Background/Purpose: Ex vivo chimeric antigen receptor (CAR) T cell therapies have revolutionized cancer treatment and are demonstrating durable clinical efficacy in various autoimmune disease (AID) indications. Despite the success of current CAR T therapies, challenges in cell manufacturing, scalability, utilization of integrating viral vectors, and the need for lymphodepleting chemotherapy, highlight the necessity for an off-the-shelf in vivo CAR technology applicable to broader indications. To that aim, we developed an in vivo anti-CD19 CAR mRNA product delivered by a CD8-targeted lipid nanoparticle (tLNP) (CPTX2309). We tested the applicability of CPTX2309 to engineer T cells with an anti-CD19 CAR and demonstrated the ability for this approach to eradicate target B cells from patients with B cell involved AID.

Methods: To test the potential applicability of CPTX2309 treatment to AID patients, we evaluated the immunophenotype, tLNP-mediated CAR engineering, and functional activity of CAR T cells produced from the peripheral blood of AID patients compared with the peripheral blood of healthy subjects. Samples were obtained from patients with systemic lupus erythematosus (SLE), anti-synthetase syndrome (AS), dermatomyositis (DM), and immune-mediated necrotizing myopathy (IMNM) with various prior treatments, including in some cases immune suppressive or B cell depleting agents.

Results: Phenotypically, the composition of major immune cell populations and expression level of CD19 and CD8 on B cells and CD8+T cells, respectively, was comparable across healthy and diseased subjects, except for the lack of B cells in patients treated with B cell depleting agents. In vitro engineering of non-activated lymphocytes with CPTX2309 resulted in comparable CAR expression by CD8+ T cells from healthy and diseased patients irrespective of prior treatments. In the presence of autologous B cells, tLNP-engineered CAR T cells from AID patients demonstrated upregulation of T cell activation markers, produced cytokines associated with T cell cytotoxicity, and eliminated target cells within 72 hours, comparable to tLNP engineered CAR T cells from healthy subjects.

Conclusion:

CPTX2309 effectively engineered CD8+ T cells from autoimmune disease patients irrespective of prior treatments including immune suppressive agents, to highly express anti-CD19 CAR, and rapidly eradicate primary B cells in vitro.  This may allow for broadening the applicability of CAR technology to B cell involved autoimmune diseases through in vivo engineering of anti-CD19 CAR T cells using a scalable and tunable technology devoid of cells, viral vectors or components, and obviating the need for lymphodepleting conditioning.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effective-engineering-of-cd8-t-cells-from-autoimmune-disease-patients-utilizing-a-cd8-targeted-lipid-nanoparticleencoding-an-anti-cd19-car-mrnacptx2309/