Identification of a novel T cell receptor targeting mutated KRAS in the peripheral blood of a pancreatic cancer patient
2Oncology Institute, Sheba Medical Center, Tel Hashomer
3Faculty of Medical and Health Sciences, Tel Aviv University, Tel Aviv
4Ella Lemelbaum Institute for Immuno-Oncology, Sheba Medical Center, Tel Hashomer
Introduction
Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with <9% five-year survival and remains refractory to most available therapies. As 95% of PDAC express KRAS tumor mutations, the therapeutic potential of creating a vast off-the-shelf T-cell receptors (TCRs) library targeting the common KRAS mutations is immense. We recently initiated a clinical trial at Sheba Medical Center using engineered T-cells expressing mutated KRAS-specific TCRs, in which one patient was treated. This work aims to identify and isolate novel TCRs targeting KRAS driver mutations, and to explore their potential use to treat PDAC patients.
Materials and Methods
We have used a non-invasive method to probe tumor-specific T-cells in the peripheral blood of four PDAC patients by in vitro stimulation with the mutated KRAS peptide presented by autologous antigen-presenting cells. Briefly, we isolated T-cells of each patient and sorted CD4+ and CD8+ memory T-cells, which were stimulated for 10 days with the mutated KRAS peptide. Following expansion and restimulation, we have probed the reactivity of the expanded cells against the relevant KRAS mutations by examining the upregulation of activation molecules and secretion of IFNγ.
Results and discussion
Unprecedentedly, in the case of pancreatic cancer, we have identified circulating mutation-specific T-cells in one patient harboring a tumor KRASG12R mutation. These cells are reactive against the mutated but not the WT peptide. TCR sequencing revealed one dominant clone, which we cloned and retrovirally transduced into autologous T-cells, confirming a specific recognition of the KRASG12R mutation. We have also determined the reactive TCR`s HLA restriction (DQA1*05:05/DQB1*03:01).
Conclusions
In this study, we demonstrated the presence of mutation-specific T-cells in the peripheral blood of a PDAC patient and confirmed the feasibility of their isolation. We have also identified a novel KRASG12R-specific, HLA-DQA1*05:05/DQB1*03:01-restricted TCR, which will be used in our recent clinical trial at Sheba Medical Center to treat pancreatic cancer patients.