What targeted therapies are available for Breast Cancer

Targeted Therapies for Breast Cancer

Targeted therapies are drugs designed to attack specific features of cancer cells. Unlike chemotherapy, which affects many cells in your body, targeted therapies work more like "smart bombs"—they focus on particular proteins or mutations that help cancer cells grow. Let me walk you through the main types available for breast cancer.

How Doctors Choose Targeted Therapy

According to NCCN Guidelines, your oncologist will first test your tumor for specific characteristics:

• Hormone receptor status (ER/PR positive or negative)
• HER2 status (HER2 positive or negative)
• Specific gene mutations (like PIK3CA, BRCA1/2, PARP-deficiency)

These test results determine which targeted therapies might work best for YOUR specific cancer.

---

Main Types of Targeted Therapies

1. HER2-Targeted Therapies (for HER2-positive breast cancer)

HER2 is a protein that can be overproduced in some breast cancers, causing them to grow faster. NCCN Guidelines describe three approaches to target HER2:

HER2 Antibodies - These are proteins that block HER2 signals from outside the cancer cell and also help your immune system attack the cancer:

• Trastuzumab (Herceptin) and biosimilars
• Pertuzumab (Perjeta)

HER2 Inhibitors - These stop HER2 signals from working inside the cell:

• Neratinib (Nerlynx)
• Tucatinib (Tukysa)

HER2 Antibody-Drug Conjugates (ADCs) - These are antibodies that deliver chemotherapy directly into HER2-positive cells:

• Ado-trastuzumab emtansine (T-DM1/Kadcyla)
• Fam-trastuzumab deruxtecan (Enhertu)

Important note: Your heart function will be monitored during HER2-targeted therapy because these drugs can affect heart health.

---

2. CDK4/6 Inhibitors (for hormone receptor-positive, HER2-negative breast cancer)

CDK4/6 are proteins that help cancer cells divide and grow. Blocking them can help control cancer longer and improve survival, according to NCCN Guidelines.

Available CDK4/6 inhibitors:

• Abemaciclib (Verzenio)
• Palbociclib (Ibrance)
• Ribociclib (Kisqali)

These are typically combined with endocrine (hormone) therapy. Important: If you're premenopausal, you'll also need ovarian suppression or ablation (stopping your ovaries from making hormones) while on these drugs.

---

3. PARP Inhibitors (for BRCA-mutated or homologous recombination-deficient cancers)

PARP is a protein that repairs damaged cancer cells. Blocking PARP causes cancer cells to die because they can't fix themselves.

Available PARP inhibitors:

• Olaparib (Lynparza) - FDA approved
• Talazoparib (Talzenna) - FDA approved

These are particularly important if you have a BRCA1 or BRCA2 mutation, which NCCN Guidelines recommend testing for in all metastatic breast cancer patients.

---

4. PI3K/AKT/mTOR Pathway Inhibitors (for specific mutations)

These target proteins in a growth pathway that's often overactive in breast cancer. According to ASCO Guidelines, testing for specific mutations helps guide treatment:

PIK3CA Mutations:

• Alpelisib (Piqray) - a PIK3 kinase inhibitor
• Capivasertib (Truqap) - an AKT inhibitor

mTOR Overactivity:

• Everolimus (Afinitor) - usually combined with endocrine therapy

Why this matters: ASCO Guidelines note that capivasertib and alpelisib can cause side effects like diarrhea and rash, but these can often be managed with supportive medications.

---

5. Immunotherapy (for triple-negative breast cancer)

Immunotherapy helps your immune system recognize and attack cancer cells.

Available immunotherapy:

• Pembrolizumab (Keytruda) - FDA approved for early-stage triple-negative breast cancer, often combined with chemotherapy

---

6. Estrogen Receptor Degraders (SERDs) (for hormone receptor-positive cancers)

These newer drugs destroy estrogen receptors rather than just blocking them:

• Elacestrant (Orserdu) - particularly useful for tumors with ESR1 mutations, according to ASCO Guidelines
• Fulvestrant (Faslodex)

---

How Treatment is Sequenced

NCCN Guidelines emphasize that breast cancer treatment typically involves multiple lines of therapy given in sequence. This means:

• You might start with one targeted therapy + endocrine therapy
• If that stops working, your doctor will switch to a different combination based on your tumor's genetics
• Testing for mutations like ESR1, PIK3CA, and AKT1 helps guide these decisions

---

Questions to Ask Your Oncologist

Since targeted therapy selection depends heavily on YOUR specific tumor characteristics, here are key questions:

1. "What specific mutations or characteristics does my tumor have?" (Ask for a copy of your pathology and genomic testing results)

2. "Which targeted therapies are appropriate for my specific cancer type and stage?"

3. "What are the side effects I should expect, and how will they be managed?"

4. "How will we know if the treatment is working, and how often will we check?"

5. "Are there clinical trials available for my type of breast cancer?" (Clinical trials may offer access to newer targeted therapies)

6. "If this treatment stops working, what are my next options?"

---

Key Takeaway

Targeted therapies have transformed breast cancer treatment by offering options tailored to each tumor's specific characteristics. According to NCCN Guidelines, most patients with hormone receptor-positive breast cancer will have access to multiple lines of targeted therapy before needing chemotherapy—which is a significant advantage.

Your oncologist will determine the most appropriate approach for YOUR case based on your complete clinical picture, including your tumor's genetics, stage, and overall health.

---

This information is for educational purposes only. Always consult your healthcare team for personalized medical advice and decisions.