Therapeutics
Challenges and opportunities in the treatment of rare diseases
There are approximately 7,000 rare diseases, which from a regulatory perspective are defined as those diseases where there are less than 200,000 patients in the US or that affect no more than five in 10,000 of the general population in the EU.
S
uch diseases usually have a genetic basis, often affecting patients early in childhood, and are frequently progressive, disabling and life threatening in nature. These characteris- tics can have a devastating psychological impact on families of children suffering from these dis- eases. Better known examples of rare disease include Duchenne Muscular Dystrophy, Cystic Fibrosis, the Mucopolysaccharidoses (MPS) and rare cancers. While each rare disease alone affects a small number of patients, it has been estimated that the combined number of people suffering from a rare disease in the US and EU exceeds 55 million1, highlighting the huge societal impact of these diseases.
A number of unique clinical, regulatory and commercial challenges are associated with the development of therapies for the treatment of rare diseases. In recognition of these challenges, there has been legislation in the US, EU and elsewhere in the world which provides regulatory and financial incentives aimed at stimulating investment in ‘orphan drugs’ to treat rare diseases (Table 1). In addition, the FDA has created the Office of Orphan Products Development to focus on the challenges of developing therapeutics for the treat- ment of rare disease and to help companies navi- gate the regulatory review process. In addition, in 2010 the FDA created the Rare Disease Program
Drug Discovery World Spring 2013
within the Office of New Drugs with the specific focus of developing the policies and procedures for the review of new drug applications for orphan drug products and to ensure the appropriate train- ing for FDA reviewers. In both the US and the EU, orphan drug designation can be applied for at any stage of the development process.
Orphan drug legislation has generally been con- sidered to be extremely successful. Prior to these legislative acts there were essentially no drugs specifically developed to treat rare diseases, where- as since passage of the Orphan Drug Act in the US in 1983, 2,755 agents have received an orphan drug designation in the US, with 424 orphan drug approvals. An analysis of compounds progressing from clinical development to approval in the US between 2006 and 2010 shows that 28% of all new drug applications were for rare diseases, and that approval rates for rare and common disease applications have been similar2.
Recent success in the development of orphan drugs coupled with productivity challenges in the classic pharma R&D model for indications with a higher prevalence, has resulted in a number of major pharmaceutical companies recently estab- lishing business units focused on rare diseases. In turn, this has resulted in increased investment of venture capital companies and early stage biotechs in rare disease programmes. In part the increased
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By Dr Philip J. Vickers
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