Tyrosine Kinase Inhibitor Shows Positive Results in Slowing Slide to MS Disability

A selective tyrosine kinase inhibitor being studied for primary progressive multiple sclerosis (PPMS) and nonactive secondary progressive MS showed a 37% reduction in the risk of progression to disability at its lower dose, according to phase 2b/3 study results released Sunday at MSVirtual 2020: 8th Joint ACTRIMS-ECTRIMS Meeting.

The higher dose of the drug was not different than placebo, however, and will not be pursued further.

Mastinib is also being studied in amyotrophic lateral sclerosis, Alzheimer disease, and other indications; it is believed to have neuroprotective effect through its activity on mast cells. It is already approved as a veterinary drug for use in dogs with mast cell cancers.

The study, conducted in 7 countries, compared the efficacy and safety of masitinib at 4.5 mg/kg/day versus matched placebo, or masitinib at 4.5 mg/kg/day with a dose escalation to 6 mg/kg/day after 3 months of treatment versus matched placebo (ie, the 2 doses were assessed with their own control group).

The primary outcome measure was the Expanded Disability Status Scale (EDSS) after 96 weeks of treatment in the overall study group as well as in the subgroup analysis. Patients, aged 18 to 75, were randomized (2:1) in the double-blind trial. EDSS changes were assessed at 8 time points between weeks 12 and weeks 96.

During the presentation, the lead investigator, Patrick Vermersch, MD, PhD, of Hôpital Salengro in Lille, France, noted that 50% of the patients receiving oral mastinib at the lower dose had EDSS scores of 6; the median EDSS score was 5.5, and the mean and median age was about 50.

Of the 4.5mg/kg/d group,199 received mastinib and 101 received placebo.

According to the Kaplan-Meier analysis, the cumulative probability of a confirmed EDSS progression at 12 weeks was reduced by 37% (HR, 0.63; 95% CI, 0.33-1.20; P = .159).

There was also a significant reduced relative risk of 42% to first progression (HR, 0.58; 95% CI, 0.35-0.96, P = .034).

The safety analysis showed that 94.5% of patients receiving mastinib had at least 1 adverse event (AE) compared with 87.1% for placebo. Serious AEs were 21.1% for mastinib and 12.9% for placebo, which is in line with the known safety profile of mastinib, according to the presentation.

Masitinib is being developed by AB Science and it is its main compound under development.

Reference

Vermersch P, Hermine O. Masitinib in primary progressive (PPMS) and non-active secondary progressive (nSPMS) multiple sclerosis: Results from phase 3 study AB07002. Presented at MSVirtual 2020: 8th Joint ACTRIMS-ECTRIMS Meeting; September 11-13, 2020. Presentation FC04.01.