Boston-based Sensei Biotherapeutics saw its stock price more than triple in early trading on Wednesday following the announcement that it has acquired clinical-stage biotechnology company Faeth Therapeutics and secured a concurrent $200 million private placement financing.

The company’s shares opened at $28 on February 18, representing a 206% increase from the previous day’s close of $9.13. The stock was trading at $25.6 mid-morning, as investors responded positively to the strategic transactions that will significantly expand Sensei’s pipeline and balance sheet.

Acquisition and Financing Details

The all-stock acquisition brings Faeth’s lead asset PIKTOR, an investigational all-oral combination of serabelisib and sapanisertib designed to inhibit multiple nodes of the PI3K/AKT/mTOR pathway, into Sensei’s portfolio. The therapy is being developed across solid tumor settings, including endometrial and breast cancer.

Concurrent with the acquisition, Sensei entered into a definitive agreement for the sale of Series B non-voting convertible preferred stock in a private placement financing expected to generate approximately $200 million in gross proceeds. The financing saw participation from B Group Capital, Balyasny Asset Management, Columbia Threadneedle Investments, Cormorant Asset Management, Fairmount, Logos Capital, RA Capital Management, Vivo Capital, and multiple other leading life sciences funds and institutional investors.

Ownership Structure

According to the company’s SEC filing, following the transactions, pre-acquisition Sensei equityholders will own approximately 4.9% of the combined company’s common stock. Faeth equityholders will own approximately 40.8%, while investors in the private placement will hold approximately 54.3%, calculated on a fully-diluted, as-converted-to-common basis.

The acquisition was structured as a stock-for-stock transaction, with Faeth’s outstanding equity interests exchanged 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 basis).

The private placement investors will be issued approximately 14,440 shares of Series B non-voting convertible preferred stock (or 14,440,395 on an as-converted basis) at a price of approximately $13,850 per share. Subject to stockholder approval, each preferred share will automatically convert into 1,000 shares of common stock.

Clinical Pipeline and Milestones

Sensei expects to use the proceeds primarily to advance PIKTOR through key clinical milestones, including topline data from an ongoing Phase II trial (NCT06463028) in second-line advanced endometrial cancer and the initiation of a Phase Ib trial in HR+/HER2- advanced breast cancer, both expected by year-end 2026.

In a completed Phase Ib trial, PIKTOR plus paclitaxel demonstrated an overall response rate of 47% in response-evaluable patients (n=15) averaging four prior lines of therapy. Among patients with PI3K pathway mutations, the response rate was 71%, including three complete responses—two in endometrial cancer—with progression-free survival of 26.9 and 20.0 months.

“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,” said Anand Parikh, Co-founder of Faeth Therapeutics and new Chief Operating Officer and director of Sensei.

Strategic Review Background

The acquisition follows a cost-saving initiative that Sensei launched in October of last year. The strategic review aimed to “explore potential options focused on maximizing shareholder value”. At that time, the company reported having approximately $46 million in cash, cash equivalents, and marketable securities.

At the time the company also stated its intention to not to initiate a new clinical study. Adding that it will also “wind down the ongoing Phase I/II clinical trial (NCT05864144)”.