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Ado-Trastuzumab Emtansine Approved for Advanced Breast Cancer

Kate Traynor

BETHESDA, MD 22 Feb 2013— FDA External Link and GenentechExternal Link on February 22 announced the approval of ado-trastuzumab emtansine, a drug–antibody conjugate, for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer.

According to Genentech, ado-trastuzumab emtansine will be available within two weeks under the brand name Kadcyla.

Labeling External Link for Kadcyla states that it consists of the humanized anti-HER2 monoclonal antibody trastuzumab covalently linked to the drug DM1, a microtubule inhibitor. On average, each antibody molecule is linked to 3.5 DM1 molecules.

Ado-trastuzumab emtansine is indicated for use in patients previously previously treated with trastuzumab and a taxane, separately or in combination, for HER2-positive metastatic breast cancer.

The median survival time in clinical trial participants treated with ado-trastuzumab emtansine was about six months longer than in patients treated with lapatinib plus capecitabine.

The conjugated therapy is not a replacement for trastuzumab, and neither drug should be substituted for the other.

A boxed warning in the drug's labeling cites impaired heart function, liver failure, death, and fetal harm as serious adverse events that may occur during therapy.

The most commonly reported adverse events in clinical studies of ado-trastuzumab emtansine were fatigue, nausea, musculoskeletal pain, thrombocytopenia, headache, constipation, and liver-enzyme elevations.

The recommended dosage of ado-trastuzumab emtansine is 3.6 mg/kg delivered by i.v. infusion once every every 21 days until the disease progresses or unacceptable toxicity occurs.

The first infusion should be administered over 90 minutes. Subsequent doses can be administered over 30 minutes if the first dose was well tolerated. Patients should be closely observed for signs of extravasation during the infusion and for infusion reactions during and after the administration of each dose.

Patients should never receive ado-trastuzumab emtansine at a dosage greater than 3.6 mg/kg. Dosage reductions to 3.0 mg/kg and then 2.4 mg/kg may be made in response to adverse events. If unacceptable toxicity occurs with the minimum recommended dose, the therapy should be discontinued.

The labeling includes instructions for dosage reductions and discontinuation of therapy in response to adverse hepatic, cardiac, hematologic, pulmonary, and neurologic events.

Ado-trastuzumab emtansine will be available in 100- and 160-mg single-use vials. The vials should be refrigerated at 2–7 °C and never frozen or shaken.

Instructions for reconstituting ado-trastuzumab emtansine are included in the drug's labeling. In brief, Sterile Water for Injection, USP, should be injected into the vial and the contents gently mixed until completely dissolved. The reconstituted solution should be used immediately or refrigerated for no more than four hours before use.

 

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