A Phase 3 interventional study of PF-07220060 and letrozole in Breast Cancer, sponsored by Pfizer. Active, not recruiting at 463 sites in 30 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-19.
Sponsored by Pfizer · Phase 3, Interventional, and Treatment
The purpose of this study is to determine the safety and efficacy of PF-07220060 with letrozole compared to approved treatments (ie, palbociclib, ribociclib or abemaciclib with letrozole) in people with breast cancer:
Approximately half of the participants will receive PF-07220060 plus letrozole while the other half of participants will receive the investigator's choice of treatment plus letrozole.
The study team will monitor how each participant is doing with the study treatment during regular visits at the study clinic.
Exclusion Criteria:
PF-07220060 tablet taken by mouth plus Letrozole tablet taken by mouth
Drug: PF-07220060 · Drug: letrozole
Investigator's Choice of CDK4/6 inhibitor (tablet/capsule) taken by mouth with letrozole tablet taken by mouth
Drug: letrozole · Drug: abemaciclib · Drug: palbociclib · Drug: ribociclib
CDK4 inhibitor
endocrine therapy
CDK4/6 inhibitor
CDK4/6 inhibitor
CDK4/6 inhibitor
Progression Free Survival (PFS) by BICR
Time from the date of randomization to the date of the first documentation of objective progressive disease as determined by blinded independent central review (BICR) per RECIST v1.1, or death due to any cause, whichever occurs first
Time frame: From the date of randomization until disease progression or death due to any cause (up to approximately 4 years)
Overall Survival (OS)
Time from the date of randomization to the date of death due to any cause
Time frame: From the date of randomization until death due to any cause (up to approximately 13 years).
Progression Free Survival (PFS) by Investigator
Time from the date of randomization to the date of the first documentation of objective progressive disease as determined by investigator per RECIST v1.1, or death due to any cause, whichever occurs first
Time frame: From the date of randomization until disease progression or death due to any cause (up to approximately 4 years)
OR by BICR and by investigator
Time from randomization date (every 8 weeks during the first 48 weeks and then every 12 weeks) to the date of progression OR death whichever occurs first
Time frame: From randomization to progression or death whichever occurs first (up to approximately 4 years)
Duration of Response (DoR) by BICR and by investigator
Time from the date of CR or PR to the first documentation of objective progressive disease, or death due to any cause, whichever occurs first
Time frame: From the date of CR or PR until objective progressive disease, or death (up to approximately 4 years)
Incidence of treatment emergent treatment related adverse events (AE)
Incidence and severity of AEs graded according to the NCI CTCAE v5.0
Time frame: Duration of the study approximately up to 13 years.
Incidence of treatment emergent treatment related serious adverse events
Incidence and severity of AEs graded according to NCI CTCAE v5.0
Time frame: Duration of the study approximately up to 13 years.
Estimated mean change from baseline in EORTC QLQ C30
Time frame: Baseline to end of treatment (up to approximately 4 years)
Estimated mean change from baseline in BPI-SF
Time frame: Baseline to end of treatment (up to approximately 4 years)
Estimated mean change from baseline in EQ-5D-5L
Time frame: Baseline to end of treatment (up to approximately 4 years)
Estimated mean change from baseline in EORTC Breast Cancer Module (BR42)
Time frame: Baseline to end of treatment (up to approximately 4 years)
Mean change from baseline of ctDNA
Time frame: Baseline to end of treatment (up to approximately 4 years)
Showing the first 100 of 463 sites across 30 countries.
Plan to share: Yes — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
This study is active, not recruiting, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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