Trastuzumab
Trastuzumab (Herceptin)
Trastuzumab
(traz-TOO-zah-mab)
Pregnancy Category: B Herceptin (Rx)

Classification: Antineoplastic, miscellaneous

See Also: See also Antineoplastic Agents.

Action/Kinetics: A recombinant DNA-derived humanized monoclonal antibody that selectively binds with high affinity to the extracellular domain of the human epidermal growth factor receptor 2 protein (HER2). Results in inhibition of the proliferation of human tumor cells that overexpress HER2 and mediates antibody-dependent cellular cytotoxicity. The HER2 protein is overexpressed in 25% to 30% of primary breast cancers. t1/2, following loading dose of 4 mg/kg and weekly dose of 2 mg/kg: Average of 5.8 days. Mean serum trough levels of trastuzumab, when given with paclitaxel, were elevated 1.5 fold compared to use in combination with anthracycline plus cyclophosphamide.

Uses: Treatment of metastatic breast cancer with tumor overexpressing the HER2 protein either alone or in combination with paclitaxel in those who have not received chemotherapy for their metastatic disease. Use only in those whose tumors have HER2 protein overexpression.

Special Concerns: Use with extreme caution in those with preexisting cardiac dysfunction. Probability of cardiac dysfunction is highest in those receiving trastuzumab with an anthracycline; advanced age may also increase the incidence of cardiac dysfunction. Use with caution during pregnancy and in those with sensitivity to Chinese hamster ovary proteins. Safety and efficacy have not been determined in children.

Side Effects: CV: Tachycardia, vascular thrombosis pericardial effusion, heart arrest, hemorrhage, shock arrhythmia hypotension, syncope. Cardiomyopathy, including ventricular dysfunction and CHF. Cardiac dysfunction, including dyspnea, increased cough, paroxysmal nocturnal dyspnea, peripheral edema, S₃ gallop, reduced ejection fraction. GI: Diarrhea, anorexia, N&V;, hepatic failure gastroenteritis, hematemesis, ileus, intestinal obstruction, colitis, esophageal ulcer, stomatitis, pancreatitis, hepatitis. CNS: Dizziness, insomnia, paresthesia, peripheral neuritis, depression, neuropathy, convulsion, ataxia, confusion, manic reaction. Respiratory: Increased cough, dyspnea, pharyngitis, rhinitis, sinusitis, apnea, pneumothorax, asthma, hypoxia, laryngitis. Dermatologic: Rash, acne, herpes simplex, herpes zoster, skin ulceration. Hematologic: Anemia, leukopenia, pancytopenia, acute leukemia, coagulation disorder, lymphangitis. Musculoskeletal: Arthralgia, bone pain, pathological fractures, bone necrosis, myopathy. GU: Hydronephrosis, kidney failure, cervical cancer, hematuria, hemorrhagic cystitis, pyelonephritis. Metabolic: Peripheral edema, edema, hypoglycemia, growth retardation, weight loss. First-infusion-associated symptoms: Chills, fever, N&V;, pain, rigors, headache, dizziness, dyspnea, hypotension, rash, asthenia. Miscellaneous: Increased incidence of infections, especially of the URT; abdominal pain, accidental injury, allergic reaction, asthenia, back pain, chills, fever, flu syndrome, headache, pain, UTI, cellulitis, anaphylactoid reaction ascites, hydrocephalus, radiation injury, deafness, amblyopia, hypothyroidism.

Laboratory Test Alterations: Hypercalcemia, hypomagnesemia, hyponatremia.

How Supplied: Powder, lyophilized: 440 mg

Dosage
•IV Metastatic breast cancer.
Initial: 4 mg/kg infused over 90 min; maintenance: 2 mg/kg weekly, infused over 30 min if initial dose was tolerated.