Molecular profiling in cancer has identified potential actionable drug targets that have prompted attempts to discover clinically validated biomarkers to guide therapeutic decision-making and enrollment to clinical trials. We evaluated whether comprehensive genetic analysis of patients with pancreatic adenocarcinoma is feasible within a clinically relevant timeframe and whether such analyses provide predictive and/or prognostic information along with identification of potential targets for therapy. Archival or prospectively acquired FFPE samples and matched normal DNA from = 336 patients with pancreatic cancer were analyzed using a hybridization capture-based, next-generation sequencing assay designed to perform targeted deep sequencing of all exons and selected introns of 410 key cancer-associated genes. Demographic and treatment data were prospectively collected with the goal of correlating treatment outcomes and drug response with molecular profiles. The median time from protocol consent to reporting of the genomic results was 45 days with a median time from tissue delivery of 20 days. All genetic alterations identified were stratified based upon prior evidence that the mutation is a predictive biomarker of drug response using the MSKCC OncoKB classification. Three of 225 patients (1%) received a matched therapy based upon the sequencing results. The practical application of molecular results to guide individual patient treatment is currently limited in patients with pancreatic adenocarcinoma. Future prospective molecular profiling efforts should seek to incorporate routine germline genetic analysis and the identification of DNA profiles that predict for clinical benefit from agents that target DNA damage repair and or immunotherapy. .

The pathology of biliary carcinomas is diverse with different gross and histological features in tumors arising in the different segments of the biliary system. Various epidemiological risk factors, varied genetic makeup, and tissue microenvironment are contributory factors. As biliary tumors have been shown to be a part of the Lynch syndrome tumor spectrum, it is plausible to speculate that DNA mismatch repair (MMR) deficiency plays a role in biliary tumors. Literature data suggest that DNA MMR deficiency indeed occurs in these tumors, albeit infrequently with the reported frequencies (weighted for sample size) of high level microsatellite instability (MSI) being 5% each for gallbladder carcinoma and carcinoma of extra-hepatic bile ducts, and 10% each for intrahepatic cholangiocarcinoma and ampullary carcinoma. Importantly, the presence of MMR deficiency in these tumors has been shown to have different implications with regard to its association with Lynch syndrome, tumor histological features, and other clinical characteristics, when compared with non-biliary tumors or among the biliary tumors from the different segments of the biliary system. Ongoing and future efforts that utilize large scale sequencing techniques and aim at detecting actionable molecular targets should emphasize a multidisciplinary approach that integrates genomic discoveries with not only functional studies but also studies of tumor pathology and the tumor's clinical and biological behavior.

Background Intraductal tubulopapillary neoplasm (ITPN) is a relatively recently described member of the pancreatic intraductal neoplasm family. Thus, the literature on its histologic and immunohistochemical features, clinical behavior, and its similarities and differences from other pancreatic neoplasms is limited. Design Thirty-three cases of ITPN, the largest series to date, were identified. Immunohistochemical labeling for cytokeratins, glycoproteins, pancreatic enzymes, markers for intestinal and neuroendocrine differentiation, and antibodies associated with genetic alterations previously described in pancreatic neoplasms were performed. Clinicopathologic features and survival was assessed. Results Seventeen patients were female, fourteen were male. Mean age was 55 years (range, 25–79). Median overall tumor size was 4.5 cm (range, 0.5–15). Forty-five percent of the tumors occurred in the head, 32% in the body/tail, and 23% showed diffuse involvement. Microscopically, the tumors were characterized by intraductal nodules composed of tightly packed small tubular glands lined by cuboidal cells lacking apparent mucin. Although it was often challenging to determine its extent, invasion was present in 71%. Almost all tumors labeled for CAM5.2, CK7 and CK19; most expressed CA19.9, MUC1 and MUC6. CDX2, MUC2, trypsin, chymotrypsin, chromogranin and synaptophysin were not expressed. SMAD4 expression was retained in 100%, p16 expression and p53 overexpression was seen in 33% and 27%. Follow-up information was available for twenty-two patients (median follow-up, 45 months; range, 11–173). Two patients with invasive carcinoma died of disease at 23 and 41 months. One patient died of unrelated causes at 49 months. Twelve patients were alive with disease. Seven patients were alive with no evidence of disease. The overall 1-, 3- and 5-year survival rates were 100% in patients without an invasive component and 100%, 91% and 71% in patients with an invasive component (p=0.7). Conclusions ITPN is a distinct clinicopathologic entity in the pancreas. Despite the difficulties of determining the extent of invasive carcinoma in many cases, the overall outcome appears relatively favorable and substantially better than that of conventional ductal adenocarcinoma, even when only the cases with invasive carcinoma are considered.

Although p53 inactivation promotes genomic instability1 and presents a route to malignancy for more than half of all human cancers2,3, the patterns through which heterogenous TP53 (encoding human p53) mutant genomes emerge and influence tumorigenesis remain poorly understood. Here, in a mouse model of pancreatic ductal adenocarcinoma that reports sporadic p53 loss of heterozygosity before cancer onset, we find that malignant properties enabled by p53 inactivation are acquired through a predictable pattern of genome evolution. Single-cell sequencing and in situ genotyping of cells from the point of p53 inactivation through progression to frank cancer reveal that this deterministic behaviour involves four sequential phases—Trp53 (encoding mouse p53) loss of heterozygosity, accumulation of deletions, genome doubling, and the emergence of gains and amplifications—each associated with specific histological stages across the premalignant and malignant spectrum. Despite rampant heterogeneity, the deletion events that follow p53 inactivation target functionally relevant pathways that can shape genomic evolution and remain fixed as homogenous events in diverse malignant populations. Thus, loss of p53—the ‘guardian of the genome’—is not merely a gateway to genetic chaos but, rather, can enable deterministic patterns of genome evolution that may point to new strategies for the treatment of TP53-mutant tumours.

The genomic-plasticity of the immune system creates a broad immune repertoire engaged to tackle cancer cells. Promising clinical activity has been observed with several immune therapy strategies in solid tumors including melanoma, lung, kidney, and bladder cancers, albeit as yet immunotherapy-based treatment approaches in pancreatic ductal adenocarcinoma (PDAC) remain to have proven value. While translational and early clinical studies have demonstrated activation of antitumor immunity, most recent late-phase clinical trials have not confirmed the early promise in PDAC except in MSI-High PDAC patients. These results may in part be explained by multiple factors, including the poorly immunogenic nature of PDAC along with immune privilege, the complex tumor microenvironment, and the genetic plasticity of PDAC cells. These challenges have led to disappointments in the field, nonetheless they have also advanced our understanding that may tailor the future steps for immunotherapy for PDAC. Therefore, there is significant hope that progress is on the horizon.