Studies Involving Masitinib Suspended

AB Science will suspend recruitment and treatment in all studies involving masitinib, a tyrosine kinase inhibitor being investigated for amyotrophic lateral sclerosis (ALS) and several other conditions.

The voluntary suspension follows the identification of a potential risk of ischemic heart disease — a condition of recurring chest pain or discomfort — associated with masitinib use.

AB Science is filing for a temporary hold on all ongoing studies, including a Phase 3 clinical trial in ALS called Study AB19001 (NCT03127267), until concluding an investigation into this potential safety risk.

“Patient safety is our priority,” the company wrote in a press release.

In addition to the ALS study, the suspension will affect a Phase 3 study in mastocytosis (NCT04333108), and a Phase 2 study in patients with moderate-to-severe COVID-19 (NCT04622865).

The decision was made following consultation with France’s National Agency for the Safety of Medicines and Health Products and other regulatory entities.

“AB Science is working in full collaboration with the regulatory authorities in order to resume patient enrollment in these studies,” the company stated.

Masitinib is an orally-administered antibody designed to block the activity of several cell types involved in inflammatory and neurodegenerative processes  by preventing signaling through proteins called tyrosine kinases.

Study AB19001 is comparing the safety and effectiveness of masitinib in combination with Sanofi’s Rilutek (riluzole) versus a combination of placebo with Rilutek in up to 495 adult participants.

Eligible patients must have been diagnosed in the past two years, and their disease should be progressing at a normal or fast pace — defined as a 0.3 or greater monthly decline in their ALS functional rating scale-revised (ALSFRS-R) scores, a measure of disability.

The study aims to confirm the findings of an earlier Phase 2/3 clinical trial (NCT02588677), which  evaluated the safety and efficacy of masitinib at either 4.5 or 3.0 mg/kg doses, versus a placebo, among 394 adults who had been diagnosed with ALS within three years of entering the trial.

Results indicated that the 4.5 mg/kg dose was associated with a significant, 27% slower decline in participants’ abilities to perform daily activities at 48 weeks, compared with those receiving placebo.

This effect was observed initially only in individuals whose ALS progressed at a typical rate of fewer than 1.1 points per month on the ALSFRS-R scale, prior to entering the study. Those who progressed faster did not appear to benefit as much from the addition of masitinib.

However, a subsequent analysis of separate patient groups within the overall trial population suggested that masitinib could significantly delay progression in patients with fast-progressing disease if treatment began at less severe stages.

“AB Science is committed to continue the development of masitinib in the indications initiated, while ensuring patient safety,” the company wrote.