ArsenalBio cuts 99 jobs in pivot to in vivo CAR-T

Arsenal Biosciences said it is making a major strategic shift to concentrate on in vivo CAR-T therapies, eliminating 99 jobs—described as the majority of its workforce across teams, functions and locations.

A small “core team” will remain to advance the new in vivo strategy and assess strategic options for the company’s existing technologies and assets.

The company is redirecting capabilities built in T-cell biology, synthetic biology, computation and cell engineering toward treatments for hematologic cancers and autoimmune disease.

The move follows a roughly 50% workforce reduction in September 2025, after which ArsenalBio reportedly had 127 employees. The company has not disclosed its post-cut headcount, so the remaining staff cannot be reliably calculated from that earlier figure.

The shift appears to halt development of ArsenalBio’s ex vivo clinical assets, as the company pivots away from its prior solid-tumor cell-therapy focus.