RAS mutations and their correlation with survival of patients with advanced pancreatic adenocarcinoma.

Abstract

325 Background: The prognosis of pancreatic adenocarcinoma (PA) remains poor despite FOLFIRINOX and nab-paclitaxel-gemcitabine based chemotherapy. The epidermal growth factor receptor (EGFR) has a major role in pancreatic cancer carcinogenesis.The RAS status showed to be a predictive factor for response to anti-EGFR therapy in colon cancer. We aim to analyze the K-RAS and N-RAS status in PA and its prognostic impact. Methods: Retrospective analysis included 24 patients with metastatic (67%) or locally advanced (29%) PA at diagnosis (AEMOC, Brazil). K-RAS and N-RAS profile were performed by polymerase chain reaction and bidirectional sequencing (codons 12, 13, 61, 117, 146). The results were then analyzed in regards to overall survival (OS) and progression-free survival (PFS) in PA. Results: The sample showed: median age of 63 years (28-86), 62.5% male, 45.8% smoker, head site (67%), ductal (68%), and mild differentiation features (45%). The first-line therapy was FOLFIRINOX (62.5%) and gemcitabine (33.3%). The median PFS and OS were 6.5 and 13 months (mo), respectively. Nineteen patients (79.1%) presented mutation in K-RAS: four c.35G>A (G12D), four c.34G>C (G12R), four c.35G>T (G12V), three c.35G>C (G12A), one c.437C>T (A146V), and one c.34G>T (G12C). Mutation in N-RAS (c.38G>A (G13D) was detected in only one patient (4%). The only independent factor for survival was K-RAS status: the c.35G>A (G12D) polymorphism yielded worse PFS and OS when compared to non-c.35G>A (G12D) mutation: 3 vs 7 mo [HR 0.25, 95% CI, (0.04–1.63)] for PFS (p<0,0043) and 3.5 vs13 mo [HR 0.17, 95% CI, 0.01-1.58)] for OS (p<0,0001), respectively. Conclusions: K-RAS was the only prognostic factor for PFS and OS, with the polymorphism c.35G>A (G12D) being related to a worse prognostic. Further studies are necessary to better evaluate whether K-RAS and N-RAS status is prognostic and/or predictive factor.