Cytolytic Activity of CAR T Cells and Maintenance of Their CD4+ Subset Is Critical for Optimal Antitumor Activity in Preclinical Solid Tumor Models

• Published in: Cancers Vol. 13; no. 17; p. 4301
• Main Authors: Csaplár, Marianna, Szöllősi, János, Gottschalk, Stephen, Vereb, György, Szöőr, Árpád
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 26.08.2021; MDPI
• Subjects: Antibiotics; Antibodies; Antigens; Antitumor activity; Antitumor agents; Breast cancer; Cancer therapies; CC chemokine receptors; CCR7 protein; CD28 antigen; CD4 antigen; CD45RA antigen; CD8 antigen; Cell differentiation; Cell lineage; Cell surface; Cell therapy; Chimeric antigen receptors; Cloning; Cytokines; Cytolytic activity; Effector cells; ErbB-2 protein; Flow cytometry; Hematology; Immunological memory; Leukemia; Lymphocytes; Lymphocytes T; Lymphoma; Memory cells; Patients; Proteins; Solid tumors; Tumors; Minneapolis Minnesota; United States > US; Japan
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers13174301

Correlative studies of clinical studies for hematological malignancies have implicated that less differentiated, CD8+-dominant CAR T cell products have greater antitumor activity. Here, we have investigated whether the differentiation status of CAR T cell products affects their antitumor activity in preclinical models of solid tumors. We explored if different activation/expansion protocols, as well as different co-stimulatory domains in the CAR construct, influence the short- and long-term efficacy of CAR T cells against HER2-positive tumors. We generated T cell products that range from the most differentiated (CD28.z; OKT3-antiCD28/RPMI expansion) to the least differentiated (41BB.z; OKT3-RetroNectin/LymphoONE expansion), as judged by cell surface expression of the differentiation markers CCR7 and CD45RA. While the effect of differentiation status was variable with regard to antigen-specific cytokine production, the most differentiated CD28.z CAR T cell products, which were enriched in effector memory T cells, had the greatest target-specific cytolytic activity in vitro. These products also had a greater proliferative capacity and maintained CD4+ T cells upon repeated stimulation in vitro. In vivo, differentiated CD28.z CAR T cells also had the greatest antitumor activity, resulting in complete response. Our results highlight that it is critical to optimize CAR T cell production and that optimal product characteristics might depend on the targeted antigen and/or cancer.