ABSTRACT
PURPOSE: Leiomyosarcoma and liposarcoma frequently express PD-L1 but are generally resistant to PD-1/PD-L1 inhibition (immune checkpoint inhibitor). Trabectedin is FDA approved for leiomyosarcoma and liposarcoma. This study aimed to evaluate the safety and efficacy of trabectedin with anti-PD-L1 antibody avelumab in patients with advanced leiomyosarcoma and liposarcoma. PATIENTS AND METHODS: A single-arm, open-label, Phase 1/2 study tested avelumab with trabectedin for advanced leiomyosarcoma and liposarcoma. The phase I portion evaluated safety and feasibility of trabectedin (1, 1.2, and 1.5 mg/m2) with avelumab at standard dosing. Primary endpoint of the phase II portion was objective response rate (ORR) by RECIST 1.1. Correlative studies included T-cell receptor sequencing (TCRseq), multiplex IHC, and tumor gene expression. RESULTS: 33 patients were evaluable: 24 with leiomyosarcoma (6 uterine and 18 non-uterine) and 11 with liposarcoma. In Phase 1, dose-limiting toxicities (DLT) were observed in 2 of 6 patients at both trabectedin 1.2 and 1.5 mg/m2. The recommended Phase 2 dose (RP2D) was 1.0 mg/m2 trabectedin and 800-mg avelumab. Of 23 patients evaluable at RP2D, 3 (13%) had partial response (PR) and 10 (43%) had stable disease (SD) as best response. Six-month PFS was 52%; median PFS was 8.3 months. Patients with PR had higher Simpson Clonality score on TCRseq from peripheral blood mononuclear cells versus those with SD (0.182 vs. 0.067, P = 0.02) or progressive disease (0.182 vs. 0.064, P = 0.01). CONCLUSIONS: Although the trial did not meet the primary objective response rate endpoint, PFS compared favorably with prior studies of trabectedin warranting further investigation.
Subject(s)
Leiomyosarcoma , Liposarcoma , Antibodies, Monoclonal, Humanized , Antineoplastic Agents, Alkylating/therapeutic use , B7-H1 Antigen/genetics , Humans , Leiomyosarcoma/drug therapy , Leiomyosarcoma/genetics , Leiomyosarcoma/pathology , Leukocytes, Mononuclear/pathology , Liposarcoma/drug therapy , Liposarcoma/genetics , Liposarcoma/pathology , TrabectedinABSTRACT
IMPORTANCE: Anthracycline-based therapy is standard first-line treatment for most patients with advanced and metastatic sarcomas. Although multiple trials have attempted to show improved outcomes in patients with soft-tissue sarcoma over doxorubicin monotherapy, each has fallen short of demonstrating improved outcomes. OBJECTIVE: To evaluate the safety and efficacy of doxorubicin in combination with pembrolizumab in patients with advanced, anthracycline-naive sarcomas. DESIGN, SETTING, AND PARTICIPANTS: This nonrandomized clinical trial used a 2-stage phase 2 design and was performed at a single, academic sarcoma specialty center. Patients were adults with good performance status and end-organ function. Patients with all sarcoma subtypes were allowed to enroll with the exception of osteosarcoma, Ewing sarcoma, and alveolar and embryonal rhabdomyosarcoma. INTERVENTIONS: Two dose levels of doxorubicin (45 and 75 mg/m2) were tested for safety in combination with pembrolizumab. MAIN OUTCOMES AND MEASURES: Objective response rate (ORR) was the primary end point. Overall survival (OS) and progression-free survival (PFS) were secondary end points. Correlative studies included immunohistochemistry, gene expression, and serum cytokines. RESULTS: A total of 37 patients (22 men; 15 women) were treated in the combined phase 1/2 trial. The median (range) patient age was 58.4 (25-80) years. The most common histologic subtype was leiomyosarcoma (11 patients). Doxorubicin plus pembrolizumab was well tolerated without significant unexpected toxic effects. The ORR was 13% for phase 2 patients and 19% overall. Median PFS was 8.1 (95% CI, 7.6-10.8) months. Median OS was 27.6 (95% CI, 18.7-not reached) months at the time of this analysis. Two of 3 patients with undifferentiated pleomorphic sarcoma and 2 of 4 patients with dedifferentiated liposarcoma had durable partial responses. Tumor-infiltrating lymphocytes were present in 21% of evaluable tumors and associated with inferior PFS (log-rank P = .03). No dose-limiting toxic effects were observed. CONCLUSIONS AND RELEVANCE: In this nonrandomized clinical trial, doxorubicin plus pembrolizumab was well tolerated. Although the primary end point for ORR was not reached, the PFS and OS observed compared favorably with prior published studies. Further studies are warranted, especially those focusing on undifferentiated pleomorphic sarcoma and dedifferentiated liposarcoma. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02888665.
