Molecular profile of ampulla of vater carcinoma (AVC): A rare tumor type with meaningful molecular alterations.
4119 Background: AVC is a rare type of cancer with dismal prognosis and limited therapeutic options due to the lack of specific clinical trials. Two histologic subtypes predominate, namely pancreatobiliary and intestinal. A variety of molecular alterations have been described in AVC, but their clinical and therapeutic implications have not been studied in detail. Methods: Retrospective cohort study of patients (pts) diagnosed with AVC treated in our institution from 2010 to 2018. We routinely performed Next Generation Sequencing in all AVC tumors. Our main objectives were to describe the molecular profile of AVC and correlate with clinical outcomes. Results: Out of 26 pts with AVC, 13 pts were male (50%), median age 65 (range 43-83), 7 pts (27%) had stage IV disease at diagnosis. Histologic type was pancreatobiliary in 18 pts (69%), intestinal in 7 pts (27%) and mixed in one case (4%). We identified KRAS mutations (mut) in 10 pts (7 pancreatobiliary, 2 intestinal, 1 mixed), TP53 mut in 6 pts (4/1/1), PIK3CA mut in 3 pts (3/0/0), ERBB2 mut in 3 pts (2/1/0), CTNNB1 mut in 3 pts (2/1/0). In pancreatobiliary we found single cases with RNF43, BRCA1 and CHEK2 mut; while in intestinal we found single cases with NRAS and BRAF mut. One tumor of intestinal subtype had microsatellite instability (MSI). Three pts were included in phase I clinical trials, 2 of them with trials based on tumor profile (ERBB2 mut with pan-HER inhibitor and MSI with immunotherapy). Median overall survival (OS) was 21 months for pts with stage I, II and III disease (95% CI 12.37-not reached) and 13.2 months for stage IV disease at diagnosis (95% CI 5.73-not reached). In cox models, median OS was not dependent on KRAS or TP53 mutation status, or histological subtypes. Conclusions: AVC is a rare type of cancer with two differentiated histological subtypes harboring unique molecular alterations that can be matched to investigational therapies. A broader knowledge of the biology of these tumors is needed to improve patient outcomes.