Artiva Biotherapeutics said it will cut 94% of its workforce and explore strategic options after two patient deaths and concerns about AlloNK durability in rheumatoid arthritis and other autoimmune indications. The company paused a planned Phase 3 pivotal study following a risk-benefit review and said the fatal neurological event was deemed likely chemotherapy-associated neurotoxicity after FDA notification and DSMB/provider scrutiny. The decision highlights how quickly late-stage execution and safety signals can force pivots in off-the-shelf NK cell programs—particularly when durability and causality questions persist. For investors and competitors, it underscores the importance of patient-risk stratification, lymphodepletion protocols, and clear endpoint durability assumptions early in development.