Drug repurposing for cancer treatments: a well-intentioned, but misguided strategy

• Published in: The lancet oncology Vol. 21; no. 9; pp. 1134 - 1136
• Main Authors: Tran, Audrey A, Prasad, Vinay
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2020; Elsevier Limited
• Subjects: Aspirin - therapeutic use; Bias; Cancer; Cancer therapies; Costs; Drug Repositioning; Drugs; Humans; Lung cancer; Medical diagnosis; Metformin - therapeutic use; Neoplasms - drug therapy; Neoplasms - epidemiology; Researchers; Statins; Vitamin D - therapeutic use
• ISSN: 1470-2045; 1474-5488
• DOI: 10.1016/S1470-2045(20)30424-1

Potential selection bias was mitigated by the exclusion of prevalent statin users and estimation of inverse probability weights for outcome models, and immortal-time bias was addressed by defining statin therapy initiation among survivors. [...]compared with previous studies, the study by Emilsson and colleagues had more rigorous methodology. Emilsson and colleagues also observed that, as investigators allowed more time to define a statin user (ie, anyone who takes statins in the first 6, 12, or 18 months after a cancer diagnosis), the magnitude of benefit became more favourable. [...]the longer and more permissive the definition of statin use became, the more effective statins seemed to be, indicating the presence of immortal-time bias. Because these drugs lack single-agent activity in cancer, they cannot be assessed in uncontrolled, phase 2 studies, which is common in oncological research.