Artiva’s NK cell therapy takes FDA RMAT status for rheumatoid arthritis

Edited by Robert McTiernan··4 min read

San Diego-based Artiva Biotherapeutics, Inc. (Nasdaq: ARTV) announced receipt of US FDA Regenerative Medicine Advanced Therapy (RMAT) designation for AlloNK (AB-101) in combination with rituximab for refractory rheumatoid arthritis treatment, coinciding with five data presentations at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress in London. AlloNK is an allogeneic, off-the-shelf, non-genetically modified, cryopreserved natural killer (NK) cell therapy designed to enhance the antibody-dependent cellular cytotoxicity (ADCC) effect of anti-CD20 monoclonal antibodies to drive deep B-cell depletion.

RMAT designation, established under the 21st Century Cures Act, applies to cell therapies, gene therapies, and tissue-engineered products intended to treat serious conditions, and confers early and frequent FDA interactions, rolling review eligibility, and potential qualification for accelerated and priority review. Artiva has not previously disclosed any other expedited designation for AlloNK.

The designation is grounded in Phase II data from two basket trials — a company-sponsored Phase IIa study and an investigator-initiated trial — enrolling patients with long-standing, highly active RA who had failed multiple prior biologic or targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs). As of the April 3, 2026 data cutoff, in the company-sponsored Phase IIa trial, 71% of patients with six months of follow-up achieved an ACR50 response (5 of 7 patients). In the investigator-initiated trial, 5 of 6 patients with six months of follow-up achieved an ACR50 or modified ACR50 response. Across the pooled RA dataset of 21 patients with at least 12 weeks of follow-up, clinical responses emerged as early as three months and deepened at six months. As of the data cutoff, no patient had experienced loss of response, required high-dose steroids, or initiated a new b/tsDMARD following treatment. No p-values have been reported; all data derive from single-arm, non-randomized studies.

Baseline patient characteristics reported in a May 8, 2026 data release — which contains more granular detail than the EULAR announcement — indicated a mean age of 52.5 years, 100% female, mean disease duration of 14.8 years, mean baseline Clinical Disease Activity Index (CDAI) of 50.7, mean baseline DAS28-ESR of 7.3, and 81% of patients having failed two or more prior b/tsDMARDs.

Translational data from 51 evaluable autoimmune patients demonstrated uniform B-cell depletion by Day 13 following treatment with the conditioning regimen of cyclophosphamide and fludarabine, AlloNK, and rituximab. Complete B-cell depletion, confirmed by high-sensitivity assay, was observed in all 28 evaluable RA patients. B-cell reconstitution was characterized by a predominance of naïve and transitional B cells, consistent with the proposed immune reset hypothesis.

Safety data from 55 autoimmune patients treated with AlloNK plus rituximab showed no cytokine release syndrome (CRS), no immune effector cell-associated neurotoxicity syndrome (ICANS), no AlloNK-related serious adverse events, and no treatment discontinuations due to adverse events. The rate of Grade 3 or higher infections was 2%. Two of 55 patients were hospitalized for treatment-emergent adverse events during the initial 28-day post-treatment period, neither deemed related to AlloNK.

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EULAR 2026 presentations also included initial data in Sjögren disease (SjD) and systemic sclerosis (SSc). In SjD, mean stimulated salivary flow increased from 0.65 mL/min at baseline to 1.23 mL/min at six months, with high baseline disease activity (mean ClinESSDAI 16.1, mean ESSPRI 8.0). In SSc, mean modified Rodnan skin score improved by 9.5 points at six months, all patients achieved rCRISS25, and 50% achieved rCRISS50. These indications are not covered by the RMAT designation.

Artiva plans to initiate a Phase III registrational trial evaluating AlloNK plus rituximab versus rituximab alone in refractory RA in 2026, with ACR50 at six months as the primary endpoint and approximately 150 patients enrolled. The company has cited FDA alignment on this registrational strategy and stated that capital from a recent financing is expected to extend runway into 2029.

Research context

Refractory RA represents a population with limited options after failure of multiple b/tsDMARDs. The current treatment landscape includes TNF inhibitors, IL-6 receptor antagonists, JAK inhibitors, and rituximab, none of which reliably produce deep, durable responses in multiply-refractory patients.

The most directly competitive approach is CD19-directed CAR-T cell therapy. Early investigator-initiated data with autologous CD19 CAR-T, including work from groups at Erlangen and elsewhere, have reported sustained drug-free remissions in small numbers of RA patients, generating substantial interest in B-cell depletion as a disease-modifying strategy. However, autologous CAR-T requires patient-specific manufacturing, inpatient administration, and access to specialized centers, constraints that limit scalability. Artiva has positioned AlloNK as delivering comparable depth of B-cell depletion to CD19 CAR-T — a claim supported by the 100% complete depletion rate in evaluable patients — while using an allogeneic, off-the-shelf product that the company contends is compatible with outpatient, community rheumatology settings.

Unlike autologous CAR-T, AlloNK is not genetically modified and does not carry a CD19-targeting construct; instead, it relies on enhancing the ADCC activity of co-administered rituximab to achieve B-cell killing. This distinction has implications for manufacturing scalability and the absence of CRS and ICANS in the current dataset, though the dataset remains small and non-randomized. Whether the depth and durability of B-cell depletion observed with AlloNK plus rituximab will replicate in a randomized Phase III setting, and how it will compare against the emerging autologous CAR-T data in RA, remains to be established.

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