Predicting clinicAL outcoMes During First-line CDK4/6 Inhibitors Plus Endocrine Therapy in Patients With Advanced Hormone REceptor-poSitive HER2-negative Breast Cancer: the Retrospective-prospective Multicenter Italian PALMARES-2 Study

Who May Qualify: - Diagnosis of HR+/HER2- advanced Breast Cancer (aBC), as defined as at least 1% estrogen receptor (ER) and/or progesterone receptor (PgR) positivity at IHC. HER2 negativity is defined on the basis of an IHC score of 0, 1+, or 2+ with absence of gene amplification at in situ hybridization (ISH) analyses. - Have received or are candidate to receive treatment with palbociclib, ribociclib or abemaciclib in combination with endocrine therapy as first-line treatment for HR+/HER2- aBC. Who Should NOT Join This Trial: - Less than 3 months of follow up from the CDK4/6i start to the date of data cut-off; - Have received CDK4/6i as monotherapy; - Have received CDK4/6i as adjuvant treatment for localized disease. Always talk to your doctor about whether this trial is right for you.