RESUMO
BACKGROUND: The worldwide increase in the occurrence of cancer associated with the limitations of immunotherapy and the emergence of resistance have impaired the prognosis of cancer patients, which leads to the search for alternative treatment methods. Drug repositioning, a well-established process approved by regulatory agencies, is considered an alternative strategy for the fast identification of drugs, because it is relatively less costly and represents lower risks for patients. AREAS OF UNCERTAINTY: We report the most relevant studies about drug repositioning in oncology, emphasizing that its implementation faces financial and regulatory obstacles, making the creation of incentives necessary to stimulate the involvement of the pharmaceutical industry. DATA SOURCES: We present 63 studies in which 52 non-anticancer drugs with anticancer activity against a number of malignancies are described. THERAPEUTIC INNOVATIONS: Some have already been the target of phase III studies, such as the Add-Aspirin trial for nonmetastatic solid tumors, as well as 9 other drugs (aprepitant, artesunate, auranofin, captopril, celecoxib, disulfiram, itraconazole, ritonavir, and sertraline) in the CUSP9* clinical trial for the treatment of recurrent glioblastoma. Others have already been successful in repositioning such as thalidomide, zoledronic acid, celecoxib, methotrexate, and gemcitabine. CONCLUSIONS: Therefore, drug repositioning represents a promising alternative for the treatment of oncological disorders; however, the support from funding agencies and from the government is still needed, the latter regarding regulatory issues.