A Study of Vepdegestrant (ARV-471, PF-07850327) Plus Palbociclib Versus Letrozole Plus Palbociclib in Participants With Estrogen Receptor Positive, Human Epidermal Growth Factor Negative Advanced Breast Cancer
About the study
The purpose of this study is to understand the safety and effects of the study medicine ARV-471 (PF-07850327) given together with palbociclib in advanced breast cancer. In particular, the study will compare the combination of ARV-471 plus palbociclib to standard of care therapy (letrozole plus palbociclib). Both letrozole and palbociclib are medicines already used for treatment of breast cancer. ARV-471 is a new medicine under study.
This study is seeking participants who have breast cancer that:
* Have a locally advanced or metastatic disease and cannot be fully cured by surgery or radiation therapy. A metastatic disease is when disease has spread to other parts of the body.
* Is sensitive to hormonal therapy such as tamoxifen. This is called estrogen receptor positive disease.
* Have not received any prior medicine for advanced disease. Example medications include tamoxifen or letrozole or exemestane.
The study will have an open-label SLI (study lead-in) before initiation of Phase 3 trial. During SLI, two dose levels of palbociclib in combination with ARV-471 will be explored in parallel. Assignment to the palbociclib dose is by chance. Half of the participant will receive one dose and the other half another palbociclib dose. The purpose of SLI is to determine the recommended Phase 3 dose of palbociclib to be administered in combination with ARV-471.
In the Phase 3, half of the participants will take ARV-471 plus palbociclib while the other half will take letrozole plus palbociclib. In both SLI and Phase 3, participants will take the study medicines by mouth, with food, once a day. Participants will take the study medicines until breast cancer increase in size or side effects become too severe. Side effects refer to unwanted reactions to medications. Participants will visit the study clinic about once every 4 weeks.
Who can take part
You may be eligible to participate in the study if you meet the following criteria:
INCLUSION CRITERIA
Inclusion Criteria:
- Adult participants with loco-regional recurrent or metastatic disease not amenable to curative treatment
- Confirmed diagnosis of ER+/HER2- breast cancer
- No prior systemic treatment for loco-regional recurrent or metastatic disease
- Measurable disease evaluable per Response Evaluation Criterion in Solid Tumors (RECIST) v.1.1 or non-measurable bone-only disease
- Eastern Cooperative Oncology Group (ECOG) performance status 0-2
- Phase 3 only: Participants should be willing to provide blood and tumor tissue
EXCLUSION CRITERIA
Exclusion Criteria:
- Disease recurrence while on, or within 12 months of completion of adjuvant endocrine therapy
- Prior treatment with cyclin dependent kinase 4/6 inhibitors (CDK4/6i), fulvestrant, elacestrant and other investigational drugs including novel endocrine therapies, any selective estrogen receptor degraders (SERDs), covalent antagonists (SERCAs) and complete ER antagonists (CERANs).
- Inadequate liver, kidney and bone marrow function
- Impaired cardiovascular function or clinically significant cardiovascular diseases
- Refractory nausea and vomiting, inability to swallow capsules and tablets whole, chronic gastrointestinal diseases, significant gastric (total or partial) or bowel resection that would preclude adequate absorption of study interventions.
- Current use or anticipated need for food, herbal supplements or drugs that are known strong CYP3A4 inhibitors or inducers.
Study Locations
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How to Apply
Contact the study center to learn if this study is a good match for you.
Study’s details
Contition
Breast Cancer
Age (in years)
18+
Phase
PHASE3
Participants needed
1180
Est. Completion Date
Jul 26, 2030
Treatment type
INTERVENTIONAL
Sponsor
Pfizer
ClinicalTrials.gov identifier
NCT05909397
Study number
C4891002
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