The Company has not generated revenue from product sales. The Company has generated revenue from contracts with customers (option, license and collaboration agreements), which include upfront payments for licenses or options to obtain licenses, payments for research and development services and milestone payments.

The Company recognized revenue from the following strategic partnerships and other license agreements (in thousands):

As of March 31, 2024, under the Company’s existing strategic partnerships and other license agreements, the Company could receive the following potential milestone payments (in millions):

On May 19, 2021, the Company and Genentech, Inc., or Genentech, entered into a Research Collaboration and License Agreement, or the Genentech Agreement, to discover, develop and commercialize locally delivered respiratory and ophthalmology therapies that leverage the Company’s proprietary Anticalin technology. Upon signing the Genentech Agreement, Genentech paid the Company a $20 million upfront fee.

Under the terms of the Genentech Agreement, the Company was responsible for discovery and preclinical development of two initial programs. In April and May 2023, Genentech and the Company decided to discontinue the discovery-stage programs in ophthalmology and respiratory, respectively, for scientific reasons. Pursuant to this decision, the material right performance obligations related to the target swaps for these programs also expired. Based on these decisions, there are no more active performance obligations remaining under the collaboration and the Company recognized all remaining revenue, or $12.5 million, under the collaboration in the three months ended June 30, 2023.

Genentech still has an option to select additional programs with the payment of a fee and that option expires in May 2024. If Genentech exercises its option to start additional programs, the Company would be eligible to receive additional milestone payments, as well as tiered royalty payments on net sales, subject to certain standard reductions and offsets. Genentech’s options to nominate two additional collaboration targets of their choosing is subject to the legal availability of the target to be researched. As of March 31, 2024, any variable consideration related to the exercise of such options is considered fully constrained.

On April 24, 2021, the Company and BP Asset XII, Inc., or Boston Pharmaceuticals, a subsidiary of Boston Pharma Holdings, LLC, entered into an Exclusive Product License Agreement, or the BP Agreement, to develop BOS-342, also referred to as PRS-342, a 4-1BB/GPC3 preclinical immuno-oncology Mabcalin^TM (antibody-Anticalin fusion) protein.

Under the terms of the BP Agreement, Boston Pharmaceuticals exclusively licensed worldwide rights to BOS-342. The Company received an upfront payment and is further entitled to receive development, regulatory and sales-based milestone payments, tiered royalties up to low double-digits on sales of BOS-342 and a percentage of consideration received by Boston Pharmaceuticals in the event of a sublicense of a program licensed under the BP Agreement or a change of control of Boston Pharmaceuticals.

The Company recognized the full transaction price as revenue in 2021 and has no remaining obligations. In August 2023, the first patient was dosed in the Boston Pharmaceuticals sponsored Phase 1/2 study of PRS-342/BOS-342 in hepatocellular carcinoma (HCC), for which the Company received a milestone payment of $2.5 million.

On February 8, 2018, the Company entered into a license and collaboration agreement, or the Pfizer Collaboration Agreement, and a non-exclusive Anticalin platform technology license agreement, or the Pfizer Platform License, and together with the Pfizer Collaboration Agreement, the Pfizer Agreements, with Pfizer Inc., or Pfizer, pursuant to which the parties agreed to develop multiple targeted bispecific IO treatments for solid tumors and blood cancers.

Under the terms of the Pfizer Agreements, the companies agreed to pursue multiple antibody-Anticalin fusion proteins during the research phase. The Pfizer Agreements provide Pfizer an option to select up to three programs for further development, which Pfizer did, and Pfizer is responsible for developing, funding and commercializing each of these programs.

On March 24, 2021, the Company entered into a Second Pfizer Amendment (formerly the Second Seagen Amendment), to amend the existing immuno-oncology collaboration agreement relating to joint development and commercial rights for one program in the alliance. Under the Second Pfizer Amendment, the Company retains a co-promotion option in the United States for one program, while Pfizer remains solely responsible for the development and overall commercialization of that program. The Company will also be entitled to increased royalties from that program if it chooses to exercise the co-promotion option.

Under the Pfizer Agreements, the Company is eligible to receive other various research, development, commercial and sales milestones. There is uncertainty that the events to obtain the research and development milestones will be achieved given the nature of clinical development and the stage of the Company’s technology. The Company has thus determined that all research and development milestones will be constrained until it is deemed probable that a significant revenue reversal will not occur, with the exception of the $5.0 million milestone as described in the following paragraph.

In January 2023, the Company achieved a milestone for the first program in the Pfizer collaboration for $5.0 million. The Company evaluated the recognition of the milestone under ASC 606 and concluded that the constraints on the milestone no longer existed as of December 31, 2022 and therefore recorded the full $5.0 million as revenue for the year ended December 31, 2022.

In September 2023, Pfizer and the Company entered into an amendment of the Second Pfizer Amendment that provides Pfizer with collaboration product licenses and no changes to the amounts achievable under the collaboration agreement. The effect of the September 2023 amendment was to transfer responsibility for substantially all activities previously performed by the Company to Pfizer. Subsequently, in December 2023, the transfer of the programs was fully approved by the combined joint steering committee. Accordingly, the Company recognized revenue of approximately $10.1 million for the delivery on its performance obligations related to the two programs for the year ended December 31, 2023. With this amendment, the Company has satisfied all remaining obligations under the collaboration.

On May 2, 2017, the Company entered into a license and collaboration agreement, or the AstraZeneca Collaboration Agreement, and a non-exclusive Anticalin platform technology license agreement, or AstraZeneca Platform License, and together with the AstraZeneca Collaboration Agreement, the AstraZeneca Agreements, with AstraZeneca AB, or AstraZeneca, which became effective on June 10, 2017, following expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.

In addition to elarekibep (formerly known as PRS-060/AZD1402), or the AstraZeneca Lead Product, the Company and AstraZeneca agreed to collaborate, under the original terms of the AstraZeneca Collaboration Agreement, to progress four additional novel Anticalin proteins against undisclosed targets for respiratory diseases, or the AstraZeneca Collaboration Products, and together with the AstraZeneca Lead Product, the AstraZeneca Products. The first two discovery-stage programs were discontinued in 2022. The third discovery-stage program was discontinued in the second quarter of 2023, which led to recognition of $4.0 million of revenue in that same quarter.

In June 2023, based on non-clinical safety findings in a 13-week toxicology study of elarekibep in non-human primates previously disclosed by the Company, AstraZeneca notified us of its decision to discontinue and cease dosing in the ongoing clinical studies of elarekibep. There was no effect to revenue as a result of the discontinuation of this program.

On July 17, 2023, as a result of the non-clinical safety finding in the 13-week toxicology study of elarekibep in non-human primates, AstraZeneca notified the Company of its intention to terminate the AstraZeneca Collaboration Agreement and the AstraZeneca Platform License, effective October 15, 2023. As a result of this, the remaining amount of current deferred revenue, or $3.5 million, related to the fourth discovery-stage program was recognized in revenue in the third quarter of 2023. With the termination of the AstraZeneca Agreements, there are no more active programs or performance obligations related to the collaboration. Following the termination date, the Company determined that it would not continue development of the programs under the AstraZeneca Agreements.

In 2017, the Company entered into a license and collaboration agreement, or Servier Collaboration Agreement, and a non-exclusive Anticalin platform license agreement, or Servier Platform License, and together with the Servier Collaboration Agreement, the Servier Agreements, with Les Laboratoires Servier and Institut de Recherches Internationales Servier, or Servier, pursuant to which the Company and Servier agreed to initially pursue five bispecific therapeutic programs. The intention of the collaboration and defined programs was to combine antibodies from the Servier portfolio with one or more Anticalin proteins based on the Company’s proprietary platform to generate innovative IO bispecific drug candidates.

Since inception, four of the five initially committed programs have been discontinued by Servier. The Company does not presently intend to continue development of the four discontinued programs but retains full rights to advance the development and commercialization of those products on a world-wide basis in the future.

In July 2023, the Company notified Servier of its decision to opt out of co-development and commercialization of S095012, also referred to asPRS- 344, a 4- 1BB/PD- L1 bispecific Mabcalin protein, in the United States. Servier retains exclusive, even as to the Company, worldwide rights to the program, including the right to continue to advance development and potential commercialization of S095012 in the United States. As a result of the Company's decision to opt out of co-development, the Company will be entitled to increased royalty rates and potential royalties and milestones, if any, for S095012 under the terms of the Servier Agreement. With the decision to opt out of co-development of S095012 , the Company recognized the remaining revenue under the collaboration, or $4.7 million, in 2023 and there are no more active co-development programs under the collaboration.

The Company receives payments from its collaboration partners based on payments established in each contract. Upfront payments and fees are recorded as deferred revenue upon receipt or when due until such time as the Company satisfies its performance obligations under each arrangement. A contract asset is a conditional right to consideration in exchange for goods or services that the Company has transferred to a customer. Amounts are recorded as accounts receivable when the Company’s right is unconditional.

There were no additions to deferred revenue during the three months ended March 31, 2024. There were no reductions to deferred revenue for the three months ended March 31, 2024 and reductions to deferred revenue were $1.7 million for the three months ended March 31, 2023.