Real-world outcomes of metastatic clear cell sarcoma sequential chemotherapy.

Clear cell sarcoma is an ultra-rare chemoresistant subtype of soft tissue sarcoma. This retrospective analysis aimed to clarify the efficacy of palliative chemotherapy in CCS by assessing response rates, progression-free survival (PFS), and overall survival (OS) at a referral center. A retrospective analysis of palliative treatment was conducted on patients with CCS treated at the sarcoma unit from 1997 to 2023. Treatment responses were assessed using RECIST criteria, and the Kaplan-Meier method was used to calculate PFS and OS. The analysis covered 23 CCS chemotherapy-treated patients with 11 (47.8%) men. The median age at the palliative treatment start was 32 years (range 18-59). The median follow-up was 8.2 months. Four patients were referred to our centre for M1 disease, and 6 received perioperative chemotherapy and progressed during follow-up. In the first line, 14 patients received anthracycline-based chemotherapy (60.9%), five were treated with ifosfamide (HD-IFO), and four received other regimens. One patient (4.3%) achieved partial response (PR), and 12 patients (52.2%) achieved stable disease (SD) as the best response. Median PFS in 1 line was 2.79 months (95% CI: 2.04-8.38), and 1.76 months (95% CI: 0.72-6.97) in the second line. The median OS from first-line palliative chemotherapy was 8.2 months (95% CI: 6.2-14), and the second-line palliative chemotherapy mOS was 4.6 months (95% CI: 3.9-NA). Perioperatively anthracycline-pretreated worsened patients' median PFS in the M1 setting. Poor responses to conventional chemotherapy were observed in CCS, indicating a need for further clinical trials in this indication.