Breast Cancer Coverage from Every Angle

KATE2 Trial: Updated Overall Survival With Immunotherapy Combination in Advanced Breast Cancer

By: Kelly M. Hennessey, PhD
Posted: Tuesday, November 19, 2019

In the randomized phase II KATE2 clinical trial, the anti–PD-L1 monoclonal antibody atezolizumab plus trastuzumab emtansine (T-DM1) did not demonstrate a statistically significant progressive-free survival benefit compared with T-DM1 plus placebo in patients with advanced HER2-positive breast cancer. However, a post hoc analysis found that progression-free survival was longer in the T-DM1 group in those whose tumors expressed PD-L1, reported Leisha A. Emens, MD, PhD, of UPMC Hillman Cancer Center in Pittsburgh. A second analysis of the study was presented at the European Society for Medical Oncology Congress 2019 (Abstract 305O) and published in the Annals of Oncology.

Included in the KATE2 study were a total of 202 patients with advanced HER2-positive metastatic breast cancer. They were randomly assigned 2:1 to receive atezolizumab plus T-DM1 (n = 133) or T-DM1 plus placebo (n = 69) and grouped by PD-L1 immune cell status. In the atezolizumab/T-DM1 group, 43% of the patients had PD-L1–positive immune cells, compared with 39% in the placebo group.

In the PD-L1 subgroup, the overall 1-year survival rate with atezolizumab plus T-DM1 was 94%, compared with 88% in patients who did not receive atezolizumab.

“Although the number of events is small,” concluded Dr. Emens during her presentation, “the data suggest an overall survival benefit with the addition of atezolizumab to T-DM1, specifically in PD-L1 immune cell–positive patients. Based on these results, we believe that further study of HER2-targeted agents plus atezolizumab in previously treated HER2-positive, PD-L1–positive, advanced breast cancer is warranted.”

Disclosure: For the full disclosures of the study authors, visit

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