AB Science’s share price has taken a hit after European Medicine Agency's advisors rejected approval of masitinib for amyotrophic lateral sclerosis.

The Committee for Medicinal Products for Human Use said reliability of the data provided in the submission was not robust enough to support a registration, based on a Good Clinical Practice inspection at two of the main clinical study sites.

It also failed to recognise the clinical relevance of the distinction made by AB Science between patients with "normal" progression (accounting for 85 percent of patients in the study) and for whom an improvement on the primary endpoint - ALSFRS score - has been demonstrated, and those with “rapid" progression (accounting for 15 percent of patients in the study), the firm noted.

The company has requested a re-examination of the decision, and said it would provide further analyses to address the CHMP’s concerns.

ALS, which is also referred to as Lou Gehrig's disease, is a rare degenerative disorder that causes muscle wasting and progressive paralysis.

Around 50,000 people in the European Union and in the US currently have the condition, with more than 16,000 new cases diagnosed each year in these regions. The prognosis for patients is very poor, as the disease has a fatal outcome for most within five years of diagnosis.

The condition is inherited in 5 percent to 10 percent of cases, but the cause for the majority of cases is not well understood, and there is currently no cure.

Masitinib is a new orally administered tyrosine kinase inhibitor that targets mast cells and macrophages, important cells for immunity, through inhibiting a limited number of kinases.

A second opinion from the CHMP on the drug, which carried orphan status in both the US and EU, is expected in July.