AB Science SA Reports Positive Clinical Study Data: Masitinib Significantly Extends Overall Survival in Patients with Gleevec-resistant Gastrointestinal Stromal Tumors

AB Science SA announced encouraging results from a phase 2 study with its investigational drug, masitinib, in Gleevec-resistant gastrointestinal stromal tumors (GIST). Masitinib significantly improved overall survival in patients with GIST as compared to Sutent (sunitinib) from Pfizer. In this study, 44 patients with inoperable, locally advanced or metastatic GIST and showing disease progression while treated with Gleevec (imatinib) (400 to 800 mg/day) received either masitinib (23 patients) at 12 mg/kg/day or Sutent (21 patients) until progression. After a median follow-up of 14 months, median overall survival was not reached for masitinib versus 15 months for Sutent (p=0.022 HR:3.2). After 18 months, 79% of patients treated with masitinib were still alive, versus 20% for patients treated with Sutent. After 2 years, 53% of patients treated with masitinib were still alive, versus 0% for the patients treated with Sutent. The study also demonstrated that masitinib was significantly better tolerated than Sutent. The safety profile of masitinib was better than that of sunitinib, with a significantly longer Safety Event Free Survival (p=0.002), and a lower occurrence of severe adverse events. In masitinib treated patients, nausea, diarrhea and asthenia were the most common related adverse events. Full data has been submitted for publication to the American Society of Clinical Oncology (ASCO) 2012 Annual Meeting.