Real-world outcomes of patients receiving salvage therapies for immune checkpoint inhibitor-resistant Merkel cell carcinoma: a rationale for future clinical trials

Cancer research · Merkel cell carcinoma

Adding radiation to immunotherapy was the only salvage treatment regimen clearly linked to better survival after disease progression on immunotherapy.

In this prospective single‑center cohort of 106 Merkel cell carcinoma (MCC) patients who progressed during or shortly after immune‑checkpoint inhibitor (ICI) therapy, salvage interventions were evaluated. Patients were stratified as primary resistance (no response to initial ICI) or acquired resistance (loss of ICI response after initial benefit). The primary outcomes were progression‑free survival (PFS) and disease‑specific survival (DSS). Median PFS was 9.5 months for acquired resistance versus 4.7 months for primary resistance (p=0.006). Median DSS was not reached for acquired resistance and 14.3 months for primary resistance (p=0.006). Only the combination of ICI plus radiation therapy (RT) was significantly associated with improved DSS relative to ICI alone (adjusted HR 0.35, 95% CI 0.14–0.91).

These findings provide baseline survival metrics for patients with ICI‑refractory Merkel cell carcinoma and support future trials testing multimodal salvage strategies, particularly combining radiation with immunotherapy.

Evidence level: Korai humán adat. Kis vagy feltáró emberi adat.

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