New therapies are desperately needed for patients with advanced cancer, but making safe and efficacious drugs remains expensive and time consuming. Meanwhile, multiple non-oncology drugs have been successfully repurposed for cancer, including thalidomide for multiple myeloma and aspirin for prevention of colorectal cancer. While the benefits of repurposing are clear, successes to date have been largely serendipitous. We have created two foundational tools to identify drug repurposing opportunities at a much greater scale: a new world-class screening library of more than 4,000 drugs/clinical candidates and a multiplexed method to rapidly conduct cellular viability assays across hundreds of cell lines.

PRISM, a recently developed high-throughput assay, employs DNA-barcoded cell lines to enable rapid testing of many drugs against pools of cancer cell lines. We have tested 4,100 compounds against 578 genomically characterized cancer cell lines using PRISM. Our experiment is among the largest cell line screens ever undertaken. Global analysis has revealed multiple strong clusters of active drugs, including vitamin D agonists, bromodomain inhibitors, and statins. In addition, many novel and established drug-biomarker relationships were identified, including alkylating agent response and low MGMT expression, BRAF inhibitor response and BRAF mutation, and MDM2 inhibitor response and TP53 wild-type status. Surprisingly, more than 100 non-oncology drugs unexpectedly killed multiple cancer cell lines, making them attractive repurposing candidates. For example, the FDA-approved phosphodiesterase inhibitor anagrelide selectively kills PDE3A-high lung cancer and melanoma cell lines. Confirmatory experiments are underway to validate screening results, evaluate putative biomarkers, and test drug activity in preclinical models. Importantly, this approach is expected to enable rapid initiation of clinical trials, dramatically accelerating patient access to potential new therapies.

Citation Format: Steven M. Corsello, Christopher C. Mader, Jordan Bryan, Jennifer Roth, David Peck, John Davis, Samantha Bender, Li Wang, Alice Wang, Joshua Bittker, Francisca Vazquez, Aravind Subramanian, Aviad Tsherniak, Todd R. Golub. Accelerating drug repurposing for cancer therapy using multiplexed viability assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4025. doi:10.1158/1538-7445.AM2017-4025