In May 2013, the Company entered into a lease for office space in Burlington, Massachusetts (the “Lease”). The term of the Lease was for 42 months with minimum monthly lease payments beginning at $17,588 per month and escalating over the lease term. In July 2015, the Company amended the Lease to add approximately 4,700 square feet of additional office space, with the option to lease an additional 5,400 square feet in the same building in Burlington, Massachusetts. In addition, at the time, the Company leased approximately 6,700 square feet of temporary space for use prior to delivery of the additional space. This amendment also extended the term of the Lease through October 31, 2019. On September 30, 2015, the Company exercised its option for the additional 5,400 square feet of office space. On September 21, 2016, the Company entered into another amendment to extend the Lease for the 6,700 square feet of temporary space until October 31, 2017.

On April 7, 2017, the Company further amended the Lease to extend the term to October 31, 2023 on the then-existing office space, including the temporary space, consisting of approximately 28,600 square feet of office space in Burlington, Massachusetts. From November 2016 through October 2017, the Company’s lease payment for this space was approximately $80,000 per month. Also, as part of this amendment to the Lease, the Company leased an additional 1,471 square feet of office space beginning in 2018. The lease payment for the 1,471 square feet of office space is approximately $4,100 per month.

On October 6, 2017, the Company exercised its option for an additional 6,450 square feet of space, and the term for the space commenced in April 2018. The Company has approximately 36,500 square feet of office space in Burlington, Massachusetts under a lease term expiring on October 31, 2023. Starting in December 2017, the Company’s minimum monthly lease payment is approximately $87,000 and it increases over the life of the amended Lease. In addition to the base rent for the office space, which increases over the term of the amended Lease, the Company is responsible for its share of operating expenses and real estate taxes.

The straight-line lease cost for the Lease amounted to $0.3 million for the three months ended March 31, 2019 and was included in operating expenses. As of March 31, 2019, the remaining lease term on the Lease was 4.6 years.

In February 2017, the Company entered into a five-year lease for laboratory space located in Woburn, Massachusetts with a monthly lease payment of approximately $15,000, which increases over the term of the lease, plus a share of operating expenses.

Upon adoption of ASU 2016-02, the Company recorded a right-of-use asset and corresponding lease liability for the Lease on January 1, 2019, by calculating the present value of lease payments, discounted at 8.4%, the Company’s estimated incremental borrowing rate, over the 3.2-year remaining term. The Woburn lease includes an option to extend the term of the lease for two years. Since the Company adopted ASU 2016-02 using the Comparatives under 840 approach, it did not reassess the determination of its operating leases as leases, and therefore no options to extend the lease were included in the calculation of the lease liability as of March 31, 2019. The straight-line lease cost for the Woburn lease amounted to $46 thousand for the three months ended March 31, 2019 and was included in operating expenses. As of March 31, 2019, the remaining lease term on the Woburn lease was 2.9 years.

In July 2015, the Company and Patheon UK Limited (“Patheon”) entered into a Manufacturing and Supply Agreement (the “Manufacturing Agreement”) and Technical Transfer and Service Agreement (the “Technical Transfer Agreement”) for the manufacture of ZILRETTA.

Patheon agreed in the Technical Transfer Agreement to undertake certain transfer activities and construction services needed to prepare Patheon’s United Kingdom facility for the commercial manufacture of ZILRETTA in dedicated manufacturing suites. The Company provided Patheon with certain equipment and materials necessary to manufacture ZILRETTA and pays Patheon a monthly fee for such activities and reimburses Patheon for certain material, equipment and miscellaneous expenses and additional services.

The initial term of the Manufacturing Agreement is 10 years from approval by the FDA of the Patheon manufacturing suites for ZILRETTA, or until October 6, 2027. The Company pays a monthly base fee to Patheon for the operation of the manufacturing suites and a per product fee for each vial based upon a forecast of commercial demand. The Company also reimburses Patheon for purchases of materials and equipment made on its behalf, certain nominal expenses and additional services. The Manufacturing Agreement will remain in full effect unless and until it expires or is terminated. Upon termination of the Manufacturing Agreement (other than termination by Flexion in the event that Patheon does not meet the construction and manufacturing milestones or for a breach by Patheon), Flexion will be obligated to pay for the costs incurred by Patheon associated with the removal of Flexion’s manufacturing equipment and for Patheon’s termination costs up to a capped amount.

The Manufacturing Agreement with Patheon contains an operating lease for the use of dedicated manufacturing suites. With the adoption of ASU 2016-02, the Company recorded a right-of-use asset and corresponding lease liability for the operating lease. As of March 31, 2019, the remaining lease term on the Patheon leases was 8.6 years. As of March 31, 2019, the discount rate was 8.24%. The straight-line lease cost amounted to $45 thousand for the three months ended March 31, 2019 and is included in inventory as part of manufacturing overhead.

(In thousands)	For the three months ended March 31,
Operating lease cost	2019		2018
Operating lease cost included in operating expenses	$	369	$	—
Operating lease cost included in inventory		45		—
Total operating lease cost		414		—

Operating cash flows from operating leases		505		—

Maturities of lease liability due under these lease agreements as of March 31, 2019 were as follows:

Year	Operating Lease Obligations (in thousands)
2019	$	1,253
2020		1,710
2021		1,752
2022		1,623
2023		1,380
Thereafter		677
Present value of imputed interest		(1,760	)
Total	$	6,635

As of December 31, 2018, future minimum lease payments under the Company’s lease obligations under ASC 840 were as follows:

Year	Aggregate Minimum Payments (in thousands)
2019		1,491
2020		1,533
2021		1,576
2022		1,447
2023		1,203
Total	$	7,250

As of December 31, 2018, future minimum payments under the Company’s agreed obligations under the Manufacturing Agreement with Patheon were as follows:

Year	Aggregate Minimum Payments (in thousands)
2019		8,027
2020		8,027
2021		8,027
2022		8,027
2023		8,027
2024 and thereafter		30,102
Total	$	70,237

In November 2016, the Company entered into a Supply Agreement with Evonik Corporation (“Evonik”) for the purchase of PLGA which is used in the manufacturing of clinical and commercial supply of ZILRETTA. Pursuant to the Supply Agreement, Flexion is obligated to submit rolling monthly forecasts to Evonik for PLGA supply, a portion of which will constitute binding orders. In addition, Flexion agreed to certain minimum purchase requirements, which do not apply (i) during periods in which Evonik is in material breach of the Supply Agreement or is unable to perform its obligations due to a force majeure event, (ii) with respect to orders that Evonik is unable to supply in excess of binding orders, (iii) for orders Evonik is unable to timely deliver or does not deliver conforming product and provides a credit for such order, or (iv) during an uncured material quality failure by Evonik. Flexion agreed to purchase PLGA batches at a specified price per gram in U.S. dollars, subject to adjustment from time to time, including due to changes in price indices and in the event the initial term of the Supply Agreement is extended. The total term of the agreement is five years. Upon termination of the Supply Agreement (other than termination due to the bankruptcy of either Evonik or Flexion) Flexion is obligated to pay the costs associated with the binding supply forecast provided to Evonik. The Supply Agreement will renew for two successive two year terms upon mutual written consent by both parties.

In December 2017, the Company entered into a definitive agreement with GeneQuine Biotherapeutics GmbH (“GeneQuine”) to acquire the global rights to FX201. As part of the asset purchase transaction with GeneQuine, the Company made an upfront payment to GeneQuine of $2 million. The Company may also be required to make additional milestone payments during the development of FX201, including up to $8.7 million through Phase 2 proof of concept (PoC) clinical trial and, following successful PoC, up to an additional $54 million in development and global regulatory approval milestone payments. The transaction was accounted for as an asset acquisition, as it did not qualify as a business combination. The upfront fee was attributed to the intellectual property acquired, and recognized as research and development expense in December 2017 as the FX201 product candidate had not been commercially approved, and had no alternative future use. Future milestone payments earned prior to regulatory approval of FX201 would be recognized as research and development expense in the period when the milestone events become probable of being achieved. Future milestones earned upon regulatory approval would be recognized as an intangible asset and amortized to expense over the estimated life of FX201. The first milestone of $750,000 was achieved on October 24, 2018 when the GLP toxicology study was initiated upon the dosing of the first animals. This milestone was recognized as research and development expense in the fourth quarter of 2018. As of March 31, 2019, no other milestones under the arrangement have been achieved. As part of the transaction, the Company became the direct licensee of certain underlying Baylor College of Medicine (Baylor) patents and other proprietary rights related to FX201 for human applications. The Baylor license agreement grants the Company an exclusive, royalty-bearing, world-wide right and license (with a right to sublicense) for human applications under its patent and other proprietary rights directly related to FX201, with a similar non-exclusive license to certain Baylor intellectual property rights that are not specific to FX201. The license agreement with Baylor includes a low single-digit royalty on net sales of FX201 and requires the Company to use reasonable efforts to develop FX201 according to timelines set out in the license agreement. In December 2017, the Company also entered into a Master Production Services Agreement with SAFC Carlsbad, Inc., a part of MilliporeSigma, for the manufacturing of preclinical and initial clinical supplies of FX201.