Phase 1 trial SERENA-1 (ClinicalTrials.gov identifier: NCT03616587) has demonstrated that camizestrant is well tolerated and has improved clinical activity as monotherapy or in combination with CDK4/6 inhibitors in ER+/HER2− advanced breast cancer patients who had received one or more previous lines of endocrine therapy including CDK4/6 inhibitors [116]. Here, ESR1 is linked to breast cancer.