Elpamotide

Gemcitabine is a key drug for the treatment of pancreatic cancer; however, with its limitation in clinical benefits, the development of another potent therapeutic is necessary. Vascular endothelial growth factor receptor 2 is an essential target for tumor angiogenesis, and we have conducted a phase I clinical trial using gemcitabine and vascular endothelial growth factor receptor 2 peptide (elpamotide). Based on the promising results of this phase I trial, a multicenter, randomized, placebo‐controlled, double‐blind phase II/III clinical trial has been carried out for pancreatic cancer. The eligibility criteria included locally advanced or metastatic pancreatic cancer. Patients were assigned to either the Active group (elpamotide + gemcitabine) or Placebo group (placebo + gemcitabine) in a 2:1 ratio by the dynamic allocation method. The primary endpoint was overall survival. The Harrington–Fleming test was applied to the statistical analysis in this study to evaluate the time‐lagged effect of immunotherapy appropriately. A total of 153 patients (Active group, n = 100; Placebo group, n = 53) were included in the analysis. No statistically significant differences were found between the two groups in the prolongation of overall survival (Harrington–Fleming P‐value, 0.918; log–rank P‐value, 0.897; hazard ratio, 0.87, 95% confidence interval [CI], 0.486–1.557). Median survival time was 8.36 months (95% CI, 7.46–10.18) for the Active group and 8.54 months (95% CI, 7.33–10.84) for the Placebo group. The toxicity observed in both groups was manageable. Combination therapy of elpamotide with gemcitabine was well tolerated. Despite the lack of benefit in overall survival, subgroup analysis suggested that the patients who experienced severe injection site reaction, such as ulceration and erosion, might have better survival.

Background Elpamotide is an HLA-A*24:02-restricted epitope peptide of vascular endothelial growth factor receptor 2 (VEGFR-2) and induces cytotoxic T lymphocytes (CTLs) against VEGFR-2/KDR. Given the high expression of VEGFR-2 in biliary tract cancer, combination chemoimmunotherapy with elpamotide and gemcitabine holds promise as a new therapy. Patients and Methods Patients with unresectable advanced or recurrent biliary tract cancer were included in this single-arm phase II trial, with the primary endpoint of overall survival. Survival analysis was performed in comparison with historical control data. The patients concurrently received gemcitabine once a week for 3 weeks (the fourth week was skipped) and elpamotide once a week for 4 weeks. Results Fifty-five patients were registered, of which 54 received the regimen and were included in the full analysis set as well as the safety analysis set. Median survival was 10.1 months, which was longer than the historical control, and the 1-year survival rate was 44.4 %. Of these patients, injection site reactions were observed in 64.8 %, in whom median survival was significantly longer (14.8 months) compared to those with no injection site reactions (5.7 months). The response rate was 18.5 %, and all who responded exhibited injection site reactions. Serious adverse reactions were observed in five patients (9 %), and there were no treatment-related deaths. Conclusion Gemcitabine and elpamotide combination therapy was tolerable and had a moderate antitumor effect. For future development of therapies, it will be necessary to optimize the target population for which therapeutic effects could be expected.