FOURLIGHT-1
In FOURLIGHT-1, a CDK4-only inhibitor designed to avoid the low blood counts of current CDK4/6 drugs improved progression-free survival in second line.
Positive topline phase 2 (early 2026): atirmociclib + fulvestrant improved PFS versus fulvestrant after progression on a CDK4/6 inhibitor, with lower neutropenia than dual CDK4/6 inhibitors. Phase 3 FOURLIGHT-3 (first-line vs CDK4/6 + letrozole) is enrolling.
Setting
HR+/HER2- advanced breast cancer after CDK4/6 inhibitor: atirmociclib + fulvestrant vs fulvestrant
Phase
Phase 2
Sponsor
Pfizer
Registry
Headline result
PFS improved (HR not yet published in detail).
Reported
2026
Enrolled
400
Replication
Phase 3 pending.
Pages like this
not linked directly; found by shared links- TrialPALOMA-2
- TrialpostMONARCH
- TrialMONALEESA-2
- PersonAngela DeMichele
- TrialPALLAS & PENELOPE-B
- CompanyCircle Pharma
- PersonDebu Tripathy
- PersonMatthew P. Goetz