Phesgo Pertuzumab and Trastuzumab Injection 15 mL

1. Indications and Usage
Metastatic Breast Cancer: In combination with docetaxel, indicated for the first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer.
Early Breast Cancer: In combination with chemotherapy and trastuzzumab, indicated for the adjuvant treatment of patients with HER2-positive early breast cancer at high risk of recurrence (neoadjuvant or adjuvant setting).
2. Dosage and Administration
Recommended Dosage: Pertuzumab: 840 mg IV loading dose, followed by 420 mg IV every 3 weeks. Trastuzzumab: 8 mg/kg IV loading dose, followed by 6 mg/kg IV every 3 weeks.
Administration Sequence: Pertuzumab and trastuzumab must be administered sequentially, not simultaneously. They can be given in any order.
Timing with Chemotherapy: For patients receiving taxanes, pertuzumab and trastuzumab should be administered before the taxane.
3. Mechanism of Action
HER2 Dimerization Inhibition: Pertuzumab binds to subdomain II of the HER2 receptor and inhibits heterodimerization with other HER family members.
Signal Transduction Blockade: Trastuzumab binds to subdomain IV of HER2. Together, they block downstream signaling pathways, inhibit tumor cell proliferation, and mediate antibody-dependent cellular cytotoxicity (ADCC).
4. Safety and Warnings
Embryo-Fetal Toxicity: Can cause fetal harm. Effective contraception is required during treatment and for 7 months after the final dose.
Diarrhea: Diarrhea and dehydration are common. Aggressive management with antidiarrheals and hydration is required.
Left Ventricular Dysfunction: Monitor left ventricular ejection fraction (LVEF) before initiation and periodically during treatment.
Infusion-Related Reactions: Monitor for hypersensitivity reactions during and after infusion.
5. Adverse Reactions and Clinical Research
Most Common Adverse Reactions: Diarrhea, neutropenia, nausea, rash, fatigue, alopecia, and increased LVEF monitoring.
Serious Adverse Reactions: Severe diarrhea, left ventricular dysfunction, and interstitial lung disease (ILD)/pneumonitis.
Clinical Research Highlights: Clinical trials (e.g., CLEOPATRA, ANALYST) demonstrated significant improvements in progression-free survival and overall survival compared to trastuzumab alone.
6. Drug Interactions
CYP Enzyme Substrates: Trastuzumab does not induce or inhibit CYP enzymes. Pertuzumab pharmacokinetics are not significantly affected by CYP-mediated interactions.
Cardiotoxic Agents: Concomitant use with anthracyclines increases the risk of cardiotoxicity; anthracyclines should be completed prior to starting this combination.
7. Pharmaceutical Information
Chemical Composition: Active ingredients: Pertuzumab and Trastuzumab (recombinant DNA-derived humanized monoclonal antibodies).
Appearance: Clear to slightly opalescent, colorless to pale yellow liquid.
Packaging: Supplied in single-use glass vials.
Storage: Store in a refrigerator at 2°C to 8°C; do not freeze or shake. Protect from light.