Unfundable: Clinical trials for rare diseases and orphan drugs

Unfundable: Clinical trials for rare diseases and orphan drugs

By John W Henson IV
Director, Neurology

The study of acetazolamide for idiopathic intracranial hypertension described on page 9 of the Spring issue of BrainWaves raises an important question about a neglected aspect of clinical trials: How do investigators obtain funding to study the efficacy of a drug that has no commercial potential?

Only 300 of the approximately 7,000 known human diseases are of interest to the biopharmaceutical industry from the standpoint of prevalence or commercial potential, according to the Office of Rare Diseases Research (ORDR) at the National Institutes of Health (NIH). The Orphan Drug Act of 1983 sought to use patent protection and tax incentives to promote development of drugs for diseases with a small market. In this context, the word “orphan” refers to a condition or drug that has not been “adopted” by the pharmaceutical industry because of limited commercial potential and a rare disease is one that affects 200,000 or fewer Americans. In the twenty years following enactment of the ODA, 249 orphan drugs received marketing authoriza¬tion, compared to 10 in the preceding decade, with the most notable being Amgen’s erythropoietin.

Commercial potential alone does not determine value

Low prevalence does not equate to limited commercial potential, of course, because pricing must also be considered. The vigorous development of expensive new treatments for diseases of moderate or low prevalence, such as temozolomide for malignant gliomas and natalizumab for multiple sclerosis, are good examples. But when the condition is rare or the treatment of interest is post-patent, as with the study of acetazolamide for idiopathic intracranial hypertension (IIH), there is double jeopardy against much needed advances for patients with such disorders.

A survey of the NIH clinical trials registration web site, reveals that acetazolamide is under evaluation as a single agent in three clinical trials in the United States. All three are sponsored by the NIH. The four-year, $1.5- million study of acetazolamide for IIH is one of two studies funded by the National Eye Institute. The other study is funded through the NIH Office of Rare Diseases Research.

The biopharmaceutical industry has been spectacularly successful in developing new treatments for many of the most important human diseases, but the study of acetazolamide for IIH is a reminder that new treatments for orphan diseases usually require federal or private foundation funding.

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