Mature survival and integrated biomarker analyses of the randomised ADMEC-O trial of adjuvant nivolumab in Merckel cell carcinoma

ADMEC-O

Patient / Population Intervention / Exposure Comparison Outcome

In patients with completely resected stage I-IV Merkel cell carcinoma, one year of adjuvant nivolumab did not significantly improve disease-free or overall survival compared with observation.

N

179patients

Design

Phase II, open-label, multicentre trial randomised 2:1 to one year of adjuvant nivolumab or observation after complete resection of stage I-IV Merkel cell carcinoma (NCT02196961; EudraCT 2013-000043-78).

Endpoint

Disease-free survival.

ResultDisease-free survival with nivolumab vs observation HR 0.70 (95% CI 0.38-1.26), a numerical but not statistically significant improvement. Overall survival HR 0.98 (95% CI 0.43-2.27). Grade 3-4 treatment-related adverse events occurred in 40% of nivolumab-treated patients. Mature tertiary lymphoid structures were the only biomarker showing evidence of predictive value for adjuvant nivolumab.

Becker JCC, Dalkoohi M, Ugurel-Becker S, et al. Presented at ESMO Congress 2026, abstract LBA60, 25 October. Not yet published.

Discussion & critique

This final analysis of a 179-patient randomised phase II trial shows no significant gain in disease-free survival from one year of adjuvant nivolumab, and the overall survival hazard ratio of 0.98 has a wide confidence interval. The abstract gives no median follow-up, event counts, arm-level survival rates or P values, so maturity and precision are hard to judge, and the 40% rate of grade 3-4 treatment-related adverse events weighs against the absent survival benefit. The open-label comparison against observation may bias disease-free survival and quality-of-life assessments, and quality-of-life results are not reported. The benefit in patients aged 65 years or younger and the predictive signal for mature tertiary lymphoid structures are exploratory, are reported without figures, and need prospective confirmation.