Atirmociclib
A next-generation pill that blocks only CDK4, not CDK6, to keep the benefit of today's drugs without the low blood counts.
Pfizer's CDK4-selective inhibitor. Phase 2 FOURLIGHT-1 (second line, with fulvestrant) positive in early 2026 with lower neutropenia than dual inhibitors; phase 3 FOURLIGHT-3 compares atirmociclib + letrozole with a CDK4/6 inhibitor + letrozole in first line. Rationale: CDK6 inhibition drives neutropenia while CDK4 carries most of the antitumour effect in luminal breast cancer.
1.Cyclin D1-CDK4 phosphorylates RB in luminal breast cancer cells
- Route
- Oral
- Schedule
- Twice daily (phase 2/3 dosing under evaluation)
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- Feb 2026DesignationGlobal
Positive topline phase 2 FOURLIGHT-1 source
Trials
topRecruiting now (live from ClinicalTrials.gov)
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Landmark trials in OnCo
Latest papers
topQuery for this drug: (TITLE:"Atirmociclib" OR ABSTRACT:"Atirmociclib" OR TITLE:"PF-07220060" OR ABSTRACT:"PF-07220060") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Atirmociclib, not a curated reading list.
Pages like this
not linked directly; found by shared links- ProductRibociclib
Shares CDK4-selective inhibitors as the new first-line backbone, The cell-cycle engine (cyclins & CDKs), CDK4/6 inhibitors, CDK4/6.
- TermHallmark: evading growth suppressors
Shares The cell-cycle engine (cyclins & CDKs), CDK4/6 inhibitors, CDK4/6.
- ProductAbemaciclib
Shares CDK4-selective inhibitors as the new first-line backbone, The cell-cycle engine (cyclins & CDKs), CDK4/6 inhibitors, CDK4/6.
- TrialPALOMA-2
- TermEndocrine resistance
Shares The cell-cycle engine (cyclins & CDKs), CDK4/6, HR-positive / HER2-negative breast cancer.
- TargetLIV-1 (SLC39A6)
Shares Pfizer (incl. Seagen), HR-positive / HER2-negative breast cancer.
- TrialpostMONARCH
- ProductPalbociclib
Shares CDK4-selective inhibitors as the new first-line backbone, The cell-cycle engine (cyclins & CDKs), CDK4/6 inhibitors, CDK4/6.