Phase II trial of adjuvant immunotherapy with autologous tumor-derived Gp96 vaccination in patients with gastric cancer.
117 Background: Autologous, tumor-derived heat shock protein Gp96 peptides complexes have shown antitumor potential in various cancers. We conducted the first Phase II trial to evaluate the safety and efficacy of Gp96 vaccination in adjuvant settings for patients with gastric cancer. Methods: Consecutive patients from November 2012 to December 2015 were enrolled. Participants were allocated to the experimental group or control group, receiving Gp96 vaccination plus chemotherapy or chemotherapy alone respectively. The primary endpoints were disease-free survival and toxicity. The secondary outcomes were overall survival and tumor-specific immune responses. Results: Thirty-nine and forty patients received Gp96 vaccination plus chemotherapy and chemotherapy alone in the adjuvant settings respectively. Significant increased tumor-specific immune responses were observed after Gp96 vaccination. There were comparable disease-free survival ( p = 0.413; HR: 0.75; 95% CI: 0.37−1.48) and overall survival ( p = 0.485; HR: 0.68; 95% CI: 0.24−1.96) between experimental group and control group. In subgroup of patients with stage II and stage III gastric cancer, patients who have received Gp96 vaccination had improved disease-free survival compared those who have not ( p = 0.044; HR: 0.45; 95% CI: 0.22−0.96). Gp96 vaccination plus chemotherapy was well tolerated and no Gp96-related serious adverse event has been observed. Conclusions: Gp96 vaccination could elicit tumor-specific immune responses and could be safely used in adjuvant settings combined with chemotherapy. Patients with less aggressive diseases might benefit from Gp96 therapy.