Drug repositioning, a strategy where drugs are repurposed to target diseases for which they were not originally intended, can offer benefits to pharma companies through shorter development times and lower development costs. The strategy maximises the value of drug assets that already have established safety profiles.
The orphan drug industry is no stranger to drug repositioning. The list of orphan drugs repurposed from drugs approved for common conditions is quite long, and the FDA hosts a Rare Disease Repurposing Database (RDRD) that lists orphan designated drugs that are already market-approved for the treatment of other diseases.
Some examples of orphan drugs repurposed from drugs for more common indications include:
- Amphotericin B, originally an antifungal, has received orphan designation for leishmaniasis, aspergillosis, cryptococcosis and forms of candidiasis.
- Thalidomide, originally developed (and later withdrawn) for morning sickness has orphan drug designation for multiple myeloma.
- Sildenafil, originally marketed by Pfizer as Viagra for erectile dysfunction, has received orphan drug designation for pulmonary arterial hypertension as Refacto.
- Everolimus is marketed by Novartis as Certican in transplantation medicine but also as orphan drug Afinitor for renal angiomyolipomas in patients with tuberous sclerosis complex
Drug repositioning in the orphan drug market could have significant commercial value and can breathe new life into existing or withdrawn assets. However, a letter to the BMJ in 2012 argued that the price increases of repurposed drugs were not justified. The authors examined Belgian hospital prices of drugs for common diseases that were then repurposed for rare indications. They found that medicine prices for the rare indication were nearly always higher than for the common indication – and in some cases this amounted to a 200-fold difference. The authors argued that in the cases they examined, evidence supporting the effectiveness of the medicine for the rare indication had been published many years prior to the orphan drug designation application. Thus they determined that the observed price differences were in excess of the higher costs of R&D and market access.
What do you think about drug repurposing for orphan drugs? Are repurposed medicines still too expensive in the orphan drug market? Is the price increase justified?
The World Orphan Drug Congress Europe brings together pioneers from the orphan drug community, including key opinion leaders from the payer, HTA, public health and patient advocacy bodies. Read more about the World Orphan Drug Congress Europe 2013, 14-15 November 2013, Geneva.