Giving Drugs a Second Chance: Overcoming Regulatory and Financial Hurdles in Repurposing Approved Drugs As Cancer Therapeutics

Abstract

The repositioning or "repurposing" of existing therapies for alternative disease indications is an attractive approach that can save significant investments of time and money during drug development. For cancer indications, the primary goal of repurposed therapies is on efficacy, with less restriction on safety due to the immediate need to treat this patient population. This report provides a high-level overview of how drug developers pursuing repurposed assets have previously navigated funding efforts, regulatory affairs, and intellectual property laws to commercialize these "new" medicines in oncology. This article provides insight into funding programs (e.g., government grants and philanthropic organizations) that academic and corporate initiatives can leverage to repurpose drugs for cancer. In addition, we highlight previous examples where secondary uses of existing, Food and Drug Administration- or European Medicines Agency-approved therapies have been predicted in silico and successfully validated in vitro and/or in vivo (i.e., animal models and human clinical trials) for certain oncology indications. Finally, we describe the strategies that the pharmaceutical industry has previously employed to navigate regulatory considerations and successfully commercialize their drug products. These factors must be carefully considered when repurposing existing drugs for cancer to best benefit patients and drug developers alike.

Keywords: drug repurposing; funding opportunities; in silico predictions; in vitro validation; intellectual property laws; oncology indications; regulatory approval.

Figure 1

Overview of process to repurpose existing drugs for cancer indications. Symbolic (i.e., hourglass) representation of a proposed timeline for new chemical entities (dashed hourglass outline) and repurposed drugs (solid, colored hourglass) from hypothesis generation and project funding, to product commercialization and patient benefit. Labels within funding, discovery, approval, and commercialization stages denote requirements/strategies for successful movement through each. The center of the hourglass denotes the “bottleneck” between approval and commercialization, and highlights the facilitated approval of drugs for rare oncological indications (purple dashed oval) compared with drugs repurposed for other indications (gray dashed oval).