In vitro elimination of EGFR-overexpressing cancer cells by CD32A chimeric receptor T cells in combination with cetuximab or panitumumab

Cetuximab and panitumumab bind the human epidermal growth factor receptor (EGFR). While the chimeric cetuximab (IgG1) triggers antibody-dependent-cellular-cytotoxicity (ADCC) of EGFR positive target cells, panitumumab (a human IgG2) does not. The inability of panitumumab to trigger ADCC reflects the poor binding affinity of human IgG2 Fc for the FcγRIII (CD16) on natural killer (NK) cells. However, both human IgG1 and IgG2 bind the FcγRII (CD32A) to a similar extent. This study compares the ability of T cells, engineered with a novel low-affinity CD32A131R -chimeric receptor (CR), and those engineered with the low-affinity CD16158F -CR T cells, in eliminating EGFR positive epithelial cancer cells (ECCs) in combination with cetuximab or panitumumab. Following T cell transduction, the percentage of CD32A131R -CR T cells was 74 ± 10% while the percentage of CD16158F -CR T cells was 46 ± 15%. Only CD32A131R -CR T cells bound panitumumab. CD32A131R -CR T cells combined with the mAb 8.26 (anti-CD32) and CD16158F -CR T cells combined with the mAb 3 g8 (anti-CD16) eliminated colorectal carcinoma (CRC), HCT116FcγR+ cells, in a reverse ADCC assay in vitro. Cross-linking of CD32A131R -CR on T cells by cetuximab or panitumumab and CD16158F -CR T cells by cetuximab induced elimination of triple negative breast cancer (TNBC) MDA-MB-468 cells, and the secretion of IFNγ and TNFα. Neither cetuximab nor panitumumab induced Fcγ-CR T anti-tumor activity against KRAS-mutated HCT116, non-small-cell-lung-cancer, A549 and TNBC, MDA-MB-231 cells. The ADCC of Fcγ-CR T cells was associated with the over-expression of EGFR on ECCs. In conclusion, CD32A131R -CR T cells are efficiently redirected by cetuximab or panitumumab against BC cells overexpressing EGFR. This article is protected by copyright. All rights reserved.