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Simple Summary: We present a case series of 16 patients with pancreatic acinar cell carcinoma treated at our institution for whom available molecular information was evaluated. Most of the patients had metastatic disease, and all patients tested for KRAS mutations were KRAS wild type. Five of 12 patients who underwent DNA damage repair gene testing had germline and/or somatic mutations. One patient was found to have RET fusion and responded favorably to selpercatinib for over 42 months. We also include two additional cases who underwent BostonGene testing, including genomic alterations, RNA expression, and tumor microenvironment (TME) features. One of the two cases was found to have NTRK1 fusion. These findings highlight the need for further investigation of acinar cell carcinoma using larger samples to refine treatment strategies for this rare pancreatic cancer. Objectives: Acinar cell carcinoma (ACC) accounts for about 1% of pancreatic cancers. The molecular and clinical features of ACC are less characterized than those of pancreatic ductal adenocarcinoma. Methods: We retrospectively evaluated the clinical and molecular features of ACC patients who underwent germline and/or somatic molecular testing at The University of Texas MD Anderson Cancer Center from 2008 to 2022 and two cases from 2023–2024 who underwent RNA and TME analysis by Boston Gene. Patient information was extracted from our institutional database with the approval of the Institutional Review Board. Results: We identified 16 patients with available molecular testing results. Fourteen patients had metastatic disease, one had borderline resectable disease, and one had localized resectable disease at diagnosis. Fifteen patients were wild type for KRAS (one patient had unknown KRAS status). Somatic/germline mutations of DNA damage repair genes (BRCA1/2, PALB2, and ATM) were present in 5 of 12 patients tested for these genes. One patient was found to have RET fusion and responded favorably to selpercatinib for over 42 months. The median overall survival (OS) was 24 months for patients with metastatic disease. One of the additional two cases who underwent BostonGene testing was found to have NTRK1 fusion. RNA and TME analysis by Boston Gene of the two cases reported immune desert features and relatively lower RNA levels of CEACAM5, CD47, CD74, and MMP1 and higher RNA levels of CDH6 compared with PDAC. [ABSTRACT FROM AUTHOR]

BackgroundPancreatic adenosquamous carcinoma has historically been characterized as having a more aggressive clinical course than ductal adenocarcinoma. The natural history of this disease, however, is essentially unknown.MethodsWe evaluated the clinical characteristics of all patients with pancreatic adenosquamous carcinoma recorded in the California Cancer Registry 2000-2007 and compared them to those of patients with ductal adenocarcinoma.ResultsNinety-five patients with pancreatic adenosquamous carcinoma and 14,746 patients with ductal adenocarcinoma were identified. Demographics were similar between subtypes (p > 0.05). Disease stage at presentation was also similar; over 50% of each diagnostic group presented with metastatic disease (p = 0.62). Surgical resection was more common among patients with locoregional adenosquamous carcinoma than adenocarcinoma (p = 0.0004), but rates of adjuvant therapy administration were similar (p > 0.05). The cohorts' median overall survival durations were similar in a Cox proportional hazards model (p = 0.45); overall survival was also similar when only patients with resected disease were considered (p = 0.65). Early stage, resection and receipt of radiation or chemotherapy were favorable independent prognostic factors among patients with adenosquamous carcinoma. The median overall survival duration of patients with resected adenosquamous carcinoma was 12 months (95% CI, 8-52).ConclusionsAdenosquamous carcinoma has a natural history similar to that of ductal adenocarcinoma when treated with prevalent clinical patterns of care.