Recent developments in salvage chemotherapy for patients with metastatic soft tissue sarcoma

The number of effective cytotoxic agents for the treatment of patients with metastatic adult soft tissue sarcoma is limited, especially when patients have failed anthracycline- and ifosfamide-based chemotherapy. For the subgroup of patients with inoperable gastrointestinal stromal tumour (GIST), progress has been made via the rapid development and approval of the targeted therapy imatinib. Small round cell tumours (SRCTs), such as Ewing's sarcoma/primitive neuroectodermal tumour, desmoplastic SRCT and rhabdomyosarcoma, are chemotherapy-sensitive and potentially curable malignancies, which are treated with multimodality, dose-intensive, neoadjuvant protocols regardless of size or overt metastatic disease. Most other high-grade (grading >I), so-called 'adult type', soft tissue sarcomas such as fibrosarcoma, liposarcoma, pleomorphic and synovial sarcomas are treated with an anthracycline-based regimen with or without ifosfamide as front-line therapy. In relapsed 'adult type' soft tissue sarcomas, trofosfamide, gemcitabine and trabectedin (ecteinascidin 743) appear to be drugs associated with some activity and an acceptable toxicity profile. A high activity has been reported for the taxanes, in particular for paclitaxel, in vascular sarcomas located in the scalp or face and in Kaposi's sarcoma. It is interesting to note that the different drugs have particular effects in distinct subtypes of soft tissue sarcoma; however, it should be taken into account that the number of patients included in the phase II trials is limited. The role of the newer agents (e.g. epothilones, brostallicin) is currently undefinable. Targeted therapy inhibiting vascular endothelial growth factor receptor, epidermal growth factor receptor, RAF kinase, c-KIT or platelet-derived growth factor receptors will continue to be tested in GIST patients refractory to imatinib and in other sarcoma histologies.