Breast cancer:

Indications for PHESGO:

In combination with chemotherapy for the neoadjuvant treatment of patients with HER2-positive, locally advanced, inflammatory, or early stage breast cancer (either >2cm in diameter or node positive) as part of a complete treatment regimen for early breast cancer (EBC); or for adjuvant treatment of patients with HER2-positive EBC at high risk of recurrence. In combination with docetaxel for the treatment of patients with HER2-positive metastatic breast cancer (MBC) who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease.


Do not substitute for or with pertuzumab, trastuzumab, ado-trastuzumab emtansine, or fam-trastuzumab deruxtecan. Give as SC inj into thigh only; rotate inj sites between left and right thigh. Initially 1200mg/600mg/30000 Units over ~8mins, followed by 600mg/600mg/20000 Units over ~5mins every 3 weeks. Switching from IV pertuzumab/trastuzumab (if <6 weeks since last dose): give 600mg/600mg/20000 Units as a maintenance dose and every 3 weeks subsequently. Neoadjuvant: give every 3 weeks for 3–6 cycles as part of a treatment regimen. Following surgery, complete 1 year of treatment (up to 18 cycles) or until disease recurrence or unmanageable toxicity. Adjuvant: give every 3 weeks for a total of 1 year (up to 18 cycles) or until disease recurrence or unmanageable toxicity. Start on Day 1 of the first taxane-containing cycle (if standard anthracycline- and/or taxane-based chemotherapy is part of regimen). MBC: give initially with docetaxel 75mg/m2 IV infusion, may increase to 100mg/m2 every 3 weeks if initial dose is well tolerated. Continue until disease progression or unmanageable toxicity, whichever occurs first. Dose modification: see full labeling.


Not established.

Boxed Warning:

Cardiomyopathy. Embryo-fetal toxicity. Pulmonary toxicity.


Increased risk of cardiomyopathy. Conduct cardiac assessment (eg, history, physical exam, LVEF) prior to initiation. Assess LVEF at regular intervals during treatment (eg, every 12wks for MBC or EBC [once for neoadjuvant therapy]); permanently discontinue if LVEF has not improved, declined further, and/or symptomatic after repeat assessment within 3wks. Monitor and assess LVEF every 6 months for ≥2yrs after therapy (if adjuvant). Pretreatment LVEF value of <55% (EBC) or <50% (MBC), history of CHF, uncontrolled hypertension, recent MI, serious cardiac arrhythmia requiring treatment or a cumulative prior anthracycline exposure to >360mg/m2 of doxorubicin or its equivalent: not studied. Symptomatic intrinsic lung disease. Extensive tumor involvement of the lungs. Discontinue if anaphylaxis, angioedema, interstitial pneumonitis, or acute respiratory distress syndrome occurs. Monitor for hypersensitivity and injection-related reactions during and for 30mins after initial dose, and for 15mins after subsequent doses; slow or interrupt the injection and treat if occurs; permanently discontinue if anaphylaxis or severe reactions occur. Test for HER2 protein overexpression and HER2 gene amplification using FDA-approved tests specific for breast cancer. Elderly. Embryo-fetal toxicity (eg, oligohydramnios); monitor during pregnancy or within 7 months prior to conception. Advise females of reproductive potential to use effective contraception during and for 7 months after the last dose. Pregnancy: exclude status prior to initiation. Nursing mothers.

Pharmacologic Class:

Human epidermal growth factor receptor (HER2) dimerization inhibitor + HER2 inhibitor + endoglycosidase.


Increased cardiomyopathy with anthracycline-containing chemotherapy; if possible, avoid for up to 7 months after discontinuing Phesgo. Increased neutropenia with other myelosuppressive chemotherapy.

Adverse Reactions:

Alopecia, nausea, diarrhea, anemia, asthenia, neutropenia, fatigue, rash, myalgia, arthralgia, peripheral neuropathy, lab abnormalities; hypersensitivity reactions, inj site reactions, exacerbation of chemotherapy-induced neutropenia.

Generic Availability:


How Supplied:

Single-dose vial—1

Pricing for PHESGO

10ml of 600mg/600mg/20000 units vial (Qty: 1)
Appx. price $8650