TARGETED DRUG THERAPY IN CANCER: MECHANISMS, ADVANCES, AND CHALLENGES

Cancer includes many diseases in which genetic and epigenetic changes disturb the normal controls of cell growth, survival, DNA repair, and communication with surrounding tissues. Conventional chemotherapy remains an important part of cancer treatment, but it can also damage healthy cells that divide quickly, often causing side effects. Targeted drug therapy takes a more selective approach by acting on particular molecular changes that help a tumour grow or survive. Biomarker testing can identify patients who may benefit from certain treatments, as shown in cancers with specific, actionable genetic alterations. However, this approach still faces several difficulties, including differences between cancer cells within the same tumour, drug resistance, treatment-related adverse effects, and unequal access to diagnostic testing. This review describes the biological basis of targeted cancer therapy, its main mechanisms, important clinical developments, and the challenges that influence treatment outcomes. It also considers emerging approaches such as antibody–drug conjugates, targeted protein degradation, carefully selected drug combinations, and biomarker-guided treatment.