Clinically relevant subtypes exist for pancreatic ductal adenocarcinoma (PDAC), but molecular characterization is not yet standard in clinical care. We implemented a biopsy protocol to perform time-sensitive whole-exome sequencing and RNA sequencing for patients with advanced PDAC. Therapeutically relevant genomic alterations were identified in 48% (34/71) and pathogenic/likely pathogenic germline alterations in 18% (13/71) of patients. Overall, 30% (21/71) of enrolled patients experienced a change in clinical management as a result of genomic data. Twenty-six patients had germline and/or somatic alterations in DNA-damage repair genes, and 5 additional patients had mutational signatures of homologous recombination deficiency but no identified causal genomic alteration. Two patients had oncogenic in-frame deletions, and we report the first clinical evidence that this alteration confers sensitivity to MAPK pathway inhibition. Moreover, we identified tumor/stroma gene expression signatures with clinical relevance. Collectively, these data demonstrate the feasibility and value of real-time genomic characterization of advanced PDAC. Molecular analyses of metastatic PDAC tumors are challenging due to the heterogeneous cellular composition of biopsy specimens and rapid progression of the disease. Using an integrated multidisciplinary biopsy program, we demonstrate that real-time genomic characterization of advanced PDAC can identify clinically relevant alterations that inform management of this difficult disease. .

Objective Evidence suggests that CD274 (PD-L1, B7-H1) immune checkpoint ligand repress anti-tumour immunity through its interaction with the PDCD1 (programmed cell death 1, PD-1) receptor of T lymphocytes in various tumours. We hypothesised that tumour CD274 expression levels might be inversely associated with T-cell densities in colorectal carcinoma tissue. Design We evaluated tumour CD274 expression by immunohistochemistry in 823 rectal and colon cancer cases within the Nurses’ Health Study and Health Professionals Follow-up Study. We conducted multivariable ordinal logistic regression analyses to examine the association of tumour CD274 expression with CD3+, CD8+, CD45RO (PTPRC)+, or FOXP3+-cell density in tumour tissue, controlling for potential confounders including tumour status of microsatellite instability (MSI), CpG island methylator phenotype, LINE-1 methylation level, and KRAS, BRAF, and PIK3CA mutations. Results CD274 expression in tumour cells or stromal cells (including immune cells) was detected in 731 (89%) or 44 (5%) cases, respectively. Tumour CD274 expression level correlated inversely with FOXP3+-cell density in colorectal cancer tissue (outcome) (Ptrend=0.0002). For a unit increase in outcome quartile categories, multivariable odds ratio in the highest (vs. lowest) CD274 expression score was 0.22 (95% confidence interval 0.10–0.47). Tumour CD274 expression was inversely associated with MSI-high status (P=0.001). CD274 expression was not significantly associated with CD3+, CD8+, or CD45RO+-cell density, pathological lymphocytic reactions, or patient survival prognosis. Conclusions Tumour CD274 expression is inversely associated with FOXP3+ cell density in colorectal cancer tissue, suggesting a possible influence of CD274-expressing carcinoma cells on regulatory T (Treg) cells in the tumour microenvironment.