CD22.BBz CAR T cells had reduced ERK/MAPK and LAT signaling and were less effective against NALM6CD22low than NALM6WT tumors. To rescue efficacy, Pham-Danis et al. developed a dual CAR platform (ALA-CART), pairing a standard BBz CAR with a CAR linked to intracellular LAT. ALA-CART cells effectively targeted two antigens (CD22 and CD19) or one (with two high-affinity CD22 binders). Inclusion of the LAT-CAR reduced CAR T cell differentiation and boosted expansion, persistence, ERK/MAPK signaling, and downstream NFAT/AP-1 activity, altogether improving efficacy over standard CD22.BBz CAR-T cells in CD22low tumors, without toxicity.
Contributed by Alex Najibi
ABSTRACT: Chimeric antigen receptor (CAR) T cells induce responses in patients with relapsed/refractory leukemia; however, long-term efficacy is frequently limited by relapse. The inability to target antigen-low cells is an intrinsic vulnerability of second-generation CAR T cells and underlies most relapses following CD22BBz CAR T cell therapy. Here, we interrogate CD22BBz CAR signaling in response to low antigen and find inefficient phosphorylation of the linker for activation of T cells (LAT) limiting downstream signaling. To overcome this, we designed the adjunctive LAT-activating CAR T cell (ALA-CART) platform, pairing a second-generation CAR with a LAT-CAR incorporating the intracellular domain of LAT. ALA-CART cells demonstrate reduced differentiation during manufacturing and increased LAT phosphorylation, MAPK signaling, and AP-1 activity. ALA-CART cells show improved cytotoxicity, proliferation, persistence, and efficacy against antigen-low leukemias that were refractory to clinically active CD22BBz CAR T cells. Restoration of LAT signaling through the ALA-CART platform represents a promising strategy for overcoming multiple mechanisms of CAR T cell failure.
Author Info: (1) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. (2) Department of Pediatrics, University of Colorado Anschutz Medical Campus, A
Author Info: (1) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. (2) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. (3) Department of Biomedical Informatics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Biostatistics & Bioinformatics Shared Resource, University of Colorado Cancer Center, Aurora, CO 80045, USA. (4) Division of Oncology and Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. (5) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. (6) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA. (7) Proteomics and Mass Spectrometry Core, Department of Biochemistry, University of Colorado, Boulder, CO 80309, USA. (8) Division of Oncology and Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics & Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA. (9) Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Division of Blood and Marrow Transplantation & Cellular Therapy, Center for Cancer and Blood Disorders, Children's Hospital Colorado, Aurora, CO 80045, USA. Electronic address: mark.kohler@cuanschutz.edu.
