Volume 109, Issue 6, Pages 964–967
Jonathan P. Jarow, M.D.
Personalized medicine has many definitions. This term is often used synonymously with precision medicine, which is defined as the classifying patients with a disease or condition based on their phenotypic findings, such as biomarkers or genomics, into subpopulations that differ in their response to a specific treatment. Personalized medicine, however, can also mean the treatment of individual patients based on many contextual factors, such as response to therapy and patient preferences, in addition to predefined phenotypic findings. Regulatory approval for the marketing of a new drug or a new indication for a marketed drug requires a positive benefit risk profile and substantial evidence of effectiveness. The indication is based on the eligibility criteria and outcomes of the clinical trial(s) underpinning the regulatory approval. For precision medicine, drugs are often developed with companion diagnostics that are necessary for selection of the subgroup of patients, in contrast to personalized medicine which may be directed at a single patient. Most drugs are approved with a fixed dosage regimen for the approved population, but some drugs and biologics are approved with instructions to tailor therapy for individual patients, whether it be dosing, combination with other therapies, or selection among a class of medications. Hence, more often than not, personalized medicine directed at individual patients is achieved through the practice of medicine rather than regulatory action.