With more than 260 candidates identified, the range of non-cancer drugs with the potential to be used in new cancer treatments is much larger than previously thought according to a study published in the open access journal ecancer. The study is the latest publication from the Repurposing Drugs in Oncology (ReDO) project, an international collaboration between the Anticancer Fund, based in Belgium, and the US-based GlobalCures.

As the high cost of new cancer treatments still at the top of political agendas in many countries, interest in the use of the drug repurposing approach has been increasing. In contrast to the standard industry approach of developing new drugs, the repurposing strategy seeks new medical uses from existing licensed medicines. Among the advantages of this approach is the availability of existing data on drug safety, the known profile of side effects, knowledge on the best dosing to use and the existing availability of the drugs in pharmacies. For generic drugs in particular there are also cost advantages in that these medicines are often widely available, and at lower prices than many existing cancer drugs.

Focus on what is available

The science team at the ReDO project has been building a database of potential repurposing candidates over many years by scanning the cancer literature actively looking for evidence of anticancer effects in pre-clinical and clinical data. According to Dr Pan Pantziarka, of the Anticancer Fund and lead author of this study, ‘Instead of looking for new molecules or pathways, we focused on what already exists. We used peer-reviewed published data sources to identify candidate cancer drugs. Data from test tube studies, animal studies and human data, including case reports and clinical trials, allow us to ascertain whether a non-cancer drug may be useful as an active anticancer agent.’

Viagra and aspirin as cancer drug candidates

This repurposing database, which is also being made available as an online and open access resource, features over 260 different drugs. There are drugs from all areas of medicine included in the database, from everyday medicines like aspirin and metformin, to antibiotics like doxycycline, blood pressure drugs like propranolol and even drugs like viagra and tadalafil used to treat erectile dysfunction.

‘Around 85% of the drugs in our database are available as generics,’ says Pantziarka. ‘Over 70% have some level of human data. There is a pipeline of potential new treatment options here, but we need investment to prove that these drugs can be effective.’. The end point of the ReDO project is that the identified repurposing candidates are proved to be effective via well-designed clinical trials, the final step in bringing new treatment options to patients.

Investing for new cures in old drugs

Belgium-based Anticancer Fund focuses on supporting clinical trials for new cancer treatments where commercial interest is missing and patient needs are high. Repurposed drugs candidates need to prove efficacy in clinical trials, and these require significant investment – which can be a challenge where there is no industry sponsorship. As this ReDO study shows, currently less than 4% of late-stage repurposing trials have a commercial sponsor.

Lydie Meheus, the Managing Director of the Anticancer Fund, agrees. ‘Repurposing faces financial obstacles due to a lack of financial incentives. Generic drugs found to be effective in a new disease are not in scope for industry to develop. The funding of the required clinical trials falls on private philanthropy and public funds to fill in the gaps – but unfortunately finding “new” drugs seems more attractive to funders rather than the potential of repurposed drugs.’

By publishing this new paper and making the database available to all, the ReDO project aims to accelerate the growth of interest in repurposing and to push for greater levels of investment.

Source: The Anticancer Fund