Orphan Drug for Proteus Syndrome Gets Rare Pediatric Designation

James Radke

The U.S. Food and Drug Administration (FDA) has granted ArQule, Inc a rare pediatric disease designation for miransertib (ARQ 092) to treat Proteus syndrome, a rare overgrowth disease.

The rare pediatric disease designation means that if miransertib gets approved, the company will be eligible for a Priority Review Voucher.

The voucher can be used on any future drug to reduce the FDA review time by 4 months.  The voucher is also transferable and many small biotech companies sell their voucher to larger pharmaceutical companies. Earlier this year, Sarepta sold their voucher for $125 million to Gilead Sciences.

Proteus syndrome is characterized by bones, skin, and other tissues growing out of proportion to the rest of the body. The overgrowth is often asymmetric. The syndrome is named after Proteus, a Greek God who could change his shape.

Symptoms vary with each patient but the overgrowth tends to start in early childhood and the most observable symptoms are usually those involving asymmetric growth of 1 limb or extremity. These patients tend to be at risk for deep vein thrombosis and pulmonary embolism due to the blood vessel abnormalities that can occur with this condition. It needs to be noted that the current understanding of Proteus syndrome is extremely limited—mostly because it is extremely rare. At present, only about 120 cases have been documented worldwide.

Proteus syndrome is due to a mutation in the AKT1 gene. Under normal circumstances, the AKT1 gene helps regulate cell growth and proliferation. A mutation of the gene can disrupt the cell's ability to regulate its own growth. Miransertib (ARQ 092) is a selective small molecule inhibitor of the AKT kinase.

A phase 1/2 trial is currently enrolling patients with overgrowth diseases, including Proteus syndrome. The phase 1, dose escalation, study is enrolling 6 patients and an additional 10 patients will be enrolled in the phase 2 trial.  For patients unable to travel to the clinical trial site in Bethesda, Maryland (due to disease severity), ArQule may supply miransertib to those patients.

The clinical trial is being conducted at the National Institutes of Health (NIH) Clinical Center in Bethesda. The principal investigator is Leslie G Biesecker, M.D., Chief of the Medical Genomics and Metabolic Genetics Branch at the National Human Genome Research Institute (NHGRI) who discovered the important role AKT plays in the pathophysiology of Proteus syndrome.

In a news release,  Brian Schwartz, M.D., Head of Research and Development and Chief Medical Officer at ArQule said, “The FDA’s granting of the Rare Pediatric Disease Designation and Orphan Drug Designation underscores the unmet medical need in Proteus syndrome and the potential for miransertib to address this unmet need.”

Dr Shwartz added, “We plan to work closely with the FDA and clinical experts, including Dr. Leslie G. Biesecker.”

Image courtesy wikimedia commons. 

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