Qin et al. generated a clinically relevant anti-CD19 CD4/CD8 (1/1) CAR T cell product with a 4-1BB costimulatory endodomain (liso-cel). BTK inhibitors ibrutinib (ibr) and acalabrutinib (aca) had direct, cell autonomous effects on liso-cel, enhancing cytokine production and expanding activated CD8+ CAR T cells in vitro. Serial stimulation of liso-cel with CD19+ cells and ibr expanded Th1 CD4+ T cells with memory-like expression profiles and enhanced target cell killing. In a mouse tumor model, ibr or aca addition to suboptimally dosed liso-cel enhanced CAR T cell expansion, delayed tumor growth, and enhanced survival, supporting the utility of combination therapy.
Contributed by Samuel Goldman
Chimeric antigen receptor (CAR) T-cell therapy is a promising treatment for patients with CD19 B-cell malignancies. Combination strategies that improve CAR T-cell potency, limit tumor environment-mediated immune dysfunction, and directly reduce tumor burden may increase the potential for durable clinical benefit of CAR T-cell therapy. Lisocabtagene maraleucel (liso-cel) is a product therapy candidate being tested in patients with relapsed/refractory non-Hodgkin lymphoma or chronic lymphocytic leukemia. This study assessed the in vitro and in vivo functionality of CAR T cells transduced to express the anti-CD19 CAR of liso-cel in combination with ibrutinib or acalabrutinib. In prolonged stimulation assays, the presence of ibrutinib or acalabrutinib improved the CAR T-cell effector function. RNA-Seq analysis and surface marker profiling of these CAR T cells treated with ibrutinib but not acalabrutinib revealed gene expression changes consistent with skewing toward a memory-like, type 1 T-helper, Bruton tyrosine kinase phenotype. Ibrutinib or acalabrutinib improved CD19 tumor clearance and prolonged survival of tumor-bearing mice when used in combination with CAR T cells. A combination of the defined cell product therapy candidate, liso-cel, with ibrutinib or acalabrutinib is an attractive approach that may potentiate the promising clinical responses already achieved in CD19 B-cell malignancies with each of these single agents.