207 Background:ATTRACTION-1/ONO-4538-07 (AT-1), an open-label, single-arm, multicenter phase 2 clinical trial conducted in Japan, evaluated the clinical activity and safety of nivolumab in patients with advanced esophageal squamous cell carcinoma (ESCC) refractory/intolerant to fluoropyrimidine-, platinum-, and taxane-based chemotherapy. We previously reported the 2-year follow-up findings of AT-1, in which nivolumab demonstrated antitumor activity with a manageable safety profile for these patients. Here we report the final findings from AT-1 at a minimum follow-up of 5 years. Methods:Patients aged ≥20 years with an Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1 received 3 mg/kg nivolumab intravenously every 2 weeks in 6-week cycles until disease progression or unacceptable toxicity. The primary endpoint was centrally-assessed objective response rate (ORR), defined as the proportion of patients whose best overall response was either a complete or partial response. Secondary endpoints included overall survival (OS), investigator-assessed ORR, progression-free survival (PFS), change in tumor burden, time to response, time to disease progression, and duration of response. Results:Between February 25 and November 14, 2014, a total of 65 patients were enrolled. Sixty-four patients were evaluated for the efficacy, and all patients were evaluated for the safety. At the final database lock on August 6, 2020, 11 (17.2%, 95% confidence interval [CI] 9.9-28.2) of 64 patients had an objective response by central assessment. The median OS was 10.8 months (95% CI, 7.4-13.9), and the estimated 5-year OS rate was 6.3% (95% CI, 2.0-14.0). The median PFS was 1.5 months (95% CI, 1.4-2.8), and the estimated 5-year PFS rate was 6.8% (95% CI, 2.2-15.1). Treatment-related adverse events that occurred with a frequency of > 10% were diarrhea and rash. The presentation will include characteristics of long-term survivors as well as detailed efficacy and safety data of nivolumab. Conclusions:This final assessment represents the longest follow-up of patients with advanced ESCC treated with nivolumab. Nivolumab demonstrated continued long-term efficacy in these patients based on a minimum of 5-year long-term survival update of AT-1. Furthermore, no new safety signals with nivolumab were identified during long-term follow-up. These findings are consistent with those of nivolumab monotherapy for various types of cancer. Clinical trial information: No.142422.
Monitoring disease progression and treatment efficacy with circulating tumor cells in esophageal squamous cell carcinoma: A case report