Rx Update: January 1999

Trastuzumab

Mary Ross, R.Ph., M.B.A.
Peer Review Status: Internally Reviewed

Trastuzumab (Herceptin[R]) was approved by the FDA for the treatment of breast cancer. Trastuzumab as monotherapy is indicated for the treatment of patients with breast cancer whose tumors overexpress the HER2/neu protein and who have received one or more chemotherapy regimens for their metastatic disease. In combination with paclitaxel, trastuzumab is indicated for treatment of patients with metastatic breast cancer whose tumors overexpress the HER-2/neu protein and who have not received chemotherapy for their metastatic disease. Trastuzumab should only be used in patients whose tumors have HER-2/neu protein overexpression.

In approximately 7% of patients, trastuzumab administration can result in the development of cardiac dysfunction. The incidence is even higher when it is administered with an anthracycline. Cardiac function must be monitored closely when administering trastuzumab and caution should be used in treating patients with preexisting cardiac dysfunction. In about 40% of patients, an infusion-related symptom complex consisting of chills and/or fever is observed with the first infusion. The infusion-related adverse effects generally subside with subsequent infusions. Other adverse effects that have been reported with trastuzumab include diarrhea, nausea, vomiting, pain, rigors, headache, dizziness, dyspnea, hypotension, rash, and asthenia.

The recommended loading dose of trastuzumab is 4 mg/kg by intravenous infusion over 90 minutes. The recommended weekly maintenance dose of trastuzurmab is 2 mg/kg; this can be administered as a 30-minute infusion if the initial loading dose was well tolerated. It should not be administered as an IV push or bolus. Trastuzumab should be diluted in 250mL of 0.9% sodium chloride. Dextrose solutions should not be used.

Trastuzumab is available as 440mg vials for intravenous use. The prescribing of trastuzumab is restricted to Adult Hematology/Oncology.

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