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Palbociclib + Letrozole OR Fulvestrant
Palbociclib inhibits cyclin-dependent kinases 4 and 6 to block cell cycle progression, combined with either letrozole (aromatase inhibitor) or fulvestrant (estrogen receptor antagonist) to suppress hormone-driven breast cancer growth.
Palbociclib inhibits cyclin-dependent kinases 4 and 6 to block cell cycle progression, combined with either letrozole (aromatase inhibitor) or fulvestrant (estrogen receptor antagonist) to suppress hormone-driven breast cancer growth. Used for Hormone receptor-positive, HER2-negative metastatic or advanced breast cancer (first-line or subsequent lines, depending on trial arm).
At a glance
| Generic name | Palbociclib + Letrozole OR Fulvestrant |
|---|---|
| Also known as | Ibrance, Femara, Faslodex |
| Sponsor | SOLTI Breast Cancer Research Group |
| Drug class | CDK4/6 inhibitor + endocrine therapy (aromatase inhibitor or selective estrogen receptor degrader) |
| Target | CDK4/6 (palbociclib); Aromatase (letrozole) or Estrogen Receptor (fulvestrant) |
| Modality | Small molecule |
| Therapeutic area | Oncology |
| Phase | Phase 3 |
Mechanism of action
Palbociclib is a CDK4/6 inhibitor that prevents phosphorylation of the retinoblastoma protein, halting G1/S cell cycle transition in hormone receptor-positive breast cancer cells. Letrozole blocks estrogen synthesis via aromatase inhibition, while fulvestrant degrades the estrogen receptor itself. The combination leverages dual mechanisms: cell cycle arrest plus hormonal suppression.
Approved indications
- Hormone receptor-positive, HER2-negative metastatic or advanced breast cancer (first-line or subsequent lines, depending on trial arm)
Common side effects
- Neutropenia
- Leukopenia
- Anemia
- Fatigue
- Nausea
- Diarrhea
- Hot flashes
- Arthralgia
Key clinical trials
- Capivasertib+Fulvestrant asTreatment for Locally Advanced(Inoperable) or Metastatic HR+/HER2- Breast Cancer in Chinese Patients (PHASE3)
- Targeted Therapy Directed by Genetic Testing in Treating Patients With Locally Advanced or Advanced Solid Tumors, The ComboMATCH Screening Trial (PHASE2)
- A Study to Evluate Efficacy and Safety of HRS-8080 Combined With Dalpiciclib in Patients With Advanced or Metastatic Breast Cancer Resistant to Adjuvant Endocrine Therapy. (PHASE3)
- Study of ECI830 Single Agent or in Combination in Patients With Advanced HR+/HER2- Breast Cancer and Other Advanced Solid Tumors (PHASE1, PHASE2)
- A Study of LOXO-783 in Patients With Breast Cancer/Other Solid Tumors (PHASE1)
- Efficacy and Safety of Tinengotinib Tablets Combined With Fulvestrant Injection in Patients With HR Positive and HER-2 Negative Recurrent or Metastatic Breast Cancer Who Have Failed Prior Treatment (PHASE2)
- Liquid-biopsy Informed Platform Trial to Evaluate CDK4/6-inhibitor Resistant ER+/HER2- Metastatic Breast Cancer (PHASE2)
- ORION-1: Study of AVZO-023 as a Single Agent and in Combination With AVZO-021, and/or Endocrine Therapy in Advanced Solid Tumors (PHASE1, PHASE2)
Primary sources
Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.
| Source | Used for |
|---|---|
| ClinicalTrials.gov | Trial enrolment, design, endpoints, results |
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