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The prognosis of metastatic pancreatic cancer remains poor despite recent advances in treatment with multidrug chemotherapy regimens. Use of immune checkpoint inhibitors and molecular targeted therapies has so far been disappointing. This report describes a patient with chemotherapy-refractory metastatic pancreatic ductal adenocarcinoma (PDAC) whose tumor was characterized by an activating mutation in exon 19 of the epidermal growth factor receptor (EGFR). He experienced response to erlotinib for 10 months, and then developed disease progression in association with emergence of the T790M mutation. Activating EGFR mutations in cancers other than lung are uncommon, but when present may predict response to EGFR tyrosine kinase inhibitors (TKIs). Development of the T790M mutation in this case suggests that EGFR-targeted TKIs may follow similar patterns of resistance regardless of tumor type. Although actionable mutations are detected infrequently in PDAC, this case illustrates the potential benefit of offering genomic analysis to all patients with advanced disease.

Background: This study sought to assess microsatellite and KRAS status, prevalence, and impact on outcome in stage IV colorectal cancer (CRC). Materials and Methods: The 2010 to 2016 US National Cancer Database was queried for adult patients with stage IV CRC. Prevalence of microsatellite status (microsatellite instability–high [MSI-H] or microsatellite stable [MSS]) and KRAS status (KRAS mutation or wild-type) of the primary CRC was assessed. Overall survival (OS) was evaluated using multivariable Cox proportional hazards models in patients with complete data on both microsatellite and KRAS status and information on follow-up. Results: Information on microsatellite and KRAS status was available for 10,844 and 25,712 patients, respectively, and OS data were available for 5,904 patients. The overall prevalence of MSI-H status and KRAS mutation was 3.1% and 42.4%, respectively. Prevalence of MSI-H ranged between 1.6% (rectosigmoid junction) and 5.2% (transverse colon), and between 34.7% (sigmoid colon) and 58.2% (cecum) for KRAS mutation. MSI-H rates were highest in East North Central US states (4.1%), and KRAS mutation rates were highest in West South Central US states (44.1%). Multivariable analyses revealed longer OS for patients with KRAS wild-type versus mutation status (hazard ratio [HR], 0.91; 95% CI, 0.85–0.97; P=.004), those with MSS versus MSI-H status (HR, 0.75; 95% CI, 0.62–0.9; P=.003), and those with left-sided versus right-sided CRC (multivariable HR, 0.65; 95% CI, 0.6–0.7; P<.001). The effect of KRAS mutation further varied with CRC site and microsatellite status (P=.002 for interaction). Conclusions: Depending on the primary site and US geography, stage IV CRC shows distinct mutational behavior. KRAS mutation, MSI-H, and primary CRC sidedness independently affect OS and interact with distinct prognostic profiles. Generically classifying adenocarcinomas at different sites as CRC might deprecate this diversity.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, with a 5-year survival of 8%. Current therapeutic regimens are largely ineffective and underscore the need for novel treatment strategies. Chromosomal rearrangements involving the anaplastic lymphoma kinase (ALK) gene have been identified in several neoplasms. In addition, ALK protein inhibitors have proven efficacy in patients with ALK-rearranged tumors. However, ALK translocations in PDAC have not been described. Through comprehensive genomic profiling of 3,170 PDACs, we identified 5 cases (0.16%) that harbored an ALK fusion gene: an exon 6 EML4–exon 20 ALK translocation (n=3), an exon 13 EML4–exon 20 ALK translocation (n=1), and an exon 3 STRN–exon 20 ALK translocation (n=1). Among the most prevalent PDAC-related genes, activating KRAS mutations were absent in all 5 cases, who were <50 years of age. Among patients aged <50 years in our study cohort, ALK translocations constituted 1.3% of PDACs. Four of 5 patients were treated with an ALK inhibitor, and 3 of these patients demonstrated stable disease, radiographic response, and/or normalization of serum CA 19-9. Although rare, ALK fusions occur in PDAC, and screening for ALK rearrangements should be considered in young patients with PDAC.