The HER2 (or c-erbB2) proto-oncogene encodes a transmembrane receptor protein of 185 kDa, which is structurally related to the epidermal growth factor receptor. Herceptin has been shown, in both in vitroassays and in animals, to inhibit the proliferation of human tumor cells that overexpress HER2.

Herceptin is a HER2/neu receptor antagonist used in adult patients for:

Adjuvant treatment of HER2-overexpressing breast cancer:

Metastatic HER2-overexpressing breast cancer:

Metastatic HER2-overexpressing gastric or gastroesophageal junction adenocarcinoma:

Adjuvant Breast Cancer:

• • Weekly: 4 mg/kg loading → 2 mg/kg weekly during chemo → 6 mg/kg q3w maintenance (total 52 weeks).

  • Every 3 weeks: 8 mg/kg loading → 6 mg/kg q3w x 52 weeks.

Metastatic Breast Cancer:

• • 4 mg/kg loading → 2 mg/kg weekly until progression.

Metastatic Gastric Cancer:

• • 8 mg/kg loading → 6 mg/kg q3w until progression.

Most common (≥10%):

Adjuvant/Metastatic Breast Cancer: Fever, chills, headache, infection, CHF, insomnia.

Metastatic Gastric Cancer: Neutropenia, diarrhea, fatigue, anemia, stomatitis.

None

Herceptin carries serious risks that must be carefully monitored:

Cardiomyopathy: Risk of CHF and decreased LVEF; exacerbated with anthracyclines.

Infusion Reactions/Pulmonary Toxicity: Can be severe or fatal (e.g., ARDS).

Embryo-Fetal Toxicity: May cause oligohydramnios, pulmonary hypoplasia, and neonatal death.