In a real-world cohort of older patients in Austria, avelumab (Bavencio) was determined to be effective for treating Merkel cell carcinoma (MCC), despite frequent adverse events (AEs).

“Avelumab achieved clinically meaningful outcomes in this older, less-selected routine care cohort,” said first author Magdalena Forstinger, MD, a physician-researcher with Sigmund Freud Privatuniversität and Klinik Hietzing, Vienna. “Adverse events affected treatment in some patients, underscoring the importance of careful monitoring,” she added.

Forstinger presented the findings on October 2 at the European Academy of Dermatology and Venereology (EADV) 2026 Congress in Vienna. 

In 2017, avelumab, a programmed death ligand-1 (PD-L1)-blocking antibody, became the first treatment approved by the FDA for MCC. The study abstract noted, however, that evidence of the drug’s efficacy and safety in a routine clinical care context was limited, particularly among older patients, a population more likely to be immunocompromised and have comorbidities, who are underrepresented in trials. 

The nationwide, multicenter, retrospective chart review included patients with inoperable locally advanced or metastatic MCC who had received at least one cycle of avelumab, with no other exclusion criteria applied, Forstinger said. A total of 49 patients were included in the study, with a median age of 81 years (range, 62-96). The most common comorbidities were cardiovascular, metabolic, oncologic, and pulmonary. 

The primary endpoint was real-world progression-free survival (rwPFS). Secondary endpoints included real-world overall survival (rwOS), objective response rate (rwORR), duration of response (rwDOR), and time to response (rwTTR), and safety.

At the start of treatment, 42.9% of participants had stage IIIB MCC and 57.1% had stage IV MCC. A total of 16.3% were immunocompromised or immunosuppressed, and 77.6% had an ECOG performance status ≤ 1. Avelumab was administered as first-line monotherapy in 77.6% of cases, with 22.4% also receiving other modalities such as radiotherapy. Median follow-up was 8.9 months (range, 0-73.1). 

Nearly half of evaluable patients (n=48) responded to avelumab, Forstinger said, and median rwPFS, the primary endpoint, was 10.1 months (95% CI, 1.8-18.4). The rwORR was 47.9% (95% CI, 34.5-61.7), and median rwOS was 22.9 months (95% CI, 5.0-40.8). Median rwTTR was 3.9 months (range, 1.4-12.7), and median rwDOR among responders was 19.2 months (95% CI, 8.9-29.5).

Forstinger observed that rwPFS and rwOS were in a similar range to those reported in the 2021 phase 2 JAVELIN Merkel 200 trial (which evaluated first-line avelumab in patients with metastatic MCC), although rwORR was lower. JAVELIN did not include immunocompromised patients, she added.

Overall, 71.4% of patients experienced an AE and 53.1% experienced an immune- and/or treatment-related AE, including 24.5% who had a grade ≥ 3 AE. AEs led to treatment interruption or discontinuation in 28.6% of participants, including permanent discontinuation in 12.2% of cases.

Previously reported AEs for avelumab in patients with MCC include fatigue, musculoskeletal pain, infusion-related reactions, rash, nausea, constipation, cough, and diarrhea. Potentially serious immune-mediated adverse reactions include pneumonitis, colitis, hepatitis, endocrinopathies, nephritis with renal dysfunction, and dermatologic reactions.

In a post-hoc analysis, scores of ≤ 1 on the ECOG performance status scale, which describes a patient’s level of function, were associated with lower hazard ratios (HRs) for rwPFS (HR, 0.257; 95% CI, 0.100-0.658; P = .005) and rwOS (HR, 0.157; 95% CI, 0.047-0.521; P = .002). Forstinger said these findings should be interpreted as “hypothesis-generating.”

Forstinger has reported no relevant financial relationships.

Scott Harris has covered dermatology for more than a decade. He lives near Washington, DC.