Repurposed drugs present the promise of enabling patients’ access to much-needed therapies sooner and at a lower cost. The promise is especially great for patients suffering from rare diseases that lack effective therapies. The traditional development path in pharma is long and costly. In the case of rare diseases, this expense has to be recouped by charging very high prices to the small affected population during the period of exclusivity provided by regimes like the Orphan Drug Act.
Providing treatments costing in excess of $200,000 annually to a total population of 25 million to 30 million rare-disease patients could consume almost 50 percent of the gross domestic product. These levels of spending obviously are not sustainable. Making it easier to produce drugs without spiking prices is therefore a pressing, unmet policy need. Additionally, many patients suffering from rare diseases can’t wait twelve to seventeen years for a new treatment to be discovered, developed, and marketed.
The development of repurposed drugs (wherein a drug that already is approved for a specific condition can be repurposed to treat another) is promising in that it enables a faster regulatory path to market since the safety profile of the product already has been established, reducing the risk and cost to get these much needed drugs to patients. Yet historically, biotech and pharma have not pursued repurposing because of the difficulties in establishing exclusivity under the current regulatory paradigm.
The ongoing and expanding drug repurposing project of evaluating auranofin (Ridaura®), a rheumatoid arthritis agent first approved in 1985, for Chronic Lymphocytic Leukemia (CLL) is a great example. CLL satisfies the definition of a rare disease. The auranofin drug repurposing project successfully advanced this treatment from an in vitro screen to use for patients diagnosed with this hematologic malignancy in eleven months. This drug is being developed through The Learning Collaborative, a partnership between the Institute for Advancing Medical Innovation (IAMI) at the University of Kansas Medical Center (KUMC), The Leukemia & Lymphoma Society (LLS), and the National Center for Advancing Translational Sciences (NCATS) at NIH.
Although there are drug repurposing success stories with agents such as thalidomide and rapamycin (cases where specific regulatory quirks allowed for additional exclusivity), a major challenge for most repurposed drugs is lack of a clear exclusivity path. Although exclusivities provided by patents and the Orphan Drug Act protection may be nominally applicable to the new use, such exclusivities can be undermined by physician decisions to prescribe the generic version of the old drug “off-label” for the new indication.
Lack of exclusivity (typically afforded by the composition of matter patents for new drugs) creates challenges for innovator firms, generic manufacturers, and investors, making it difficult to fund drug development activities required for market approval. And even though rare diseases represent the most pressing case, the solution for repurposing existing or abandoned drugs (therapeutic candidates whose development has been discontinued by innovator firms for non-safety reasons) should be useable beyond rare diseases. The solution itself must be repurposable—for diseases like Alzheimer’s, diabetes, or many other chronic conditions that might benefit from existing therapeutic agents.