Related Party Transactions

12 Months Ended

Dec. 31, 2023

Related Party Transactions [Abstract]

Related Party Transactions

15. Related Party Transactions

We have an ongoing relationship with Sutro Biopharma. In 2013, Sutro Biopharma provided support to facilitate the establishment of our Company. As of December 31, 2021 and 2020, Sutro Biopharma owned approximately 1.6 million shares of our common stock. As of December 31, 2019, Sutro Biopharma also owned warrants to purchase 31,857 shares of our common stock (the “Common Stock Warrant”) at an exercise price of $0.79289 per share and 59,276 shares of our Series C redeemable convertible stock (the “Preferred Stock Warrant”) at an exercise price of $11.5215 per share. The Common Stock Warrant and the Preferred Stock Warrant were automatically net exercised pursuant to their terms for 30,278 shares and 16,591 shares, respectively, of our common stock in connection with our initial public offering in June 2020. In the agreements and amendments identified herein, we licensed certain intellectual property and acquired certain supply rights from Sutro Biopharma, including the right to use the XpressCF platform to discover and develop vaccine candidates for the treatment or prophylaxis of infectious diseases. On October 12, 2015, we and Sutro Biopharma (the “Parties”) entered into the Sutro Biopharma License Agreement, which amended and restated an agreement dated August 1, 2014. The Sutro Biopharma License Agreement was subsequently amended on May 9, 2018 (“License Amendment A1”) and May 29, 2018 (“License Amendment A2”). In consideration for the License Amendment A2, we issued to Sutro Biopharma the Preferred Stock Warrant to purchase 59,276 shares of Series C redeemable convertible preferred stock at a purchase price of $11.5215 per share. We also entered into a separate supply agreement with Sutro Biopharma on May 29, 2018 (the “Sutro Biopharma Supply Agreement”). As of June 2, 2021, Sutro Biopharma was no longer considered a related party.

Under the Sutro Biopharma License Agreement, Sutro Biopharma granted us an exclusive, worldwide license to research, develop, manufacture and commercialize vaccine products addressing infectious disease, which are discovered or produced based on the use of Sutro Biopharma’s proprietary cell-free protein expression technology, known as XpressCF, which utilizes extracts derived from strains of E. coli. In connection with the Sutro Biopharma License Agreement, under the Sutro Biopharma Supply Agreement, Sutro Biopharma has agreed to manufacture and supply extracts and reagents for us on a cost-plus basis. In consideration for the rights licensed, we are obligated to pay a 4% royalty on worldwide aggregate annual net sales of our vaccine products for human health and a 2% royalty on annual net sales of vaccine products for animal health. In License Amendment A1, the Parties amended the license agreement to remove a pre-IND regulatory meeting as a diligence milestone and to agree that certain other diligence milestones had been satisfied. In License Amendment A2, the Parties amended the license agreement to add certain terms confirming our obligation to purchase Sutro Biopharma’s proprietary extract from E. coli (“Extract”) from Sutro Biopharma. In addition, the Parties amended the license agreement to specify our rights to a transfer of certain know-how relating to the manufacture of Extract in the event of a declaration of bankruptcy by Sutro Biopharma. Finally, the Parties agreed to terms providing for injunctive relief in the event of a breach or threatened breach by the other party.

In the Sutro Biopharma Supply Agreement, the Parties agreed to terms for the supply of manufactured Extract and custom reagents by Sutro Biopharma for us to use in manufacturing vaccine compositions in non-clinical research or in Phase 1 or Phase 2 clinical trials. The term of the Sutro Biopharma Supply Agreement is from execution until the later of July 31, 2021 and the date the parties enter into and commence activities under the supply agreement unless extended through a subsequent supply agreement for the supply of Extract and custom reagents for vaccine compositions for Phase 3 and commercial uses as contemplated in the Supply Agreement. In February 2021, we entered into an amendment to the Sutro Biopharma Supply Agreement and extended the term to July 31, 2022.

As Sutro Biopharma was no longer considered a related party as of June 2, 2021, we excluded expenses after that date from related party transaction expenses. We recognized expense related to the Supply Agreement of $0 million, $0 million and $2.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.