Early Breast Cancer (EBC): Phesgo is indicated in combination with chemotherapy for:

• Neoadjuvant treatment of patients with HER2-positive locally advanced, inflammatory, or early-stage breast cancer (tumor >2 cm or node-positive) as part of a complete early breast cancer treatment regimen.
• Adjuvant treatment of patients with HER2-positive early breast cancer who are at high risk of recurrence.

Metastatic Breast Cancer (MBC): Phesgo is indicated in combination with docetaxel for patients with HER2-positive metastatic or locally recurrent unresectable breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease.

Pertuzumab and trastuzumab are recombinant humanized IgG1κ monoclonal antibodies that target the human epidermal growth factor receptor 2 (HER2/ErbB2), a transmembrane glycoprotein with intrinsic tyrosine kinase activity. Both antibodies bind to different HER2 subdomains—pertuzumab binds to subdomain II and trastuzumab binds to subdomain IV—without competing with each other. This complementary binding results in more effective inhibition of HER2 signaling pathways. When used together, they produce enhanced anti-proliferative effects both in vitro and in vivo. In addition, the Fc region of both antibodies activates antibody-dependent cell-mediated cytotoxicity (ADCC), leading to immune-mediated destruction of cancer cells. ADCC activity is stronger against HER2-overexpressing tumor cells compared to cells with normal HER2 expression.

Patient Selection: Patients treated with Phesgo should have HER2-positive tumor status, defined as a score of 3+ by immunohistochemistry (IHC) or a ratio of ≥ 2.0 by in situ hybridization (ISH), assessed by a validated test. To ensure accurate and reproducible results, the testing must be performed in a specialized laboratory, which can ensure validation of the testing procedures.

Administration of Phesgo: Phesgo therapy should only be administered under the supervision of a healthcare professional experienced in the treatment of cancer patients. Substitution by any other biological medicinal product requires the consent of the prescribing physician. Patients currently receiving intravenous pertuzumab and trastuzumab can switch to Phesgo. Switching treatment from intravenous pertuzumab and trastuzumab to Phesgo (or vice versa) was investigated in study MO40628. In order to prevent medication errors, it is important to check the vial labels to ensure that the drug being prepared and administered is Phesgo. Phesgo is for subcutaneous (SC) use in the thigh only. Do not administer intravenously.

Metastatic and Early Breast Cancer

• Loading dose: 1200 mg pertuzumab / 600 mg trastuzumab
• Maintenance dose (every 3 weeks): 600 mg pertuzumab / 600 mg trastuzumab

Early Breast Cancer (EBC): In the neoadjuvant setting (before surgery), it is recommended that patients are treated with Phesgo for three to six cycles depending on the regimen chosen in combination with chemotherapy. In the adjuvant setting (after surgery), Phesgo should be administered for a total of one year (maximum 18 cycles or until disease recurrence, or unmanageable toxicity, whichever occurs first), as part of a complete regimen for early breast cancer, including standard anthracycline- and/or taxane-based chemotherapy. Phesgo treatment should start on Day 1 of the first taxane-containing cycle and should continue even if chemotherapy is discontinued. Patients who start Phesgo in the neoadjuvant setting should continue to receive adjuvant Phesgo to complete 1 year of treatment (maximum 18 cycles).

Metastatic Breast Cancer (MBC): Phesgo should be administered in combination with docetaxel until disease progression or unmanageable toxicity. Treatment with Phesgo may continue even if treatment with docetaxel is discontinued.

Phesgo is contraindicated in patients with known hypersensitivity to pertuzumab, trastuzumab, or any of the excipients in the formulation.

Phesgo should be used during pregnancy only if the potential benefit to the mother outweighs the potential risk to the fetus. Since human IgG is excreted in breast milk and its effect on the infant is unknown, breastfeeding should be discontinued during treatment and for 7 months after the last dose of Phesgo.

Pediatric use: The safety and efficacy of Phesgo in patients under 18 years of age have not been established.

Geriatric use: No dose adjustment is required in patients aged 65 years or older.

Renal impairment: No dose adjustment is needed in mild to moderate renal impairment. There are insufficient pharmacokinetic data to recommend dosing in severe renal impairment.

Hepatic impairment: The safety and efficacy of Phesgo in patients with hepatic impairment have not been established, and no dose recommendation can be made.

Targeted cancer therapy

Store at 2°C to 8°C. Keep the vial in the outer carton to protect from light. Do not freeze.