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For Twenty-Five Million Zebras: New Hope for Therapies

Several generations of North American trained doctors were taught: if you hear hoofbeats, think horses not zebras. This graphic image reinforced an important aspect of medicine for young physicians seeing mostly severely ill patients in tertiary care hospitals: if an otherwise healthy patient is coughing, it is most likely a bad cold. It is almost certainly not pneumonic plague.

What Congress, FDA, and NIH have learned over the last 30 years is that there are many more medical zebras in the United States than anyone imagined. NIH has catalogued nearly 7,000 rare diseases. More are being discovered all the time. Altogether, it is estimated that 25 to 30 million Americans are affected by rare diseases.

When I first became involved in health policymaking in the mid-1970’s, the “war on cancer” was in its first, high-growth phase and cardiovascular disease was rampant. An “orphan drug” was one that would help third world diseases. During that decade, there were less than a dozen therapies developed for diseases that were rare in the US and elsewhere in the world.

The realization that there could be political strength in unity among those with rare diseases led to the creation of the National Organization for Rare Disorders (NORD) and the passage of the Orphan Drug Act of 1983 (ODA). A rare disease was defined as one that affects fewer than 200,000 Americans. Many rare disease populations are above 100,000, but far more are under a few thousand.

As a result of the ODA, more than 350 orphan products have been approved. The growth of biotechnology and the growth of orphan drugs have been closely aligned. Likewise, knowledge gained through orphan drug development has returned benefits for patients with more prevalent diseases.

More aggressive efforts are being undertaken to stimulate the development of orphan products. Just this year, FDA has been involved in:

  • Helping to develop and work with NIH’s Therapeutics for Rare and Neglected Diseases program (TRND), which is intended to move promising orphan drugs forward in the drug development pipeline until they meet FDA requirements for an Investigational New Drug (IND) application.
  • Creating a new position, Associate Director for Rare Diseases in the Center for Drug Evaluation and Research, who will assist stakeholders and developers of drug and biologic products in navigating the complex regulatory requirements for approval of therapies for rare diseases.
  • Developing the Rare Disease Repurposing Database that identifies drugs that are deemed promising for rare diseases and are already approved by FDA for another disease.
  • Stepping up its training of medical product reviewers to devote more time and focus to the construction and analysis of small clinical trials.

These efforts have been welcomed by the rare disease community as important steps. Deservedly so.

But will these actions prompt a change in thinking at FDA? FDA claims that orphan drugs are reviewed with the same standards for safety and effectiveness as other drugs. This has become a barrier rather than an advantage.

When reviewing medical product applications for rare diseases, FDA needs to apply a somewhat difference set of rules to account for the special challenges of developing treatments for very small patient populations. Simply put, you can’t expect a 500-person safety database in a disease that only affects 500 people.

With more than 25 million “zebras” roaming the United States, such special considerations seem the least we can do. It is imperative that we advance the scientific and regulatory knowledge that provides these patients with hope and, ultimately, with therapies.


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