obtain future rights, to commercialize drug therapies for specific diseases using the Company’s NAV® Technology Platform. License agreements generally have a term equal to the life of the underlying patents and are terminable only at the option of the licensee. License agreements may require licensees to pay non-refundable up-front fees, option fees and annual maintenance fees. Additional contingent consideration under the licenses may include sublicense fees, milestone fees and royalties on net sales of commercialized products. Sublicense fees vary by license and range from a mid-single digit percentage to a low-double digit percentage of license fees received by licensees as a result of sublicenses. Royalties on net sales of commercialized products vary by license and range from a mid-single digit percentage to a low-teen percentage of net sales by licensees.

Milestone fees are payable to the Company upon the achievement of specific clinical and regulatory developments by licensees. As of December 31, 2016, the Company’s license agreements, excluding additional licenses that could be granted upon the exercise of options by licensees, could result in aggregate milestone fees payable to the Company of up to $0.5 million upon the submission of preclinical regulatory filings, $24.7 million upon the commencement of various stages of clinical trials, $40.0 million upon the submission of regulatory approval filings, $97.5 million upon the approval of commercial products by regulatory agencies and $92.0 million upon the achievement of specified sales targets for licensed products.

License revenue consists of the following (in thousands):

	Years Ended December 31,
	2016		2015		2014
Up-front fees and option fees for commercial licenses	$	3,050	$	5,900	$	4,000
Maintenance fees for commercial licenses		910		635		385
Milestone fees		—		250		—
Research and other license revenue		343		240		190
	$	4,303	$	7,025	$	4,575

Grant Programs

In December 2012, as part of a consortium of research and development entities called MeuSIX, the Company was awarded a long-term grant by the European Commission’s Seventh Framework Program, to perform preclinical and clinical research and development services for the treatment of MPS VI, a severe lysosomal storage disorder. Under the grant agreement, the Company is reimbursed by the grantor for 75 percent of qualified research and development costs, up to approximately €2.3 million of such costs over the five year grant period. Funds received under the grant are subject to refund in the case of non-compliance with the provisions of the grant, which include, but are not limited to, the eligibility of costs, calculation of personnel rates, selection of subcontractors, and other provisions. As of December 31, 2016, the Company is in compliance with all provisions of the grants and no refunds are payable to the grantor. During the years ended December 31, 2016, 2015 and 2014, the Company incurred $0.2 million, $0.9 million and $1.1 million, respectively, of research and development expenses under the grant program. The Company recorded grant revenue of $0.1 million, $0.3 million and $0.8 million related to the grant program for the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016 and 2015, the Company had $0.6 million and $0.5 million, respectively, of accounts receivable under the grant program.