Central memory phenotype drives success of checkpoint inhibition in combination with CAR T cells

Abstract

The immunosuppressive microenvironment in solid tumors is thought to form a barrier to the entry and efficacy of cell-based therapies such as chimeric antigen receptor (CAR) T cells. Combining CAR T cell therapy with checkpoint inhibitors has been demonstrated to oppose immune escape mechanisms in solid tumors and augment antitumor efficacy. We evaluated PD-1/PD-L1 signaling capacity and the impact of an inhibitor of this checkpoint axis in an in vitro system for cancer cell challenge, the coculture of L1CAM-specific CAR T cells with neuroblastoma cell lines. Fluorescence-activated cell sorting-based analyses and luciferase reporter assays were used to assess PD-1/PD-L1 expression on CAR T and tumor cells as well as CAR T cell ability to kill neuroblastoma cells. Coculturing neuroblastoma cell lines with L1CAM-CAR T cells upregulated PD-L1 expression on neuroblastoma cells, confirming adaptive immune resistance. Exposure to neuroblastoma cells also upregulated the expression of the PD-1/PD-L1 axis in CAR T cells. The checkpoint inhibitor, nivolumab, enhanced L1CAM-CAR T cell-directed killing. However, nivolumab-enhanced L1CAM-CAR T cell killing did not strictly correlate with PD-L1 expression on neuroblastoma cells. In fact, checkpoint inhibitor success relied on strong PD-1/ PD-L1 axis expression in the CAR T cells, which in turn depended on costimulatory domains within the CAR construct, and more importantly, on the subset of T cells selected for CAR T cell generation. Thus, T cell subset selection for CAR T cell generation and CAR T cell prescreening for PD-1/PD-L1 expression ---This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Obstacles and Coping Strategies of CAR-T Cell Immunotherapy in Solid Tumors

“…The persistence of CAR-T cells is associated with the curative effect. Selecting specific T cell subtypes to construct CAR-T cells (such as Tn or Tcm) or adopting measures to promote the production of these cells enables CAR-T cells to survive longer with a longer anti-tumor effect in the body ( 45 , 46 ). A few researchers used different subtypes of T cells to construct CAR-T cells ( 47 ).…”

GD2-directed bispecific trifunctional antibody outperforms dinutuximab beta in a murine model for aggressive metastasized neuroblastoma

“…20 Quantification of GD2 surface expression and binding analysis of EKTOMUN/SUREK QuantiBRITE PE calibration beads (BD Biosciences) were used to determine GD2 antigen density on neuroblastoma cells according to the manufacturer's instructions as previously described. 21 To assess binding of EKTOMUN and SUREK to GD2+ neuroblastoma cell lines, we incubated 200 000 SK-N-BE(2) cells with EKTOMUN and 200 000 NXS2 cells with SUREK for 1 hour at 4°C. Subsequently, cells were stained with a PE-labeled secondary antibody directed against mouse IgG2a (cat#407108, Biolegend) for 30 min at 4°C and flow cytometric analysis was performed.…”

Strategies to Improve Chimeric Antigen Receptor Therapies for Neuroblastoma

“…Likewise, the safety and efficacy of anti-PD-L1 combined with CAR T cells have been investigated for B-cell malignancies (NCT03310619) and various types of solid tumor including cervical cancer, sarcoma, and non-small cell lung cancer (NCT04556669). In this direction, checkpoint inhibition may be turning the neuroblastoma microenvironment to respond to immunological treatment and enhance the efficacy of CAR therapy against neuroblastomas as well [192,193].…”