Artiva Biotherapeutics (ARTV) said Friday that early clinical data from ongoing AlloNK autoimmune disease trials showed encouraging responses in refractory rheumatoid arthritis patients, supporting a planned Phase 3 registrational study in 2026.

The company said 71% of rheumatoid arthritis patients in its Phase 2a trial achieved an ACR50 response at six months, while 19 of 21 patients across two studies showed meaningful reductions in disease activity, with no new biologic or targeted therapies needed after treatment with AlloNK plus rituximab.

The US Food and Drug Administration aligned with plans for a single Phase 3 registrational trial comparing AlloNK plus rituximab with rituximab alone in about 150 refractory rheumatoid arthritis patients, the company said.

The trial is expected to begin in the second half of 2026, with primary efficacy data anticipated in the second half of 2028.

Artiva Biotherapeutics shares were up nearly 20% in premarket activity.