Pre-operative Immunotherapy Combination Strategies in Breast Cancer

ECLIPSE is an international, open label, window of opportunity phase II trial that aims to evaluate the effects of immunotherapy based treatment combinations in women with untreated, histologically confirmed, operable, ER+, HER2-negative breast cancer. The study is designed with the flexibility to open new treatment arms as new treatments become available, or modify the patient population e.g. with regards to biomarker status. Only combinations with adequate safety data will be tested. The trial will include Luminal B and non-Luminal B patients irrespective of PD-L1 status, but the number of patients with non-Luminal B tumours will be capped at 50% of the total study population. Luminal B tumours will be defined as high Ki67 (≥20%) and/or histological grade 3 or alternatively defined via PAM50 assay. All other types will be defined as non-Luminal B. Eligible patients will be randomised with an approximately equal ratio (1:1:1:1) to one of four treatment arms (three experimental arms: (1) Atezolizumab + Cobimetinib, (2) Atezolizumab + Ipatasertib, (3) Atezolizumab + Cobimetinib + Bevacizumab and a control arm: Atezolizumab alone. Additional patients may be enrolled to ensure balance among treatment arms with respect to demographic and baseline characteristics, including potential predictive biomarkers, to enable further subgroup analysis. Thereafter, the randomisation ratio will depend on the number of experimental arms that are open for enrolment (e.g. if an arm is added or enrolment in an arm is suspended pending analysis of results. Randomisation will take into account arm-specific exclusion criteria and patients will be ineligible for a specific arm if they meet any of the exclusion criteria outlined for that arm. Patients will receive treatment for 3 weeks prior to surgery or neoadjuvant therapy. Thereafter, patients will either be considered for definitive surgery or primary medical treatment (e.g. neoadjuvant chemotherapy) at the discretion of the treating physician. Surgery or neoadjuvant chemotherapy should be started within 3 weeks (±3 days) from the start of the study treatment. Patients will not be allowed to receive endocrine therapy prior to surgery.