Sensei Biotherapeutics Announces Significant Downsizing and R&D Termination

Sensei Biotherapeutics, a Boston-based biotech company, has revealed plans for a substantial workforce reduction and the cessation of all research and development activities. The announcement, made in the company's third-quarter earnings report, marks a significant shift in Sensei's operations and future prospects.

Drastic Workforce Reduction and R&D Termination

Sensei has disclosed that it will downsize its workforce by approximately 65%, retaining only a small team of employees. This decision comes as part of a broader strategic review of the company's business. The remaining staff will be tasked with exploring strategic alternatives and maintaining compliance with financial reporting requirements.

In addition to the layoffs, Sensei has made the critical decision to terminate all of its R&D operations. This includes halting work on its lead asset, solnerstotug, a conditionally active monoclonal antibody targeting the VISTA checkpoint. The company's remaining employees will oversee the "orderly cessation of development activities," according to the announcement.

Financial Position and Future Outlook

Despite the drastic measures, Sensei reported a cash position of $25 million in cash, cash equivalents, and marketable securities as of September 30, 2025. The company's third-quarter financial results showed an operating loss of $4.6 million, an improvement from the $7.3 million loss reported during the same period last year.

Sensei is currently evaluating several strategic alternatives, including:

1. A potential merger
2. Sale of the company
3. Licensing arrangements for its assets
4. An orderly wind-down of operations

The company has not specified how long it expects its current cash runway to last, leaving questions about its long-term viability.

Industry Context and Recent History

Sensei's announcement comes amid a challenging year for the biotech industry, with numerous companies implementing layoffs. The third quarter of 2025 saw a 280% year-on-year increase in terminations across the sector, according to BioSpace.

For Sensei, this is not the first round of cuts. In November 2024, the company had already reduced its workforce by 46% as part of a resource realignment initiative aimed at supporting the development of solnerstotug. At that time, the restructuring was expected to extend the company's runway into the second quarter of 2026.

The decision to halt R&D activities affects not only solnerstotug but also three preclinical candidates that were in development for the treatment of solid tumors. The Phase I/II study of solnerstotug, which was being tested both as a monotherapy and in combination with Regeneron's PD-1 blocker Libtayo for advanced solid tumors, will now be discontinued.