Camrelizumab combined with liposomal doxorubicin and dacarbazine as first-line therapy for advanced, recurrent, and metastatic undifferentiated pleomorphic sarcoma: A phase II study.

11513 Background: This phase II study aims to evaluate the efficacy and safety of camrelizumab combined with liposomal doxorubicin and dacarbazine in patients with advanced, recurrent and metastatic undifferentiated pleomorphic sarcoma (UPS). Methods: Patients with histologically confirmed advanced, recurrent and metastatic UPS, treatment-naïve for advanced disease, and at least one measurable lesion per RECIST v1.1 were eligible. Camrelizumab was administered in combination with liposomal doxorubicin and dacarbazine for up to six cycles, followed by camrelizumab maintenance therapy. The primary endpoint was investigator-assessed objective response rate (ORR) per RECIST v1.1. Secondary endpoints included progression-free survival (PFS), overall survival (OS), duration of response (DoR), and safety. Results: Between October 2022 and August 2025, 28 pts were enrolled and received study treatment, of whom 24 were evaluable for efficacy analyses. Partial response occurred in 7 patients, with no complete responses observed, resulting an ORR of 29.2% (7/24). Stable disease was achieved in 14 patients, yielding a disease control rate of 87.5% (21/24). Two patients had progressive disease and four patients were not evaluable due to the absence of post-baseline tumor assessments. With a median follow-up of 11.9 months (data cutoff: December 29, 2025), 16 PFS events and 7 death events had occurred. The median PFS was 8.4 months (95% CI, 6.2-NA), while median OS had not been reached. Responses appeared durable, with a median DoR of 4.5 months among responders (n=7), though early progression was observed in some patients. An exploratory analysis revealed PD-L1-positive patients (CPS ≥1) showed a trend toward a higher ORR than PD-L1-negative patients (42.9% [3/7] vs 21.4% [3/14]). The most common treatment-related adverse events of any grade were neutropenia (35.7%), leukopenia (28.6%), rash (28.6%), and ALT elevation (25.0%). Grade ≥3 adverse events were infrequent, mainly ALT and AST elevations (both 7.1%). Immune-related adverse events included rash (28.6%), pneumonitis (7.1%), and hepatitis (7.1%), leading to treatment discontinuation in two patients. Conclusions: Camrelizumab combined with liposomal doxorubicin and dacarbazine demonstrated promising antitumor activity with durable responses and manageable safety as first-line therapy for advanced, recurrent and metastatic UPS. Exploratory analyses suggested that patients with higher PD-L1 expression may derive greater benefit from this regimen, warranting further investigation in larger, controlled studies. Clinical trial information: ChiCTR2100049974.