In a European phase II trial reported in The Lancet Oncology, Martin-Broto et al found that pazopanib showed activity in patients with typical solitary fibrous tumors.
The investigators previously reported findings with pazopanib treatment in a cohort of patients in the trial with advanced malignant or dedifferentiated solitary fibrous tumors, a different clinicopathologic subgroup, including a median progression-free survival rate of 5.6 months and a 2-year overall survival rate of 73%.
In the typical solitary fibrous tumor cohort, 31 evaluable adult patients with confirmed metastatic or unresectable disease of any location who had shown disease progression in the previous 6 months (by Choi criteria or Response Evaluation Criteria in Solid Tumors [RECIST]) were enrolled at 11 tertiary hospitals in Italy, France, and Spain. Patients received 800 mg of pazopanib once daily until disease progression, unacceptable toxicity, or delay in pazopanib administration of longer than 3 weeks.
The primary endpoint was proportion of patients with overall response on Choi criteria in those who received at least 1 month of treatment with at least one radiologic assessment. In total, 79% of patients had received any previous treatment.
“To our knowledge, this is the first prospective trial of pazopanib for advanced typical solitary fibrous tumour. The manageable toxicity and activity shown by pazopanib in this cohort suggest that this drug could be considered as first-line treatment for advanced typical solitary fibrous tumor.”— Martin-Broto et al
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Median follow-up was 18 months. Response (all partial responses) on Choi criteria and central review were observed in 18 patients (58%), and an additional 12 patients (39%) had stable disease. On RECIST criteria, partial response was observed in 2 patients (6%) and 29 (94%) had stable disease.
The median progression-free survival was 9.8 months on Choi criteria and 12.1 months on RECIST criteria by central review. Median overall survival was 49.8 months, with a 2-year survival rate of 57%.
The most common adverse events of any grade were diarrhea (53% of 34 patients in the safety population), fatigue (50%), and hypertension (50%). No grade 4 events were observed. The most common grade 3 adverse events were increased alanine aminotransferase (24%), increased aspartate aminotransferase (15%), hypertension (18%), and neutropenia (9%; no episodes of febrile neutropenia were observed). No deaths due to toxicity were observed.
The investigators concluded, “To our knowledge, this is the first prospective trial of pazopanib for advanced typical solitary fibrous tumor. The manageable toxicity and activity shown by pazopanib in this cohort suggest that this drug could be considered as first-line treatment for advanced typical solitary fibrous tumor.”
Javier Martin-Broto, MD, of Instituto de Biomedicina de Sevilla, University Hospital Virgen Del Rocio, Seville, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Spanish Group for Research on Sarcomas, Italian Sarcoma Group, French Sarcoma Group, GlaxoSmithKline, and Novartis. For full disclosures of the study authors, visit thelancet.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.