ERADICATE: A Phase Ib/II Study of Elacestrant Plus Trastuzumab Deruxtecan in Patients With CDK4/6 Inhibitor and Endocrine-resistant HR+/HER2-low or HER2-ultralow Metastatic Breast Cancer (NCT07198724)

Usually NOT eligible if any of the following apply:

• Exclusion Criteria:
• Prior treatment with aatopoisomerase inhibitor antibody drug conjugate in any setting.
• Prior treatment with an oral novel estrogen receptor degrader or modulator in the metastatic setting (SERD, SERM, PROTAC, or CERAN). Prior fulvestrant is allowed. A washout period of 7 days is required for any endocrine or targeted therapy. A washout period of 14 days is required for any chemotherapy.
• Patients with known brain metastases that are symptomatic or that require therapy for symptom control are not eligible. Patients with stable or asymptomatic brain metastases are allowed. Participants with CNS metastases treated by neurosurgical resection or brain biopsy performed within 4 weeks before day 1 of study therapy will be excluded.
• Receipt of any other investigational compound or device within 2 weeks of the first dose of treatment in this study.
• History of allergic reactions attributed to compounds of similar chemical or biologic composition to elacestrant or T-DXd.
• History of (non-infectious) pneumonitis that required steroids or current ILD by imaging at screening.
• Patients who are pregnant or breastfeeding, or who expect to become pregnant within the projected duration of the study.
• Patients with active tuberculosis.
• Uncontrolled intercurrent illness including, but not limited to: ongoing or active infection requiring systemic therapy, clinically significant cardiovascular disease including: cerebral vascular accident/stroke (\< 6 months prior to enrollment), myocardial infarction (\< 6 months prior to enrollment), unstable angina, congestive heart failure (≥ New York Heart Association Classification Class II), or serious cardiac arrhythmia requiring medication, uncontrolled diabetes mellitus, gastrointestinal disorders potentially affecting the absorption of elacestrant, inflammatory bowel disease or chronic diarrhea, short bowel syndrome, or total gastric resection, or psychiatric illness/social situations that would limit compliance with study requirements. Moderate or severe hepatic impairment (Child-Pugh B or C). Active hepatitis B or active hepatitis C infection. Ability to comply with study requirements is to be assessed by each investigator at the time of screening for study participation. History of myocardial infarction, acute coronary syndrome or coronary angioplasty/stenting/bypass grafting within the last six months OR congestive heart failure (CHF) New York Heart Association (NYHA) Class II-IV or history of CHF NYHA Class III or IV.
• Patients with a history of different malignancy are ineligible, except for those who have been disease-free for at least three years and are deemed by the investigator to be at low risk for recurrence of the prior malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 5 years: ductal carcinoma in situ of the breast, cervical cancer in situ, and basal cell or squamous cell carcinoma of the skin.