A Study Evaluating the Efficacy and Safety of Adjuvant Atezolizumab or Placebo and Trastuzumab Emtansine for Participants With HER2-Positive Breast Cancer at High Risk of Recurrence Following Preoperative Therapy (Astefania)

Roche logo


Status and phase

Phase 3


Breast Cancer


Drug: Trastuzumab Emtansine
Drug: Placebo
Drug: Trastuzumab
Drug: Atezolizumab

Study type


Funder types



2020-003681-40 (EudraCT Number)
2023-503568-18-00 (Other Identifier)

Details and patient eligibility


This is a Phase III, two-arm, randomized, double-blind placebo-controlled study in participants with HER2-positive primary breast cancer who have received preoperative chemotherapy and HER2-directed therapy, including trastuzumab followed by surgery, with a finding of residual invasive disease in the breast and/or axillary lymph nodes. As of June 4, 2024, this study is no longer accepting any newly screened participants.


1,150 estimated patients




18+ years old


No Healthy Volunteers

Inclusion criteria

  • Histologically confirmed invasive breast carcinoma
  • Centrally-confirmed human epidermal growth factor receptor 2 (HER2)-positive invasive breast cancer
  • Centrally confirmed PD-L1 and hormone receptor status
  • Clinical stage at disease presentation (prior to neoadjuvant therapy): cT4/anyN/M0, any cT/N2-3/M0, or cT1-3/N0-1/M0 (participants with cT1mi/T1a/T1b/N0 are not eligible)
  • Completion of pre-operative systemic chemotherapy including at least 9 weeks of taxane and 9 weeks of trastuzumab (anthracycline and/or additional HER2-targeted agents are permitted)
  • <=12 weeks between primary surgery and randomization
  • Eastern Cooperative Oncology Group (ECOG) Performance Status 0 or 1
  • Screening left ventricular ejection fraction (LVEF) >= 50% and no decrease in LVEF by >15% from the pre-chemotherapy LVEF. If no pre-chemotherapy LVEF, screening LVEF >= 55%
  • Life expectancy >= 6 months
  • Adequate hematologic and end organ function

Exclusion criteria

  • Stage IV breast cancer
  • An overall response of disease progression according to the investigator at the conclusion of preoperative systemic therapy
  • Prior treatment with T-DM1, or atezolizumab, or other immune checkpoint inhibitors
  • History of exposure to various cumulative doses of anthracyclines
  • History of other malignancy within 5 years prior to screening, except for appropriately treated carcinoma in situ of the cervix, non-melanoma skin carcinoma, Stage I uterine cancer, or ductal carcinoma in situ (DCIS)
  • Current grade >=2 peripheral neuropathy
  • History of idiopathic pulmonary fibrosis, organizing pneumonia, or pneumonitis
  • History of or active autoimmune disease or immune deficiency
  • Treatment with immunostimulatory or immunosuppressive agents
  • Cardiopulmonary dysfunction
  • Any known active liver disease

Trial design

Primary purpose




Interventional model

Parallel Assignment


Double Blind

1,150 participants in 2 patient groups

Arm A: Placebo + Trastuzumab Emtansine
Active Comparator group
Participants will receive an intravenous (IV) infusion of placebo prior to the IV infusion of trastuzumab emtansine on Day 1 of each 21-day cycle for a total of 14 cycles.
Drug: Trastuzumab
Drug: Placebo
Drug: Trastuzumab Emtansine
Arm B: Atezolizumab + Trastuzumab Emtansine
Experimental group
Participants will receive an IV infusion of atezolizumab prior to the IV infusion of trastuzumab emtansine on Day 1 of each 21-day cycle for a total of 14 cycles.
Drug: Trastuzumab
Drug: Atezolizumab
Drug: Trastuzumab Emtansine

Trial contacts and locations



Central trial contact

Reference Study ID Number: WO42633 https://forpatients.roche.com/

Data sourced from clinicaltrials.gov

Clinical trials

Find clinical trialsTrials by location
© Copyright 2024 Veeva Systems