Supplementary Material for: Pancreatic adenocarcinoma with co-occurrence of KRAS and EGFR mutations, case report and literature review

Introduction: Mutation in KRAS (Kristin ras sarcoma virus) oncogene is the main driver in pancreatic ductal adenocarcinoma (PDAC) and is present in nearly 90% of patients with PDAC. EGFR (epidermal growth factor receptor) mutation is rare in PDAC and is mostly present in the absence of KRAS mutation. Co-occurrence of KRAS and EGFR mutations is extremely rare, and the value of EGFR inhibition in these cases is unknown. Case Presentation: Here we present a case of metastatic PDAC with co-occurrence of KRAS G12V and EGFR L730R. Despite primary resistance to FOLFIRINOX (folinic acid, fluorouracil, irinotecan, oxaliplatin) and Gemcitabine/nab-paclitaxel, this patient had biochemical response (decrease in carbohydrate antigen (CA) 19-9), and disease control of seven months on Gemcitabine/Erlotinib (an EGFR inhibitor). This response is remarkable in the late-line PDAC treatment setting and is unusual after progression of the tumor on Gemcitabine/nab-paclitaxel chemotherapy. Conclusion: This case suggests that Gemcitabine/Erlotinib could be an effective treatment in patients with PDAC and co-occurrence of EGFR and KRAS mutations.