Masitinib for the Treatment of Severe Mast Cell Activation Syndrome

Inclusion Criteria include:

• Patient with mast cell activation syndrome (MCAS).

• Patient with severe symptoms over the 14-day run-in period defined as at least one of the following: Pruritus score ≥ 9; Number of flushes per week ≥ 8; Hamilton rating scale for depression (HAMD-17) score ≥ 19

• Patient with documented treatment failures of his/her handicap(s) (within last two years) with at least two of the symptomatic treatments used at optimized dose.

• Patients must be on a stable dose of Anti-H1 for a minimum of 4 weeks before screening and should remain at a stable dose throughout the study period.

Exclusion Criteria include:

• Previous treatment with any Tyrosine Kinase Inhibitor.

• Any change in the symptomatic treatment of MCAS, including systemic corticosteroids, or administration of any new treatment for MCAS within 4 weeks prior to screening.

• Patient with systemic indolent mastocytosis.

• Female patients who are pregnant or are breastfeeding.