Masitinib in Severe Indolent or Smoldering Systemic Mastocytosis

This was a prospective, multicenter, randomized, placebo-controlled, parallel-group, phase 3 study, conducted in 15 countries, evaluating the efficacy and safety of masitinib (6 mg/kg/day administered orally in two daily intakes over 24-weeks with a double-blind extension period possible) for the treatment of indolent systemic mastocytosis, smoldering mastocytosis or cutaneous mastocytosis, in patients with mast cells mediator release symptoms that are refractory to conventional symptomatic treatment. A study protocol amendment restricted enrolment to patients with severe indolent and smoldering systemic mastocytosis. The objective of this phase 3 study was therefore to evaluate masitinib efficacy and safety in severe systemic mastocytosis patients, with or without D816V mutation of c-Kit. The primary objective of the phase 3 study was to detect a statistically significant difference between masitinib (plus optimal concomitant symptomatic treatments) and placebo (plus optimal concomitant symptomatic treatments) in cumulative response on four severe symptoms, referred to also as handicaps.