Sensei Biotherapeutics announced it has acquired Faeth Therapeutics and secured approximately $200 million in gross proceeds through a concurrent private placement, positioning the combined company to advance its oncology pipeline through key clinical milestones in endometrial and breast cancer.
The transaction brings Faeth’s lead asset, PIKTOR, into Sensei’s portfolio. PIKTOR is an investigational all-oral combination therapy designed to inhibit multiple nodes of the PI3K/AKT/mTOR pathway, including PI3K-alpha and dual mTORC1/2. The program is being developed across solid tumor settings, including endometrial and breast cancer.
Concurrent with the acquisition, Sensei entered into a definitive agreement to sell Series B non-voting convertible preferred stock in a private placement expected to generate approximately $200 million in gross proceeds before expenses. Participants in the financing included B Group Capital, Balyasny Asset Management, Columbia Threadneedle Investments, Cormorant Asset Management, Fairmount, Logos Capital, RA Capital Management, Vivo Capital, and other institutional investors.
Sensei said it plans to use the proceeds primarily to advance PIKTOR through key clinical milestones. These include topline data from an ongoing Phase 2 trial in second-line advanced endometrial cancer and the initiation of a Phase 1b trial in HR+/HER2- advanced breast cancer, both anticipated by year-end 2026. Remaining funds are expected to support general corporate purposes and the completion of Sensei’s ongoing Phase 1/2 trial of solnerstotug, its V-domain Ig suppressor of T cell activation inhibitor, in patients with advanced solid tumors.
PIKTOR previously demonstrated encouraging activity in a completed Phase 1b trial. In response-evaluable patients, the combination plus paclitaxel showed an overall response rate of 47% among patients who had received an average of four prior lines of therapy. Among patients with PI3K pathway mutations, the response rate reached 71%, including three complete responses, two in endometrial cancer, with progression-free survival of 26.9 and 20.0 months.
Under the terms of the acquisition, Faeth equityholders exchanged their interests for a combination of 252,210 shares of Sensei common stock and approximately 10,604 shares of Series B non-voting convertible preferred stock, representing 10,604,490 shares on an as-converted-to-common basis. In the private placement, investors will receive approximately 14,440 shares of Series B preferred stock, or 14,440,395 shares on an as-converted basis, at approximately $13,850 per share of preferred stock.
Following the transactions and on a fully diluted, as-converted basis, pre-acquisition Sensei equityholders will own approximately 4.9% of the combined company’s common stock, Faeth equityholders will own approximately 40.8%, and private placement investors will own approximately 54.3%. The total number of common shares outstanding, including shares underlying the Series B preferred stock, will be approximately 26.3 million on an as-converted basis.
The acquisition was approved by the boards of both companies and by Faeth’s stockholders. Conversion of the Series B preferred stock into common stock remains subject to approval by Sensei stockholders.
Support: Lucid Capital Markets served as financial advisor to Sensei, with Sidley Austin LLP acting as legal counsel. Leerink Partners acted as exclusive placement agent for the financing, with Cantor and Citi serving as capital markets advisors. Cooley LLP served as legal counsel to Faeth.
KEY QUOTES:
“The clinical data, the caliber of the scientific team, and the investor syndicate that came together for these transactions reinforce our conviction in the program. With these proceeds, we believe the company is well capitalized to execute through key clinical milestones in endometrial and breast cancer.”
Bob Holmen, Chairman of the Board of Directors, Sensei Biotherapeutics
“In the PI3K pathway, the field has repeatedly run into the same constraint. Single-node inhibitors force a tradeoff between efficacy and tolerability. PIKTOR is designed to change that tradeoff by inhibiting PI3K-alpha and mTORC1/2 simultaneously, and we believe we can achieve more complete pathway suppression with improved tolerability. We saw the signal in our Phase 1b, including a number of complete responses in endometrial cancer patients after multiple prior lines of therapy. This financing takes us through topline Phase 2 data in that population and advances the Phase 1b breast cancer program.”
Anand Parikh, Co-founder, Faeth Therapeutics, and Chief Operating Officer and Director, Sensei Biotherapeutics
