Background: Autologous chimeric antigen receptor (CAR) T-cell therapies have shown remarkable clinical activity in B-cell–mediated autoimmune (AI) diseases via B-cell targeting, with many patients achieving durable, drug-free remission [1–3]. However, toxicity-related safety concerns persist for CAR T-cell therapies, including cytokine release syndrome (CRS), immune effector cell–associated neurotoxicity syndrome (ICANS), and graft-versus-host disease [4,5]. Further, long manufacturing times and complex logistics limit patient access and broader adoption [6]. Allogeneic natural killer (NK)-cell therapies may help address these challenges. NKX019 is an investigational, allogeneic, off-the-shelf, cryopreserved, CD19-targeted, CAR NK-cell therapy derived from healthy donor peripheral blood mononuclear cells (PBMCs) [7]. NKX019 expresses a humanised, anti-CD19, single-chain variable fragment CAR that includes costimulatory (OX40) and signalling (CD3ζ) domains to enhance killing, along with membrane-bound interleukin-15 to support persistence [7]. Preliminary data from a phase 1 clinical trial in relapsed or refractory B-cell malignancies (NCT05020678) demonstrated robust B-cell depletion and a favourable safety profile, including no events of ICANS or CRS grade >3, as well as encouraging antitumour activity [7], with additional studies evaluating the efficacy and safety of NKX019 underway.

Objectives: To evaluate in vitro and in vivo data assessing the therapeutic potential of NKX019 in B-cell–mediated AI diseases and to demonstrate that NKX019 effectively depletes CD19+ cells derived from participants with non-Hodgkin lymphoma (NHL) and B-cell–mediated AI diseases and from CD19+ lymphoma models.

Methods: Samples from participants with NHL and PBMCs obtained from participants with various B-cell–mediated AI diseases (systemic lupus erythematosus [SLE], systemic sclerosis [SSc], idiopathic inflammatory myopathy [IIM], myasthenia gravis [MG], rheumatoid arthritis [RA], and multiple sclerosis [MS]) were evaluated to assess CD19+ B-cell depletion, B-cell reconstitution, and immune repertoire using flow cytometry and genomic analyses (10x Genomics 5′ single-cell gene expression profiling paired with B-cell receptor [BCR] sequencing). In vivo studies were performed in NOD scid gamma (NSG) mice inoculated with human CD19+ B-cell lymphoma cell lines treated with NKX019 to evaluate activity and biodistribution of NKX019 in tissue samples by bioluminescence imaging (IVIS Spectrum) and quantitative polymerase chain reaction, respectively.

Results: NKX019 targeted and killed CD19+ cells from participants with NHL and B-cell–mediated AI diseases. In nonclinical studies, NKX019 potently and selectively depleted B cells from participants with SLE, SSc, IIM, MG, RA, and MS in a dose-dependent manner. In a B-cell lymphoma in vivo efficacy model, NKX019 eliminated CD19+ lymphoma cells and trafficked to several organs, including secondary lymphoid tissue, kidneys, and lungs ( Figure 1 ). Translational data from participant samples from the NHL study demonstrated that NKX019 induced potent and sustained depletion of circulating CD19+ cells. Furthermore, following NKX019 treatment, detailed analyses of the BCR repertoire diversity and phenotypic characterisation revealed a notable increase in the proportion of B cells with a naïve-dominant profile, indicating an immune reset of the B-cell compartment ( Figure 2 ).

Conclusions: In summary, nonclinical in vitro and in vivo data demonstrated that NKX019 effectively depleted CD19+ cells derived from participants with B-cell–mediated AI diseases and in CD19+ lymphoma models, respectively. In participants with NHL, NKX019 induced robust B-cell depletion followed by reconstitution of the B-cell compartment. These data provide compelling support for NKX019 as a novel therapeutic approach for the treatment of B-cell–mediated AI diseases. The safety and tolerability of NKX019 is currently being evaluated in two ongoing phase 1/2 basket studies in participants with B-cell–mediated AI diseases, including lupus nephritis and primary membranous nephropathy (NCT06557265, NTRUST-1) and SSc, IIM, and ANCA–associated vasculitis (NCT06733935, NTRUST-2), as well as investigator-sponsored trials for SLE (NCT06518668) and generalized MG.

REFERENCES: [1] Müller F, et al. N Engl J Med . 2024;390(8):687-700.

[2] Ohno R, et al. Semin Arthritis Rheum . 2024;67:152479.

[3] Schett G, et al. Immunity . 2024;57(12):2705-9.

[4] Xie G, et al. EBioMedicine . 2020;59:102975.

[5] Michaelson JS, et al. J Exp Med . 2024;221(5):e20240499.

[6] Lin H, et al. Front Immunol . 2021;12:744823.

[7] Dickinson M, et al. HemaSphere . 2023;7(S3):e37234fb.

Acknowledgments: NIL.

Disclosure of Interests: Mira Tohme owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., and received travel support and other services from Nkarta, Inc., Meriam Vejiga owns stock in Nkarta, Inc., is an employee of Nkarta, Inc. and received travel support and other services from Nkarta, Inc., Wendy Yu owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Emily Kang may own stock in Nkarta, Inc., is a former employee of Nkarta, Inc., Katharine Yu owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Jessica Wei owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Jessica Sood owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Max Zhang owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Nikki Kimura may own stock in Nkarta, Inc., is a former employee of Nkarta, Inc., Damie Juat owns stock in Nkarta, Inc., is a former employee of Nkarta, Inc. and received travel support from Nkarta, Inc., Ivan Chan owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., received travel support from Nkarta Inc., and has patent(s) issued or pending from Nkarta, Inc., Kyle Hansen owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., received travel support from Nkarta, Inc., and has patent(s) issued or pending from Nkarta, Inc., James Trager may own stock in Nkarta, Inc., is a former employee of Nkarta, Inc., Sandeep Hora owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Shawn Rose owns stock in Nkarta, Inc., is an employee of Nkarta, Inc., Ann Kapoun received payment from Nkarta, Inc. for consulting services, David Shook may own stock in Nkarta, Inc., is a former employee of Nkarta, Inc., Phung Gip Phung Gip owns stock in Nkarta, Phung Gip is an employee of Nkarta, Inc, Phung Gip has received travel support from Nkarta, Inc.