Analysis of clinical characteristics and immunotherapy outcomes in Chinese patients with Merkel cell carcinoma.

e21507 Background: Merkel cell carcinoma (MCC) is a rare neuroendocrine tumour of cutaneous origin. Due to its high malignancy and low incidence, few prospective clinical studies have been conducted. In addition to surgery, the main treatment for MCC is immunotherapy. However, whether immunotherapy is effective for MCC patients in China has not been reported in clinical studies. Therefore, it is necessary to analyze clinical characteristics and their treatment-related information. Methods: A total of 40 patients with Merkel cell carcinoma diagnosed by histopathology from November 2011 to October 2024 at Tianjin Medical University Cancer Hospital were included in this study. Sixteen of these patients had sufficient clinical information to be included in the analysis. SPSS 23.0 was used for clinical characteristics analyses. For the patients who had received immunotherapy, the therapeutic effect was summarized and analyzed. Results: A total of 40 patients with Merkel cell carcinoma were included in our study with basic information. Of these, 20 patients only had pathological consultation and were not undergoing follow-up treatment. Four patients were lost to follow-up, and finally 16 patients had sufficient clinical information to be included in the final analysis. In total MCC patients, the median age was 71 years (range 25-91 years), with 25 women and 15 men. Of the 16 patients ultimately included in the analysis, 15 underwent extensive resection and 1 did not. Among the patients treated with surgery, 1 (1/15) patient operative area received postoperative adjuvant radiotherapy, and 2 (2/15) patients underwent regional lymph node dissection in addition to extensive resection of the primary site. Analyzed from the perspective of systemic therapy, a total of Four patients received Pembrolizumab 200 mg every 3 weeks. According to the Resist 1.1 evaluation criteria, three patients benefited significantly and the efficacy evaluation was CR. Unfortunately, one patient died due to other reasons after 4 cycles of drug treatment and did not have time for efficacy evaluation. Of the three patients with CR, two patients were evaluated as CR on imaging after immunotherapy and later confirmed as pathological CR. No significant adverse reactions were observed during the administration of the drug in all patients who received immunotherapy. Conclusions: MCC develops at an older age, and although its treatment options are limited, favorite results from clinical studies in Western countries can also benefit Chinese MCC patients.