Patient background and laboratory variables associated with the efficacy of nivolumab after chemoradiotherapy in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is refractory to multidisciplinary treatment. Immunotherapy targeting programmed cell death protein 1 has shown promise in recent years; however, predicting its therapeutic efficacy remains difficult. The present study aimed to identify the factors associated with treatment response in patients receiving nivolumab after radical chemoradiotherapy for ESCC and to predict treatment efficacy based on these factors. A total of 22 patients were classified into partial response (PR) + stable disease (SD) and progressive disease (PD) groups based on their response to nivolumab. Factors associated with the treatment response were analyzed, including clinical stage, patient background and pre-treatment blood test results. Among the 22 patients, nine and 13 were classified into the PR + SD and PD groups, respectively. Notably, treatment efficacy had a significant impact on prognosis. Variables such as height, weight, body mass index, white blood cell count, basophil fraction, platelet count, albumin, creatinine and C-reactive protein were also evaluated. Cut-off values were determined using the Youden index for body weight (53.5 kg), white blood cells (5,000/mm), basophils (0.6%), platelets (145x10/mm), albumin (3.9 m g/dl) and C-reactive protein (0.10 mg/dl). The number of favorable variables was calculated for each patient based on these cut-off values. Nine patients in the PR + SD group had three or more favorable variables, whereas 13 patients in the PD group had two or fewer. In conclusion, although the current study had a limited sample size, the six identified variables appear promising for predicting the efficacy of immune checkpoint inhibitors.