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Masitinib: could this be the next MS market blockbuster?


03/07/2020

AB Science announced positive results of a phase 3 clinical trial of masitinib in the treatment of progressive forms of multiple sclerosis (MS). Findings could be the precursor to a blockbuster outstripping the success of medications like Roche’s Ocrevus (ocrelizumab). What is it about masitinib that might lead its producer to a triumph?



Masitinib demonstrated clinical efficacy in treating primary progressive MS (PPMS) and non-active secondary progressive MS (nSPMS) in a phase 3 study involving 301 patients. Results were announced in February 2020.

Coordinating investigator for the study, Prof. Vermersch of Lille University, said that while numerous treatments based on targeting of B-cells and T-cells of the adaptive immune system are available for patients with relapsing forms of MS, these strategies have been unsuccessful in PPMS and nSPMS.

Consequently, there remains a very high medical need for people with progressive forms of MS, he said.

Patrick Vermersch is a professor of neurology and a key opinion leader in the field of MS. He was one of the leaders in the development and registration of Ocrevus, the MS medication which achieved blockbuster status in 2018, making $2.4 billion in sales in its first year of commercialisation.

“Masitinib does not target the adaptive immune system and the results from this study represent a scientific breakthrough because this is the first time that the novel strategy of targeting the innate immune system via mast cells and microglia has been able to significantly slow progression of clinical disability in progressive forms of MS,” Vermersch explained.
 

Multiple sclerosis and the unmet need

MS is an incurable neurodegenerative disorder in which sufferers see specific neurological functions decline, causing a variety of worsening symptoms over time: commonly, loss of mobility, fatigue, and paralysis. The variations in the rate at which the disease advances depend upon which form of MS a person suffers from.

The most common diagnosis is relapsing-remitting MS (RRMS) in which a person experiences relapses during which symptoms worsen, with the condition generally advancing in line with these events. More severe cases involve continuous, gradual progression of symptoms, with or without relapses.

In the US, the National MS Society estimates that 1 million people are living with an MS diagnosis. 80-85% of initial diagnoses are for RRMS, and 10-15% for PPMS. However, about 50% of all RRMS cases will have transitioned to a form of SPMS after 10 years, and 90% after 25 years.

PPMS and nSPMS function quite differently to other courses of MS, and as such are not easily treated. While there are 10 treatments on the market for RRMS, there are only 2 available for progressive MS sufferers: ocrelizumab and siponimod., the latter being only registered in active SPMS.

The toxicity of both of these medications as a result of their immunosuppressive functions means that there are limitations on who can use them and on how long treatment is considered safe. Evidence from a number of studies suggests that masitinib, on the other hand, is very well tolerated by patients, with longer-term therapy cycles a distinct possibility. Given the chronic nature of MS, this alone would give masitinib the potential to be a disruptive product.
 
The unique function of masitinib, in targeting two separate components of the innate immune system, means that there is nothing like it available to patients – making it an exciting area of medical science. This might give the treatment a unique potential to bridge the gap in what is a poorly met medical need, one about which MS sufferers are vocal.
 

Innovative and versatile

Masitinib is a tyrosine kinase inhibitor, a small synthetic molecule, quite different from the anti-body-derived competition. The drug has had success in different clinical applications, building a resumé that suggests versatility and strong market positioning.

President of the Science Committee at AB Science, Prof. Olivier Hermine, projected confidence on the topic of masitinib’s accomplishments in clinical trials.

“Indeed, this is the second piece of supportive evidence delivered by the masitinib clinical program. The first one was the positive Phase 2B/3 study with masitinib in amyotrophic lateral sclerosis (ALS),” he said.

“The two studies taken together clearly demonstrate that targeting the innate immune system via macrophage/microglia and mast cells, as masitinib does, is one of the right strategies to treat neurodegenerative disorders. This is a true innovation that justifies the long-term efforts from AB Science to develop masitinib in ALS, progressive forms of MS and Alzheimer’s disease,” Professor Hermine concluded.

A new patent was filed based on results of this recent study. Following the success, AB Science is consulting with the regulators to discuss the pathway to reaching patients as soon as possible. The company plans to present detailed study results at a medical meeting in the coming months.