J. Commitments and Contingencies

Leases

The Company currently has a lease agreement with CRP/King 830 Winter L.L.C. for the rental of approximately 120,000 square feet of laboratory and office space at 830 Winter Street, Waltham, MA through March 2026. The Company uses this space for its corporate headquarters and other operations. The Company may extend the lease for two additional terms of five years. Pursuant to lease amendments executed through December 2015, the Company received construction allowances totaling approximately $2 million to build out office and lab space to the Company’s specifications. The Company executed a fourth amendment to this lease in April 2018, leasing an additional 10,000 square feet of office space in order to accommodate employees being retained from the future Norwood closure previously discussed. The Company is entitled to a construction allowance of $400,000 to build normal tenant improvements in this space to its specifications. The Company began recording rent expense for this space during the quarter ending September 30, 2018, when it took control of the space for construction. The Company is required to pay certain operating expenses for the leased premises subject to escalation charges for certain expense increases over a base amount.

In 2016, the Company entered into a lease agreement with PDM 930 Unit, LLC for the rental of 10,281 square feet of additional office space at 930 Winter Street, Waltham, MA through August 31, 2021. The Company received $617,000 as a construction allowance to build out the office space to the Company’s specifications. The Company is required to pay certain operating expenses for the leased premises based on its pro-rata share of such expenses for the entire rentable space of the building. The Company is actively seeking to sub-lease this space.

The Company also leases 43,850 square feet of manufacturing and office space at 333 Providence Highway, Norwood, MA under an agreement through February 28, 2019. The Company is required to pay certain operating expenses for the leased premises subject to escalation charges for certain expense increases over a base amount.

Effective in 2013, the Company entered into a lease agreement with River Ridge Limited Partnership for the rental of 7,507 square feet of additional office space at 100 River Ridge Drive, Norwood, MA. The initial term of the lease was for five years and two months commencing in July 2013 and the lease was terminated during 2018.

Facilities rent expense, net of sublease income, was $7.7, $6.8, $3.5, and $6.5 million during the years ended December 31, 2018 and 2017, the six months ended December 31, 2016, and fiscal year 2016, respectively.

As of December 31, 2018, the minimum rental commitments for the next five years and thereafter under the non‑cancelable operating lease agreements discussed above are as follows (in thousands):


2019	$	5,498
2020		5,419
2021		5,257
2022		5,323
2023		5,450
Thereafter		12,336
Total minimum lease payments	$	39,283

In addition to the above table, the Company is responsible for variable operating costs and real estate taxes approximating $3.0 million per year through March 2026. There are no obligations under capital leases as of December 31, 2018, as all of the capital leases were single payment obligations which have all been made.

Collaborations and Licenses

The Company is contractually obligated to make potential future success‑based regulatory milestone payments in conjunction with certain collaborative agreements. These payments are contingent upon the occurrence of certain future events and, given the nature of these events, it is unclear when, if ever, the Company may be required to pay such amounts. Further, the timing of any future payment is not reasonably estimable. As of December 31, 2018, the maximum amount that may be payable in the future under the Company’s current collaborative agreements is $80 million.

Manufacturing Commitments

As of December 31, 2018, the Company has noncancelable obligations under several agreements related to in-process and future manufacturing of antibody and cytotoxic agents required for clinical supply of the Company’s product candidates totaling $1.3 million, all of which will be paid in calendar 2019.

In the fourth quarter of 2018, the Company executed a commercial agreement, which superseded a previous letter agreement, with one of its manufacturers for future production of antibody through calendar 2022. Pursuant to the agreement, the Company’s noncancelable commitment is approximately €22 million at December 31, 2018.

Litigation

The Company is not party to any material litigation.