Student guest post on drug repurposing

Antiques Become Modern

     The repositioning process for drugs means discovering new clinical benefits for a drug that has been already approved to treat other diseases or conditions, according to The National Center for Advancing Translational Sciences, part of the National Institutes of Health (NIH), US Department of Health and Human Services. It has been estimated that 30% of new drugs and vaccines approved by the US FDA in recent years attributes to the process of drug repurposing, repositioning, and rescue. This process offers many advantages including the costs and time saved from circumventing the extensive testing typically required for demonstrating the safety of a newly developed drug. Since these drugs have already been approved for human use, the well characterized properties (pharmacology, toxicology, and formulation) of these candidates allow for the process involved in therapeutic switching to a novel clinical use to occur relatively quickly. Because of the extensive financial commitments and time required for developing a new drug, the goal of bringing a new drug to market with a relatively low cost is very attractive.  The cost associated with the development of a new drug is estimated at over $2 billion, and the timeline typically involves more than 12 - 16 years. In contrast, a repurposed drug can be approved in an extensively shorter time frame, 3- 12 years, with an average cost of $300 million. In addition, approval rates for new drugs are typically close to 10%, but is often 30% for therapeutically switched drugs. Finally, the process of repositioning of drugs could represent substantial assistance for low income patients who have chronic diseases, for example autoimmune lymphoproliferative syndrome (ALPS), since they can obtain their medications for considerably lower prices.

     There are a number of successful drug repurposing stories. Perhaps the most famous stories of a repurposed drug involves thalidomide. Thalidomide had been used to treat morning sickness in pregnant women in the 50s of the last century, then it was withdrawn from markets due to birth deformities. This drug has been synthesized as racemic mixture because it is a chiral compound. Lately, it was discovered that one of the enantiomers (the (R)-(+)-enantiomer) was effective to treat pregnant morning sickness, while, the (S)-(-)-enantiomer made the congenital malformations. Nowadays, this drug has been repurposed and has been approved by FDA to treat leprosy in 1998 and multiple myeloma in 2006. Another success story involves sildenafil. This drug was originally developed to treat hypertension, but it failed during development. However, during clinical trials, it was noticed that sildenafil could improve erectile dysfunction. As a result, it was approved to treat erectile dysfunction. Since that time, sildenafil has been subjected for further re-tasking and is now approved to treat pulmonary hypertension.

References:

1.      I. Agranat, H. Caner, J. Caldwell, “The Thalidomide Tragedy: The Myth of a Missed Opportunity,” Nature Reviews Drug Discovery 1, 753-768 (2002).

2.      https://ssir.org/articles/entry/repurposing_social_impact_bonds_for_medicine.

3.      28. Joseph A. DiMasi & Henry G. Grabowski, The Cost of Biopharmaceutical R&D: Is Biotech Different?, 28 MANAGERIAL & DECISION ECON. 469, 469 & 475 (2007).

4.      UNITED STATES GOVERNMENT ACCOUNTABILITY OFFICE (GAO), NEW DRUG DEVELOPMENT: SCIENCE, BUSINESS, REGULATORY, AND INTELLECTUAL PROPERTY ISSUES CITED AS HAMPERING DRUG DEVELOPMENT EFFORTS 1 (2006).