RATIONALE 311: tislelizumab plus concurrent chemoradiotherapy for localized esophageal squamous cell carcinoma

Definitive chemoradiotherapy is the standard of care for inoperable locoregionally advanced esophageal squamous cell carcinoma (ESCC). Immune checkpoint inhibitors such as anti-PD-1/PD-L1 antibodies have led to a paradigm shift in advanced, metastatic ESCC treatment; however, the effect of incorporating checkpoint inhibitors in the definitive management of ESCC is unclear. Tislelizumab is an anti-PD-1 antibody specifically engineered to minimize Fc gamma R binding on macrophages to abrogate antibody-dependent phagocytosis, a mechanism of T-cell clearance and potential resistance to anti-PD-1 therapy. The RATIONALE 311 study described here (BGB-A317-311; NCT03957590) is a registrational multicenter, double-blind, placebo-controlled, randomized, Phase III clinical trial designed to evaluate the efficacy and safety of tislelizumab combined with concurrent chemoradiotherapy in patients with inoperable localized ESCC. Lay abstract: Esophageal cancer is a challenging disease that seriously threatens patients' health and life. Esophageal squamous cell carcinoma (ESCC) is the most common type of esophageal cancer. Most patients who have inoperable stage II-IV ESCC are currently treated with a sequential combination of chemotherapy and radiation therapy, with the hopes of increasing the positive effects seen from either therapy alone. Immune checkpoint inhibitors such as anti-PD-1/PD-L1 antibodies have shown encouraging results in patients with ESCC, but it is not known if combining checkpoint inhibitors with simultaneous chemotherapy and radiation therapy will provide additional benefits. The safety and efficacy of tislelizumab, an anti-PD1 antibody specifically engineered to limit potential resistance to anti-PD-1 therapy, is being investigated in combination with simultaneous chemotherapy and radiation therapy in patients with inoperable stage II-IV ESCC in an actively enrolling clinical trial, RATIONALE 311 (NCT03957590). Our trial in progress article explains the reason RATIONALE 311 was started and provides important enrollment information for doctors.