HR and breast cancer: SERENA-4 (ClinicalTrials.gov identifier: NCT04711252) is an ongoing phase 3 randomized, double-blind study that is assessing the efficacy and safety of camizestrant plus palbociclib versus anastrozole plus palbociclib as first-line therapy for patients with HR+/HER2− advanced breast cancer who have not established systemic treatment for advanced disease.