Study to Evaluate the Safety and Tolerability of Camizestrant in Combination With Atirmociclib in Women With Advanced Breast Cancer

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age18 Years to no maximum
• SexFemale
• Healthy volunteersNo

You may be able to join if

• Main Inclusion Criteria:
• Participants with advanced adenocarcinoma of the breast and must have received prior adequate therapy in accordance with local practice for their tumor type and stage of disease.
• Metastatic or locoregionally recurrent disease and radiological or objective evidence of progression on or after the last systemic therapy prior to starting investigational medicinal products.
• Eastern cooperative oncology group (ECOG)/World Health Organization (WHO) performance status 0 to 1, and a minimum life expectancy of 12 weeks.
• At least one lesion that is measurable and/or non-measurable, as per RECIST 1.1 and that can be accurately assessed at baseline and is suitable for repeated assessment by computed tomography (CT), magnetic resonance imaging (MRI), or plain X-ray, or clinical examination.
• Menopausal status
• Pre-menopausal women must start GnRH agonist therapy at least 4 weeks before study treatment and continue throughout the study.
• Post-menopausal women must meet one of these criteria: bilateral oophorectomy, age ≥60 years, age ≥50 years with ≥12 months amenorrhea and intact uterus without hormonal therapy, or age <60 years with ≥12 months amenorrhea and post-menopausal hormone levels.
• Histological or cytological confirmation of adenocarcinoma of the breast.
• Participants of childbearing potential must agree to use one highly effective contraceptive measure.
• Documentation of ER-positive tumor irrespective of progesterone receptor status.
• Main Exclusion Criteria:
• A participant who has received 2 or more lines of CDK4/6 inhibitors in the advanced disease setting.
• A participant who has received prior camizestrant or atirmociclib treatment in the advanced disease setting.
• Patients previously treated with other next generation selective estrogen receptor degrader (SERDs) or other experimental ETs in the advanced disease setting.
• Patients previously treated with other experimental cyclin-dependent kinase (CDK) inhibitors are not eligible.
• Inability to swallow oral medications.
• Any unresolved toxicities of Grade ≥ 2 from prior anti-cancer therapy (with the exception of alopecia).
• Presence of life-threatening metastatic visceral disease.
• Any evidence of severe or uncontrolled systemic diseases.
• Contraindication to or known intolerance/hypersensitivity of/to camizestrant or atirmociclib.

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

camizestrant. An orally available selective estrogen receptor degrader (SERD), with potential antineoplastic activity. Upon administration, camizestrant binds to the estrogen receptor (ER) and induces a conformational change that results in the degradation of the receptor. This prevents ER-mediated signaling and inhibits the growth and survival of ER-expressing cancer cells. NCI Drug Dictionary

CDK4 inhibitor PF-07220060. An orally bioavailable inhibitor of cyclin-dependent kinase 4 (CDK4), with potential antineoplastic activity. Upon administration, CDK4 inhibitor PF-07220060 selectively inhibits CDK4, which inhibits the phosphorylation of retinoblastoma protein (Rb) early in the G1 phase, prevents CDK-mediated G1-S-phase transition and leads to cell cycle arrest. This suppresses DNA replication and inhibits tumor cell proliferation. CDK4, a serine/threonine kinase, is upregulated in many tumor cell types and plays a key role in the regulation of both cell cycle progression from the G1-phase into the S-phase and tumor cell proliferation. NCI Drug Dictionary

Treatments listed in the registry

• Camizestrant (Drug): Camizestrant will be administered orally.
• Atirmociclib (Drug): Atirmociclib will be administered orally.

Na · Single Group · masking: None

Main goals

• Number of participants with adverse events (AEs) and serious AEs (Up to Post-Treatment Follow up (Day 30 Post Dose))

Other goals

• Maximum concentration observed (Cmax)
• Area under plasma concentration-time curve from time 0 to infinity (AUCinf)
• Area under plasma concentration-time curve from time 0 to last quantifiable concentration (AUClast)
• Time to reach maximum (peak) plasma concentration following drug administration (tmax)
• Terminal elimination rate constant (λz)
• Terminal elimination half-life (t½λz)
• Apparent total body clearance (CL/F)
• Apparent volume of distribution at steady state (Vss/F)
• Apparent volume of distribution based on the terminal phase (Vz/F)
• Maximum concentration observed at steady state (Cssmax)
• Area under the curve from 0 to the end of dosing interval (AUC0-tau)
• Area under the curve from 0 to the end of dosing interval at steady state (AUCss0-tau)
• Time to reach maximum plasma concentration at steady state (tssmax)
• Objective Response Rate (ORR)
• Duration of Response (DOR)
• Clinical Benefit Rate at 24 Weeks (CBR24)
• Percentage change in tumor size
• Progression Free Survival (PFS)
• Progression-free survival landmark 6 months (PFSLM6m)
• Progression-free survival landmark 12 months (PFSLM12m)

Planned enrollment: 24 (estimated).

• Research Site, St Louis, Missouri
• Research Site, East Providence, Rhode Island
• Research Site, Nashville, Tennessee

3 recruiting sites outside the US. Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT07427394
• NCI Drug Dictionary: C160603
• NCI Drug Dictionary: C175962

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Sep 28, 2026. Public record; not medical advice.