Sensei Biotherapeutics has acquired Faeth Therapeutics and announced a concurrent $200m private placement to advance the investigational PI3K pathway inhibitor PIKTOR in endometrial and breast cancer.

The acquisition adds Faeth’s lead asset PIKTOR to Sensei’s oncology pipeline. PIKTOR is an investigational, all-oral combination of serabelisib and sapanisertib designed to inhibit multiple nodes of the PI3K/AKT/mTOR pathway through PI3K-alpha and dual mTORC1/2 targeting. The programme is being developed across solid tumour indications, including endometrial and hormone receptor-positive, HER2-negative advanced breast cancer.

Concurrent with the transaction, Sensei entered into a definitive agreement for the sale of Series B non-voting convertible preferred stock in a private placement expected to generate gross proceeds of approximately $200m before expenses.

The company said the proceeds will primarily support advancement of PIKTOR through key clinical milestones, including topline data from an ongoing Phase 2 trial in second-line advanced endometrial cancer and initiation of a Phase 1b trial in HR+/HER2- advanced breast cancer, both anticipated by the end of 2026. Remaining funds will be allocated to general corporate purposes and completion of Sensei’s ongoing Phase 1/2 trial of solnerstotug.

Bob Holmen, chairman of the board of directors of Sensei Biotherapeutics, said: “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.” He added: “With these proceeds, we believe the company is well capitalized to execute through key clinical milestones in endometrial and breast cancer.”

Anand Parikh, co-founder of Faeth Therapeutics and newly appointed chief operating officer and director of Sensei, said: “In the PI3K pathway, the field has repeatedly run into the same constraint. Single-node inhibitors force a tradeoff between efficacy and tolerability.”

He added: “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.”

The announcement combines a pipeline acquisition with significant financing, positioning the merged company to focus on clinical execution over the next 12 months. While early data from Phase 1b have been cited as supportive, PIKTOR remains investigational and will require further validation in ongoing and planned trials.