Artiva Halts AlloNK, Cuts 94% of Workforce After Review of Response Durability
Key Facts
Artiva Biotherapeutics announced on October 27 that it was halting development of AlloNK, including canceling a planned pivotal Phase 3 trial, after longer follow-up showed response durability below the level the company considers necessary to continue the program. The board had approved the development halt on October 22, according to the company’s filing with the U.S. Securities and Exchange Commission. Artiva said measures of B-cell depletion and clinical response remained consistent with prior results, but longer follow-up did not support continued development. Under the decision, no new patients will receive doses in any ongoing AlloNK study, and the planned pivotal trial will not begin. The decision turns an anticipated clinical update into a broad company downsizing and a review of its future.
The decision followed a safety review that included two deaths among participants in the Phase 2a clinical trial. Artiva said one participant experienced a fatal neurological event diagnosed as leukoencephalopathy after treatment that included cyclophosphamide and fludarabine. The responsible investigator and an independent safety review considered the event likely related to fludarabine-associated neurotoxicity. In a second case, a participant died suddenly about two months after starting treatment. The investigator assessed the death as unrelated to AlloNK or any other component of the treatment regimen, while its cause had not been determined. After being notified of the first death, the U.S. Food and Drug Administration asked the company to suspend enrollment and dosing in the Phase 2a study; Artiva also suspended planned Phase 3 enrollment and dosing.
In an earlier update issued in August, Artiva said 5 of 7 patients with treatment-resistant rheumatoid arthritis who had completed six months of follow-up had achieved an ACR50 response as of the April 3, 2026 data cutoff, a rate of 71%. It said at the time that none of the patients in the reported group had lost response, required high-dose steroids, or started a new biologic or targeted synthetic drug. But in announcing the program halt, the company said response durability over longer follow-up did not meet the threshold for continued development. Its plan in September included reporting updated data from at least 20 patients, each with at least six months of follow-up, with at least 10 meeting the key eligibility criteria for the proposed trial. It also planned a randomized trial of about 150 patients comparing AlloNK plus rituximab with rituximab alone, measuring ACR50 response after six months.
The company had said its program targets B-cell-driven autoimmune diseases, led by treatment-resistant rheumatoid arthritis. It described AlloNK as a cryopreserved, unmodified donor-derived natural killer cell therapy candidate. In an earlier announcement, Artiva planned to present data from at least 20 patients with rheumatoid arthritis, 11 patients with Sjögren’s disease and at least five with systemic sclerosis, with at least six months of follow-up for all groups. But it withdrew its data presentation scheduled for ACR Convergence 2026 and canceled the investor webcast set for November 9. As a result, the data the company had announced it would present at the conference will not be released on the planned schedule.
The program halt coincides with Artiva reducing its workforce by about 94%, a step it said is intended to preserve capital while it evaluates strategic alternatives. The company expects to complete the workforce reduction in the first quarter of 2027, while the vast majority of costs to wind down activities are expected to be incurred in the fourth quarter of 2026. In its filing, it said the total costs and charges associated with winding down activities could not be reasonably estimated at this time. Artiva has retained Lerink Partners as financial adviser to review its options. The alternatives it cited include a merger or commercial transaction, an asset sale or license, or the dissolution and liquidation of the company, with no assurance that a transaction will be completed or any particular outcome reached.
Artiva’s cash, cash equivalents and investments totaled about $319.1 million on September 30, 2026, according to the company’s preliminary, unaudited estimate. Its balance was $349.4 million on June 30, and in August it said that amount would fund operations through 2029. The September balance provides financial context for the workforce reduction and options review, but does not determine which path the company will choose or the fate of its assets. Artiva shares closed at $6.16 on October 26, according to EL7 data. The company has not announced an alternative date to present the data after withdrawing from the conference and canceling the webcast.