Targeted Therapy for Cancer: Explained Simply
What Is Targeted Therapy?
Targeted therapy is a type of cancer treatment that uses special drugs to attack specific parts of cancer cells—like a laser that locks onto a target.
These drugs look for unique features on cancer cells (like certain genes or proteins) and try to stop the cancer from growing or spreading, without harming too many healthy cells.
This is different from chemotherapy, which kills both cancer cells and some healthy cells that grow quickly (like hair or stomach cells), causing more side effects.
What Makes a Therapy “Targeted”?
Targeted therapy focuses on cancer cells with:
- Gene mutations (changes in the DNA) like EGFR or BRAF
- Too many receptors (proteins on the surface), like HER2
- Broken signals that tell cancer cells to keep growing, like the PI3K pathway
- Unique markers on cancer cells, like CD20 in certain blood cancers
Types of Targeted Therapy (with examples)
| Type | What It Does | Examples |
|---|---|---|
| Small molecule inhibitors | Go inside cancer cells and block signals they need to grow | Erlotinib (EGFR), Imatinib (CML) |
| Monoclonal antibodies | Attach to cancer cells and block their growth | Trastuzumab (HER2), Cetuximab (EGFR) |
| Antibody-drug conjugates | Deliver a cancer-killing drug directly to the cancer cell | T-DM1 for HER2-positive breast cancer |
| Immune checkpoint inhibitors | Help the immune system recognize and attack cancer | Keytruda (PD-1), Tecentriq (PD-L1) |
| Hormone therapies | Block hormones that help cancer grow | Tamoxifen for hormone-positive breast cancer |
Common Targets in Cancer
| Target | Cancers Treated | Example Drugs |
| HER2 | Breast, stomach | Trastuzumab, Lapatinib |
| EGFR | Lung, colon | Erlotinib, Osimertinib |
| BRAF | Melanoma, colon | Vemurafenib |
| ALK | Lung cancer | Crizotinib, Alectinib |
| BRCA1/2 | Breast, ovarian | Olaparib (PARP inhibitor) |
| CD20 | Lymphoma | Rituximab |
| PD-1 / PD-L1 | Many cancers | Nivolumab, Pembrolizumab |
What Are Companion Diagnostics?
Before giving a targeted therapy, doctors often run a test on your tumor to check if it has the right marker for the drug to work. These tests are called companion diagnostics.
For example:
- If your cancer has HER2, you may benefit from Herceptin
- If you have an EGFR mutation, you might get Erlotinib
These tests are usually done using a sample from your tumor or a blood test.
Benefits of Targeted Therapy
- More precise: Works best in people whose tumors have specific markers
- Fewer side effects than chemotherapy
- Personalized: Treatment is tailored to your specific cancer
Limitations to Know
- Not all patients respond to targeted therapy
- Cancer can become resistant over time by changing again
- Not all cancer cells in a tumor may have the target
- Can be expensive, and insurance coverage may vary
Talk to Your Doctor About:
- Whether your cancer has a target that can be treated
- If you need biomarker testing before starting treatment
- The benefits vs. risks of targeted therapy
- If you qualify for a clinical trial
Final Thought
Targeted therapy is one of the biggest advances in cancer treatment. It works by attacking the cancer’s weak spots, often with fewer side effects. But it’s not a one-size-fits-all—it depends on your tumor’s unique makeup.
