Artiva discontinues cell therapy after two patient deaths, cuts workforce by 94%

Artiva Biotherapeutics announced on October 27, 2026, that it is discontinuing development of its lead cell therapy AlloNK and cutting 94% of its workforce after two trial participants died. Researchers linked one death to the pre-treatment chemotherapy fludarabine and deemed the second unrelated to AlloNK, but the FDA paused trials and testing showed insufficient response durability. Artiva holds $319.1 million in cash while exploring a strategic review, reverse merger, or asset sale.

AlloNK discontinuation and trial halts

• ▪Following a reported patient death, the U.S. Food and Drug Administration requested that Artiva Biotherapeutics pause its ongoing Phase 2a clinical trial of AlloNK
• ▪Artiva Biotherapeutics announced that it is halting the development of its experimental natural killer cell therapy, AlloNK, for autoimmune conditions
• ▪Artiva Biotherapeutics canceled its planned presentations of AlloNK trial results at an October 2026 medical meeting and an investor conference call scheduled for November 9, 2026
• ▪Artiva Biotherapeutics announced that testing showed AlloNK lacked the level of clinical response durability required to support continued drug development

First patient death and fludarabine role

• ▪Patients in cell therapy trials standardly receive lymphodepleting chemotherapies such as fludarabine prior to infusion to lower white blood cell counts
• ▪A study investigator and independent safety review determined that a fatal case of leukoencephalopathy in Artiva Biotherapeutics' AlloNK trial was likely caused by the chemotherapy drug fludarabine rather than AlloNK
• ▪Artiva Biotherapeutics Chief Executive Officer Fred Aslan stated the company plans to publish findings regarding the fludarabine-associated death in its AlloNK trial due to the chemotherapy's widespread use in cell therapy conditioning regimens
• ▪One participant in Artiva Biotherapeutics' Phase 2 trial of AlloNK developed fatal leukoencephalopathy, a severe neurological complication, following treatment

Second patient death

• ▪A trial researcher concluded that a second patient's sudden death in Artiva Biotherapeutics' AlloNK trial was unrelated to AlloNK or any component of the AlloNK treatment regimen, though the exact cause remains undetermined
• ▪A second participant in Artiva Biotherapeutics' AlloNK trial experienced sudden death approximately two months after initiating treatment

Workforce reduction

• ▪Artiva Biotherapeutics announced plans on October 27, 2026, to reduce its workforce by approximately 94 percent following the discontinuation of AlloNK after two patient deaths in its trial
• ▪Prior to the workforce reduction announced on October 27, 2026, Artiva Biotherapeutics reported having 104 full-time employees as of December 31, 2025

Financial position and market reaction

• ▪As of September 30, 2026, Artiva Biotherapeutics reported holding approximately $319.1 million in cash, cash equivalents, and investments
• ▪Shares of Artiva Biotherapeutics fell 30 percent in premarket trading on October 27, 2026, following news of the AlloNK trial halt and 94% workforce cuts
• ▪Artiva Biotherapeutics hired a financial adviser to evaluate strategic alternatives, a process that may result in a reverse merger, asset sale, or technology licensing

Competitor trial pauses and safety events

• ▪Competitors Novartis and Bristol Myers Squibb also paused multiple autoimmune cell therapy trials in 2026 following reported patient deaths and severe inflammatory safety events
• ▪Novartis reported three patient deaths caused by a serious immune reaction in a trial of its cellular medicine rap-cel