Targeted therapy is a form of cancer treatment that focuses on specific molecular features of cancer cells, aiming to block the signals that drive tumor growth and survival while sparing most healthy cells. It arises from detailed knowledge of genes, proteins and signaling pathways that become altered in cancer, such as mutations, amplifications or abnormal activation of growth receptors.

Many targeted drugs are small molecules or monoclonal antibodies. Small molecules often inhibit enzymes like tyrosine kinases inside cells, interfering with pathways that control cell division, metabolism or DNA repair. Monoclonal antibodies usually act on targets at the cell surface or in the surrounding environment. They can block growth factor receptors, tag cancer cells for immune attack or deliver toxic payloads directly to tumors.

Examples include inhibitors that block mutant forms of EGFR, ALK, BRAF or HER2, and agents that target angiogenesis by inhibiting VEGF signaling, cutting off a tumor’s blood supply. These drugs are often used when tests show that a patient’s tumor carries the relevant molecular alteration, making diagnostic biomarkers and genomic profiling central to treatment planning.

Targeted therapies can produce substantial responses and may be less toxic than traditional chemotherapy, but resistance frequently develops. Tumor cells may acquire new mutations, activate alternative pathways or change their dependence on the original target. Research is therefore exploring combination regimens, sequential targeting of pathways, and next generation inhibitors designed to overcome resistance. Ongoing work also seeks new targets and better biomarkers to identify which patients are most likely to benefit.