Collaboration Agreements	12 Months Ended
Dec. 31, 2021
Collaboration Agreements [Abstract]
Collaboration Agreements	7. Collaboration Agreements Collaboration and License Agreement with Hanmi In December 2019, the Company entered into a Collaboration and License Agreement with Hanmi (“Hanmi Agreement”), pursuant to which the Company granted Hanmi an exclusive license to develop, manufacture and commercialize FLX475 and related compounds and products with respect to human cancers in the Republic of Korea, the Republic of China (Taiwan) and the People’s Republic of China, including the special administrative regions of Macau and Hong Kong (the “Hanmi Territory”), and certain sublicense rights. In consideration of such rights, under the Hanmi Agreement, the Company was entitled to $10.0 million, which consisted of an upfront payment of $4.0 million and a development milestone payment of $6.0 million that were received in December 2019 and April 2020, respectively. Additionally, the Company is eligible to receive contingent payments of up to $108.0 million upon the achievement of specified milestones, as well as double-digit royalties on future net sales of FLX475 in the Hanmi Territory. The Company identified the following promised goods and services at the inception of the Hanmi Agreement, including (1) the exclusive development, manufacturing and commercialization license in the Hanmi Territory; (2) the transfer of know-how, technology, research data and information, and any improvements in technology; (3) the obligation to participate in the joint steering committee and appoint an alliance manager; (4) the responsibility to complete certain Phase 2 clinical trials; and (5) the supply of FLX475 for use in Hanmi’s Phase 2 clinical trials for which Hanmi will reimburse the Company for the supply of FLX475. The Company determined that the identified performance obligations, except for the supply of FLX475, are not distinct and should be combined into one distinct performance obligation. The Company considered factors such as the novelty of the drug candidate and that the promised goods and services are highly interdependent and are expected to significantly modify one another. The Company determined that the transaction price as of December 31, 2019 was $10.0 million, which consisted of the upfront fee of $4.0 million and an unconstrained development milestone payment of $6.0 million. In December 2020, Hanmi requested the Company to supply FLX475, and as a result, the Company increased the transaction price by $0.4 million. Other future development milestones were constrained as their achievement was highly dependent on factors outside the Company’s control. The Company expects that the revenue from sales milestone and royalty payments will be recognized when the sales occur or the milestone is achieved. The Company will re-evaluate the transaction price at each reporting period. The Company recognizes revenue for the performance obligation by applying the cost-based input method over the estimated service period. The Company determined that this method most faithfully depicts the transfer of its performance obligations to Hanmi as it reflects the progress made towards providing Hanmi with the necessary know-how to continue developing FLX475 in the Hanmi Territory. For the years ended December 31, 2021 and 2020, $3.8 million and $5.0 million of revenue was recognized pursuant to the Hanmi Agreement, respectively. As of December 31, 2021, deferred revenue related to the Hanmi Agreement was $1.5 million and is expected to be recognized over the over the remaining period of the Company’s Phase 1/2 clinical trial of FLX475. Clinical Trial Collaboration and Supply Agreement with Merck In November 2018, the Company entered into a clinical trial collaboration and supply agreement with an affiliate of Merck (known as MSD outside the United States and Canada) under which the Company will conduct a clinical trial evaluating FLX475 in combination with pembrolizumab (KEYTRUDA^®), Merck’s anti-PD-1 therapy, in patients with advanced cancers. The Company is the sponsor of the clinical trial, and Merck will supply pembrolizumab for use in the clinical trial.

Collaboration Agreements

12 Months Ended

Dec. 31, 2021

7. Collaboration Agreements

Collaboration and License Agreement with Hanmi

In December 2019, the Company entered into a Collaboration and License Agreement with Hanmi (“Hanmi Agreement”), pursuant to which the Company granted Hanmi an exclusive license to develop, manufacture and commercialize FLX475 and related compounds and products with respect to human cancers in the Republic of Korea, the Republic of China (Taiwan) and the People’s Republic of China, including the special administrative regions of Macau and Hong Kong (the “Hanmi Territory”), and certain sublicense rights.

In consideration of such rights, under the Hanmi Agreement, the Company was entitled to $10.0 million, which consisted of an upfront payment of $4.0 million and a development milestone payment of $6.0 million that were received in December 2019 and April 2020, respectively. Additionally, the Company is eligible to receive contingent payments of up to $108.0 million upon the achievement of specified milestones, as well as double-digit royalties on future net sales of FLX475 in the Hanmi Territory.

The Company identified the following promised goods and services at the inception of the Hanmi Agreement, including (1) the exclusive development, manufacturing and commercialization license in the Hanmi Territory; (2) the transfer of know-how, technology, research data and information, and any improvements in technology; (3) the obligation to participate in the joint steering committee and appoint an alliance manager; (4) the responsibility to complete certain Phase 2 clinical trials; and (5) the supply of FLX475 for use in Hanmi’s Phase 2 clinical trials for which Hanmi will reimburse the Company for the supply of FLX475.

The Company determined that the identified performance obligations, except for the supply of FLX475, are not distinct and should be combined into one distinct performance obligation. The Company considered factors such as the novelty of the drug candidate and that the promised goods and services are highly interdependent and are expected to significantly modify one another.

The Company determined that the transaction price as of December 31, 2019 was $10.0 million, which consisted of the upfront fee of $4.0 million and an unconstrained development milestone payment of $6.0 million. In December 2020, Hanmi requested the Company to supply FLX475, and as a result, the Company increased the transaction price by $0.4 million. Other future development milestones were constrained as their achievement was highly dependent on factors outside the Company’s control. The Company expects that the revenue from sales milestone and royalty payments will be recognized when the sales occur or the milestone is achieved. The Company will re-evaluate the transaction price at each reporting period.

The Company recognizes revenue for the performance obligation by applying the cost-based input method over the estimated service period. The Company determined that this method most faithfully depicts the transfer of its performance obligations to Hanmi as it reflects the progress made towards providing Hanmi with the necessary know-how to continue developing FLX475 in the Hanmi Territory.

For the years ended December 31, 2021 and 2020, $3.8 million and $5.0 million of revenue was recognized pursuant to the Hanmi Agreement, respectively. As of December 31, 2021, deferred revenue related to the Hanmi Agreement was $1.5 million and is expected to be recognized over the over the remaining period of the Company’s Phase 1/2 clinical trial of FLX475.

Clinical Trial Collaboration and Supply Agreement with Merck

In November 2018, the Company entered into a clinical trial collaboration and supply agreement with an affiliate of Merck (known as MSD outside the United States and Canada) under which the Company will conduct a clinical trial evaluating FLX475 in combination with pembrolizumab (KEYTRUDA^®), Merck’s anti-PD-1 therapy, in patients with advanced cancers. The Company is the sponsor of the clinical trial, and Merck will supply pembrolizumab for use in the clinical trial.