In May 2019, the FDA approved a new indication for Kadcyla (ado-trastuzumab emtansine; from Genentech) for adjuvant (additional) treatment of patients with HER2-positive early breast cancer and residual invasive disease after endocrine treatment with a taxane and Herceptin (trastuzumab). At the same time, the FDA approved 2 tests that should be used to select appropriate patients for adjuvant treatment with Kadcyla. Kadcyla was initially approved in 2013 for HER2-positive metastatic breast cancer.
This new approval was based on a clinical trial of 1486 patients with HER2-positive early breast cancer who received Kadcyla or Herceptin for a total of 14 cycles. After an average of 40 months, patients who received Kadcyla showed significant reduction in residual invasive disease versus those who received Herceptin. The most common side effects with Kadcyla are fatigue, nausea, musculoskeletal and joint pain, bleeding, low platelet count, headache, and peripheral neuropathy.