Boundless Bio Lays Off 33% of Staff Following Stumble of Lead Program

Boundless Bio announced it is laying off 33% of its workforce—about 20-21 employees—after disappointing results from a phase 1/2 trial of its lead cancer program.123

The company's lead asset, CHK1 inhibitor BBI-355, failed to show promise as a monotherapy due to hematological toxicity and a narrow therapeutic window, halting plans for single-agent development.1

Attempts to combine BBI-355 with other agents (EGFR inhibitor erlotinib and FGFR inhibitor futibatinib) were also unsuccessful because of safety and tolerability issues at active doses.1

Earlier, Boundless Bio had already discontinued clinical development of another candidate, RNR inhibitor BBI-825, due to suboptimal drug exposure in patients.1

The layoffs are intended to extend Boundless Bio's cash runway into the first half of 2028, with the company reporting $138.3 million in cash and equivalents as of March 31, 2025.23

The company is now pivoting to focus on new combination therapy approaches after abandoning the current trial arms for its lead programs.14

Sources:

1. https://www.fiercebiotech.com/biotech/boundless-bio-lays-33-staff-lead-program-stumbles

2. https://www.fiercebiotech.com/biotech/fierce-biotech-layoff-tracker-2025

3. https://www.biospace.com/biospace-layoff-tracker

4. https://www.tipranks.com/news/company-announcements/boundless-bio-announces-major-workforce-reduction-strategy