A Study of Camizestrant in ER+/HER2- Early Breast Cancer After at Least 2 Years of Standard Adjuvant Endocrine Therapy

Inclusion Criteria:

• Women and Men, ≥18 years at the time of screening (or per national guidelines)

• Histologically confirmed ER+/HER2- early-stage resected invasive breast cancer withhigh or intermediate risk of recurrence, based on clinical-pathological riskfeatures, as defined in the protocol.

• Completed adequate (definitive) locoregional therapy (surgery with or withoutradiotherapy) for the primary breast tumour(s), with or without (neo)adjuvantchemotherapy

• Completed at least 2 years but no more than 5 years (+3 months) of adjuvant ET (+/-CDK4/6 inhibitor)

• Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 1

• Adequate organ and marrow function

Exclusion criteria:

• Inoperable locally advanced or metastatic breast cancer

• Pathological complete response following treatment with neoadjuvant therapy

• History of any other cancer (except non-melanoma skin cancer or carcinoma in situ ofthe cervix or considered at very low risk of recurrence per investigator judgement)unless in complete remission with no therapy for a minimum of 5 years from the dateof randomisation

• Any evidence of severe or uncontrolled systemic diseases which, in theinvestigator's opinion precludes participation in the study or compliance

• Known LVEF <50% with heart failure NYHA Grade ≥2.

• Mean resting QTcF interval >480 ms at screening

• Concurrent exogenous reproductive hormone therapy or non-topical hormonal therapyfor non-cancer-related conditions

• Any concurrent anti-cancer treatment not specified in the protocol with theexception of bisphosphonates (e.g. zoledronic acid) or RANKL inhibitors (eg,denosumab)

• Previous treatment with camizestrant, investigational SERDs/investigational ERtargeting agents, or fulvestrant

• Currently pregnant (confirmed with positive serum pregnancy test) or breastfeeding

• Patients with known hypersensitivity to active or inactive excipients ofcamizestrant or drugs with a similar chemical structure or class to camizestrant. Inpre-/peri-menopausal female and male patients, known hypersensitivity or intoleranceto LHRH agonists, that would preclude the patient from receiving any LHRH agonist