A protocol for a randomized trial evaluating the role of carbon-ion radiation therapy plus camrelizumab for patients with locoregionally recurrent nasopharyngeal carcinoma

Purpose: Management of locoregionally recurrent nasopharyngeal carcinoma (LR NPC) is difficult. Although carbon-ion radiation therapy (CIRT) could substantially improve the overall survival (OS) of those patients, around 40% of the patients may still develop local failure. Further improvement of the disease control is necessary. Immunotherapy, such as immune checkpoint inhibitors (ICIs) becomes a promising antitumor treatment. The role of ICIs was proved in head and neck cancers including recurrent/metastatic NPC. Preclinical studies indicated potential synergistic effects between radiation therapy and ICIs. Therefore, we conduct a randomized phase 2 trial to evaluate the efficacy and safety of camrelizumab, an anti-PD-1 monoclonal antibody, along with CIRT in patients with LR NPC.Methods: Patients will be randomly assigned at 1:1 to receive either standard CIRT with 63 Gy (relatively biological effectiveness, [RBE]) in 21 fractions, or standard CIRT plus concurrent camrelizumab. Camrelizumab will be administered intravenously with a dose of 200 mg, every 2 week, for a maximum of 1 year. We estimate addition of camrelizumab will improve the 2-year progression-free survival (PFS) from 45% to 60%. A total of 146 patients (with a 5% lost to follow-up rate) is required to yield a type I error of 0.2, and a power of 0.8.Results and Conclusion: The results of the trial may shed insights on the combined therapy with ICIs and CIRT.