Trabectedin is an effective second-line treatment in soft tissue sarcoma patients

Efficacy and tolerability of trabectedin in elderly patients with sarcoma: subgroup analysis from a phase III, randomized controlled study of trabectedin or dacarbazine in patients with advanced liposarcoma or leiomyosarcoma

Background

Treatment options for soft tissue sarcoma (STS) patients aged ≥65 years (elderly) can be limited by concerns regarding the increased risk of toxicity associated with standard systemic therapies. Trabectedin has demonstrated improved disease control in a phase III trial (ET743-SAR-3007) of patients with advanced liposarcoma or leiomyosarcoma after failure of anthracycline-based chemotherapy. Since previous retrospective analyses have suggested that trabectedin has similar safety and efficacy outcomes regardless of patient age, we carried out a subgroup analysis of the safety and efficacy observed in elderly patients enrolled in this trial.

Patients and methods

Patients were randomized 2 : 1 to trabectedin (n = 384) or dacarbazine (n = 193) administered intravenously every-3-weeks. The primary end point was overall survival (OS); secondary end points were progression-free survival (PFS), time-to-progression, objective response rate (ORR), duration of response, symptom severity, and safety. A post hoc analysis was conducted in the elderly patient subgroup.

Results

Among 131 (trabectedin = 94; dacarbazine = 37) elderly patients, disease characteristics were well-balanced and consistent with those of the total study population. Treatment exposure was longer in patients treated with trabectedin versus dacarbazine (median four versus two cycles, respectively), with a significantly higher proportion receiving prolonged therapy (≥6 cycles) in the trabectedin arm (43% versus 23%, respectively; P = 0.04). Elderly patients treated with trabectedin showed significantly improved PFS [4.9 versus 1.5 months, respectively; hazard ratio (HR)=0.40; P = 0.0002] but no statistically significant improvement in OS (15.1 versus 8.0 months, respectively; HR = 0.72; P = 0.18) or ORR (9% versus 3%, respectively; P = 0.43). The safety profile for elderly trabectedin-treated patients was comparable to that of the overall trabectedin-treated study population.

Conclusions

This subgroup analysis of the elderly population of ET743-SAR-3007 suggests that elderly patients with STS and good performance status can expect clinical benefit from trabectedin similar to that observed in younger patients.

Trial registration

www.clinicaltrials.gov, NCT01343277.

Managing sarcoma: where have we come from and where are we going?

Sarcomas are a heterogeneous group of neoplasms of mesenchymal origin. Approximately 80% arise from soft tissue and 20% originate from bone. To date more than 100 sarcoma subtypes have been identified and they vary in molecular characteristics, pathology, clinical presentation and response to treatment. While sarcomas represent <1% of adult cancers, they account for approximately 21% of paediatric malignancies and thus pose some of the greatest risks of mortality and morbidity in children and young adults. Metastases occur in one-third of all patients and approximately 10-20% of sarcomas recur locally. Surgery in combination with preoperative and postoperative therapies is the primary treatment for localized sarcoma tumours and is the most promising curative possibility. Metastasized sarcomas, on the other hand, are treated primarily with single-agent or combination chemotherapy, but this rarely leads to a complete and robust response and often becomes a palliative form of treatment. The heterogeneity of sarcomas results in variable responses to current generalized treatment strategies. In light of this and the lack of curative strategies for metastatic and unresectable sarcomas, there is a need for novel subtype-specific treatment strategies. With the more recent understanding of the molecular mechanisms underlying the pathogenesis of some of these tumours, the treatment of sarcoma subtypes with targeted therapies is a rapidly evolving field. This review discusses the current management of sarcomas as well as promising new therapies that are currently underway in clinical trials.

Efficacy of trabectedin for the treatment of liposarcoma

INTRODUCTION

Trabectedin (ET-743) is a synthetic marine derived alkylating agent, extracted originally from a Caribbean Sea sponge. It is approved for the treatment of Soft Tissue sarcomas (STS) in Europe and recently by the FDA for liposarcomas and leiomyosarcomas.

AREAS COVERED

Trabectedin has multiple mechanisms of action, including one targeting the FUS-CHOP oncogene in Myxoid/Round cell Liposarcomas. Numerous Phase I, II and III clinical trials have been conducted with Trabectedin. It has been studied as monotherapy or in combination with other chemotherapeutic agents. The recommended dose based on clinical trials is 1.5 milligrams/m(2) continuous infusion over 24 hours once every 3 weeks for STS with evidence of disease control in multiple clinical trials at this dose. The most common Grade 3/4 toxicities include neutropenia and transient noncumulative elevations of ALT and AST. Steroid pretreatment has shown efficacy in reducing liver and bone marrow toxicity. In phase III testing comparing trabectedin to dacarbazine, trabectedin was associated with a significantly improved progression free survival rate in patients with advanced lipo- and leiomyosarcomas.

EXPERT OPINION

Trabectedin is an important new addition to the limited treatment options currently available for STS, especially for patients with liposarcoma that have progressed on standard chemotherapeutic regimens.