Several pivotal studies established the high prognostic value of tumor-infiltrating lymphocytes (TILs) in patients with solid tumors, including colorectal (CRC) and ovarian (OvCa) cancer. Albeit the association between clinicopathological outcomes and tumor infiltration supports the intervention with immunotherapeutic strategies, TIL-adoptive cell transfer (ACT) only led to clinical results in a subset of patients with non-melanoma tumors, raising the question of the abundance of tumor-reactive T cells in these cancers. In the present study, we interrogated CRC and OvCa patients for the presence and features of neoantigen (neoAg) and tumor-specific T cells in in vitro-expanded and also in situ TILs.
We collected tumors from 30 patients with either early and advanced CRC or advanced OvCa. Neoepitope- and tumor-specific CD8 T cells were identified and FACS-sorted from blood or in vitro-expanded TILs. In parallel, T-cell receptor sequencing (TCR-Seq), including single cell TCR-seq (scTCR-seq) was performed on tumor samples followed by TCR annotation based on a robust in-house pipeline for TCR cloning and screening.
Tumor-specific in vitro-expanded TILs were identified in most CRC and OvCa patients and originated from clonotypes of a broad range of intratumoral frequencies. In CRC, the presence of TILs targeting NeoAg correlated with the density of activated and exhausted TILs in both tumor and stroma. Furthermore, higher structural affinity TCRs preferentially infiltrated tumors. By interrogating libraries of scRNA/TCRseq from tumor samples, several additional tumor-specific TCRs were identified and their transcriptomic profile led to a signature and a predictor of tumor specific TCRs.
Although tumor-specific TILs are consistently detected in CRC and OvCa patients, they are not clonally expanded in tumors and do not efficiently proliferate in conventional cell culture conditions. Their transcriptomic profiles represent a unique dataset that can be exploited to determine cell culture conditions to guide next generation immunotherapies as well as biomarkers discriminating patients eligible for TIL-ACT.
The authors.
Ludwig Institute for Cancer Research.
L. Kandalaft: Financial Interests, Institutional, Full or part-time Employment: CHUV Lausanne University Hospital, Ludwig Cancer Research Institute Lausanne Branch; Financial Interests, Institutional, Research Grant: Research Foundation for the treatment of Ovarian cancer; Financial Interests, Institutional, Research Grant, Development of a Novel B Cell-based Vaccine for Metastatic Solid Cancers: ISREC Foundation; Financial Interests, Institutional, Research Grant, Development of a lung personalized Dendritic Cell Vaccine: Impact Cancer Foundation; Financial Interests, Institutional, Research Grant, Development of a Pancreatic personalized Dendritic Cell Vaccine in combination with PDL-1: BMS. G. Coukos: Financial Interests, Institutional, Research Grant: Celgene, Boehringer Ingelheim, Roche, BMS, Iovance Therapeutics, Kite Pharma; Financial Interests, Institutional, Advisory Board: Genentech, BMS, AstraZeneca, NextCure, Geneos Tx, Sanofi/Aventis, Roche. All other authors have declared no conflicts of interest.