Continuous vs intermittent imatinib treatment in advanced GIST after one year: A prospective randomized phase III trial of the French Sarcoma Group

9006 Background: Imatinib (Im) is usually given in advanced GIST until progression or intolerance. Secondary resistance to Im is often related to the clonal expansion of clones with Im insensitive KIT mutations. Whether intermittent administration of Im may prevent the long term emergence of resistant clones is unknown. Methods: BFR14, a prospective multicentric phase III study of continuous vs interrupted imatinib treatment in advanced GIST, was initiated in June 2002. Inclusion criterias were: advanced GIST, expressing KIT or PDGFRa mutation. After 1 year of treatment with Im, patients are randomized between 1) continuous (CONT) or 2 ) interruption (STOP) of Im until progression and restart. Patients declining randomization were followed. Primary endpoint was progression free survival. Early stopping rule in case of high rates of re-progression at 3 months were scheduled after the randomisation of 14 patients (n>5) and 29 pts (n>10). Results: As of December 2003, 159 pts were included: 61% were males, 3...