The Food and Drug Administration has approved the antibody-drug conjugate trastuzumab emtansine (T-DM1) for adjuvant treatment of patients with HER2-positive early breast cancer who have residual invasive disease after neoadjuvant treatment with a taxane and trastuzumab (Herceptin).
Approval of adjuvant T-DM1, marketed as Kadcyla, was based on a reduced risk of breast cancer recurrence or death in the phase 3 KATHERINE trial. In KATHERINE, over 1,400 patients with HER2-positive early breast cancer who had residual invasive disease after neoadjuvant taxane and trastuzumab-based treatment were randomized to adjuvant therapy with T-DM1 or trastuzumab. The 3-year invasive disease-free survival rate was 88.3% for those taking T-DM1, compared with 77.0% for patients assigned to adjuvant trastuzumab (hazard ratio, 0.50; 95% confidence interval, 0.39-0.64; P less than .0001). Results of KATHERINE were presented at the 2018 San Antonio Breast Cancer Symposium and simultaneously published in the New England Journal of Medicine.
The most common grade 3 or greater adverse events for those in the T-DM1 arm included decreased platelet count in 5.7% and hypertension in 2.0%. The most common side effects with T-DM1 were fatigue, nausea, increased blood levels of liver enzymes, musculoskeletal pain, bleeding, decreased platelet count, headache, numbness in the hands or feet, and joint pain.
T-DM1 was previously approved to treat metastatic HER2-positive breast cancer after prior treatment with trastuzumab and a taxane.
“This approval is a significant treatment advance for HER2-positive early breast cancer. By working closely with the FDA and participating in the Real-Time Oncology Review pilot program, we are able to make Kadcyla available for people with residual invasive disease after neoadjuvant therapy much sooner than anticipated,” said Sandra Horning, MD, chief medical officer and head of global product development at Genentech (Roche), the developer of T-DM1, in a press release announcing the current approval.