Idelalisib for optimized CD19‐specific chimeric antigen receptor T cells in chronic lymphocytic leukemia patients

Abstract

Despite encouraging results with chimeric antigen receptor T (CART) cells, outcome can still be improved by optimization of the CART cell generation process. The proportion of less‐differentiated T cells within the transfused product is linked to enhanced in vivo CART cell expansion and long‐term persistence. The clinically approved PI3Kδ inhibitor idelalisib is well established in the treatment of B cell malignancies. Besides B cell receptor pathway inhibition, idelalisib can modulate T cell differentiation and function. Here, detailed longitudinal analysis of idelalisib‐induced effects on T cell phenotype and function was performed during CART cell production. A third generation CD19.CAR.CD28.CD137zeta CAR vector system was used. CART cells were generated from peripheral blood mononuclear cells of healthy donors (HDs) and chronic lymphocytic leukemia (CLL) patients. Idelalisib‐based CART cell generation resulted in an enrichment of less‐differentiated naïve‐like T cells (CD45RA+CCR7+), decreased expression of the exhaustion markers PD‐1 and Tim‐3, as well as upregulation of the lymph node homing marker CD62L. Idelalisib increased transduction efficiency, but did not impair viability and cell expansion. Strikingly, CD4:CD8 ratios that were altered in CART cells from CLL patients were approximated to ratios in HDs by idelalisib. Furthermore, in vivo efficacy of idelalisib‐treated CART cells was validated in a xenograft mouse model. Intracellular TNF‐α and IFN‐γ production decreased in presence of idelalisib. This effect was reversible after resting CART cells without idelalisib. In summary, PI3Kδ inhibition with idelalisib can improve CART cell products, particularly when derived from CLL patients. Further studies with idelalisib‐based CART cell generation protocols are warranted.

Optimizing Manufacturing Protocols of Chimeric Antigen Receptor T Cells for Improved Anticancer Immunotherapy

“…However, CLL patient samples without prior T cell selection showed an unbalanced CD4:CD8 ratio with predominant CD4+ T cells that could be approximated towards a 1:1 ratio by the supplementation of idelalisib during the manufacturing process [49]. The reduced expression of exhaustion markers was another positive effect of the application of a PIK3δ inhibitor during CART cell production [49,128]. The use of antagonists against PI3Kδ and the vasoactive intestinal peptide (VIP) during ex vivo expansion of DLBCL patient T cells led to the inhibition of the terminal T cell differentiation, reduced PD-1 expression, and improved T cell persistence in immune-deficient mice [130].…”

“…The cellular composition at the beginning of the production process can influence the phenotype of the CART cells, as patients with high number of tumor cells in the PB, such as untreated CLL patients, showed low numbers of less differentiated T cells within their PBMCs [49]. Endogenous cellular elements can be a sink for supplemented cytokines and, therefore, may reduce the cytokine-mediated effects on CART cells [50].…”

“…In addition to eliminating malignant B cells, idelalisib can degrade T reg cells, and thereby reverse the immune tolerance of cancer cells [126,127]. The ex vivo treatment of CART cells with a PI3Kδ inhibitor mediated higher amounts of less differentiated CCR7+ CD62L+ T cells and improved the functional capacity of mesothelin-specific [128], CD33-specific [129], and CD19-specific CART cells [49]. In healthy donors, the supplementation of IL-7/IL-15 during the production process led to a very balanced CD4:CD8 ratio.…”

“…In healthy donors, the supplementation of IL-7/IL-15 during the production process led to a very balanced CD4:CD8 ratio. However, CLL patient samples without prior T cell selection showed an unbalanced CD4:CD8 ratio with predominant CD4+ T cells that could be approximated towards a 1:1 ratio by the supplementation of idelalisib during the manufacturing process [49]. The reduced expression of exhaustion markers was another positive effect of the application of a PIK3δ inhibitor during CART cell production [49,128].…”

Ibrutinib for improved chimeric antigen receptor T‐cell production for chronic lymphocytic leukemia patients

“…[15][16][17] Optimized CART cell production protocols enriching for these T cell subsets may improve therapeutic outcome. 18 Several specific pathway inhibitors can interfere with the differentiation of T cells. For example, mTOR inhibition not only enhances the formation of CD8+ memory T cells but also augments their antitumor functions.…”