Mast cells
The European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) has recommended refusal of the marketing authorization for masitinib (Masipro).
Masitinib is a tyrosine kinase inhibitor being developed by AB Science to treat adults with smoldering or indolent severe systemic mastocytosis (SM).
To support the application for masitinib, AB Science presented data from a study involving 135 SM patients who had severe symptoms, including at least one of the following: itching, hot flashes, depression, and tiredness.
Researchers compared masitinib to placebo in these patients, looking for improvements in any of the symptoms during the first 24 weeks of treatment.
The CHMP said it was concerned about the reliability of the study results because a routine good clinical practice inspection at the study sites revealed serious failings in the way the study had been conducted.
In addition, major changes were made to the study design while the study was underway, which made the results difficult to interpret.
Finally, data on the safety of masitinib were limited. And the CHMP was concerned about side effects, including neutropenia and harmful effects on the skin and liver, which were particularly relevant because masitinib was intended to be used long-term.
Therefore, the CHMP concluded the benefits of masitinib do not appear to outweigh the risks, and the committee recommended the drug be refused marketing authorization.
The CHMP informed AB Science of this negative opinion in May, and the company asked the committee to re-examine its opinion. However, the CHMP ultimately concluded that masitinib should be refused marketing authorization.
AB Science said this decision does not have any consequences for patients in clinical trials or compassionate use programs of masitinib.
The company also said it intends to initiate a confirmatory study in patients with smoldering or indolent severe SM that is unresponsive to optimal symptomatic treatment in order to confirm the results from the first pivotal study.
