Driven by industry efforts to accelerate pipelines and reduce risk, drug repurposing and second medical use patents are gaining renewed importance. Companies are leveraging known compounds to unlock new indications, extend product lifecycles and increase value by evolving their IP and regulatory exclusivity strategies to meet the voracious demands of our increasingly competitive global pharmaceutical markets.
In this blog, we explore drug repurposing and second medical use patents, explaining how known medicines can generate new clinical and commercial value, examining the benefits, risks and lifecycle extension and protection strategies using the very real example of thalidomide to illustrate how drug repurposing and second medical use patents can totally transform the fortunes of a pharmaceutical innovation.
Drug repurposing
Traditional drug development is a lengthy, costly and high-risk process. Before a medicinal product can obtain market authorisation, a new candidate compound must first undergo extensive pre-clinical evaluation. Only compounds demonstrating an acceptable safety and efficacy profile progress to clinical development. This requires both clinical trials and regulatory review. From initial discovery to regulatory approval, the development of a novel therapeutic agent commonly requires 10 to 15 years and significant investment, with only a very small proportion of candidate compounds ever ultimately reaching commercialisation.
Drug repurposing (also referred to as drug repositioning) is an increasingly popular commercial strategy. Drug repurposing involves identifying new therapeutic indications for compounds that are already approved, previously marketed, or have undergone substantial clinical investigation for another disease area. Rather than beginning with an entirely novel chemical entity, repurposing seeks to exploit existing pharmacological and clinical knowledge to accelerate development of therapies for unmet medical needs.
From both clinical and commercial perspectives, drug repurposing offers several significant advantages. First, reduced development timelines may enable more rapid patient access to therapies, which is particularly valuable in areas of urgent unmet need such as oncology, neurodegenerative diseases, inflammatory disorders, infectious diseases and rare diseases.
Furthermore, repurposing may substantially reduce financial risk and attrition rates.
Since safety liabilities are often already characterised, the probability of late-stage failure due to toxicity may be lower than for entirely novel compounds. This is particularly attractive where commercial incentives for first-in-class drug discovery are limited, including orphan diseases and smaller patient populations. Repurposing may, therefore, provide a commercially viable route for developing treatments that might not otherwise justify the substantial investment associated with conventional pharmaceutical research and development.
Drug repurposing can also extend the commercial lifecycle of existing pharmaceutical products. By identifying novel therapeutic applications, pharmaceutical companies may obtain additional regulatory exclusivities or IP protection through second medical use patents, thereby creating renewed commercial value for compounds approaching patent expiry.
Consequently, repurposing has become an increasingly important component of pharmaceutical lifecycle management strategies as well as a mechanism for promoting therapeutic innovation.
A drug repurposing and second medical use patent case study: Thalidomide - From tragedy to therapeutic repositioning
Originally marketed in the late 1950s and early 1960s as a sedative and treatment for morning sickness, thalidomide was later found to cause foetal abnormalities when administered during pregnancy. It is now recognised as one of the most teratogenic medicines ever marketed.
It is estimated that approximately 10,000 children worldwide were born with severe congenital abnormalities including limb deformities, organ defects, blindness and deafness, while many additional pregnancies resulted in miscarriage or stillbirth. The thalidomide tragedy prompted sweeping reforms in pharmaceutical regulation across numerous jurisdictions, resulting in more rigorous standards for demonstrating safety and efficacy prior to market approval.
Despite this tragic history, subsequent scientific research revealed that thalidomide possesses significant anti-angiogenic, anti-inflammatory and immunomodulatory properties. These effects are now understood to arise principally through modulation of cytokine activity, particularly inhibition of tumour necrosis factor-α (TNF-α), together with effects on T-cell activation and angiogenesis pathways.
As understanding of these mechanisms developed, researchers began to recognise that the same biological properties responsible for some of thalidomide’s adverse effects could potentially be therapeutically valuable in diseases characterised by abnormal immune signalling, inflammation or pathological blood vessel formation.
These pharmacological characteristics prompted renewed clinical interest in thalidomide from the 1990s onwards. Over time, the drug demonstrated efficacy across a broad range of conditions, including:
- Certain solid tumours, such as renal, pancreatic, oesophageal and endometrial cancers
- Haematological malignancies, particularly multiple myeloma
- Inflammatory skin disorders and autoimmune diseases
- Inflammatory bowel disease and other chronic inflammatory conditions
Most significantly, thalidomide was successfully repositioned and subsequently approved by the U.S. Food and Drug Administration for the treatment of erythema nodosum leprosum, a severe inflammatory complication of leprosy and later for multiple myeloma.
In oncology, thalidomide became a cornerstone therapy and ultimately gave rise to an entire class of immunomodulatory agents, including lenalidomide and pomalidomide. Its reintroduction into clinical practice, however, occurred under exceptionally stringent regulatory controls, including mandatory pregnancy prevention programmes, restricted distribution systems and extensive patient monitoring designed to minimise teratogenic risk.
Thalidomide therefore represents a striking example of successful drug repurposing, a compound once withdrawn because of its devastating adverse effects repurposed into a clinically valuable therapy for serious and often difficult to treat diseases.
The repurposing of existing drugs inevitably raises important intellectual property questions, particularly concerning how innovators may obtain protection for newly discovered therapeutic uses once the original composition of matter patent has expired. These issues lie at the heart of second medical use patents and supplementary protection certificate protection.
Intellectual Property rights available for repurposed drugs
The commercial viability of drug repurposing is closely linked to the availability of effective intellectual property protection and regulatory exclusivity. The active pharmaceutical ingredient is inevitably already known, and any original composition of matter patent may have expired or be nearing expiry.
Without further protection, there may be limited commercial incentive to invest in the costly clinical trials and regulatory processes required to establish a new therapeutic indication. As such, companies developing repurposed therapies frequently rely on a combination of patent protection and regulatory exclusivity to secure a period of competitive advantage.
In Europe and the UK, the principal patent mechanism for protecting repurposed medicines is the second medical use patent, which requires the known compound to have a new and non-obvious therapeutic use.
Regulatory exclusivities also play an important role in protecting repurposed medicines. Developers may benefit from data and market exclusivity under pharmaceutical regulatory frameworks in the UK and EU. Such exclusivities can prevent competing manufacturers from relying on the originator’s regulatory data for a defined period, thereby supplementing or, in some cases, partially compensating for weaker patent protection.
Second medical use patents also present distinct enforcement challenges. A recurring issue arises where generic manufacturers market the same active ingredient for non-patented indications using so-called “skinny labels”, thereby seeking to avoid infringement of the patented therapeutic use. Consequently, the scope, validity, and enforcement of second medical use patents, together with associated regulatory exclusivities, remain among the most commercially significant and heavily litigated issues in pharmaceutical law.
Given the complexity of protecting repurposed medicines, it is important to develop a coherent protection strategy involving both intellectual property and regulatory exclusivity at an early stage. This may include identifying potentially patentable therapeutic uses, formulation developments, dosage regimens, or methods of administration, while also considering the interaction between patent rights, supplementary protection certificates and regulatory exclusivities.
Our life sciences team at Potter Clarkson offer a wealth of knowledge and experience in drug repurposing and second medical use patents. If you would like to discuss intellectual property strategies for a repurposed therapy or require advice on securing and enforcing protection in this area, please contact us today.
