Real-world evidence of the efficacy and tolerability of trabectedin in patients with advanced soft-tissue sarcoma

INTRODUCTION

The efficacy and tolerability of trabectedin in patients with soft tissue sarcoma (STS) have been confirmed by various clinical studies involving lipo- and leiomyosarcomas as well as many other subtypes including translocation-related sarcomas. These data have been obtained from randomized phase II and III clinical trials. Studies in real-world clinical practice are necessary to bridge the efficacy-effectiveness gap and complete the body of evidence. Furthermore, reinforcing clinical experience with data from routine clinical practice allows drug management to be optimized and clinical benefits to be maximized.

AREAS COVERED

The present review provides the most significant data on the efficacy of trabectedin in real-world studies, and the interpretation of real-world experience with trabectedin, in patients with advanced STS.

EXPERT OPINION

Trabectedin has demonstrated durable disease control and an adequate safety profile, indicating it to be a suitable long-term treatment drug associated with a good quality of life. Personalized strategies and individualized objectives are the way forward in the management of STS.

Getting up-to-date in the management of soft tissue sarcoma

Surgery (+ radiation therapy in selected cases) is standard treatment for adult-type localized soft tissue sarcoma (STS). Accumulating randomized clinical evidence also supports adjuvant chemotherapy as a treatment option, although this remains contentious. Doxorubicin (± ifosfamide) is the standard first-line systemic treatment for advanced STS; however, newer chemotherapeutic agents may improve outcomes achieved with single-agent doxorubicin. In a Phase II study, adding olaratumab to doxorubicin markedly improved overall survival. Agents for second- and further lines include trabectedin, which combines long-term tumor stabilization with good quality of life, and gemcitabine + docetaxel which can produce a marked clinical response although at the cost of high toxicity. Pazopanib, eribulin, aldoxorubicin and regorafenib are other options for use in advanced STS.

Review of past and present clinical cases with a view to future treatment options

In the 10 years that have elapsed since trabectedin was first granted approval in Europe for treatment of advanced soft tissue sarcoma (STS), other cytotoxic agents and targeted therapies have been approved and numerous randomized controlled trials have been completed or are underway. As an academic exercise and positive proof of the advances in STS management that have occurred during the past decade, it is interesting to compare current and future treatment approaches. In this review, present and future treatment approaches are examined by case study for three STS subtypes: uterine leiomyosarcoma, abdominal dedifferentiated liposarcoma and malignant solitary fibrous tumor.

Trabectedin for the treatment of soft tissue sarcomas

INTRODUCTION

Trabectedin, a marine-derived DNA-binding antineoplastic agent, has been registered by the EMA and recently also by the FDA for the treatment of patients with advanced soft-tissue sarcoma (STS), a rare and heterogeneous disease.

AREAS COVERED

The antitumor activity of trabectedin is related both to direct effects on cancer cells, such as growth inhibition, cell death and differentiation, and indirect effects related to its anti-inflammatory and anti-angiogenic properties. Furthermore, trabectedin is the first compound that targets an oncogenic transcription factor with high selectivity in mixoid liposarcomas. This peculiar mechanism of action is the basis of its clinical development. The clinical pharmacology of trabectedin, the subsequent phase I, II and III trials are summarized and put into perspectives in this review.

EXPERT OPINION

Trabectedin is a relevant pleiotropic antitumoral agent within the complex scenario of the management of STS. It can be used in advanced STS, either after failure of anthracyclines and ifosfamide or in patients unfit for these drugs, especially when reaching a high-tumor control and a long-term benefit is a priority. Toxicity profile is acceptable and manageable with no reported cumulative toxicities. Therefore, trabectedin has become one relevant therapeutic option in metastatic STS, especially in selected histologies.

Optimizing the use of trabectedin for advanced soft tissue sarcoma in daily clinical practice

SUMMARY 

Compared with conventional chemotherapy for advanced soft tissue sarcoma, trabectedin has several distinguishing characteristics which, when optimized, may maximize clinical benefits for patients. In this review, evidence is examined with the aim of answering some vital questions about the use of trabectedin in clinical practice. Who should be treated? When should patients be treated? For how long should patients be treated? What is the safety profile of trabectedin? How should trabectedin be administered?

In brief, trabectedin has shown activity and clinical benefit in nearly all subtypes of soft tissue sarcoma. Improved efficacy outcomes are observed when trabectedin is administered as second-line therapy compared with later-line use. In line with this observation, the European Society for Medical Oncology clinical practice guidelines for soft tissue sarcoma recommend use of trabectedin in the second-line setting. Trabectedin has a role for treatment of elderly patients in whom alternatives are lacking, and can be administered for prolonged periods without cumulative toxicity. A statistically significant improvement in median progression-free survival has been observed when trabectedin is administered uninterrupted until disease progression. The flexibility of trabectedin administration in terms of dose, interval and duration allows for patient-tailored treatment optimization.

Trabectedin clinical cases: use according to indication in diverse clinical scenarios

SUMMARY 

Background: Key distinguishing characteristics of trabectedin in the treatment of advanced soft tissue sarcoma are its prolonged tumor control activity in multiple histological subtypes, positive outcomes in translocation-related sarcomas, maintenance of response, option to rechallenge after treatment interruption and lack of cumulative toxicity. Trabectedin is indicated for use in advanced soft tissue sarcoma after failure of anthracyclines and ifosfamide, or as front-line treatment in patients unsuited to receive these agents. Methods: In this review, cases studies are presented in which trabectedin was used according to its indication but in diverse clinical settings. Results: As second-line treatment of uterine leiomyosarcoma, trabectedin produced prolonged tumor control with good quality of life. In treatment of recurrent synovial sarcoma, the best objective response (partial response) and longest disease control (37 months) was achieved under treatment with trabectedin. As neoadjuvant treatment of undifferentiated pleomorphic sarcoma in a patient unsuited to receive doxorubicin-based chemotherapy, trabectedin induced a pathological response with 85% of necrosis. Conclusion: These cases illustrate the broad range of indications for trabectedin in advanced soft tissue sarcoma and highlight how its unique characteristics can be optimized to achieve maximum clinical benefit.

Soft tissue sarcomas, a look into the future: different treatments for different subtypes

 Soft tissue sarcomas (STS) are a heterogeneous group of rare malignancies frequently studied and treated as if they were one and the same disease. Evidence is emerging that distinct histopathological differences between the subtypes can significantly impact on optimal management of patients with STS. For the majority of patients with localized disease, surgery is the treatment of choice, sometimes combined with radiotherapy. For patients with advanced/refractory disease, there are a number of options. The first option is to consider cytotoxic chemotherapy with doxorubicin ± ifosfamide to reduce tumor size and make the tumor more amenable to surgery. If this is not possible, treatment should be aimed at reducing symptoms, improving patients' wellbeing and prolonging life. In this regard, understanding of the different biologies and sensitivities of the various histological subtypes of STS continues to expand, and an increasing number of targeted therapies are becoming available. Examples of more specific treatment options include taxanes in angiosarcoma, and trabectedin in leiomyosarcoma, liposarcoma and undifferentiated pleomorphic sarcoma. Although much remains to be learned about these rare malignancies, it is anticipated that small steps taken in recent years will lead to bigger leaps forward in future.