Challenges for orphan drug development
There are a number of barriers to the development of orphan drugs which subsequently deter companies from developing these treatments under standard marketing conditions.
Small patient populations
There are a number of barriers to the development of orphan drugs which subsequently deter companies from developing these treatments under standard marketing conditions. One of the key challenges in rare diseases is that patient populations are often small and fragmented. This results in several challenges:
- There is little awareness about the condition in the general public or medical profession
- Consequently, very few researchers or doctors have sufficient expertise to progress drug development
- The lack of research interest and lack of patients means that there is limited knowledge about the mechanisms of the disease
- This also results in a limited understanding of disease natural history (the way in which the disease progresses and affects people over their lifetime)
- The small and fragmented patient population means that very few patients are eligible for clinical trials and those that are, are hard to find
- A small number of patients also means that there is a small market for drug developers
Productivity in the pharmaceutical industry
De novo drug development can be a long and expensive process which involves funding the drug from synthesis through to laboratory testing, toxicity testing, Phase I, II and III clinical trials, all the way to regulatory approval. Most drugs, however, do not make it all the way through this process and tests might fail at any of these stages. Pharmaceutical companies have therefore seen a significant increase in spending on research and development over time, which has contributed to a reduction in the number of treatments being produced. To put it simply, drug development is becoming less efficient, which is bad news for patients with untreated conditions.
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Pricing in rare diseases
Due to smaller populations of patients with rare diseases, and subsequent increase in risk associated with developing treatment for these conditions, there exists a large price disparity between non-orphan and orphan drugs. Whilst a licensed non-orphan drug can cost on average around $20–35,000 per patient per year, orphan drugs often cost in the region of $150,000 per patient per year, making them substantially more expensive and therefore less accessible for rare disease patients. As more high-cost orphan drugs are developed, healthcare providers are finding it harder and harder to pay these high prices, meaning many new drugs are not reaching patients.
If you would like to find out more about orphan drug price disparity you can visit the Evaluate website.
Given these challenges, it is necessary to find new approaches to drug development to complement the existing pathway. Drug repurposing is one such approach.
Benefits of drug repurposing
Drug repurposing provides solutions to some of these challenges by offering a route that takes less time to complete, requiring less financial investment into research and development and ultimately lowering the cost of a drug for patients. Key benefits of drug repurposing include:
- Removal of the need for de novo drug discovery and candidate synthesis since a compound already exists.
- As the pharmacokinetic characteristics of the drug are already well understood it is possible to match compounds that act on a known biochemical pathway, to a disease where the pathway in question is affected. It is therefore likely that only a few candidates will need to be screened, rather than several thousands.
- As the drug will probably have been used in a variety of populations (e.g. of different ages), there is already likely to be a good understanding of the safety profile. Therefore, the need for safety trials is reduced (with the caveat that dose/formulation changes will need to be thoroughly tested).
- Drug repurposing tends to have a high likelihood of success and typically more repurposed drugs will advance to market than those being developed using the traditional de novo route. This further decreases the overall cost of repurposed treatments as less time and money has been spent working on therapies that were ultimately unsuccessful.
Whilst there is a perception that drug repurposing is not as exciting or innovative as de novo drug discovery, the key benefit of drug repurposing is that it allows therapies to be delivered to patients far more quickly, which is crucial for the multitude of rare diseases for which there are no treatments available.