title: 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 functionin vitroas well asin vivoCAR 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 toin vivoCAR T cell expansion.
authors.affiliation: Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC-Cancer Institute , Rotterdam , Netherlands.
authors.forename: Yarne
authors.initials: Y
authors.lastname: Klaver
authors.affiliation: Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC-Cancer Institute , Rotterdam , Netherlands.
authors.forename: Sabine C L
authors.initials: SC
authors.lastname: van Steenbergen
authors.affiliation: Department of Medical Oncology, Erasmus MC-Cancer Institute , Rotterdam , Netherlands.
authors.forename: Stefan
authors.initials: S
authors.lastname: Sleijfer
authors.affiliation: Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC-Cancer Institute , Rotterdam , Netherlands.
authors.forename: Reno
authors.initials: R
authors.lastname: Debets
authors.affiliation: Laboratory of Tumor Immunology, Department of Medical Oncology, Erasmus MC-Cancer Institute , Rotterdam , Netherlands.
authors.forename: Cor H J
authors.initials: CH
authors.lastname: Lamers
keywords: T cell; T cell expansion; T cell maturation; T cell persistence; carboxy-anhydrase-IX; chimeric antigen receptor; immune monitoring; renal cell cancer