Masitinib in Severe Indolent or Smoldering Systemic Mastocytosis Unresponsive to Optimal Symptomatic Treatment

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the efficacy and safety of oral masitinib versus placebo in the treatment of patients suffering from smouldering or indolent systemic mastocytosis with severe symptoms of mast cell mediator release, unresponsive to optimal symptomatic treatment.

Detailed Description
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Masitinib is a selective tyrosine kinase inhibitor that modulates mast cell activity via inhibition of c-Kit, Lyn and Fyn kinase signaling pathways. This is a multicenter, randomized, double-blind, placebo-controlled, 2-parallel-group, trial comparing oral masitinib versus placebo in the treatment of patients suffering from smouldering or indolent systemic mastocytosis with severe symptoms of mast cell mediator release (also referred to as handicaps), unresponsive to optimal symptomatic treatment. The treatment period is 24 weeks. Participants receive masitinib (3.0 mg/kg/day), given orally twice daily, with a dose escalation to 4.5 mg/kg/day after 4 weeks of treatment, followed by dose escalation to 6.0 mg/kg/day after 4 weeks of treatment. Each ascending dose titration is subjected to a safety control.

Official Title
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Phase 3 Study to Compare Oral Masitinib to Placebo in Treatment of Patients With Smouldering or Indolent Severe Systemic Mastocytosis, Unresponsive to Optimal Symptomatic Treatment

Conditions
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Indolent Systemic Mastocytosis

Intervention / Treatment
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* Drug: Masitinib
* Other: Placebo
* Other: Best Supportive Care


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient with one of the following documented mastocytosis subtypes (variants): Smouldering Systemic Mastocytosis, Indolent Systemic Mastocytosis An excess of mast cells or a presence of abnormal mast cells in at least two organs (among skin, bone-marrow and GI Tract). Patient with documented systemic mastocytosis and evaluable disease based upon histological criteria Patient with documented treatment failure of his/her symptom(s) (within the past 2 years) with at least two of the symptomatic treatments used at optimized dose: Anti H1, Anti H2, Proton pump inhibitor, Antidepressants, Cromoglycate Sodium, Antileukotriene. Patient with severe symptoms of mastocytosis over the 14-day run-in period including at least one among pruritus, flushes, and depression: pruritus score ≥ 9, number of flushes per week ≥ 8, Hamilton rating scale for depression (HAMD-17) score ≥ 19. Exclusion Criteria: Patient with one of the following mastocytosis: Cutaneous Mastocytosis, Systemic Mastocytosis with an Associated clonal Hematologic Non Mast cell lineage Disease (SM-AHNMD), Mast cell leukemia (MCL), Aggressive systemic mastocytosis (ASM) Previous treatment with any Tyrosine Kinase Inhibitor Treatment with any investigational agent within 8 weeks prior to screening.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Masitinib & BSC<br>Experimental Arm: Masitinib (titration to 6.0 mg/kg/day) administered as an add-on to optimal concomitant symptomatic treatment (i.e. best supportive care, BSC). Participants receive masitinib (3.0 mg/kg/day), given orally twice daily, with a dose escalation to 4.5 mg/kg/day after 4 weeks of treatment, followed by dose escalation to 6.0 mg/kg/day after 4 weeks of treatment. Each ascending dose titration is subjected to a safety control. | Drug: Masitinib<br>* Masitinib 6 mg/kg/day<br>* Other names: AB1010;Other: Best Supportive Care<br>* Optimal concomitant symptomatic treatments. Includes: H1- and H2-antihistamines, proton pump inhibitors (PPI), sodium cromoglycate, antidepressants, leukotriene antagonists and corticosteroids.<br>|
| Placebo Comparator: Placebo & BSC<br>Placebo Comparator: Matching placebo administered as an add-on to optimal concomitant symptomatic treatment (i.e. best supportive care, BSC) | Other: Placebo<br>* Matching placebo<br>Other: Best Supportive Care<br>* Optimal concomitant symptomatic treatments. Includes: H1- and H2-antihistamines, proton pump inhibitors (PPI), sodium cromoglycate, antidepressants, leukotriene antagonists and corticosteroids.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cumulative response (3R75%) | Cumulative response in at least one of three severe baseline symptoms of mast cell mediator release (pruritus, flushes, or depression). Response was defined as a 75% improvement from baseline for any of these three symptoms. Cumulative response was defined as the number of actual responses between weeks 8 and 24, divided by the total number of possible responses over the same treatment period (ie, with five scheduled visits, each patient had a maximum of five to 15 possible responses depending on the number of severe baseline symptoms). | 24 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cumulative response (4R75%) | Cumulative response in at least one of four severe baseline symptoms of mast cell mediator release (pruritus, flushes, depression, or asthenia). Response is defined as a 75% improvement from baseline for any of these four symptoms. Cumulative response was defined as the number of actual responses between weeks 8 and 24, divided by the total number of possible responses over the same treatment period (ie, with five scheduled visits, each patient had a maximum of five to 20 possible responses depending on the number of severe baseline symptoms). | 24 weeks | 
| Cumulative response (2R75%) | Cumulative response in at least one of two severe baseline symptoms of mast cell mediator release (pruritus or flushes). Response is defined as a 75% improvement from baseline for either of these two symptoms. Cumulative response is defined as the number of actual responses between weeks 8 and 24, divided by the total number of possible responses over the same treatment period (ie, with five scheduled visits, each patient had a maximum of five to 10 possible responses depending on the number of severe baseline symptoms). | 24 weeks | 
| Cumulative response | Cumulative response on each of the individual handicaps. Response is defined as a 75% improvement from baseline for either of these two symptoms. Cumulative response is defined as the number of actual responses between weeks 8 and 24, divided by the total number of possible responses over the same treatment period. | 24 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Mastocytosis with handicap, Mastocytosis, Mast cell, Mast cell infiltration, Skin, Bone marrow, Pruritus, Flushes, c-kit, c-kit mutation, Wild Type, Mutation Asp-816-Val(D816V), Indolent systemic mastocytosis, smoldering systemic mastocytosis