Targeted Therapy

Targeted therapy is a cancer treatment that uses drugs to specifically target the genes, proteins, or other molecules that help cancer cells grow and survive. Unlike chemotherapy, which affects all fast-dividing cells, targeted therapy works by blocking specific pathways that are critical for cancer growth. It can also affect the environment that supports tumor growth, such as blood vessels that supply nutrients to the cancer.

How Does Targeted Therapy Work?

Targeted therapy aims to interfere with cancer cells in various ways:

• Blocking signals that instruct cancer cells to grow and divide.

• Preventing cells from surviving longer than normal.

• Destroying cancer cells directly.

Doctors may perform genetic or molecular tests on the tumor to determine which targeted therapy will be most effective.

Types of Targeted Therapy

1. Monoclonal Antibodies:

• These drugs target specific proteins on the surface of cancer cells or in the surrounding tissue.

• Some monoclonal antibodies also deliver toxic substances (like chemotherapy or radiation) directly to cancer cells, enhancing their destruction.

2. Small Molecule Drugs:

• These drugs block the internal processes of cancer cells, preventing their growth and spread.

• A common example is angiogenesis inhibitors, which stop the formation of new blood vessels that tumors need for nutrients and growth.

Examples of Targeted Therapies for Specific Cancers

1. Breast Cancer:

• HER2-positive breast cancer, found in about 20-25% of cases, involves the overproduction of the HER2 protein. Targeted therapies like trastuzumab (Herceptin) block this protein to slow tumor growth.

2. Chronic Myeloid Leukemia (CML):

• Most cases of CML are caused by the BCR-ABL gene, which produces an enzyme that drives cancer growth. Targeted therapies like imatinib (Gleevec) block this enzyme.

3. Colorectal Cancer:

• Many colorectal cancers overproduce the epidermal growth factor receptor (EGFR). Drugs targeting EGFR help slow the cancer’s spread.

4. Lung Cancer:

• Several types of targeted therapies are used for non-small cell lung cancer (NSCLC). Some examples include:

• EGFR inhibitors

• ALK inhibitors

• ROS1 fusion inhibitors

• KRAS G12C mutation inhibitors

• NTRK fusion inhibitors

• BRAF V600E inhibitors

5. Lymphoma:

• Some lymphomas involve the overproduction of B cells. Targeted therapies can inhibit enzymes that promote this overproduction, effectively treating lymphoma and certain types of leukemia.

6. Melanoma:

• Approximately half of melanomas have a BRAF mutation. Drugs like BRAF inhibitors are effective in controlling these cancers.

Limitations of Targeted Therapy

While targeted therapy offers great promise, it may not be effective for every patient or every type of cancer:

• Not all tumors have identifiable genetic mutations or proteins that can be targeted.

• Even if a genetic mutation is present, the tumor might not respond to the drug.

• Over time, cancer cells may develop resistance to the therapy, reducing its effectiveness.

Side Effects of Targeted Therapy

Like other cancer treatments, targeted therapies can cause side effects, though they tend to affect specific areas of the body:

• Skin Problems:

• Rash, dryness, or itching on the skin.

• Hair and Nail Changes:

• Hair thinning or changes in hair texture; nails may become brittle.

• Eye Problems:

• Dryness, irritation, or vision changes.

• Digestive Issues:

• Nausea, diarrhea, or abdominal discomfort.

Conclusion

Targeted therapy is transforming cancer treatment by focusing on the molecular drivers of cancer. While it offers a more precise approach with fewer side effects compared to traditional chemotherapy, it also presents challenges, such as drug resistance and the need for specific molecular testing. As research progresses, targeted therapies continue to evolve, offering new hope for cancer patients.

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