Herceptin

Action

Selectively binds to human epidermal growth factor receptor 2 (HER2), inhibiting proliferation of human tumor cells that overexpress HER2

Availability

Lyophilized powder: 440-mg vial (each vial contains 20 ml bacteriostatic water for injection, 1.1% benzyl alcohol)

Indications and dosages

➣ Metastatic breast cancer in patients whose tumors overexpress HER2

Adults: As monotherapy, loading dose of 4 mg/kg I.V. infusion over 90 minutes, followed by weekly maintenance dose of 2 mg/kg I.V. infusion given over 30 minutes if loading dose was tolerated. Don't give by I.V. push.

Contraindications

None

Precautions

Use cautiously in:

• hypersensitivity to Chinese hamster ovary cell protein or to benzyl alcohol

• cardiac disease, anemia, leukopenia

• elderly patients

• pregnant or breastfeeding patients

• children younger than age 18 (safety and efficacy not established).

Administration

• Be aware that baseline left ventricular ejection fraction (LVEF) measurement should be performed immediately before starting drug.

• Follow facility policy for handling, administering, and disposal of carcinogenic, mutagenic, and teratogenic agents.

• Give antiemetic, as prescribed, before administering trastuzumab.

Administer by I.V. infusion only. Don't give by I.V. push or bolus.

• To reconstitute, add 20 ml of bacteriostatic water for injection to vial, pointing diluent stream at lyophilized cake. Swirl vial gently; don't shake. Withdraw prescribed dose and add it to 250 ml of normal saline solution. (Don't use dextrose 5% in water.)

• Infuse loading dose I.V. over 90 minutes. Infuse weekly doses I.V. over 30 minutes.

• Immediately after reconstituting, write a date that is 28 days from reconstitution date in the space after "Do not use after" on vial label.

• If patient has benzyl alcohol hypersensitivity, reconstitute with sterile water for injection. Use immediately after reconstitution; discard unused portion.

Never administer intrathecally; doing so causes death.

• Know that for patient who hasn't previously received chemotherapy for metastatic disease, drug is given at same dosage but in combination with paclitaxel.

Adverse reactions

CNS: dizziness, headache, depression, paresthesia, insomnia, ataxia, confusion, manic reaction, seizures

CV: peripheral edema, hypotension, tachycardia, syncope, arrhythmias, shock, pericardial effusion, vascular thrombosis, heart failure, cardiotoxicity, cardiac arrest, cardiomyopathy

EENT: amblyopia, hearing loss

GI: nausea, vomiting, diarrhea, gastroenteritis, hematemesis, colitis, esophageal ulcer, stomatitis, ileus, anorexia, intestinal obstruction, pancreatitis

GU: urinary tract infection, hematuria, hemorrhagic cystitis, hydronephrosis, pyelonephritis, renal failure

Hematologic: coagulation disorder, pancytopenia, leukemia, exacerbation of chemotherapy-induced neutropenia

Hepatic: ascites, hepatitis, hepatic failure

Metabolic: hypothyroidism, hypercalcemia, hyponatremia

Musculoskeletal: back, bone, or joint pain; myopathy; fractures; bone necrosis

Respiratory: upper respiratory infection, dyspnea, pulmonary toxicity (dyspnea, interstitial pneumonitis, pulmonary infiltrates, pleural effusions, noncardiogenic pulmonary edema, pulmonary insufficiency and hypoxia, acute respiratory distress syndrome, pulmonary fibrosis)

Skin: cellulitis, rash, acne, herpes simplex, herpes zoster, skin ulcers

Other: weight loss, edema, infection, fever, chills, flulike syndrome, lymphangitis, hypersensitivity reactions including anaphylaxis, infusion reaction

Interactions

Drug-drug. Anthracyclines, cyclophosphamide: cardiotoxicity

Patient monitoring

Monitor closely for signs and symptoms of infusion reaction (including respiratory distress). Halt infusion if these occur.

• Monitor vital signs, especially for hypotension and bradycardia.

Use with extreme caution in patients with cardiac dysfunction. Assess cardiovascular status carefully; stay alert for heart failure, cardiomyopathy, and peripheral edema.

• Assess neurologic status for depression and paresthesia.

• Monitor respiratory status. Report increased dyspnea or flulike symptoms.

• Watch closely for signs and symptoms of infection, including herpes simplex.

• Monitor electrolyte levels and CBC with white cell differential.

• Monitor LVEF measurement every 3 months during and at completion of therapy; measure LVEF at 4-week intervals if drug is withheld for significant left ventricular cardiac dysfunction. Continue LVEF measurement every 6 months for at least 2 years after completion of therapy.

Patient teaching

Instruct patient to immediately report difficulty breathing, flulike symptoms, and fever, chills, and other signs and symptoms of infection.

Advise patient to monitor weight. Tell him to report sudden weight gain as well as swelling and other signs and symptoms of heart failure.

Instruct patient to immediately report abdominal pain, change in bowel habits, yellowing of skin or eyes, and easy bruising or bleeding.

• Tell patient drug may cause depression. Advise him (or significant other as appropriate) to contact prescriber if this occurs.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs mentioned above.