Breast CancerPhase 3VERITAC-3NCT05909397
Vepdegestrant (ARV-471/PF-07850327) + Palbociclib vs Letrozole + Palbociclib in ER(+)/HER2(-) Advanced Breast Cancer
A Phase 3 study testing Vepdegestrant (ARV-471/PF-07850327), Palbociclib and Letrozole in people with Breast Cancer, run by Pfizer at 29 sites in 10 countries.
Trial summary
The purpose of this study is to understand the safety and effects of the study medicine vepdegestrant (ARV-471/PF-07850327) given together with palbociclib in advanced breast cancer. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Breast Cancer
- What is being tested?
- Vepdegestrant (ARV-471/PF-07850327), Palbociclib and Letrozole
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 59 participants
- Where
- 29 sitesin 10 countries
- Study dates
- 9 Aug 2023to 30 Dec 2026
- Phase
- Phase 3
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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), vepdegestrant, 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.
Trial locations and contacts
29 sites in 10 countries.
29 sites in 10 countries
Spain6 sites
Institut Català d'Oncologia (ICO) - Badalona
Badalona, Barcelona [barcelona], 08916
Hospital Universitari Dexeus
Barcelona, Catalunya [cataluña], 08028
Hospital Unviersitario Virgen Nieves
Granada, 18012
Complejo Hospitalario de Jaén
Jaén, JAÉN, 23007
Hospital Clinico San Carlos
Madrid, 28040
Hospital Universitario Virgen de la Victoria
Málaga, Málaga, 29010
Brazil4 sites
Centro Gaucho Integrado De Oncologia, Hematologia, Ensino E Pesquisa
Porto Alegre, Rio Grande do Sul, 90110-270
Centro de Pesquisa Clínica - Área Administrativa
Porto Alegre, Rio Grande do Sul, 90850-170
Hospital Mae de Deus
Porto Alegre, Rio Grande do Sul, 90880-480
Hospital Santa Rita de Cassia
Vitória, Espírito Santo, 29043-260
China4 sites
Cancer Hospital Chinese Academy of Medical Science
Beijing, Beijing Municipality, 100021
Sun Yat-sen University Cancer Center
Guangzhou, Guangdong, 510060
Hubei Cancer Hospital
Wuhan, Hubei, 430079
The First Affiliated Hospital of Xi'an Jiaotong University
Xi'an, Shaanxi, 710061
United States3 sites
Virginia Oncology Associates
Norfolk, Virginia, 23502
BRCR Global
Plantation, Florida, 33322
BRCR Medical Center Inc
Plantation, Florida, 33322
Italy3 sites
IRCCS - Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori"
Meldola, Emilia-Romagna, 47014
Fondazione IRCCS San Gerardo dei Tintori
Monza, Lombardy, 20900
Istituto Nazionale Tumori IRCCS Fondazione Pascale
Naples, Campania, 80131
Japan3 sites
National Cancer Center Hospital
Chuo-ku, Tokyo, 104-0045
National Cancer Center Hospital East
Kashiwa, Chiba, 277-8577
Aichi Cancer Center Hospital
Nagoya, Aichi-ken, 464-8681
Australia2 sites
Cancer Research SA
Adelaide, South Australia, 5000
Barwon Health
Geelong, Victoria, 3220
Slovakia2 sites
Nemocnica na okraji mesta n o
Partizánske, 95801
Fakultna nemocnica s poliklinikou J.A. Reimana Presov
Prešov, 080 01
About this study
Official title: A PHASE 3, RANDOMIZED, OPEN-LABEL, MULTICENTER STUDY OF VEPDEGESTRANT (ARV-471/PF-07850327) PLUS PALBOCICLIB VERSUS LETROZOLE PLUS PALBOCICLIB FOR THE TREATMENT OF PARTICIPANTS WITH ESTROGEN RECEPTOR POSITIVE, HER2 NEGATIVE BREAST CANCER WHO HAVE NOT RECEIVED ANY PRIOR SYSTEMIC ANTI CANCER TREATMENT FOR ADVANCED DISEASE (VERITAC-3)
The purpose of this study is to understand the safety and effects of the study medicine vepdegestrant (ARV-471/PF-07850327) given together with palbociclib in advanced breast cancer. In particular, the study will compare the combination of vepdegestrant plus palbociclib to standard of care therapy (letrozole plus palbociclib). Both letrozole and palbociclib are medicines already used for treatment of breast cancer. Vepdegestrant is a new medicine under study.
This study is seeking participants who have breast cancer that:
Read more
- 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 vepdegestrant 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 vepdegestrant.
In the Phase 3, half of the participants will take vepdegestrant 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.
Read the detailed description
The purpose of this study is to demonstrate that vepdegestrant (ARV-471) in combination with palbociclib provides superior clinical benefit compared to letrozole in combination with palbociclib in participants with ER(+)/HER2(-) aBC who have not received any prior systemic anti-cancer therapies for their locoregionally advanced or metastatic disease.
The study will have a Study Lead-in (SLI) and a Phase 3. In the SLI, 50 participants (approximately 25 each arm) will be randomly assigned on a 1:1 basis to one of the two dose levels (DLs). In the randomized Phase 3, approximately 1130 eligible participants (approximately 565 each arm) will be randomized in a 1:1 ratio to the Experimental Arm (ie, vepdegestrant plus palbociclib at RP3D determined in the SLI) or Control Arm (ie, letrozole plus palbociclib at the registered doses). Randomization will be stratified by menopausal status at study entry, visceral disease and de novo metastatic disease.
- Conditions
- Breast Cancer
- Being tested
- Vepdegestrant (ARV-471/PF-07850327), Palbociclib, Letrozole
- Keywords
- Advanced tumor of the breast, Advanced cancer of the breast, Breast neoplasm, Breast tumor, Breast cancer, ER positive, Estrogen receptor positive, HER2-negative, Metastatic breast cancer, Palbociclib, Letrozole, ARV-471, Vepdegestrant
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Vepdegestrant (ARV-471/PF-07850327)Drug
Also called Vepdegestrant
Pharmaceutical form: Tablets. Route of Administration: Oral
PalbociclibCombination product
Also called IBRANCE®
Pharmaceutical form: Capsules. Route of Administration: Oral.
LetrozoleDrug
Also called FEMARA®
Pharmaceutical form: Capsules. Route of Administration: Orally
PalbociclibCombination product
Also called IBRANCE®
Pharmaceutical form: Capsules. Route of Administration: Oral.
| Study group | Role | What they receive |
|---|---|---|
| Arm A (Investigational Arm) | Experimental | Participants will receive:
* Vepdegestrant, orally, once daily, continuously, in a 28-day cycle, plus
* Palbociclib, orally, once daily for 21 consecutive days followed by 7 days off treatment in a 28 day cycle Receives: Drug: Vepdegestrant (ARV-471/PF-07850327); Combination Product: Palbociclib |
| Arm B (Comparator Arm): | Active comparator | Participants will receive:
* Letrozole, orally, once daily, continuously, in a 28-day cycle, plus
* Palbociclib, orally, once daily for 21 consecutive days followed by 7 days off treatment, in a 28-day cycle. Receives: Drug: Letrozole; Combination Product: Palbociclib |
What is being measured
The primary outcome is the main question the study is designed to answer.
Study Lead-in (SLI): Incidence of Grade 4 neutropenia
It is defined as the number of participants with Grade 4 neutropenia AE (graded by NCI CTCAE v.5.0) with onset within the first 4 cycles divided by the number of participants.
Measured: From randomization date up to Cycle 4 (each cycle is 28 days).
SLI: Incidence of dose reduction
It is defined as the number of participants reducing the dose of palbociclib and/or vepdegestrant due to any cause occurring within the first 4 cycles divided by the number of participants.
Measured: From randomization date up to Cycle 4 (each cycle is 28 days).
SLI: Incidence of drug discontinuation.
It is defined as the number of participants discontinuing palbociclib and/or vepdegestrant due to any cause occurring within the first 4 cycles divided by the number of participants.
Measured: From randomization date up to Cycle 4 (each cycle is 28 days).
Phase 3: Progression-Free Survival
Progression-free survival is defined as the time interval from the date of randomization to the date of first documented tumor progression determined by Blinded Independent Central Review (BICR) as per Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) or death due to any cause, whichever come first.
Measured: From randomization date, every 12 weeks, to date of first documentation of progression or death, up to approximately 4 years.
Secondary outcomes (12)
SLI and Phase 3. Objective Response Rate
Objective response rate is defined as the proportion of participants who have a confirmed CR or PR, as best overall response determined by Investigators (SLI) or by BICR (Phase 3) as per RECIST version 1.1, from the date of randomization to the date of disease progression or death due to any cause, whichever occurs first.
Measured: From randomization date, every 12 weeks, to the date of progression or death (up to approximately 4 years).
SLI and Phase 3: Duration of Response
Duration of response is defined as the time from first documented evidence of CR or PR until progressive disease (PD) determined by Investigators (SLI) or by BICR (Phase 3) as per RECIST version 1.1 or death due to any cause, whichever occurs first.
Measured: From the date of the first objective response, every 12 weeks, to the date of disease progression or death (up to approximately 4 years).
SLI and Phase 3: Clinical Benefit Rate
Clinical benefit rate is defined as the proportion of participants who have a confirmed CR, PR at any time or SD or non CR/non PD for at least 24 weeks determined by Investigators (SLI) or by BICR (Phase 3) as per RECIST version 1.1, from the date of randomization until disease progression or death due to any cause, whichever occurs first.
Measured: Every 12 weeks From randomization date, every 12 week, to the date of progression or death (up to approximately 4 years).
Phase 3: Overall Survival
Overall survival is defined as the time interval from the date of randomization to the date of documented death, due to any cause.
Measured: From randomization date, every 3 months, to date of death (up to approximately 6 years)
SLI and Phase 3: Incidence of Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs)
It is defined as the number of participants with TEAEs and SAEs divided by the number of participants. AEs and SAEs will be graded according to NCI CTCAE V5.0.
Measured: From baseline to date to end of treatment (up to approximately 4 years)
SLI and Phase 3: Incidence of laboratory abnormalities
It is defined as the number of participants with laboratory abnormalities divided by the number of participants. Laboratory abnormalities will be graded according to NCI CTCAE V5.0.
Measured: From baseline to end of treatment (up to approximately 4 years)
SLI and Phase 3: Incidence of Electrocardiogram (ECG) Abnormalities
It is defined as the number of participants with ECG abnormalities divided by the number of participants. ECG abnormalities will be graded according to NCI CTCAE V5.0.
Measured: From baseline up to the end of treatment (up to approximately 4 years)
SLI and Phase 3: Plasma concentrations of vepdegestrant and palbociclib
Plasma concentrations of vepdegestrant and palbociclib
Measured: From randomization date up to Cycle 5 (each cycle is 28 days)
Phase 3: Health state utility and health status will be assessed using the European Quality of Life Group questionnaire with 5 dimensions and 5 levels per dimension (EQ-5D-5L)
Change from baseline between treatment comparison in Quality of Life using the EQ-5D 5L questionnaire.
Measured: From baseline, each cycle up to cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days
Phase 3: Disease-related Quality of Life will be assessed using the European Organization for Research and Treatment of Cancer (EORTC) core quality of life questionnaire (QLQ-C30)
Change from baseline between treatment comparison in Quality of Life using the EORTC QLQ-C30 questionnaire.
Measured: From baseline, each cycle up to Cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days.
Phase 3: Disease- and treatment-related Quality of Life will be assessed using the European Organization for Research and Treatment of Cancer (EORTC) breast cancer module (QLQ-BR23) questionnaire.
Change from baseline between treatment comparison in Quality of Life Using the EORTC QLQ-BR23 (Breast) questionnaire.
Measured: From baseline, each cycle up to Cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days.
Phase 3: Changes from baseline in plasma ctDNA (Circulating Deoxyribonucleic Acid)
Quantitative changes from baseline
Measured: From baseline to end of treatment (up to approximately 4 years)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Jun 2023
- Study start9 Aug 2023
- Primary completion30 Dec 2026 (estimated)
- Study completion30 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 59 participants (actual)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- Arvinas Estrogen Receptor, Inc.
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05909397
- Sponsor's protocol ID
- C4891002
- Other IDs
- 2022-500545-24-00
- Acronym
- VERITAC-3
- Status last verified
- Feb 2026
- First submitted
- 25 May 2023
- Last updated
- 10 Feb 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- 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.
Study at a glance
From the registry record, last updated by the sponsor on 10 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A PHASE 3, RANDOMIZED, OPEN-LABEL, MULTICENTER STUDY OF VEPDEGESTRANT (ARV-471/PF-07850327) PLUS PALBOCICLIB VERSUS LETROZOLE PLUS PALBOCICLIB FOR THE TREATMENT OF PARTICIPANTS WITH ESTROGEN RECEPTOR POSITIVE, HER2 NEGATIVE BREAST CANCER WHO HAVE NOT RECEIVED ANY PRIOR SYSTEMIC ANTI CANCER TREATMENT FOR ADVANCED DISEASE (VERITAC-3)
- ClinicalTrials.gov ID
- NCT05909397
- Acronym / sponsor ID
- VERITAC-3 / C4891002
- Conditions
- Breast Cancer
- Keywords
- Advanced tumor of the breast, Advanced cancer of the breast, Breast neoplasm, Breast tumor, Breast cancer, ER positive, Estrogen receptor positive, HER2-negative
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 59 participants (actual)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Collaborators
- Arvinas Estrogen Receptor, Inc.
- Study start
- 9 Aug 2023 (actual)
- Primary completion
- 30 Dec 2026 (estimated)
- Study completion
- 30 Dec 2026 (estimated)
- First posted
- 18 Jun 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to understand the safety and effects of the study medicine vepdegestrant (ARV-471/PF-07850327) given together with palbociclib in advanced breast cancer. In particular, the study will compare the combination of vepdegestrant plus palbociclib to standard of care therapy (letrozole plus palbociclib). Both letrozole and palbociclib are medicines already used for treatment of breast cancer. Vepdegestrant 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 vepdegestrant 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 vepdegestrant.
In the Phase 3, half of the participants will take vepdegestrant 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.
Detailed description
The purpose of this study is to demonstrate that vepdegestrant (ARV-471) in combination with palbociclib provides superior clinical benefit compared to letrozole in combination with palbociclib in participants with ER(+)/HER2(-) aBC who have not received any prior systemic anti-cancer therapies for their locoregionally advanced or metastatic disease.
The study will have a Study Lead-in (SLI) and a Phase 3. In the SLI, 50 participants (approximately 25 each arm) will be randomly assigned on a 1:1 basis to one of the two dose levels (DLs). In the randomized Phase 3, approximately 1130 eligible participants (approximately 565 each arm) will be randomized in a 1:1 ratio to the Experimental Arm (ie, vepdegestrant plus palbociclib at RP3D determined in the SLI) or Control Arm (ie, letrozole plus palbociclib at the registered doses). Randomization will be stratified by menopausal status at study entry, visceral disease and de novo metastatic disease.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Arm A (Investigational Arm) | Experimental | Drug: Vepdegestrant (ARV-471/PF-07850327), Combination Product: PalbociclibParticipants will receive: * Vepdegestrant, orally, once daily, continuously, in a 28-day cycle, plus * Palbociclib, orally, once daily for 21 consecutive days followed by 7 days off treatment in a 28 day cycle |
| Arm B (Comparator Arm): | Active comparator | Drug: Letrozole, Combination Product: PalbociclibParticipants will receive: * Letrozole, orally, once daily, continuously, in a 28-day cycle, plus * Palbociclib, orally, once daily for 21 consecutive days followed by 7 days off treatment, in a 28-day cycle. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- 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
Key exclusion criteria (6 listed)
- 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), vepdegestrant, 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Vepdegestrant (ARV-471/PF-07850327)Also: VepdegestrantPharmaceutical form: Tablets. Route of Administration: Oral | Drug | Arm A (Investigational Arm) |
| PalbociclibAlso: IBRANCE®Pharmaceutical form: Capsules. Route of Administration: Oral. | Combination product | Arm A (Investigational Arm) |
| LetrozoleAlso: FEMARA®Pharmaceutical form: Capsules. Route of Administration: Orally | Drug | Arm B (Comparator Arm): |
| PalbociclibAlso: IBRANCE®Pharmaceutical form: Capsules. Route of Administration: Oral. | Combination product | Arm B (Comparator Arm): |
Primary outcome
Study Lead-in (SLI): Incidence of Grade 4 neutropenia
Time frame: From randomization date up to Cycle 4 (each cycle is 28 days).
It is defined as the number of participants with Grade 4 neutropenia AE (graded by NCI CTCAE v.5.0) with onset within the first 4 cycles divided by the number of participants.
SLI: Incidence of dose reduction
Time frame: From randomization date up to Cycle 4 (each cycle is 28 days).
It is defined as the number of participants reducing the dose of palbociclib and/or vepdegestrant due to any cause occurring within the first 4 cycles divided by the number of participants.
SLI: Incidence of drug discontinuation.
Time frame: From randomization date up to Cycle 4 (each cycle is 28 days).
It is defined as the number of participants discontinuing palbociclib and/or vepdegestrant due to any cause occurring within the first 4 cycles divided by the number of participants.
Phase 3: Progression-Free Survival
Time frame: From randomization date, every 12 weeks, to date of first documentation of progression or death, up to approximately 4 years.
Progression-free survival is defined as the time interval from the date of randomization to the date of first documented tumor progression determined by Blinded Independent Central Review (BICR) as per Response Evaluation Criteria in Solid Tumors (RECIST version 1.1) or death due to any cause, whichever come first.
12 secondary outcomes
SLI and Phase 3. Objective Response Rate
Time frame: From randomization date, every 12 weeks, to the date of progression or death (up to approximately 4 years).
SLI and Phase 3: Duration of Response
Time frame: From the date of the first objective response, every 12 weeks, to the date of disease progression or death (up to approximately 4 years).
SLI and Phase 3: Clinical Benefit Rate
Time frame: Every 12 weeks From randomization date, every 12 week, to the date of progression or death (up to approximately 4 years).
Phase 3: Overall Survival
Time frame: From randomization date, every 3 months, to date of death (up to approximately 6 years)
SLI and Phase 3: Incidence of Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Events (SAEs)
Time frame: From baseline to date to end of treatment (up to approximately 4 years)
SLI and Phase 3: Incidence of laboratory abnormalities
Time frame: From baseline to end of treatment (up to approximately 4 years)
SLI and Phase 3: Incidence of Electrocardiogram (ECG) Abnormalities
Time frame: From baseline up to the end of treatment (up to approximately 4 years)
SLI and Phase 3: Plasma concentrations of vepdegestrant and palbociclib
Time frame: From randomization date up to Cycle 5 (each cycle is 28 days)
Phase 3: Health state utility and health status will be assessed using the European Quality of Life Group questionnaire with 5 dimensions and 5 levels per dimension (EQ-5D-5L)
Time frame: From baseline, each cycle up to cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days
Phase 3: Disease-related Quality of Life will be assessed using the European Organization for Research and Treatment of Cancer (EORTC) core quality of life questionnaire (QLQ-C30)
Time frame: From baseline, each cycle up to Cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days.
Phase 3: Disease- and treatment-related Quality of Life will be assessed using the European Organization for Research and Treatment of Cancer (EORTC) breast cancer module (QLQ-BR23) questionnaire.
Time frame: From baseline, each cycle up to Cycle 3, then every odd cycle to end of treatment (up to approximately 4 years). Each cycle is 28 days.
Phase 3: Changes from baseline in plasma ctDNA (Circulating Deoxyribonucleic Acid)
Time frame: From baseline to end of treatment (up to approximately 4 years)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Feb 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: 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.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Pfizer CT.gov Call Center study director
Pfizer
29 sites in 10 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing Vepdegestrant (ARV-471/PF-07850327), Palbociclib and Letrozole in people with Breast Cancer, run by Pfizer at 29 sites in 10 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 10 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 29 sites in Spain, Brazil, China, United States, Italy and 5 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Study Lead-in (SLI): Incidence of Grade 4 neutropenia (time frame: From randomization date up to Cycle 4 (each cycle is 28 days).). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Feb 2026.