What are predictive markers for drug response and why do they matter?

https://www.news-medical.net/whitepaper/20260309/What-are-predictive-markers-for-drug-response-and-why-do-they-matter.aspx Most drugs and therapies introduced to date do not perform equally well for all patients, with significant differences in efficacy and safety among individuals. Frequently, a considerable proportion of patients simply do not respond, resulting in wasted therapy costs and no benefit to the patient.