License and Collaboration Agreements	12 Months Ended
Dec. 31, 2019
License and Collaboration Agreements
License and Collaboration Agreements	9. License and Collaboration Agreements GARDP In July 2017, the Company entered into a collaboration agreement with the Global Antibiotic Research and Development Partnership, or GARDP, for the development and commercialization of a product candidate containing zoliflodacin in certain countries. Under the terms of the collaboration agreement, GARDP will use commercially reasonable endeavors to perform and fully fund the Phase 3 registration trial, including the manufacture and supply of the product candidate containing zoliflodacin, in uncomplicated gonorrhea. The Company is obligated to commit reasonably sufficient time and resources to collaborate in the design of the Phase 3 registration trial and the development of the protocol for the trial and to provide know-how relating to zoliflodacin and any future product candidate. Both parties are responsible for obtaining marketing authorizations for any future product candidate in such parts of their respective territories as they elect. In addition, under the collaboration agreement, the Company has granted GARDP a worldwide, fully paid, exclusive and royalty-free license, with the right to sublicense, to use its zoliflodacin technology in connection with GARDP’s development, manufacture and commercialization of zoliflodacin in low-income and specified middle-income countries. The Company has retained commercial rights in all other countries worldwide, including the major markets in North America, Europe and Asia-Pacific. The Company has also retained the right to use and grant licenses to its zoliflodacin technology to perform its obligations under the collaboration agreement and for any purpose other than gonorrhea or community-acquired indications. If the Company believes that the results of the Phase 3 registration trial of zoliflodacin would be supportive of an application for marketing approval, it is obligated to use its best efforts to file an application for marketing approval with the FDA within six months of the completion of the trial and to use commercially reasonable endeavors to file an application for marketing approval with the EMA. Each party is responsible for using commercially reasonable efforts to obtain marketing authorizations for the product candidate in their respective territories. Zai Lab In April 2018, the Company entered into a license and collaboration agreement with Zai Lab (Shanghai) Co., Ltd., or Zai Lab, pursuant to which Zai Lab licensed exclusive rights to durlobactam and sulbactam-durlobactam, or SUL-DUR, in the Asia‑Pacific region, or the Zai Agreement. Under the terms of the Zai Agreement, Zai Lab will fund most of the Company’s clinical trial costs in China for SUL-DUR, including all costs in China for the Company’s Phase 3 registration trial of SUL-DUR, with the exception of Phase 3 patient drug supply. Zai Lab will conduct development activities, plan and obtain regulatory approval in a specified number of countries in the Asia‑Pacific region beyond China after regulatory approval of a licensed product in China. Zai Lab is also solely responsible for commercializing licensed products in the Asia‑Pacific region and will commercialize licensed products for which it has obtained regulatory approval. The Company is obligated to conduct specified development activities for the Asia‑Pacific region. The Company is also obligated to supply Zai Lab with the licensed products for clinical development, although Zai Lab may take over manufacturing responsibilities for its own commercialization activities within a specified time period following the effective date of the Zai Agreement. Both parties are prohibited from developing and commercializing products in the Asia‑Pacific region that would compete with the licensed products. The Company received an upfront, non‑refundable payment of $5.0 million, milestone payments of $7.0 million, research support funding of $0.6 million and certain other reimbursable clinical trial costs of $0.6 million, less applicable taxes of $1.9 million from Zai Lab through December 31, 2019. The Company is eligible to receive up to an aggregate of $91.0 million in additional development, regulatory and sales milestone payments related to SUL-DUR, imipenem and other combinations with the licensed products. In the event the China Food and Drug Administration requires a modification or supplement to the trial protocol, and the Company delays Zai Lab from providing the required information and subsequently from obtaining regulatory approval for the pivotal study of SUL-DUR in China, then the future sales‑based milestone payments that become due to the Company will be reduced by an agreed amount that increases with the length of the delay. Zai Lab will pay the Company a tiered royalty equal to a high‑single digit to low‑double digit percentage based on annual net sales of licensed products in the territory, subject to specified reductions for the market entry of competing products, loss of patent coverage of licensed products and for payments owed to third parties for additional rights necessary to commercialize licensed products in the territory. The Company determined the $5.0 million non‑refundable upfront payment was the entire transaction price at the outset of the Zai Agreement. All other future potential milestone payments were excluded from the transaction price as they were fully constrained as the risk of significant reversal had not yet been resolved. The Company delivered the exclusive license and performed the initial technology transfer of licensed know-how during the second quarter of 2018. The Company recognized the entire $5.0 million transaction price as revenue during the year ended December 31, 2018. At the outset of the Zai Agreement, the achievement of the future potential milestones was not within the Company’s control and was subject to certain research and development success, regulatory approvals or commercial success and therefore carried significant uncertainty. During 2019, two of the future milestones were achieved by the Company, eliminating the need for constraint and resulting in the recognition of $7.0 million of revenue during the year ended December 31, 2019. Additionally, the Company recorded a provision for income taxes of $0.7 million and $0.5 million for the years ended December 31, 2019 and 2018, respectively, associated with China withholding taxes on the payments received under the Zai Agreement. The Company reevaluates the likelihood of achieving the future milestones at the end of each reporting period. Future development milestone revenue from the arrangement will be recognized as revenue in the period when it is no longer probable that revenue attributable to the milestone will result in a significant reversal of cumulative revenue. Payments received for research support and reimbursable clinical trial costs are recorded as an offset to research and development expense during the period in which the qualifying expenses are incurred. The Company evaluated the Zai Agreement under Topic 606 and identified two material promises: (1) an exclusive license to develop, manufacture and commercialize products containing durlobactam or SUL-DUR in the territory and (2) the initial technology transfer of licensed know‑how. The Company determined that the exclusive license and initial technology transfer were not distinct from one another, as the license has limited value without the transfer of the Company’s technology and Zai Lab would incur additional costs to recreate the Company’s know‑how. Therefore, the license and initial technology transfer were combined as a single performance obligation.

9. License and Collaboration Agreements

GARDP

In July 2017, the Company entered into a collaboration agreement with the Global Antibiotic Research and Development Partnership, or GARDP, for the development and commercialization of a product candidate containing zoliflodacin in certain countries. Under the terms of the collaboration agreement, GARDP will use commercially reasonable endeavors to perform and fully fund the Phase 3 registration trial, including the manufacture and supply of the product candidate containing zoliflodacin, in uncomplicated gonorrhea. The Company is obligated to commit reasonably sufficient time and resources to collaborate in the design of the Phase 3 registration trial and the development of the protocol for the trial and to provide know-how relating to zoliflodacin and any future product candidate. Both parties are responsible for obtaining marketing authorizations for any future product candidate in such parts of their respective territories as they elect.

In addition, under the collaboration agreement, the Company has granted GARDP a worldwide, fully paid, exclusive and royalty-free license, with the right to sublicense, to use its zoliflodacin technology in connection with GARDP’s development, manufacture and commercialization of zoliflodacin in low-income and specified middle-income countries. The Company has retained commercial rights in all other countries worldwide, including the major markets in North America, Europe and Asia-Pacific. The Company has also retained the right to use and grant licenses to its zoliflodacin technology to perform its obligations under the collaboration agreement and for any purpose other than gonorrhea or community-acquired indications. If the Company believes that the results of the Phase 3 registration trial of zoliflodacin would be supportive of an application for marketing approval, it is obligated to use its best efforts to file an application for marketing approval with the FDA within six months of the completion of the trial and to use commercially reasonable endeavors to file an application for marketing approval with the EMA. Each party is responsible for using commercially reasonable efforts to obtain marketing authorizations for the product candidate in their respective territories.

Zai Lab

In April 2018, the Company entered into a license and collaboration agreement with Zai Lab (Shanghai) Co., Ltd., or Zai Lab, pursuant to which Zai Lab licensed exclusive rights to durlobactam and sulbactam-durlobactam, or SUL-DUR, in the Asia‑Pacific region, or the Zai Agreement. Under the terms of the Zai Agreement, Zai Lab will fund most of the Company’s clinical trial costs in China for SUL-DUR, including all costs in China for the Company’s Phase 3 registration trial of SUL-DUR, with the exception of Phase 3 patient drug supply. Zai Lab will conduct development activities, plan and obtain regulatory approval in a specified number of countries in the Asia‑Pacific region beyond China after regulatory approval of a licensed product in China. Zai Lab is also solely responsible for commercializing licensed products in the Asia‑Pacific region and will commercialize licensed products for which it has obtained regulatory approval. The Company is obligated to conduct specified development activities for the Asia‑Pacific region. The Company is also obligated to supply Zai Lab with the licensed products for clinical development, although Zai Lab may take over manufacturing responsibilities for its own commercialization activities within a specified time period following the effective date of the Zai Agreement. Both parties are prohibited from developing and commercializing products in the Asia‑Pacific region that would compete with the licensed products.

The Company received an upfront, non‑refundable payment of $5.0 million, milestone payments of $7.0 million, research support funding of $0.6 million and certain other reimbursable clinical trial costs of $0.6 million, less applicable taxes of $1.9 million from Zai Lab through December 31, 2019. The Company is eligible to receive up to an aggregate of $91.0 million in additional development, regulatory and sales milestone payments related to SUL-DUR, imipenem and other combinations with the licensed products. In the event the China Food and Drug Administration requires a modification or supplement to the trial protocol, and the Company delays Zai Lab from providing the required information and subsequently from obtaining regulatory approval for the pivotal study of SUL-DUR in China, then the future sales‑based milestone payments that become due to the Company will be reduced by an agreed amount that increases with the length of the delay. Zai Lab will pay the Company a tiered royalty equal to a high‑single digit to low‑double digit percentage based on annual net sales of licensed products in the territory, subject to specified reductions for the market entry of competing products, loss of patent coverage of licensed products and for payments owed to third parties for additional rights necessary to commercialize licensed products in the territory.

The Company determined the $5.0 million non‑refundable upfront payment was the entire transaction price at the outset of the Zai Agreement. All other future potential milestone payments were excluded from the transaction price as they were fully constrained as the risk of significant reversal had not yet been resolved. The Company delivered the exclusive license and performed the initial technology transfer of licensed know-how during the second quarter of 2018. The Company recognized the entire $5.0 million transaction price as revenue during the year ended December 31, 2018. At the outset of the Zai Agreement, the achievement of the future potential milestones was not within the Company’s control and was subject to certain research and development success, regulatory approvals or commercial success and therefore carried significant uncertainty. During 2019, two of the future milestones were achieved by the Company, eliminating the need for constraint and resulting in the recognition of $7.0 million of revenue during the year ended December 31, 2019. Additionally, the Company recorded a provision for income taxes of $0.7 million and $0.5 million for the years ended December 31, 2019 and 2018, respectively, associated with China withholding taxes on the payments received under the Zai Agreement. The Company reevaluates the likelihood of achieving the future milestones at the end of each reporting period. Future development milestone revenue from the arrangement will be recognized as revenue in the period when it is no longer probable that revenue attributable to the milestone will result in a significant reversal of cumulative revenue. Payments received for research support and reimbursable clinical trial costs are recorded as an offset to research and development expense during the period in which the qualifying expenses are incurred.

The Company evaluated the Zai Agreement under Topic 606 and identified two material promises: (1) an exclusive license to develop, manufacture and commercialize products containing durlobactam or SUL-DUR in the territory and (2) the initial technology transfer of licensed know‑how. The Company determined that the exclusive license and initial technology transfer were not distinct from one another, as the license has limited value without the transfer of the Company’s technology and Zai Lab would incur additional costs to recreate the Company’s know‑how. Therefore, the license and initial technology transfer were combined as a single performance obligation.