A randomized, open-label, multicentre, phase IV study evaluating palbociclib plus endocrine treatment versus a chemotherapy based treatment strategy in patients with hormone receptor positive/HER2-negative metastatic breast cancer in a real world setting.

TPS1115 Background: Although endocrine based therapy is recommended as first-line treatment in metastatic breast cancer (MBC) in patients with an HER2-/HR+ tumour up to 50% of the patients receive chemotherapy. Palbociclib (P) a CDK4/6 inhibitor improves PFS by 42% in endocrine sensitive and resistant HER2-/HR+ MBC when added to an endocrine therapy (ET). Patients included in clinical trials are often criticised not to be representative for real world breast cancer patients. Methods: Patients with first-line HER2-/HR+ MBC who are candidate for mono-chemotherapy will be eligible to be randomised 1:1 to receive either P plus ET per label or mono-chemotherapy per investigator´s choice with or…