T Cell Maturation Stage Prior to and During GMP Processing Informs on CAR T Cell Expansion in Patients

Abstract

Autologous T cells were genetically modified to express a chimeric antigen receptor (CAR) directed toward carboxy-anhydrase-IX (CAIX) and used to treat patients with CAIX-positive metastatic renal cell carcinoma. In this study, we questioned whether the T cell maturation stage in the pre-infusion product affected CAIX CAR expression and function in vitro as well as in vivo CAR T cell numbers and expansion. During the 14 days expansion of CAR T cells prior to administration, we observed shifts from a predominant CD4 to a CD8 T cell phenotype and from a significant fraction of naïve to central effector T cells. Surface expression of the CAR was equally distributed among different T cell subsets and T cell maturation stages. During T cell culture days 14–18 (which covered patient treatment days 1–5), T cells demonstrated a decline in CAR expression level per cell irrespective of T cell maturation stage, although the proportion of CAR-positive T cells and CAR-mediated T cell effector functions remained similar for both CD4 and CD8 T cell populations. Notably, patients with a higher fraction of naïve CD8 T cells at baseline (prior to genetic modification) or central effector CD8 T cells at 2 weeks of CAR T cell culture demonstrated a higher fold expansion and absolute numbers of circulating CAR T cells at 1 month after start of therapy. We conclude that the T cell maturation stage prior to and during CAR T cell expansion culture is related to in vivo CAR T cell expansion.

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

“…Less‐differentiated T cells for adoptive immunotherapy are linked to an improved in vivo engraftment, persistence and tumor eradication . In this context, particularly T N and T SCM cells are considered important due to their high proliferative and self‐renewal capacity . The modulation of critical signaling pathways in T cell differentiation through specific pathway inhibitors can improve T cell production in adoptive immunotherapy .…”

“…24 In this context, particularly T N and T SCM cells are considered important due to their high proliferative and self-renewal capacity. [5][6][7] The modulation of critical signaling pathways in T cell differentiation through specific pathway inhibitors can improve T cell production in adoptive immunotherapy. 24 It has been reported that for example an induction of WNT-β-catenin signaling pathway through GSK3β inhibition can interrupt effector differentiation of T cells.…”

“…Thereby, transfer of defined T cell phenotypes can influence antitumor activity . Particularly less‐differentiated T cells with high expression of lymphoid homing markers such as CD62L and CCR7 have the capacity to persist and engraft long‐term in vivo . The enhanced capacity to migrate into lymphoid tissues might induce this longevity together with better response to homeostatic cytokines …”

“…4 Particularly less-differentiated T cells with high expression of lymphoid homing markers such as CD62L and CCR7 have the capacity to persist and engraft long-term in vivo. [4][5][6][7] The enhanced capacity to migrate into lymphoid tissues might induce this longevity together with better response to homeostatic cytokines. 8 In recent years, CART cell therapy evolved with regards to CAR vector design, 9 but a vast pursuit is to further expand lessdifferentiated T cells.…”

Cell therapy products: focus on issues with manufacturing and quality control of chimeric antigen receptor T‐cell therapies

“…Understanding cellular starting material profiles linked to manufacturing success or failure is an important objective for manufacturers. Application of contemporary multicolour flow cytometry to monitor immune‐cell profiles from start throughout CAR‐T manufacture is one strategy . The option to use more generic and standardised cellular starting materials would have several advantages; with significant scope to reduce manufacturing costs, improve reproducibility and widen patient access.…”