Needle in the Haystack, or Rembrandt in the Attic? Drug Repurposing's New Strategy

As the time and investment required to develop new therapies continues to climb, a strategy that has been around for some time is gaining momentum: repurposing APIs that have been discontinued or abandoned, and developing them for new indications. Examples include Pfizer’s Viagra, which was originally developed to treat angina and hypertension, and Celgene’s thalidomid, a treatment for leprosy and multiple myeloma that repurposed thalidomide, a morning sickness treatment that was found to cause birth defects and banned.

Driving renewed interest is, not only competitive pressure, but the rise of patient activism, as well as the benefits offered by orphan drug filings and the 505(b)(2) approval pathway in the U.S.

Currently, between 5–10% of the pharmaceutical market is connected to repurposed active ingredients, and the industry has “barely scratched the surface” of its potential, according to Hermann Mucke, a consultant based in Vienna, Austria, who has specialized in repurposing, and was involved in repurposing galanthamine, a plant-based drug that had been sold in Eastern Europe decades ago as a treatment for myopathy, and eventually was commercialized by Janssen as an Alzheimer’s disease therapy.

The challenge is knowing what to develop and where to find it. For individual companies, that means being able to find what Kevin Rivette, founder and CEO of the IP asset management firm, Aurigin Systems, Inc., called “Rembrandts in the Attic.”

There is a huge amount of data available in the public domain, but mining it is “backbreaking,” says Mucke, who is editor of a new journal, Drug Repurposing, Rescue and Repositioning, which is being published semi-annually as part of the peer-reviewed Assay and Drug Development Technologies. The publication covers in-silico techniques for identifying potential targets, data mining, reformulation and new delivery modes, and other topics.

Mucke has also been hard at work at the Discontinued Drug and Candidate Database (DDCD) as a reference tool to facilitate the identification of potential repurposing candidates.

The database contains information on 100 compounds so far, going back to the early 1990s, with data on APIs discontinued from development, or pulled from the market. In addition to chemical structure, INN names and/or research codes, pharmacological activities, key literature and patent references, the database contains developer statements and analyst assessments.

Currently, Mucke is using it as an internal tool, but he hopes to secure funding to develop and publish the database, ideally, as an open access tool that would facilitate drug repurposing.

Repurposing requires a mix of scientific knowledge and intuitive sense. “You have to be a clever pharmacologist, use your knowledge to connect the dots in new ways. Very often in part of repurposing you just try find a new application where you know that the known pharmacological activity should be of some use. Then you must project that there is another pharmacological activity, direct or indirect, that hasn’t been reported yet, that you can take advantage of. You can work from your own data, or from data that you mine from larger resource, patent literature,” Mucke says.

There are also legal considerations, as addressed in this paper. 

Not only economic reasons, but patient-centered strategies, could motivate more repurposing of drugs. The practice puts patent extension in a very different light from the typical “me too” and evergreenining strategies that have been seen in pharma. 

Currently, Chicago-based Cures Within Reach is crowdsourcing potential repurposing research projects, which could result in more commercial projects.

In Cambridge, UK, a recent startup called HealX is using advanced informatics to mine pharma's IP for potential cures for rare diseases, and establishing links with key patient groups. 

If these efforts are not in the mainstream right now, continued competitive pressures may make this standard practice in the near future. Trillions of dollars have been spent to develop these discontinued compounds. Why not get the most out of that investment?  

The process is not exactly a slam dunk, but eliminates a great deal of the risk that traditional drug development requires.  For an interview with Mucke, stay tuned to PharmTech’s August Outsourcing Supplement, which will be out soon.