Phesgo Application Scope

Pertuzumab and Trastuzumab is a fixed-dose combination subcutaneous injection indicated for the treatment of adult patients with:

HER2-positive early breast cancer (EBC):
- As part of a neoadjuvant regimen (prior to surgery) in combination with chemotherapy.
- As part of an adjuvant regimen (after surgery) following neoadjuvant treatment.
HER2-positive metastatic breast cancer (MBC):
- In combination with docetaxel chemotherapy for first-line treatment.

Core Requirement: Tumor must be HER2-positive, confirmed by an FDA-approved or equivalent test (IHC 3+ and/or ISH positive).

Phesgo Characteristics

Ingredients: Pertuzumab/Trastuzumab
Properties: Sterile, preservative-free, colorless to slightly yellow solution for subcutaneous (SC) injection
Packaging Specification: Single-dose vial containing 600 mg pertuzumab, 600 mg trastuzumab, and 10,000 units rHuPH20 per 15 mL solution
Storage: Store at 2°C to 8°C (36°F to 46°F)
Expiry Date: As stated on the packaging
Executive Standard: Manufactured under current Good Manufacturing Practices (cGMP)
Approval Number: BLA 761170. Numbers vary by country/region
Date of Revision: Please refer to the latest official prescribing information for the most current revision date
Manufacturer: Genentech, Inc.

Guidelines for the Use of Phesgo

Dosage and Administration:
- Recommended Dose:
  - Loading dose (initial): 1,200 mg pertuzumab + 600 mg trastuzumab + 30,000 units hyaluronidase, administered subcutaneously over ~8 minutes.
  - Maintenance dose (every 3 weeks): 600 mg pertuzumab + 600 mg trastuzumab + 20,000 units hyaluronidase, SC over ~5 minutes.
- Administration:
  - For subcutaneous use only—do not administer intravenously.
  - Injection site: thigh only. Alternate between left and right thighs; injections should be at least ~2.5 cm from previous site, and avoid areas of skin that are bruised, tender, red, or hard.
  - Use appropriate needle (25–27 gauge), and inspect vial for particulate matter or discoloration before administration; discard vial if particles or discoloration are present.
  - After withdrawing the dose, do not dilute. Administer as withdrawn.
  - Observation: After initial dose, observe patient for 30 minutes; after each maintenance dose, observe for 15 minutes for signs of hypersensitivity/administration‑related reactions.
- Missed Dose:
  - If delay between doses is less than 6 weeks, administer the maintenance dose (600 mg/600 mg + 20,000 units).
  - If delay is 6 weeks or more, repeat the loading dose (1200 mg/600 mg + 30,000 units), then resume maintenance dosing.
Adverse Reactions:
- Common Adverse Reactions:
  - Cardiomyopathy / cardiac dysfunction—PHESGO may cause subclinical or clinical heart failure, decreased left ventricular ejection fraction (LVEF). Risk increases in patients previously treated with anthracyclines. Cardiac function must be evaluated before and during treatment. Discontinue for clinically significant decrease in LVEF or symptomatic heart failure.
  - Embryo‑fetal toxicity—Exposure can lead to fetal harm, including embryofetal death or birth defects. Women of childbearing potential should use effective contraception during treatment and for a defined period after last dose.
  - Pulmonary toxicity—Cases of serious and fatal pulmonary adverse reactions have been reported (e.g., interstitial pneumonitis, acute respiratory distress). Discontinue if such reactions occur.
- Serious Adverse Reactions:
  - Alopecia (hair loss)
  - Nausea
  - Diarrhea
  - Anemia
  - Asthenia / fatigue / weakness
Contraindications:
- Known hypersensitivity to pertuzumab, trastuzumab, hyaluronidase, or any excipient.
- Severe, active respiratory disease at rest or requiring oxygen therapy.
Precautions:
- Cardiac Monitoring: Assess left ventricular ejection fraction (LVEF) via ECHO or MUGA scan prior to initiation and at regular intervals (e.g., every 3 months) during treatment.
- Embryo-Fetal Toxicity: Can cause fetal harm. Verify pregnancy status prior to initiation. Advise females of reproductive potential to use effective contraception during and for 7 months after the last dose.
- Pulmonary Toxicity: Monitor for signs (dyspnea, cough, fever). Permanently discontinue Phesgo for confirmed ILD or pneumonitis.
- Injection Site Reactions: Common but usually mild. Rotate injection sites.
- Administration with Chemotherapy: When given with anthracycline-based chemotherapy, administer sequentially, not concurrently.

Phesgo Interactions

No formal drug-drug interaction studies have been conducted.
As it contains pertuzumab and trastuzumab, the theoretical interactions are related to these components.
Cardiotoxic Drugs: Concomitant use with other cardiotoxic agents (e.g., anthracyclines) may increase the risk of cardiac dysfunction. Careful monitoring is essential.
Administrative: Do not mix Phesgo with other medicines.

Note:

If there is a new packaging for the drug, the new packaging shall prevail. The above information is sourced from DengYue Medicine.
This content is for reference only. Prescription drugs must be used under a doctor’s guidance and purchased from authorized sources.