Sensei Biotherapeutics (Nasdaq: SNSE) has acquired clinical-stage biotech Faeth Therapeutics alongside a ~$200 million private placement to advance PIKTOR, an investigational all-oral therapy targeting the PI3K/AKT/mTOR pathway in endometrial and breast cancer. The financing drew participation from an investor syndicate including RA Capital Management, Vivo Capital, Cormorant Asset Management, Fairmount, and others.
The PI3K pathway is one of the most commonly altered in solid tumors, but drugs targeting it have historically hit one node at a time – and the pathway tends to find ways to recover. PIKTOR takes a different approach, combining PI3K-alpha and dual mTORC1/2 inhibition in a single oral regimen to achieve deeper pathway suppression without the tolerability tradeoffs that have plagued earlier PI3K inhibitors.
Early clinical data is encouraging. In a completed Phase 1b trial, PIKTOR plus paclitaxel showed a 47% overall response rate in patients who had been through an average of four prior lines of therapy, with a 71% response rate in patients with PI3K pathway mutations. Among the responses were three complete responses, including two in endometrial cancer patients with progression-free survival of 26.9 and 20.0 months.
“Single-node inhibitors force a tradeoff between efficacy and tolerability,” said Faeth co-founder Anand Parikh, who becomes COO at Sensei. “PIKTOR is designed to change that tradeoff. We saw the signal in our Phase 1b, including a number of complete responses in endometrial cancer patients after multiple prior lines of therapy.”
The proceeds will fund PIKTOR through several near-term milestones: 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 expected by year-end 2026.
Faeth was co-founded in 2019 by Parikh and Oliver Maddocks, with a scientific founding team that includes Lewis Cantley (discoverer of the PI3K pathway) and Pulitzer Prize-winning physician-scientist Siddhartha Mukherjee. Following the acquisition, former Faeth equityholders will own approximately 40.8% of the combined company, with private placement investors holding 54.3%.
