Uses

Ado-trastuzumab emtansine (T-DM1) is a HER2-targeted antibody-drug conjugate indicated as a single agent for HER2-positive metastatic breast cancer in patients previously treated with trastuzumab and a taxane. It is also indicated for the adjuvant treatment of HER2-positive early breast cancer with residual invasive disease after neoadjuvant taxane and trastuzumab-based therapy.

Do not use if

No absolute contraindications are listed in the FDA label. Use is not recommended in pregnancy due to embryo-fetal toxicity. Dose modifications are required for hepatotoxicity and thrombocytopenia.

Side effects

Common adverse reactions include hepatotoxicity, thrombocytopenia, fatigue, nausea, peripheral neuropathy, and musculoskeletal pain. Serious risks include left ventricular dysfunction, pulmonary toxicity, infusion-related and hypersensitivity reactions, and embryo-fetal toxicity.

Warnings

Boxed warnings include hepatotoxicity (monitor LFTs before and during treatment), cardiac toxicity (monitor LVEF), and embryo-fetal toxicity (use effective contraception; avoid pregnancy). Monitor for infusion reactions, thrombocytopenia, pulmonary toxicity, and neurotoxicity throughout treatment.

How it works

Ado-trastuzumab emtansine consists of trastuzumab (anti-HER2 IgG1) linked to DM1, a potent microtubule inhibitor. After binding HER2 on tumor cells, the conjugate is internalized and DM1 is released intracellularly, disrupting microtubule assembly and inducing apoptosis while reducing systemic exposure to the cytotoxin.

Storage

Store vials under refrigeration at 2–8°C. Do not freeze. The reconstituted and diluted solution should be used promptly or stored refrigerated for a limited time per product labeling.