A peptide-based neoantigen vaccine for patients with advanced pancreatic cancer refractory to standard treatment.

e14563 Background: Tumor-specific neoantigens are considered as personalized and potential ultimate targets for cancer immunotherapy. Recently, neoantigen cancer vaccines have been designed to train the patient's immune system to specifically target and kill tumor cells. However, the safety and efficacy of neoantigen vaccines in pancreatic cancer treatment remain poorly understood. Methods: Personalized peptide neoantigen cancer vaccines were successfully designed and manufactured for pancreatic cancers with low tumor mutation burden. Seven patients with advanced pancreatic cancer refractory to standard treatments were enrolled and treated with personalized peptide neoantigen vaccine, iNeo-Vac-P01. Besides the evaluation of the safety and clinical efficacy of iNeo-Vac- P01, pre- and post-vaccination peripheral blood samples were collected to analyze the vaccine’s immunogenicity. Results: For all 7 patients, none sever vaccine-related adverse effects was witnessed. The mean progression free survival, overall survival (OS) and OS associated with vaccine treatment were 3.1, 24.1 and 8.3 months, respectively. For Patient P01, who had a 21-month OS associated with vaccine treatment, the abundance of the TCR clone remarkably increased after vaccination, indicating the potential of iNeo-Vac-P01 to specifically induce a subset of T cells to kill tumor cells. This study also demonstrated that the quantity of IFN-γ in peripheral blood might be a potential biomarker for OS. Conclusions: We believed that it was the first tentative study focused in the application of peptide-based neoantigen cancer vaccine in advanced pancreatic cancer. Promisingly, personalized peptide neoantigen vaccine might provide a new strategy to improve the limited clinical efficacy for pancreatic cancer. Clinical trial information: NCT03645148.