ADAM (Adjuvant Avelumab in Merkel) Trial: Using Avelumab in Stage 3 MCC to Prevent MCC Recurrence

Background

When Merkel cell carcinoma (MCC) has spread to nearby lymph nodes, it can be difficult to control even after local treatment (surgery and/or radiation). More than 50% of patients in this situation see their cancer return and historically the chance of cancer-related death was close to 50%.

The ADAM trial asked whether adding immunotherapy proactively after local treatment could reduce that risk. The study tested avelumab, an immune checkpoint inhibitor that works by releasing a “brake” on the immune system and energizing the immune cells to recognize and attack cancer cells. This was a phase 3 trial, the gold standard for evaluating new treatments, in which 100 patients were randomly assigned to receive either avelumab or a matched placebo for up to 2 years total. All patients received similar close surveillance for the possibility of cancer recurrence.

What the Study Found

Patients who received avelumab after prior local treatment went longer without their cancer returning compared to those who received placebo. The benefit was substantial: avelumab cut the risk of relapse roughly in half. The probability of MCC recurrence at 2 years was 21% in the avelumab arm and 42% in the placebo arm.

One particularly encouraging finding was that the cancer-related survival rates remained high in both groups, with 92% of all patients alive and free of MCC-related death by the end of the study period. This suggests that patients on the placebo arm were effectively treated with immunotherapy after their cancer had come back. Researchers believe that this reflects the effectiveness of checkpoint inhibitor immunotherapy both as an initial treatment and as a treatment for relapse when it does occur.

Why This Matters

For patients with stage 3 MCC with lymph node involvement, these results offer a meaningful new option for reducing the chance that cancer will return after initial treatment. The ADAM trial data will help patients and their doctors weigh the potential benefits of adjuvant immunotherapy against individual circumstances and make more informed, personalized decisions about next steps. Patients can choose to get immunotherapy proactively after surgery to minimize the chance of cancer recurrence. Alternatively, they can choose to get close surveillance and receive immunotherapy reactively upon recurrence. Either strategy offers an excellent chance of long-term survivorship.

Citation: Bhatia, S., Gooley, T., Brohl, A. S., et al  (2026). ADAM trial: A multicenter, randomized, double-blinded, placebo-controlled, phase 3 trial of adjuvant avelumab (anti-PD-L1 antibody) in patients with Merkel cell carcinoma and lymph node metastases. Journal of Clinical Oncology, 44(17), LBA9504-LBA9504.