A Phase 1b Clinical Trial of Neoadjuvant Radio-immunotherapy for Esophageal Squamous Cell Cancer

Neoadjuvant chemoradiotherapy is the recommended treatment for patients with resectable esophageal cancer but is associated with a higher incidence of adverse effects. Given the efficacy of immunotherapy, we propose a chemotherapy-free regimen of neoadjuvant radio-immunotherapy (NRIT) to balance therapeutic efficacy and potential side effects or overtreatment. In this phase 1b clinical trial, we assessed the safety and efficacy of NRIT in esophageal squamous cell cancer. The enrolled patients received 41.4 Gy of radiation and 4 cycles of 240 mg of toripalimab injection before surgery. The primary endpoint was treatment-related adverse events and the secondary endpoints were pathologic complete response and major pathologic response. Immunohistochemistry and multiplex immunofluorescence staining were used to evaluate the tumor microenvironment before and after neoadjuvant treatment. Of the 22 patients enrolled, 19 underwent R0 surgery. One patient discontinued neoadjuvant immune therapy due to experiencing a grade 3 treatment-related adverse event. Three patients did not undergo surgery due to tumor progression or side effects. Among the patients who underwent surgery, 3 patients experienced serious complications shortly after surgery. Upon pathologic evaluation, the pathologic complete response and major pathologic response rates were 47.4% and 68.4%, respectively. The NRIT regimen is safe and feasible for patients with esophageal squamous cell cancer.