Mechanisms of Action
Tyrosine Kinase Inhibitors (TKIs)
Oral small molecules (osimertinib, alectinib, imatinib) that switch off overactive growth-signaling kinases inside cancer cells.
Angiogenesis Inhibitors (VEGF)
Bevacizumab, ramucirumab and multi-kinase TKIs starve tumors by blocking the blood vessels that feed them.
PARP Inhibitors
Olaparib, niraparib and talazoparib exploit defective DNA repair in BRCA1/2-mutated ovarian, breast, prostate and pancreatic cancers (synthetic lethality).
Antibody-Drug Conjugates
Antibodies that deliver a potent chemotherapy payload directly to cells expressing a target such as HER2 or TROP2.
Actionable Molecular Targets
| Target | Common cancers | Example therapies |
|---|---|---|
| EGFR | Non-small cell lung cancer | Osimertinib, amivantamab |
| ALK | NSCLC (often never-smokers) | Alectinib, lorlatinib |
| ROS1 | NSCLC | Crizotinib, entrectinib, repotrectinib |
| BRAF V600E | Melanoma, NSCLC, colorectal, thyroid | Dabrafenib + trametinib, encorafenib combinations |
| HER2 | Breast, gastric, NSCLC, colorectal | Trastuzumab, trastuzumab deruxtecan, tucatinib |
| KRAS G12C | NSCLC, colorectal, pancreatic | Sotorasib, adagrasib |
Liquid Biopsy & Next-Generation Sequencing
Next-generation sequencing (NGS) panels test hundreds of genes from a single tumor sample, revealing every actionable alteration at once. Guidelines recommend broad NGS for advanced lung, colorectal, prostate, ovarian and many other cancers.
A liquid biopsy detects circulating tumor DNA (ctDNA) in a blood draw — useful when tissue is hard to obtain, to track response, and to identify resistance mutations as they emerge.
Frequently Asked Questions
Why does targeted therapy stop working?
Tumors can acquire new mutations or activate bypass pathways (acquired resistance). Repeat biopsies or liquid biopsies identify the mechanism so the next drug can be chosen — e.g., newer-generation TKIs.
Are combination therapies better?
Sometimes. Combining targeted agents (BRAF + MEK), or targeted therapy with chemotherapy or immunotherapy, can deepen responses and delay resistance, but also adds side effects. Trials continue to define the best combinations.
Is targeted therapy the same as immunotherapy?
No. Targeted therapy blocks a molecular driver inside the tumor; immunotherapy activates the immune system. Some monoclonal antibodies do both.
What side effects are common?
They depend on the target: rash and diarrhea (EGFR), high blood pressure (VEGF), fatigue and blood-count changes (PARP), heart function changes (HER2). Most are manageable with dose adjustments.
Medically reviewed content for education only — not a substitute for advice from your oncology team.