Artiva halts AlloNK NK-cell therapy after two trial deaths, cuts about 94% of staff

Artiva Biotherapeutics (Nasdaq: ARTV) on 27 October 2026 said it will stop developing AlloNK (AB-101), a non-genetically modified allogeneic natural-killer (NK) cell therapy tested with rituximab in rheumatoid arthritis and other B-cell-driven autoimmune diseases, cut about 94% of its workforce, and evaluate strategic alternatives (merger, sale, licensing or dissolution). BioPharma Dive notes Artiva is the third recent company to report fatal events in an autoimmune cell-therapy programme, after Novartis and Bristol Myers Squibb pauses earlier in 2026.

The two Grade 5 events

• One participant developed leukoencephalopathy after protocol lymphodepletion with cyclophosphamide and fludarabine; the investigator and an independent safety review assessed it as likely fludarabine-associated neurotoxicity. Artiva reported it to the FDA, which asked the company to pause Phase 2a enrolment and dosing; planned Phase 3 dosing was also paused.
• A second participant died suddenly about two months after starting treatment; the investigator judged the death unrelated to AlloNK or other regimen components; the cause remains undetermined.
• Artiva says it will publish findings from the fludarabine case given that drug’s widespread use in cell-therapy conditioning.

Efficacy and limits

Updated data still showed deep B-cell depletion and clinical activity consistent with earlier reports, but longer-term durability did not meet the company’s bar for continued development. No further patients will be dosed; studies will be closed out with continued safety follow-up. Cash, cash equivalents and investments were about $319.1 million (preliminary) as of 30 September 2026. This is a company announcement about a mid-stage, open-label programme; it is not a randomised comparison against standard care, and individual risk–benefit judgements belong with treating clinicians.