This clinical trial is focused on studying a condition known as Systemic Mastocytosis, which is a rare disorder where there is an excess of mast cells in the body. Mast cells are a type of white blood cell that play a role in allergic reactions and other immune responses. The study specifically targets two forms of this condition: Smouldering Systemic Mastocytosis and Indolent Systemic Mastocytosis. These forms are characterized by severe symptoms that do not respond well to standard treatments. The trial aims to evaluate the effectiveness and safety of a medication called masitinib, which is a type of drug known as a tyrosine kinase inhibitor. This medication is taken orally in the form of coated tablets.

The purpose of the study is to compare the effects of masitinib with a placebo in patients who have not found relief from their symptoms with other treatments. The trial will last for 24 weeks, with a possibility of extension. Participants will be randomly assigned to receive either masitinib or a placebo, and neither the participants nor the researchers will know who is receiving which treatment. This is known as a double-blind study. The trial will involve regular visits to monitor the participants’ health and response to the treatment.

Throughout the study, the main focus will be on assessing how well the treatment works in reducing the symptoms and improving the quality of life for those with systemic mastocytosis. The trial will also look at various biological and skin parameters to gather more information about the condition and the effects of the treatment. The ultimate goal is to find a more effective way to manage the symptoms of this challenging condition.