Japan will join an international clinical trial of a drug to treat Duchenne muscular dystrophy being developed by GlaxoSmithKline K.K., a major British pharmaceutical firm, and other entities, according to sources.
The decision is unusual in that Japan will participate in only the third and final phase of the trial, skipping the first and second phases and using data obtained overseas from the initial phases.
Duchenne muscular dystrophy (DMD) is a severe, rapidly worsening form of muscular dystrophy--a hereditary, intractable disease in which patients experience progressive loss of muscle strength.
DMD occurs in young boys and there are estimated to be about 4,000 patients nationwide. From around the age of 10, patients begin to show symptoms such as difficulty walking, which is followed by serious conditions including respiratory and heart failure, gradually developing.
The disease is caused by an absence of dystrophin protein, which supports muscle structure, due to gene mutations. Comprising substances similar to RNA, the candidate drug enables dystrophin to be produced by complementing the mutated genes. Unlike symptomatic treatment, the drug could address the fundamental cause of the disease.
Gene mutations differ slightly between patients and thus the drug must be synthesized accordingly. It is hoped the medication will be effective on a little more than 10 percent of DMD patients, or several hundred people nationwide, the sources said.
Japan's participation was approved after it established satisfactory patient registration and gene analysis systems.
In the first and second phases of the drug trial conducted in Europe, patients reportedly saw their conditions improve with dystrophin produced by their bodies. No major side effects were reported.
About 180 people from 18 nations and territories around the world are expected to take part in the third phase of the clinical trial. In Japan, 12 patients soon will be administered either the new drug or a placebo once a week for about a year to observe changes in muscle strength, the sources said.
According to the Health, Labor and Welfare Ministry, the first and the second phases can be skipped if the safety of a candidate product is confirmed in overseas clinical tests.
This is in line with the guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use, agreed on by Japan, the United States and Europe.
(Feb. 7, 2011)