Second medical use, or “repurposing”, refers to the use of a known drug for a new therapeutic purpose.
A major advantage compared to developing a new drug from scratch is that the existing drug has already shown itself to be safe in the context of the original use, so developing and obtaining marketing authorisation for new treatments can be relatively speedy and cost-effective.
The benefits of repurposing were recently shown in relation to COVID-19 where studies identified a number of existing drugs with beneficial effects, including Dexamethasone, a cheap steroid, that has saved at least a million lives and rheumatoid arthritis drug Tocilizumab, which reduces the risk of death in hospital patients[i].
Patents for second medical uses
In European Patent Convention countries (including the UK), patents are available for second medical uses provided that the idea of using the drug for the new therapeutic purpose is both novel and inventive. Such products may also attract an additional year of data exclusivity. Second medical use patents may be infringed by the intentional supply or manufacture of the drug for the new purpose. However, they can be difficult to enforce in practice, especially if the original drug is freely available as a cheaper generic option and can be used off-label for the new purpose. In this situation the ability to obtain sufficient return on the investment may depend on whether the repurposed drug involves a different formulation or dose requiring differences in manufacture and packaging.
A missed opportunity
If no patent is available (or it cannot be enforced), there may not be sufficient incentive for research-based life sciences companies to develop repurposed drugs. This represents a significant missed opportunity for health systems, especially as modern computational and other methods have much improved the ability to identify candidates for repurposing. There is currently also little incentive for generic companies to progress repurposing, although some have expressed an interest and would be in a good position to do so. The NHS England Medicines Repurposing Programme is considering suitable direct incentives for generics to take repurposing forwards, so this is a space to watch.[ii]
[i] The Guardian, 20.04.21
[ii] Opportunities to Repurpose Medicines in the NHS in England, Recommendations of the Medicines Repurposing Programme Board 2019/20 and Proposed Forward Work Programme 2020/21 – 2022/23