Morquio A Drug Confers 'Modest' Benefit: FDA Review

November 18, 2013

By Toni Clarke

(Reuters) - An experimental drug to treat a rare genetic disorder that causes skeletal malformation and a host of related lung, eye, ear and heart problems confers "modest" benefit, according to an initial review by the U.S. Food and Drug Administration.

Vimizim (elosulfase alfa) is being developed by BioMarin Pharmaceutical Inc to treat Morquio A Syndrome, also known as MPS IV-A.

The FDA review was posted on the regulator's website on Thursday ahead of a meeting of outside advisers to the agency scheduled for November 19. The advisory panel will be asked to give its own opinion on the drug. The FDA is not bound to follow the advice of its advisory panels but typically does so.

The FDA review said the main safety concerns on Vimizim relate to anaphylaxis and allergic reactions. It also said further studies might be needed to better understand the role of antibody development on long-term efficacy and safety.

Morquio A Syndrome is characterized by a deficiency of an enzyme known as N-acetylgalactosamine-6-sulfatase (GALNS), which causes excessive storage in the body of long chains of sugars known as glycosaminoglycans.

This build-up can lead to short stature and joint abnormalities that limit mobility and endurance. The disease can also cause hearing loss, eye problems and heart disease. Symptoms often appear before the age of five.

Morquio A Syndrome is one of a group of lysosomal storage disorders known as mucopolysaccharidoses (MPS). Lysosomal storage disorders are typically chronic and progressive, and involve multiple organs of the body.

The FDA reviewed a phase III trial of Vimizim. The main goal of the trial was to improve symptoms as measured by a six-minute walk test. A secondary goal was change measured by a three-minute stair climb test.

The company reported that after 24 weeks of treatment with the drug, Vimizim increased patients' six-minute walk distance by 22.5 meters compared with a placebo, a benefit the FDA reviewers called "modest."

The advisory panel will be asked to give an opinion on whether the 22.5 meter improvement is clinically meaningful.

There was no statistically significant change in the stair test compared with placebo.

Analysts, however, said they expected the advisory panel's opinion to be favorable.

"Though the FDA may have expressed somewhat more caution than some may have expected regarding Vimizim's efficacy ... overall we did not see any major surprises given what is already known about Vimizim's profile," Wells Fargo Securities analyst Brian Abrahams wrote in a note.

Vimizim has been given "orphan drug" status by the FDA, which means it will receive seven years of market exclusivity if approved. An orphan drug treats diseases that affect fewer than 200,000 patients.

Vimizim is expected to generate sales of $532 million by 2018 if approved, according to the average estimate of eight analysts polled by Thomson Reuters.

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