To more completely identify neoantigen-reactive T cells in epithelial cancer TIL samples, Yossef et al. sorted cells expressing either or both of PD-1 and a co-stimulatory molecule (CD134 or CD137) into microwells at low density (3 cells per well to reduce overgrowth by non-exhausted cells) and following expansion screened for neoantigen reactivity across the entire mutanome. The method was at least two-fold more sensitive than previous TIL fragment culture approaches, facilitated rapid TCR α/β cloning, and resulted in identification of MHC class II TCRs for two highly relevant oncogenes (KRASG12V and TP53G245S).
Adoptive cell transfer (ACT) of tumor-infiltrating lymphocytes (TILs) targeting neoantigens can mediate tumor regression in selected patients with metastatic epithelial cancer. However, effectively identifying and harnessing neoantigen-reactive T cells for patient treatment remains a challenge and it is unknown whether current methods to detect neoantigen-reactive T cells are missing potentially clinically relevant neoantigen reactivities. We thus investigated whether the detection of neoantigen-reactive TILs could be enhanced by enriching T cells that express PD-1 and/or T cell activation markers followed by microwell culturing to avoid overgrowth of nonreactive T cells. In 6 patients with metastatic epithelial cancer, this method led to the detection of CD4+ and CD8+ T cells targeting 18 and 1 neoantigens, respectively, compared with 6 and 2 neoantigens recognized by CD4+ and CD8+ T cells, respectively, when using our standard TIL fragment screening approach. In 2 patients, no recognition of mutated peptides was observed using our conventional screen, while our high-throughput approach led to the identification of 5 neoantigen-reactive T cell receptors (TCRs) against 5 different mutations from one patient and a highly potent MHC class II-restricted KRASG12V-reactive TCR from a second patient. In addition, in a metastatic tumor sample from a patient with serous ovarian cancer, we isolated 3 MHC class II-restricted TCRs targeting the TP53G245S hot-spot mutation. In conclusion, this approach provides a highly sensitive platform to isolate clinically relevant neoantigen-reactive T cells or their TCRs for cancer treatment.
Author Info: (1) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (2) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. Earle A. Chiles Research I
Author Info: (1) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (2) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. Earle A. Chiles Research Institute and the Providence Portland Medical Center, Portland, Oregon, USA. (3) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (4) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. Medical Oncology Department, Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology (VHIO), Pg. Vall d'Hebron, Barcelona, Spain. (5) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (6) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (7) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (8) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (9) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (10) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA. (11) Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
