Drug repurposing can speed up access to new therapeutic options for cancer patients. With more than 2,000 drugs approved worldwide (DrugBank), and an average of 6 relevant targets per drug (Mestres, Nature Biotechnol, 2008; 26: 983), multiple opportunities for repurposing exist. Drug repurposing also represents an efficient way to adapt to new knowledge about cancer. For instance, tadalafil inhibits myeloid-derived suppressor cells in cancer patients at doses approved for erectile dysfunction. Many non-cancer drugs could be potentially repurposed against cancer. We attempted to quantify the number of non-cancer drugs that could potentially be repurposed in cancer treatment on the basis of supporting preclinical or clinical data.
A literature search (PubMed) was performed to identify non-cancer drugs which could be repurposed in oncology. Eligible drugs needed at least one peer-reviewed article showing an anticancer effect
A total of 231 eligible non-cancer drugs were identified. 67 (29%) are on the WHO list of essential medicines and 157 (68%) are off-patent. 117 (51%) had human data in cancer patient(s). Four were listed in clinical guidelines, namely thalidomide, all-trans retinoic acid, zoledronic acid and non-steroidal anti-inflammatory drugs (NSAID). In the first 3 cases, pharmaceutical companies took the lead and re-branded or re-formulated the drugs. This was not the case for NSAIDs, listed in desmoid tumours guidelines and used off-label. Several drugs have shown a survival benefit in randomized trials such as cimetidine (colorectal cancer), progesterone (breast cancer) or itraconazole (lung cancer). Of note, several other drugs induced responses in rare tumours (e.g. clarithromycin, timolol, propranolol).
The number of repurposing opportunities is high. Since the majority of drugs identified are off-patent, joint non-commercial clinical development by academic, governmental and philanthropic organizations is likely the best way to bring new therapeutic options to patients at low cost. Such an effort would be truly innovative and may relieve healthcare systems currently under high financial stress.
Anticancer Fund
Not apploicable
Anticancer Fund
Anticancer Fund
All authors have declared no conflicts of interest.