A phase II trial of gemcitabine, irinotecan, and panitumumab in advanced cholangiocarcinoma, with correlative analysis of EGFR, KRAS, and BRAF: An interim report

4111 Background: Cholangiocarcinoma is an aggressive neoplasm. Current chemotherapy approaches achieve modest results. The epidermal growth factor receptor (EGFR) pathway appears to be associated with tumor stage, prognosis and response to therapy. This trial was designed to evaluate the tolerability and efficacy of the combination of panitumumab, a monoclonal anti-EGFR antibody, with gemcitabine and irinotecan, in patients with advanced cholangiocarcinoma. Molecular analysis of EGFR pathway genes was planned as well. Methods: Patients with advanced (unresectable or metastatic) cholangiocarcinoma, ECOG PS 0-2, and adequate liver, kidney and bone marrow function were treated with panitumumab (9 mg/kg) on day 1, and gemcitabine (1000 mg/m2) and irinotecan (100 mg/m2) on days 1 and 8 of a 21-day cycle. Tissue specimens were collected at diagnosis for correlative molecular analyses. Primary objective is to evaluate the 5-month progression-free survival (PFS) rate. Secondary objectives include overall response rate (ORR), overall survival (OS) and toxicity of the combination. Mutational analysis of EGFR (del 19; 858), KRAS (codons 12, 13) and BRAF (V600E) was done on samples with adequate material for testing. Results: There have been 26 (of planned 42) patients recruited to the study. A median of 6 (0-30) cycles were administered. There were no treatment related deaths. The most common gr 3 or higher toxicities were neutropenia (10 pts, 38%), thrombocytopenia (10 pts, 38%), skin rash (10 pts, 38%) and diarrhea (3 pts, 12%). During the study, there were 3 CR, 6 PR, 10 SD (disease control rate of 90%), and 2 PD (by RECIST) in 21 evaluable pts. Two pts went on to have surgical resection. Median OS is 12.7 months. Of 13 testable samples, no EGFR or BRAF mutations were identified; however, there were 7 KRAS mutations. Retrospective analysis showed no difference in OS by KRAS mutation status. Conclusions: Interim evaluation of this ongoing study showed encouraging tolerability and efficacy of this regimen. Several patients have KRAS mutations; there appears to be no association with response, however. The pre-specified efficacy criteria to continue enrollment were met.