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Early Breast CancerPhase 3NCT07890597

A Study of a Medicine Called Atirmociclib in Combination With Giredestrant in Adult Participants With ER-positive, HER2-negative Early-stage Breast Cancer

A Phase 3 study testing Atirmociclib and giredestrant in people with Early Breast Cancer and Estrogen Receptor Positive (ER+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-), run by Pfizer.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
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Trial summary

This Phase 3 study will evaluate whether atirmociclib plus giredestrant improves invasive breast cancer-free survival compared with giredestrant alone in adults with ER-positive, HER2-negative early breast cancer at medium or high risk of recurrence. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Atirmociclib and giredestrant
Type of treatment
Pill or oral medicine
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
3,800 participants
Where
No sites listed yet
Study dates
1 Dec 2026to 20 Aug 2042
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

  • Histologically confirmed unilateral primary adenocarcinoma of the breast
  • ER-positive by local assessment
  • documented HER2-negative
  • Node positive or node negative as defined by:
  • Pathological node positive (microscopic and/or macroscopic tumor involvement >/=pN1)
  • pN0 and pT >1cm with at least one of the following:
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  • pT4N0 or
  • histologically Grade 3 disease or
  • high-risk classification based on genomic assay
  • Randomization within 16 months of definitive breast surgery
  • If indicated, completed adjuvant and/or neoadjuvant chemotherapy, adjuvant radiation therapy >/= 21 days prior to randomization

Who cannot join

  • Distant metastases of breast cancer beyond regional lymph nodes
  • Multicentric or multifocal breast cancer if any tumor foci meet pathologic criteria for ER(-) or HER2(+)
  • Clinically significant cardiovascular disease or cardiac repolarization abnormality for 6 months prior to randomization; resting heart rate <50bpm
  • Has received the following prior systemic anti-cancer therapy for breast cancer
  • prior atirmociclib, giredestrant, other investigational anti-cancer agent
  • prior treatment with olaparib
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  • NOTES:
  • short course of prior neo/adjuvant CDK4/6 inhibitor treatment (</=8 weeks) is permitted; 10-day washout period required
  • short course of prior neoadjuvant and/or adjuvant ET (</=18 weeks) is permitted; 35-day washout period for tamoxifen is required
  • Prior treatment with investigational product within 30 days or 5 half-lives

Trial locations and contacts

No sites are listed yet. Contact the study team or a site near you to ask about taking part.

Pfizer CT.gov Call Center contact

1-800-718-1021

ClinicalTrials.gov_Inquiries@pfizer.com

About this study

Official title: AN INTERVENTIONAL, DOUBLE-BLIND, PLACEBO CONTROLLED, RANDOMIZED, MULTICENTER PHASE 3 STUDY OF ATIRMOCICLIB (PF-07220060) PLUS GIREDESTRANT COMPARED TO GIREDESTRANT MONOTHERAPY AS ADJUVANT TREATMENT IN ADULT PARTICIPANTS WITH ESTROGEN RECEPTOR (ER)-POSITIVE, HER2-NEGATIVE EARLY-STAGE BREAST CANCER WITH MEDIUM OR HIGH RISK OF RECURRENCE (FOURLIGHT-4)

This Phase 3 study will evaluate whether atirmociclib plus giredestrant improves invasive breast cancer-free survival compared with giredestrant alone in adults with ER-positive, HER2-negative early breast cancer at medium or high risk of recurrence.

This is a Phase 3, double blind, placebo controlled study of atirmociclib plus giredestrant vs. giredestrant monotherapy as adjuvant treatment in adult patients with ER+, HER2- early breast cancer. The study plans to enroll 3800 participants randomized 1:1 into one of two treatment arms (Arm A - investigational: atirmociclib plus giredestrant taken continuously in a 28-day cycle) or (Arm B - comparator: placebo plus giredestrant taken continuously in a 28-day cycle). Participants may be treated with atirmociclib/placebo up to 3 years and giredestrant up to 5 years followed by long term follow up for survival and evaluation of recurrence of disease.

Being tested
Atirmociclib, giredestrant, Atirmociclib placebo
Keywords
ER+/HR-, Adjuvant
Medical subject headings
Breast Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • AtirmociclibDrug

    Also called PF-07220060

    Atirmociclib tablet given orally twice daily, plus giredestrant capsule given orally once per day

  • giredestrantDrug

    giredestrant capsule given once a day

  • Atirmociclib placeboOther

    Atirmociclib placebo tablet given twice a day

Study groups in NCT07890597
Study groupRoleWhat they receive
Arm A : Atirmociclib + giredestrantExperimentalAtirmociclib tablet given orally twice daily, plus giredestrant capsule given orally once per day
Receives: Drug: Atirmociclib; Drug: giredestrant
Arm B: Placebo for atirmociclib + giredestrantActive comparatorPlacebo atirmociclib tablets given orally twice a day plus giredestrant capsule given once a day
Receives: Drug: giredestrant; Other: Atirmociclib placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Invasive Breast Cancer Free Survival (iBCFS)

    iBCFS is defined as the time from the date of randomization to the date of first documented occurrence of invasive ipsilateral breast tumor recurrence, local-regional invasive breast cancer recurrence, invasive contralateral breast cancer, distant recurrence, or death from any cause, as determined by investigator assessment per STEEP v2.0 criteria

    Measured: Baseline until recurrence up to 64 months

  2. Invasive Disease Free Survival (iDFS)

    iDFS defined as the time from the date of randomization to the date of first documented occurrence of invasive ipsilateral breast tumor recurrence, local-regional invasive breast cancer recurrence, invasive contralateral breast cancer, distant recurrence, second primary invasive non-breast cancer, or death from any cause, as determined by investigator assessment per STEEP v2.0 criteria

    Measured: Baseline until recurrence up to 64 months

Secondary outcomes (7)

  1. Disease Recurrence Free Survival (DRFS)

    DRFS as per investigator assessment, defined as the time from the date of randomization to the date of distant recurrence as determined by investigator assessment or death from any cause, whichever occurs first

    Measured: Baseline until recurrence up to 64 months

  2. Overall survival (OS)

    OS is defined as the time from the date of randomization to the date of death due to any cause

    Measured: Baseline until recurrence up to 64 months

  3. Number and percentage of Participants with Treatment-Emergent Adverse Events (AEs)

    Type, incidence, severity of AE graded by NCI CTCAE v 5.0, seriousness and relationship to study intervention

    Measured: Baseline until recurrence up to 64 months

  4. Percentage of participants With Clinical Laboratory Abnormalities

    Measured: Baseline until recurrence up to 64 months

  5. Percentage of Participants With ECG abnormalities

    Measured: Baseline until recurrence up to 64 months

  6. Patient Reported Outcomes (PRO)

    Change from baseline in participant reported total score, well-being subscales and symptoms scores and TOI per FACT-ES

    Measured: Baseline until recurrence up to 64 months

  7. Pre-dose Plasma Concentration (Ctrough) of atirmociclib

    Measured: Cycle 1 Day 15, Cycle 2 Day 1, and Cycle 3 Day 1. Cycle is defined as 28 days

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted22 Oct 2026
  2. Study start1 Dec 2026 (estimated)
  3. Primary completion13 Apr 2032 (estimated)
  4. Study completion20 Aug 2042 (estimated)

Resources

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
Quadruple blind
Who is masked
Participant, Care provider, Investigator, Outcomes assessor
Enrolment
3,800 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07890597
Sponsor's protocol ID
C4391026
Status last verified
Oct 2026
First submitted
16 Oct 2026
Last updated
22 Oct 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.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing Atirmociclib and giredestrant in people with Early Breast Cancer and Estrogen Receptor Positive (ER+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-), run by Pfizer.

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 11 inclusion and 10 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: opening soon, as of the sponsor's last update on 22 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.

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?

Contact Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Invasive Breast Cancer Free Survival (iBCFS) (time frame: Baseline until recurrence up to 64 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07890597.

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 22 Oct 2026.

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