Developer stops large trial of promising treatment for progressive MS
Masitinib clinical program for MS, no longer a priority, has been suspended
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A large clinical trial testing masitinib for progressive forms of MS is being suspended after its developer, AB Science, announced a change in priorities.
- AB Science has discontinued a large, late-stage trial testing its oral therapy masitinib in people with progressive multiple sclerosis.
- The trial was stopped due to a change in company priorities, not safety concerns.
- The developer announced it would advance masitinib for potential use in treating ALS.
AB Science is stopping a late-stage clinical trial testing its oral drug masitinib as a treatment for progressive forms of multiple sclerosis (MS), saying this study and the therapy’s clinical development for MS are no longer a priority for the company.
Instead, the developer will advance masitinib for potential use in amyotrophic lateral sclerosis (ALS).
This decision brings to a halt the large Phase 3 MAXIMS trial (NCT05441488), also known as Study AB20009, which had been designed to test masitinib in about 800 adults with primary progressive MS (PPMS) or nonactive secondary progressive MS (SPMS). The trial, previously expected to run through 2028, was meant to be global, though to date, sites were open only in Europe.
The announcement follows the voluntary suspension of patient enrollment in MAXIMS earlier this year while AB Science reviewed its strategic priorities. That review included the company’s pursuit of Phase 3 clinical development in MS via partnerships, as AB Science stated that it did not have marketing capabilities to support the work.
According to a company press release, the decision to stop the MAXIMS trial is not related to any safety concerns with masitinib, but is due to its nonpriority development status. In addition to MAXIMS, AB Science is discontinuing masitinib Phase 2 or 3 trials in two other conditions also no longer deemed a priority for the company.
AB Science said it will now focus its resources on two clinical programs: masitinib for ALS, another progressive neurodegenerative disease, and AB8939 for acute myeloid leukemia, a type of blood cancer.
“This decision to terminate non-priority studies for which recruitment had been suspended and for which there is no prospect of a rapid resumption reflects compliance with regulatory requirements,” said Stéphane Ledermann, chairman and CEO of AB Science. “It is also consistent with our commitment to allocate all necessary resources to ensure the two priority programs are carried out to the highest standards of quality.”
Masitinib significantly slowed MS progression in earlier trial
Masitinib was designed to block tyrosine kinases, enzymes involved in the activity of immune cells such as mast cells, microglia, and macrophages. These cells are part of the body’s innate immune system — what people are born with — and have been implicated in mechanisms that may contribute to progressive MS.
In the MAXIMS trial, cleared by the U.S. Food and Drug Administration in 2023, participants were being randomly assigned to receive either masitinib, at a dose of 4.5 mg/kg, or a placebo, daily for two years. The trial’s main goal was to determine whether masitinib could delay confirmed disability progression compared with the placebo.
The study was meant to confirm the promising results from the earlier Europe-based Phase 2b/3 ABO07002 trial (NCT01433497), which tested two masitinib doses against a placebo in 611 adults with PPMS or nonactive SPMS. Eligible participants for that study had no relapses in the prior two years but showed evidence of disability accumulation.
Final data showed that the study met its main goal, with the lower masitinib dose (4.5 mg/kg) significantly slowing disability progression, as measured by the Expanded Disability Status Scale, compared with the placebo. The benefit was seen in both PPMS and nonactive SPMS patients.
The low dose was also linked to other benefits, including a 47% greater chance of either no disability progression or reduced disability and a 42% lower risk of first disability progression. Treated patients also had a 37% lower likelihood of three-month confirmed disability progression, data showed.
Masitinib’s safety profile was generally consistent with that reported in prior studies, with no new safety concerns identified. The most commonly reported adverse events with the therapy were diarrhea, rash, nausea or vomiting, swelling, and itchy skin.
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