OBJECTIVES: The number needed to treat (NNT) analysis offers a simple approach to estimate the relative benefit of a new therapy by estimating the number of patients needed to be treated to prevent an additional outcome. CheckMate 577 was a global randomized, placebo (i.e. surveillance) controlled phase 3 trial of patients with EC/GEJC who previously received chemoradiotherapy followed by resection. Patients receiving adjuvant nivolumab had a statistically significant and clinically meaningful improvement in the primary endpoint, disease-free survival (DFS), versus surveillance. Overall survival data is currently not mature. The objective of this study was to evaluate the NNT to achieve one additional DFS event for nivolumab versus surveillance over 12, 24, and 36 months.

METHODS: Data from the CheckMate 577 trial from the Feb 2021 database lock with a median follow-up of 32.2 months were used. DFS rates at 12, 24, and 36 months were estimated based on the intention-to-treat population. NNT per additional disease-free survivor was estimated as the reciprocal of the absolute difference between the DFS rates of nivolumab and surveillance.

RESULTS: In the nivolumab arm (n = 532), the DFS rate was 62%, 48%, and 44% versus 45%, 36%, and 28% in the surveillance arm (n = 262) at 12, 24, and 36 months respectively. To prevent one disease recurrence/death at 12, 24, and 36 months, 6, 8, and 7 patients would have to be treated with nivolumab over surveillance.

CONCLUSION: In patients with resected EC or GEJC, treatment with adjuvant nivolumab was associated with higher DFS rates versus surveillance. Over three years, on average, 7 patients would have to be treated with nivolumab over surveillance to prevent 1 additional recurrence/death. The results of this study show that nivolumab has the potential to be an effective treatment option for patients with resected EC/GEJC in the adjuvant setting.