Long-term results of therapy with sunitinib in metastatic alveolar soft part sarcoma

Alveolar soft part sarcoma (ASPS) is a rare, highly vascularized soft tissue sarcoma characterized by a high frequency of metastatic disease and resistance to classical chemotherapy. The purpose of our analysis was to assess long-term sunitinib activity in the treatment of metastatic ASPS.

Between 2009 and 2015, 15 patients were diagnosed with metastatic ASPS and received therapy with sunitinib at initial continuous daily dosing of 37.5 mg. Median age was 32 years. The primary tumor sites were lower extremities (8), trunk-retroperitoneum/pelvis (2), upper extremity (3) and other (2). All patients had unresectable disease (primary or relapse in the form of metastases to the lungs ± bones). Five patients received systemic therapy before initiating sunitinib. Median follow-up from start of sunitinib was 38 months (range 5-69 months).

At the time of analysis 4 patients continue therapy and 9 are still alive. Six patients had RECIST partial remission as best response, 8 had stable disease, and 1 had disease progression. The median progression-free survival was 19 months, with 86% of patients being free of progression at 6 months. Median overall survival was 56 months; the 5-year overall survival rate was 49%. Five patients were treated with sunitinib longer than 2 years. All patients experienced some side effects: 8 patients (53%) had CTCAE grade 3/4 toxicity, 7 patients required dose reduction. The most common toxicities were neutropenia, thrombocytopenia, hypothyroidism, arterial hypertension, and hand-foot syndrome.

Our analysis confirms the long-term efficacy of sunitinib in patients with advanced ASPS.