NCT04740918

A Study of Trastuzumab Emtansine in Combination With Atezolizumab or Placebo as a Treatment for Participants With Human Epidermal Growth Factor 2 (HER2)-Positive and Programmed Death-ligand 1 (PD-L1)-Positive Locally Advanced (LABC) or Metastatic Breast Cancer (MBC)

A Randomized, Multicenter, Double-Blind, Placebo-Controlled Phase III Study of the Efficacy and Safety of Trastuzumab Emtansine in Combination With Atezolizumab or Placebo in Patients With HER2-Positive and PD-L1-Positive Locally Advanced or Metastatic Breast Cancer Who Have Received Prior Trastuzumab- (+/- Pertuzumab) and Taxane-Based Therapy (KATE3)

• Status: Terminated
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 96 (actual)
• Sponsor: Hoffmann-La Roche · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

This study will evaluate the efficacy, safety and patient-reported outcomes of trastuzumab emtansine plus atezolizumab compared with trastuzumab emtansine plus placebo in participants with HER2-positive and PD-L1-positive LABC or MBC.Participants must have progressed either during or after prior trastuzumab- (+/- pertuzumab) and taxane-based therapy for LABC/MBC; or during (or within 6 months after completing) trastuzumab- (+/-pertuzumab) and taxane-based therapy in the neoadjuvant and/or adjuvant setting.

Conditions

• Metastatic Breast Cancer

Interventions

Type	Name	Description
DRUG	Trastuzumab Emtansine	Trastuzumab emtansine 3.6 mg/kg IV infusion
DRUG	Atezolizumab	Atezolizumab 1200 mg IV infusion
OTHER	Placebo	Placebo matched to atezolizumab

Timeline

• Start date: 2021-06-07
• Primary completion: 2024-06-19
• Completion: 2024-06-19
• First posted: 2021-02-05
• Last updated: 2025-08-08
• Results posted: 2025-08-08

Locations

51 sites across 19 countries: United States, Australia, Brazil, Canada, China, Colombia, Croatia, Finland, France, Italy, Norway, Philippines, Poland, Portugal, Russia, South Korea, Spain, Turkey (Türkiye), United Kingdom

Regulatory

• FDA-regulated drug study