Dr. Bagegni on the Safety Profile of T-DM1 in Early-Stage HER2+ Breast Cancer

Nusayba Bagegni, MD, assistant professor of medicine, Division of Medical Oncology, Washington University School of Medicine, medical oncologist, Siteman Cancer Center, discusses the safety profile of ado-trastuzumab emtansine (T-DM1; Kadcyla) in early-stage HER2-positive breast cancer.

In May 2019, the FDA approved T-DM1 for the adjuvant treatment of patients with early-stage HER2-positive disease who have residual invasive disease after neoadjuvant taxane and trastuzumab (Herceptin)-based therapy.

Data from the phase 3 KATHERINE trial, which led to the regulatory decision, indicated that the toxicities with T-DM1 were similar to what has been observed in the metastatic space, says Bagegni.

Specifically, T-DM1 can cause thrombocytopenia and neuropathy; however, these toxicities tended to be low grade in the KATHERINE trial, Bagegni explains.

Five cardiac events occurred in patients on the KATHERINE study, says Bagegni. Four of these events occurred in the trastuzumab group and 1 occurred in the T-DM1 group.

Radiation pneumonitis, which is a potentially concerning toxicity, was observed in 1.5% of patients treated with T-DM1 in the KATHERINE study, says Bagegni.

Taken collectively, these results indicate that T-DM1 is an effective and well-tolerated option for this patient population.