TACTIVE RIBO

Brief Summary

TACTIVE RIBO is a prospective, open-label, multicenter, Phase 1b/2 sub-study to evaluate the safety, antitumor activity, and PK of ARV-471 with ribociclib in the treatment of participants with A/MBC. The sub-study is part of Umbrella platform, TACTIVE-U, comprising multiple sub-studies that independently evaluate ARV-471 in participants with with Estrogen Receptor Positive/Human Epidermal Growth Factor Receptor 2 Negative (ER+/HER2-) Advanced or Metastatic Breast Cancer. ARV-471 will act as the backbone therapy given in combination with other anticancer agents thought to have clinical relevance in ER+ breast cancer.

Eligibility Criteria

Inclusion Criteria

• Histological or cytological diagnosis of ER+ and HER2- advanced/metastatic breast cancer that is not amendable to surgical resection with curative intent (≥1% ER+ stained cells on the most recent tumor biopsy).
• Prior anticancer therapies: at least 1 and no more than 2 lines of prior therapies for advanced/metastatic disease; 1, and only 1, line of any CDK4/6 inhibitor-based regimen is required (in any setting eg adjuvant, metastatic)
• At least 1 measurable lesion as defined by RECIST v1.1.
• ECOG PS ≤1.

Exclusion Criteria

• Visceral crisis at risk of life-threatening complications in the short term Known history of drug-induced pneumonitis or other significant symptomatic deterioration of lung functions.
• Newly diagnosed brain metastases, or symptomatic CNS metastases, carcinomatous meningitis, or leptomeningeal disease. Participants with a history of CNS metastases or cord compression are eligible if they have been definitively treated, clinically stable and discontinued anti-seizure medications and corticosteroids for at least 14 days prior to enrollment in the of study.
• History of any other tumor malignancies within the past 3 years, except for the following: (1) adequately treated basal or squamous cell carcinoma of the skin; (2) curatively treated in situ carcinoma of the cervix.
• Inflammatory breast cancer
• Impaired cardiovascular function or clinically significant cardiovascular diseases
• Concurrent administration of medications, food, or herb supplements that are strong inhibitors and strong/moderate inducers of CYP3A and drugs known to predispose to Torsade de Pointes or QT interval prolongation.
• Renal impairment, not adequate liver function and/or bone marrow function
• Known active infection