For most of the medicines currently in use, a single drug is prescribed to many people. But sometimes, an individual patient needs a customized drug. Personalized medicine tailors treatments for a specific patient or a handful of patients. It holds great promise for treating certain life-threatening conditions. However, such treatments can be expensive, difficult to develop and labour-intensive.

Today in The Conversation Canada, Lori Burrows and Elizabeth Li of McMaster University write about the promise and challenges of personalized medicine. Treatments like CAR T-cell therapy for relapsed cancers and phage therapy for antibiotic resistant superbugs can save lives, but the high costs that come with such individualized therapies are a major barrier. There are other hurdles, too, including drug approvals and regulations.