Study With Atezolizumab in Combination With Trastuzumab and Vinorelbine in HER2-positive Advanced/Metastatic Breast Cancer

Inclusion Criteria:

• Male or female (Premenopausal or postmenopausal women)
• ECOG 0 to 2
• Histologically confirmed adenocarcinoma of the breast, metastatic or unresectablelocally advanced.
• All patients must have received at least trastuzumab and other anti-HER2 ADCs (including but not limited to T-DM1).
• Measurable disease according to RECIST 1.1 criteria.
• Adequate organ function
• Baseline LVEF ≥50%
• Participants with asymptomatic brain metastases are eligible.

Exclusion Criteria:

• Treatment with any investigational anticancer drug within 14 days of the start ofstudy treatment.
• Patient has received Vinorelbine or any other vinca alkaloids previously immediatelyprior to initiate study treatment.
• History of other malignant tumors in the past 3 years
• Known or suspected leptomeningeal disease (LMD)/ poorly controlled (> 1/week)generalized or complex partial seizures, or manifest neurologic progression due tobrain metastases.
• Symptomatic hypercalcemia requiring treatment with bisphosphonates in the 14 daysprior to inclusion
• Cardiopulmonary dysfunction
• Any other severe, uncontrolled
• Major surgery in the 28 days prior to enrolment
• Infection with HIV or active Hepatitis B and/or Hepatitis C.
• History of trastuzumab intolerance, including grade 3-4 infusion reaction orhypersensitivity.
• Known hypersensitivity or allergy to biopharmaceuticals produced in Chinese hamsterovary cells or any component of the atezolizumab formulation
• History of autoimmune disease,
• Prior allogeneic stem cell or solid organ transplantation
• History of idiopathic pulmonary fibrosis, drug-induced pneumonitis, organizingpneumonia (i.e., bronchiolitis obliterans, cryptogenic organizing pneumonia), orevidence of active pneumonitis on screening chest CT scan. (Note: History of radiationpneumonitis in the radiation field [fibrosis] is permitted.)
• Active tuberculosis
• Receipt of a live, attenuated vaccine within 4 weeks prior to enrollment
• Prior treatment with CD137 agonists, anti-PD-1, or anti-PD-L1 therapeutic antibody orimmune checkpoint targeting agents
• Treatment with systemic immunostimulatory agents (including but not limited tointerferons or interleukin [IL]-2) within 4 weeks or five half-lives of the drug priorto enrolment
• Treatment with systemic immunosuppressive medications within 2 weeks prior toenrolment, or anticipated requirement for systemic immunosuppressive medicationsduring the trial.