Repurposing non-cancer Drugs in Oncology -- How many drugs are out there?

BackgroundDrug repurposing can speed up access to new therapeutic options for cancer patients. With more than 2000 drugs approved worldwide and 6 relevant targets per drug on average, the potential is quantitatively important. In this paper, we have attempted to quantify the number of non-cancer drugs supported by either preclinical or clinical cancer data.\n\nMethodsA PubMed search was performed to identify non-cancer drugs which could be repurposed in one or more cancer types. Drugs needed at least one peer-reviewed article showing an anticancer effect in vitro, in vivo or in humans.\n\nResultsA total of 235 eligible non-cancer drugs were identified (Table 1). Main charateirstics of the drugs are summarized in Table 2. 67 (29%) are on the WHO list of essential medicines and 176 (75%) are off-patent. 133 (57%) 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). Several drugs have shown a survival benefit in randomized trials such as cimetidine (colorectal cancer), progesterone (breast cancer) or itraconazole (lung cancer). Several other drugs induced responses in rare tumours, like clarithromycin, timolol or propranolol.\n\nO_TBL View this table:\norg.highwire.dtl.DTLVardef@1392304org.highwire.dtl.DTLVardef@29e578org.highwire.dtl.DTLVardef@982f85org.highwire.dtl.DTLVardef@157ce4corg.highwire.dtl.DTLVardef@1a90325_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 1:C_FLOATNO O_TABLECAPTIONList of non-cancer drugs with at least one peer-reviewed paper supporting its use against cancer.\n\nC_TABLECAPTION C_TBL O_TBL View this table:\norg.highwire.dtl.DTLVardef@10d7610org.highwire.dtl.DTLVardef@c24a51org.highwire.dtl.DTLVardef@19d46b3org.highwire.dtl.DTLVardef@8cab37org.highwire.dtl.DTLVardef@13ccf24_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 2.C_FLOATNO O_TABLECAPTIONSome features of the 235 drugs listed\n\nC_TABLECAPTION C_TBL ConclusionWe have found that the number of off-patent repurposing opportunities is large and increasing. Joint non-commercial clinical development (academics, governments, charities) may bring new therapeutic options to patients at low cost, especially in indications for which the industry has no incentive to invest in.