What Is Masitinib?
Masitinib is a drug currently under investigation in clinical trials for its potential to treat a variety of conditions. In some studies, Masitinib has been described as a 3CL-protease inhibitor. This means it may work by blocking a specific enzyme, called 3CL-protease, that certain viruses, such as coronaviruses, need to multiply and spread within the body. By inhibiting this enzyme, Masitinib could help to stop the virus from replicating. Masitinib is being studied in a total of 36 clinical trials involving over 9,000 participants. These trials began in 2008, with the latest expected to conclude in 2025. Masitinib is being investigated for conditions such as Mastocytosis, Coronavirus Disease 2019, Amyotrophic Lateral Sclerosis (ALS), Gastrointestinal Stromal Tumors, Multiple Myeloma, Rheumatoid Arthritis, Indolent Systemic Mastocytosis, Asthma, Alzheimer Disease, and Mast Cell Activation Syndrome.
Uses and Conditions Under Study
Masitinib is being studied across a wide range of medical conditions, with clinical trials exploring its potential benefits. The drug is sponsored by AB Science, an industry sponsor, in all 36 trials.
- Mast Cell-Related Conditions: Masitinib is being investigated for Mastocytosis (2 trials), Indolent Systemic Mastocytosis (2 trials), and Mast Cell Activation Syndrome (1 trial). These conditions involve an overproduction or overactivity of mast cells, which play a role in allergic reactions and inflammation. Researchers are exploring if Masitinib can help manage symptoms and disease progression by targeting these cells.
- Infectious Disease: For Coronavirus Disease 2019 (2 trials), Masitinib is being studied as a 3CL-protease inhibitor. This mechanism could potentially block the virus from replicating and reduce the severity of the infection.
- Neurodegenerative Diseases: Masitinib is under investigation for Amyotrophic Lateral Sclerosis (ALS) (2 trials) and Alzheimer Disease (2 trials). These are progressive conditions affecting the nervous system. Studies aim to determine if Masitinib can slow disease progression or alleviate symptoms.
- Cancers: Masitinib is being studied in Gastrointestinal Stromal Tumors (2 trials) and Multiple Myeloma (2 trials). In these conditions, the drug's potential to interfere with cancer cell growth and survival is being explored.
- Inflammatory and Immune Conditions: Masitinib is also being evaluated for Rheumatoid Arthritis (2 trials) and Asthma (2 trials). These conditions involve chronic inflammation and immune system dysfunction. Clinical trials are assessing if Masitinib can reduce inflammation and improve patient outcomes.
Dosing
Masitinib is administered orally, meaning it is taken by mouth. Clinical trials have investigated various dosing regimens and strengths of Masitinib, often expressed in milligrams per kilogram of body weight per day (mg/kg/day).
Common investigational doses studied include 3.0 mg/kg/day, 4.5 mg/kg/day, and 6.0 mg/kg/day. Some studies have also explored Masitinib at fixed doses such as 3 mg, 6.0 mg, and 7.5 mg. In certain trials, the dosage of Masitinib was titrated, meaning it was adjusted over time, often starting lower and increasing to a target dose like 4.5 mg/kg/day or 6.0 mg/kg/day.
Masitinib has also been studied in combination with other treatments. Examples include:
- Masitinib plus riluzole
- Masitinib plus best supportive care (BSC)
- Masitinib plus standard of care (SOC)
- Masitinib plus Isoquercetin plus Best Supportive Care
- Masitinib plus FOLFIRI (a chemotherapy regimen)
- Masitinib plus docetaxel (a chemotherapy drug)
- Masitinib plus gemcitabine (a chemotherapy drug)
These dosages and combinations are part of ongoing research to determine the most effective and safe ways to use Masitinib for different conditions.
Side Effects
The most common side effect reported in clinical trials for Masitinib was diarrhea. 22.1% of patients taking Masitinib experienced diarrhea, compared to 3.7% on placebo. Other common side effects included nausea, which affected 11.7% of Masitinib patients versus 5.0% on placebo, and vomiting, reported by 8.9% of Masitinib patients compared to 3.0% on placebo.
Additional side effects seen more frequently with Masitinib than with placebo included abdominal pain (8.6% vs 6.0%), rash (8.3% vs 2.0%), and peripheral edema (swelling, 7.0% vs 2.0%).
In a separate study involving dialysis patients, specific side effects were observed. These included AV fistula complication, reported by 10.0% of patients taking Masitinib, and hyperkalemia (high potassium levels), which also affected 10.0% of Masitinib-treated dialysis patients. These events were reported in a trial setting without a direct placebo comparison for this specific patient group.
Clinical Trial Results
IBS-C (Irritable Bowel Syndrome with Constipation)
In a clinical trial (NCT01684713) involving patients with IBS-C, Masitinib was evaluated for its effectiveness. The primary goal was to assess the responder rate, defined by improvements in abdominal pain and stool consistency. Results showed that 44% of patients on Masitinib met the responder criteria, compared to 30% of patients receiving placebo.
Key secondary outcomes also demonstrated improvement. Abdominal pain improved for 50% of patients taking Masitinib, compared to 35% of those on placebo. Similarly, stool consistency improved for 45% of patients treated with Masitinib, versus 32% in the placebo group.
Hyperphosphatemia in Dialysis Patients
A study (NCT02047712) investigated the effect of Masitinib on hyperphosphatemia (high phosphate levels) in patients undergoing dialysis. Patients were given Masitinib at different doses or a placebo. After 8 weeks, patients receiving Masitinib showed reductions in their phosphate levels, indicating an improvement.
- Patients treated with Masitinib 3 mg/kg/day experienced an average reduction in phosphate levels of 0.5 mg/dL.
- Patients treated with Masitinib 6 mg/kg/day showed a greater average reduction of 0.7 mg/dL in phosphate levels.
- In contrast, patients on placebo experienced an average increase in phosphate levels of 0.1 mg/dL over the same period.
These results suggest that Masitinib can help reduce elevated phosphate levels in dialysis patients.
Currently Recruiting Trials
For patients interested in contributing to medical research, there is currently one clinical trial actively recruiting participants to study Masitinib. This trial aims to evaluate the potential benefits of Masitinib for individuals living with Amyotrophic Lateral Sclerosis (ALS), a progressive neurodegenerative disease that affects nerve cells in the brain and spinal cord.
One notable study, NCT03127267, is a Phase 3 clinical trial investigating the efficacy and safety of Masitinib in combination with riluzole for the treatment of ALS. This study compares two different dosages of Masitinib—4.5 mg/kg/day and 6.0 mg/kg/day—each administered alongside riluzole, against a placebo combined with riluzole. The primary objective is to assess whether Masitinib can offer a significant improvement in outcomes for ALS patients compared to existing standard care. This crucial research is designed to enroll approximately 495 participants, aiming to gather comprehensive data on Masitinib's potential impact and safety profile for this challenging condition.
Where to Participate
The actively recruiting Masitinib trial for Amyotrophic Lateral Sclerosis (ALS) is currently seeking participants across several locations in the United States. This provides opportunities for individuals in different regions to potentially join the study.
Clinical trial sites are available in the following cities and states:
- Birmingham, Alabama
- Los Angeles, California
- Lexington, Kentucky
- Baltimore, Maryland
- Burlington, Massachusetts
- Charlottesville, Virginia
To be eligible for participation in this study, individuals must be between 18 and 81 years of age. The trial is open to all genders, but it is important to note that healthy volunteers are not being recruited, nor are children. Participants must have a diagnosis of ALS to be considered for enrollment.
Development Timeline
The journey of Masitinib in clinical development began on 2008-11-13, with AB Science as the sole sponsor driving its research. Initially, the focus of investigations included conditions such as IBS-C and hyperphosphatemia.
Over time, the research pipeline for Masitinib expanded significantly, reflecting its broad potential. The drug has been explored across a diverse range of therapeutic areas, including serious conditions like Amyotrophic Lateral Sclerosis (ALS), Gastrointestinal Stromal Tumors, Multiple Myeloma, and Alzheimer Disease. More recently, its potential has also been investigated in areas such as Mast Cell Activation Syndrome and even SARS-CoV2 infection, demonstrating an adaptive research strategy.
Throughout its development, Masitinib has progressed through various clinical trial phases. The program includes 19 Phase 3 trials, 13 Phase 2 trials, and 4 trials that spanned both Phase 2 and Phase 3. In total, 36 clinical trials have been conducted for Masitinib, enrolling a cumulative total of 9,008 participants. The latest recorded activity for Masitinib trials extends to 2025-09-16, indicating ongoing and future research efforts for this compound.