Human equilibrative nucleoside transporter 1 (hENT1) in gemcitabine and FOLFOX (oxaliplatin, 5-fluorouracil, and leucovorin)-treated patients with metastatic pancreatic cancer: The randomized phase II PAN1 study

228 Background: GEM-based treatment is a standard treatment for metastatic pancreas cancer. Monotherapy efficacy is only modest, and outcomes are improved by combination treatment or the non-GEM FOLFIRINOX triplet. There is a need for biomarkers to select between these divergent options. hENT1 is a potential predictive marker of benefit from GEM, but conflicting results have been observed in studies that have evaluated resected and metastatic pancreatic cancer. This principal objective of this study was to evaluate hENT1 prospectively as a predictive marker in GEM and non-GEM treated patients. Methods: Patients with previously untreated metastatic pancreatic adenocarcinoma and tumour tissue available for hENT1 testing were randomized between GEM (1,000 mg/m2 D1, 8, 15 Q4w) or FOLFOX (oxaliplatin 85 mg/m2, 5-fluorouracil (5FU) 400 mg/m2, leucovorin 400 mg/m2 D1 and 5FU 2,400 mg/m2over 46 hours D1-3) until disease progression or unacceptable toxicity. Tumor samples were tested prospectively for hENT1 by immunohistochemistry. The primary endpoint was progression-free survival (PFS). Results: The study was open from July 2011 to February 2013, but closed after 16 of the planned 80 patients were enrolled. 1 patient who died before treatment was excluded from the outcome analysis. 7/16 patients were hENT1 high (43.8%, 95%CI 23.1-66.8%). In the GEM arm (n=7), the 4 who were hENT1 high had longer PFS and overall survivals (OS) than those who were hENT1 low (median PFS 5.7 vs. 1.8 months; median OS 13.9 vs. 3.5 months), whereas outcomes were similar with FOLFOX for both hENT1 groups. There were no unexpected adverse events. Conclusions: This prospective study showed a longer survival in those patients with high hENT1 treated with GEM. There was no difference in survival according to hENT1 expression in patients treated with FOLFOX. Given the small sample size this may be due to chance, but supports the need for further research into the predictive value of hENT1. Clinical trial information: ACTRN12610001047088.[Table: see text]