Abstract 762P
Background
Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine carcinoma. Evidence of the clinical characteristics and the efficacy of systemic therapy for patients with MCC in Japan has been lacking. Therefore, we conducted a multicenter retrospective study to clarify the efficacy of systemic treatment using real-world data.
Methods
We collected and analyzed the clinical data of patients from 36 institutions in Japan who were treated with systemic therapy between April 2018 and March 2022.
Results
We identified 76 patients treated with systemic therapy, including 72 patients (94.7%) treated with avelumab and four patients (5.3%) treated with chemotherapy using carboplatin/cisplatin plus etoposide as first-line therapy. The median follow-up period was 11.3 (range, 0.4-103.4) months. The median age was 79 (29-91) years, and 42 patients (55.3%) were stage IV. The response rate of avelumab was 43.1% and the median progression-free survival (PFS) and overall survival (OS) were 9.9 months and 38.7 months for patients with avelumab. For patients with chemotherapy, the response rate was 25.0%, and the median PFS and OS were 3.0 months and 11.1 months, respectively. Thirteen patients received chemotherapy as second-line therapy after avelumab, including seven patients with carboplatin plus etoposide, three patients with cisplatin plus etoposide, one patient with carboplatin, one patient with cyclophosphamide plus adriamycin plus vincristine, and one patient with amrubicin. Although the response rate of second-line chemotherapy was 46.2%, the durability of response was limited as the median PFS was 4.1 months. Three of four patients who received chemotherapy as first-line therapy received avelumab, and one patient achieved a complete response. A common grade 3 or greater adverse event associated with avelumab was infusion reaction (4.0%), and those associated with chemotherapy were neutrophil count decreased (47.1%), including febrile neutropenia (23.5%).
Conclusions
First-line avelumab for patients with MCC in Japan showed favorable efficacy and durability, but developing second-line therapy after avelumab is required.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
National Cancer Center Research and Development Fund (2023-J-03).
Disclosure
All authors have declared no conflicts of interest.