AB Science Begins Confirmatory Phase 3 Study of Masitinib for ALS in Europe and US

AB Science Begins Confirmatory Phase 3 Study of Masitinib for ALS in Europe and US

By, Admin 28 July 2025

AB Science SA, a pharmaceutical company focused on protein kinase inhibitors (PKIs), announced the initiation of its confirmatory Phase 3 study (AB23005) for masitinib in amyotrophic lateral sclerosis (ALS).

The study has received regulatory clearance in the first set of European countries—Spain, Greece, and Slovenia—under Step 2 of the Clinical Trials Information System (CTIS) procedure, following protocol validation by the EMA and prior authorization by the US FDA.

Scientific Rationale and Prior Evidence

Professor Albert Ludolph (University of Ulm, Germany), principal investigator, emphasized the study's strong foundation in both clinical and preclinical data. Key background includes:

  • Phase 2B/3 study AB10015 showed a median survival benefit of several months in targeted patient groups.
  • Multiple preclinical studies demonstrated masitinib’s mechanism of action, particularly its impact on neuroinflammation markers like neurofilaments (NfL), by targeting mast cells and microglia.

Study AB23005 Design and Objectives

The Phase 3 trial is a prospective, multicenter, randomized, double-blind, placebo-controlled, two-arm study.

  • Population: 408 ALS patients randomized 1:1
  • Treatment: Masitinib (4.5 mg/kg/day) + riluzole vs. riluzole + placebo
  • Duration: 48 weeks
  • Inclusion criteria:Patients with normal disease progression (ALSFRS-R decline < 1.1 points/month), no complete loss of function (minimum score of 1 on each ALSFRS-R item), U.S. patients on edaravone are eligible (stratification factor)

This patient population was chosen based on consultations with European health authorities, including the EMA’s Scientific Advisory Group on Neurology.

Why Target Patients Without Rapid Progression or Severe Functional Loss?

  • EMA experts validated that normal progressors represent a clinically relevant and definable subgroup.
  • ALSFRS-R is a widely accepted tool in clinical practice to identify patients before full functional loss.
  • Study AB10015 showed a +12-month median survival benefit in this optimal subgroup.

Optimized Statistical Design to Maximize Study Power

To strengthen statistical confidence:

  • The AB10015 study included ~90 patients per group; AB23005 will include ~200 patients per group.
  • Masitinib previously showed statistically significant benefit on the CAFS endpoint (p = 0.0290), an endpoint accepted by the FDA.

Proven Mechanism of Action in ALS

Masitinib’s therapeutic effect is rooted in its immunomodulatory activity, specifically targeting mast cells and microglia.

  • Demonstrated neuroprotective activity in preclinical ALS models.
  • Independent studies confirmed that there are reduced macrophage infiltration in spinal cord tissue. Preservation of Schwann cells and improved muscle reinnervation.
  • Reduced NfL levels and restored motor function in animal models, including zebrafish expressing TDP-43 mutations.

These findings support early intervention with masitinib, before irreversible neurodegeneration occurs.

Strong Intellectual Property Position and Orphan Drug Designation

AB Science has secured robust IP protection for masitinib in ALS:

  • Granted patents in key global markets (EU, US, Canada, China, Japan, Korea, Australia, etc.) until 2037, with potential extensions up to 2042.
  • Orphan Drug Designation granted by both EMA and FDA with10 years of market exclusivity in Europe, 7 years of exclusivity in the US. The application is underway for Japan (10-year exclusivity if granted).

About AB Science

AB Science specializes in the research, development, and commercialization of protein kinase inhibitors (PKIs). These targeted therapies are designed to interrupt key signaling pathways that drive disease progression across various therapeutic areas.

Optimize Your trial insights with Clival Database.

Are you exhausted from the uncertainty of trial insights pricing? Clival Database ensures the clarity in the midst of the global scenario for clinical trials to you.

Clival Database is one of the best databases that offers an outstanding number of clinical trial data in terms of 50,000+ molecules and from primary regulatory markets as well as new entrants like Indian and Chinese markets.

With Clival, you get accurate positioning of historical sales data, patent database, company profiling, safety & efficacy, and prediction of launch of new innovative molecules helping you to align your research and driving down the cost.

To add value, we further break down our analytics for you so that improving your operational effectiveness; optimizing your clinical trials; and offering you accurate and high-quality data at lowest possible prices becomes possible.

Elevate your trial success rate with the cutting-edge insights from Clival database.

Check it out today and make more informed sourcing decisions! Learn More!