T-CELL--RECEPTOR (TCR) THERAPY TARGETING KRAS MUTATIONS PDAC

Chani Stossel, Anat Shemer, Orit Izhaki, Abraham Nissani, Ronnie Frommer Shapira, Gal Cafri, Talia Golan 

Sheba Medical Center
 

 

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive solid tumors. Most patients are diagnosed in the advanced stage with limited overall-survival and rapid resistance to treatment. In PDAC, ~90% of patients harbor mutated KRAS genes.
Adoptive-cell-therapy with T-cell-engineered to clonally express specific T-cell-receptors(TCRs) targeting driver KRAS mutations is conceptually attractive since they are tumor-specific and crucial for tumor progression.
 

Using an off-the-shelf library of peptides and mRNA constructs covering the common KRAS mutations, we utilized our unique established PDAC biobank composed of 130 patient-derived xenografts, PBMCs, and tumor-infiltrating lymphocytes, to identify and isolate TCRs specific for mutated-KRAS. We identified patients with specific KRAS mutations and performed in-vitro validation assays with manufactured TCR's.
We treated two PDAC patients with a KRAS G12R or G12D specific and validated TCR. TCR transduction efficacy was above 50% for both constructs. High potency was observed in autologous co-culture with APCs loaded with KRAS mutated peptide versus WT. Utilizing the mouse construct antibody, we identified TCRs in the first patient's ascites fluid from day 10 post cell-infusion, indicative for a TCR pharmacodynamics effect in the human ecosystem. A multiplex immunofluorescence assay identified the TCRs and accompanying cells in ascites fluid cell blocks. Blood samples were sequentially collected undergoing analysis for TCR sequencing and persistence. A liver biopsy from the second patient post TCR treatment is currently being assets for TCR and tumor microenvironment immunophenotyping .
 

The clinical and experimental setup sets the framework for future pre-clinical data and investigation of the immune repertoire in patients treated with TCR T-cell-therapy targeting oncogenic mutations.