Trabectedin and low-dose radiation therapy in patients with advanced leiomyosarcoma.

Background and objectives: Dimensional response is an unmet need in second lines of advanced soft tissue sarcomas (STS). Indeed, the three approved drugs, pazopanib, trabectedin, and eribulin, achieved an overall response rate (ORR) of less than 10%. This fact potentially hinders the options for fast symptomatic relief or surgical rescue. The combination of trabectedin plus low-dose radiation therapy (T-XRT) demonstrated a response rate of 60% in phase I/II trial, while real-life data achieved 32.5% ORR, probably due to a more relaxed timing between treatments. These results were obtained in progressing and advanced STS. In this study, the merged databases (trial plus real life) have been analyzed, with a special focus on leiomyosarcoma patients. Design and methods: As responses were seen in a wide range of sarcoma histologies (11), this study planned to analyze whether leiomyosarcoma, the largest subtype with 26 cases (30.6%) in this series, exhibited a better clinical outcome with this therapeutic strategy. In addition, four advanced and progressing leiomyosarcoma patients, all with extraordinarily long progression-free survival of over 18 months, were collected. Results: A total of 847 cycles of trabectedin were administered to 85 patients, with the median number of cycles per patient being 7 (1-45+). A trend toward a longer progression-free survival (PFS) was observed in leiomyosarcoma patients with median PFS (mPFS) of 9.9 months [95% confidence interval (CI): 1.1-18.7] versus 5.6 months (95% CI: 3.2-7.9) for the remaining histologies, p = 0.25. When leiomyosarcoma and liposarcoma were grouped, this difference reached statistical significance, probably due to the special sensitivity of myxoid liposarcoma. The mPFS for L-sarcomas was 12.7 months (95% CI: 7-18.5) versus 4.3 months (95% CI: 3.3-5.3) for the remaining histologies, p = 0.001. Cases with long-lasting disease control are detected among leiomyosarcoma patients. Conclusion: Even when extraordinarily long-lasting responses do exist among leiomyosarcoma patients treated with T-XR, we were unable to demonstrate a significant difference favoring leiomyosarcoma patients in clinical outcomes.

Effectiveness and Safety of Trabectedin and Radiotherapy for Patients With Myxoid Liposarcoma: A Nonrandomized Clinical Trial.

Importance: Preclinical data about the synergistic activity of radiotherapy (RT) and trabectedin have been reported. The combination of trabectedin and RT in treating myxoid liposarcomas appears worth exploring. Objective: To explore the effectiveness and safety of trabectedin combined with RT. Design, Setting, and Participants: This international, open-label, phase 2 nonrandomized clinical trial including 46 patients with myxoid liposarcoma was conducted in 4 centers in Spain, 1 in Italy, and 2 in France from July 1, 2016, to September 30, 2019. Eligible patients had to have a histologic, centrally reviewed diagnosis of localized resectable myxoid liposarcoma arising from an extremity or the trunk wall. Interventions: Trabectedin was administered at the recommended dose stemming from the phase 1 trial (1.5 mg/m2), with intravenous infusion during 24 hours every 21 days for a total of 3 cycles. Radiotherapy was started after completion of the first trabectedin infusion (cycle 1, day 2). Patients received 25 fractions of radiation for a total of 45 Gy. Surgery was planned 3 to 4 weeks after the administration of the last preoperative cycle and not until 4 weeks after the end of preoperative RT. Pathologic specimens were mapped in tumor sections to estimate the histologic changes and the percentage of viable tumor after neoadjuvant treatment. Main Outcomes and Measures: The primary objective of the phase 2 part of the study was overall response. Secondary objectives were effectiveness measured by relapse-free survival and activity measured by functional imaging and pathologic response. Results: A total of 46 patients were enrolled. Four patients were not evaluable. The median age was 43 years (range, 18-77 years), and 31 patients were male (67%). Overall, 9 of 41 patients (22%) achieved a partial response with neoadjuvant treatment with trabectedin and RT, with 5 of 39 patients (13%) achieving a complete pathologic response and 20 of 39 patients (51%) having 10% or less of a viable remaining tumor. Partial responses according to Choi criteria were observed in 24 of 29 evaluable patients (83%), and no patient had disease progression. Treatment was well tolerated. Conclusions and Relevance: Although the primary end point of this phase 2 nonrandomized clinical trial was not met (Response Evaluation Criteria in Solid Tumors response in ≥70% of patients), results suggest this combination was well tolerated and effective in terms of pathologic response. Thus, trabectedin plus RT might be a treatment option regarding tolerability; further evidence should be generated in this setting.

Assessment of Safety and Efficacy of Combined Trabectedin and Low-Dose Radiotherapy for Patients With Metastatic Soft-Tissue Sarcomas: A Nonrandomized Phase 1/2 Clinical Trial.

Importance: Active therapeutic combinations, such as trabectedin and radiotherapy, offer potentially higher dimensional response in second-line treatment of advanced soft-tissue sarcomas. Dimensional response can be relevant both for symptom relief and for survival. Objective: To assess the combined use of trabectedin and radiotherapy in treating patients with progressing metastatic soft-tissue sarcomas. Design, Setting, and Participants: Phase 1 of this nonrandomized clinical trial followed the classic 3 + 3 design, with planned radiotherapy at a fixed dose of 30 Gy (3 Gy/d for 10 days) and infusion of trabectedin at 1.3 mg/m2 as the starting dose, 1.5 mg/m2 as dose level +1, and 1.1 mg/m2 as dose level -1. Phase 2 followed the Simon optimal 2-stage design. Allowing for type I and II errors of 10%, treatment success was defined as an overall response rate of 35%. This study was conducted in 9 sarcoma referral centers in Spain, France, and Italy from April 13, 2015, to November 20, 2018. Adult patients with progressing metastatic soft-tissue sarcoma and having undergone at least 1 previous line of systemic therapy were enrolled. In phase 2, patients fitting inclusion criteria and receiving at least 1 cycle of trabectedin and the radiotherapy regimen constituted the per-protocol population; those receiving at least 1 cycle of trabectedin, the safety population. Interventions: Trabectedin was administered every 3 weeks in a 24-hour infusion. Radiotherapy was required to start within 1 hour after completion of the first trabectedin infusion (cycle 1, day 2). Main Outcomes and Measures: The dose-limiting toxic effects of trabectedin (phase 1) and the overall response rate (phase 2) with use of trabectedin plus irradiation in metastatic soft-tissue sarcomas. Results: Eighteen patients (11 of whom were male) were enrolled in phase 1, and 27 other patients (14 of whom were female) were enrolled in phase 2. The median ages of those enrolled in phases 1 and 2 were 42 (range, 23-74) years and 51 (range, 27-73) years, respectively. In phase 1, dose-limiting toxic effects included grade 4 neutropenia lasting more than 5 days in 1 patient at the starting dose level and a grade 4 alanine aminotransferase level increase in 1 of 6 patients at the +1 dose level. In phase 2, among 25 patients with evaluable data, the overall response rate was 72% (95% CI, 53%-91%) for local assessment and 60% (95% CI, 39%-81%) for central assessment. Conclusions and Relevance: The findings of this study suggest that the recommended dose of trabectedin for use in combination with this irradiation regimen is 1.5 mg/m2. The trial met its primary end point, with a high overall response rate that indicates the potential of this combination therapy for achieving substantial tumor shrinkage beyond first-line systemic therapy in patients with metastatic, progressing soft-tissue sarcomas. Trial Registration: ClinicalTrials.gov Identifier: NCT02275286.