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.
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
- Conditions the study is for
- Early Breast Cancer, Estrogen Receptor Positive (ER+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-)
- 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
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.
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.
- Conditions
- Early Breast Cancer, Estrogen Receptor Positive (ER+), Human Epidermal Growth Factor Receptor 2 Negative (HER2-)
- 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 group | Role | What they receive |
|---|---|---|
| Arm A : Atirmociclib + giredestrant | Experimental | Atirmociclib tablet given orally twice daily, plus giredestrant capsule given orally once per day Receives: Drug: Atirmociclib; Drug: giredestrant |
| Arm B: Placebo for atirmociclib + giredestrant | Active comparator | Placebo 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.
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
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)
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
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
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
Percentage of participants With Clinical Laboratory Abnormalities
Measured: Baseline until recurrence up to 64 months
Percentage of Participants With ECG abnormalities
Measured: Baseline until recurrence up to 64 months
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
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.
- First posted22 Oct 2026
- Study start1 Dec 2026 (estimated)
- Primary completion13 Apr 2032 (estimated)
- Study completion20 Aug 2042 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Early 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
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 3,800 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
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.