Palbociclib

Palbociclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are downstream of signaling pathways which lead to cellular proliferation.

• IBRANCE is indicated for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with: • an aromatase inhibitor as initial endocrine-based therapy; or • fulvestrant in patients with disease progression following endocrine therapy. IBRANCE is indicated in combination with inavolisib and fulvestrant for the treatment of adult patients with endocrine-resistant, PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer, as detected by an FDA-approved test, following recurrence on or after completing adjuvant endocrine therapy.ICD-10: C50.919

• None. None.contraindicated

IBRANCE tablets are taken orally with or without food in combination with an aromatase inhibitor, fulvestrant, or inavolisib and fulvestrant. ( 2 ) • Recommended starting dose: 125 mg once daily taken with or without food for 21 days followed by 7 days off treatment. ( 2.1 ) • Dosing interruption and/or dose reductions are recommended based on individual safety and tolerability. ( 2.2 ) 2.1 Recommended Dose and Schedule The recommended dose of IBRANCE is a 125 mg tablet taken orally once daily for 21 consecutive days followed by 7 days off treatment to comprise a complete cycle of 28 days. IBRANCE tablet may be taken with or without food [see Clinical Pharmacology (12.3) ] . Administer the recommended dose of an aromatase inhibitor when given with IBRANCE. Please refer to the Full Prescribing Information for the aromatase inhibitor being used. When given with IBRANCE, the recommended dose of fulvestrant is 500 mg administered on Days 1, 15, 29, and once monthly thereafter. Please refer to the Full Prescribing Information of fulvestrant. Refer to the Full Prescribing Information for inavolisib and fulvestrant for dosing information . Advise patients to take their dose of IBRANCE at approximately the same time each day. If the patient vomits or misses a dose, an additional dose should not be taken. The next prescribed dose should be taken at the usual time. IBRANCE tablets should be swallowed whole (do not chew, crush, or split them prior to swallowing). Tablets should not be ingested if they are broken, cracked, or otherwise not intact.

• Neutropenia: Monitor complete blood count prior to start of IBRANCE therapy and at the beginning of each cycle, as well as on Day 15 of the first 2 cycles, and as clinically indicated. ( 2.2 , 5.1 ) • Interstitial Lung Disease (ILD)/Pneumonitis: Severe and fatal cases of ILD/pneumonitis have been reported. Monitor for pulmonary symptoms of ILD/pneumonitis. Interrupt IBRANCE immediately in patients with suspected ILD/pneumonitis. Permanently discontinue IBRANCE if severe ILD/pneumonitis occurs. ( 5.2 ) • Embryo-Fetal Toxicity: IBRANCE can cause fetal harm. Advise patients of potential risk to a fetus and to use effective contraception. ( 5.3 , 8.1 , 8.3 ) 5.1 Neutropenia Neutropenia was the most frequently reported adverse reaction in PALOMA-2 with an incidence of 80% and PALOMA-3 with an incidence of 83%. A Grade ≥3 decrease in neutrophil counts was reported in 66% of patients receiving IBRANCE plus letrozole in PALOMA-2 and 66% of patients receiving IBRANCE plus fulvestrant in PALOMA-3. In PALOMA-2 and PALOMA-3, the median time to first episode of any grade neutropenia was 15 days and the median duration of Grade ≥3 neutropenia was 7 days [see Adverse Reactions (6.1) ] . Monitor complete blood counts prior to starting IBRANCE therapy and at the beginning of each cycle, as well as on Day 15 of the first 2 cycles, and as clinically indicated. Dose interruption, dose reduction, or delay in starting treatment cycles is recommended for patients who develop Grade 3 or 4 neutropenia [see Dosage and Administration (2.2) ] .

The following clinically significant adverse reactions are described elsewhere in the labeling: • Neutropenia [see Warnings and Precautions (5.1) ] • ILD/Pneumonitis [see Warnings and Precautions (5.2) ] Most common adverse reactions (incidence ≥20%) in combination with either letrozole or fulvestrant, including laboratory abnormalities, were white blood cell count decreased, neutrophils decreased, blood creatinine increased, hemoglobin decreased, platelets decreased, infections, aspartate aminotransferase increased, alanine aminotransferase increased, fatigue, nausea, stomatitis, diarrhea, and alopecia. ( 6.1 ) The most common adverse reactions (incidence ≥20%) in combination with inavolisib and fulvestrant, including laboratory abnormalities, were neutrophils decreased, hemoglobin decreased, fasting glucose increased, platelets decreased, lymphocytes decreased, stomatitis, diarrhea, calcium decreased, fatigue, potassium decreased, creatinine increased, alanine aminotransferase (ALT) increased, nausea, sodium decreased, magnesium decreased, rash, decreased appetite, COVID-19 infection, and headache. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Studies Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

• Lactation: Advise not to breastfeed. ( 8.2 ) 8.1 Pregnancy Risk Summary Based on findings from animal studies and its mechanism of action, IBRANCE can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1) ] . There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of palbociclib to pregnant rats and rabbits during organogenesis resulted in embryo-fetal toxicity at maternal exposures that were ≥4 times the human clinical exposure based on AUC (see Data ) . Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%–4% and 15%–20%, respectively. Data Animal Data In a fertility and early embryonic development study in female rats, palbociclib was administered orally for 15 days before mating through to Day 7 of pregnancy, which did not cause embryo toxicity at doses up to 300 mg/kg/day with maternal systemic exposures approximately 4 times the human exposure (AUC) at the recommended dose.

Metabolism

The pharmacokinetics (PK) of palbociclib were characterized in patients with solid tumors including advanced breast cancer and in healthy subjects. Absorption The maximum observed concentration (C max ) of palbociclib is generally observed between 4 to 12 hours (time to reach maximum concentration, T max ) following oral administration of IBRANCE tablets.

• Feb 3, 2015NDANDA207103Pfizer
• Nov 1, 2019NDANDA212436Pfizer

Reference statistics from the openFDA drug-shortage dataset. For a live view, consult the FDA database directly. Not clinical guidance.

• Ibrance, Capsule, 100 mg (NDC 0069-0188-21)To be discontinued
  Sponsor: Pfizer Inc.
  Updated Apr 22, 2026
• Ibrance, Capsule, 75 mg (NDC 0069-0187-21)To be discontinued
  Sponsor: Pfizer Inc.
  Updated Apr 22, 2026

1. 1Fatigue15,64817%
2. 2White Blood Cell Count Decreased11,38112%
3. 3Neoplasm Progression10,62011%
4. 4Nausea8,5029.0%
5. 5Death7,7928.3%
6. 6Neutropenia6,6637.1%
7. 7Alopecia6,3436.7%
8. 8Diarrhoea5,9286.3%
9. 9Asthenia3,7624.0%
10. 10Off Label Use3,6563.9%
11. 11Decreased Appetite3,4693.7%
12. 12Pain3,4643.7%
13. 13Malaise3,3423.5%
14. 14Dyspnoea3,2633.5%
15. 15Vomiting3,1343.3%

The 10 most recently updated of 433 ClinicalTrials.gov registrations naming Palbociclib as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Open-Label Umbrella Study To Evaluate Safety And Efficacy Of Elacestrant In Various Combination In Participants With Metastatic Breast Cancer
  Active not recruiting · Phase 1 · Phase 2 · Interventional · 435 enrolled · Stemline Therapeutics, Inc.
  NCT05563220updated 2026-06-12
• Targeted Therapy Directed by Genetic Testing in Treating Patients With Locally Advanced or Advanced Solid Tumors, The ComboMATCH Screening Trial
  Recruiting · Phase 2 · Interventional · 2,900 enrolled · National Cancer Institute (NCI)
  NCT05564377updated 2026-06-12
• Extension Study for Participants in Studies That Include Belzutifan (MK-6482-043/LITESPARK-043)
  Recruiting · Phase 3 · Interventional · 450 enrolled · Merck Sharp & Dohme LLC
  NCT07405164updated 2026-06-12
• A Study to Evaluate the Effectiveness and Safety of Inavolisib in Participants With Endocrine-resistant, PIK3CA-mutated, Hormone Receptor-positive, HER2-negative Locally Advanced or Metastatic Breast Cancer
  Recruiting · Observational · 500 enrolled · Hoffmann-La Roche
  NCT07347600updated 2026-06-12
• Testing the Use of Neratinib or the Combination of Neratinib and Palbociclib Targeted Treatment for HER2+ Solid Tumors (A ComboMATCH Treatment Trial)
  Recruiting · Phase 2 · Interventional · 70 enrolled · National Cancer Institute (NCI)
  NCT06126276updated 2026-06-11
• To Evaluate the Safety, Tolerability, and Pharmacokinetics of Inavolisib Single Agent in Participants With Solid Tumors and in Combination With Endocrine and Targeted Therapies in Participants With Breast Cancer
  Active not recruiting · Phase 1 · Interventional · 200 enrolled · Genentech, Inc.
  NCT03006172updated 2026-06-10
• Treatment Patterns & Clinical Outcomes of Palbociclib Combinations in HR+HER2-MBC
  Completed · Observational · 185 enrolled · Pfizer
  NCT04937660updated 2026-06-10
• A Study Evaluating the Efficacy and Safety of Multiple Treatment Combinations in Participants With Breast Cancer
  Recruiting · Phase 1 · Phase 2 · Interventional · 316 enrolled · Hoffmann-La Roche
  NCT04802759updated 2026-06-09
• Genetic Analysis in Blood and Tumor Samples From Patients With Advanced or Metastatic Estrogen Receptor Positive and HER2 Negative Breast Cancer Receiving Palbociclib and Endocrine Therapy
  Active not recruiting · Observational · 68 enrolled · Mayo Clinic
  NCT03281902updated 2026-06-09
• A Study Evaluating the Efficacy and Safety of Biomarker-Driven Therapies in Patients With Persistent or Recurrent Rare Epithelial Ovarian Tumors
  Active not recruiting · Phase 2 · Interventional · 176 enrolled · Hoffmann-La Roche
  NCT04931342updated 2026-06-08

Frequently asked questions

How does Palbociclib work?

Palbociclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are downstream of signaling pathways which lead to cellular proliferation.

What is Palbociclib used for?

According to FDA labeling, Palbociclib carries indications including: IBRANCE is indicated for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with: • an aromatase inhibitor as initial endocrine-based therapy; or • fulvestrant in patients with disease progression following endocrine therapy. IBRANCE is indicated in combination with inavolisib and fulvestrant for the treatment of adult patients with endocrine-resistant, PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer, as detected by an FDA-approved test, following recurrence on or after completing adjuvant endocrine therapy.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Palbociclib?

Palbociclib is classified as Cyclin-dependent kinase (CDK) inhibitors, Kinase Inhibitor, Cytochrome P450 3A Inhibitors, Kinase Inhibitors, Cellular Proliferation Alteration.

What are the brand names for Palbociclib?

Palbociclib is marketed under brand names including Ibrance.

What are the contraindications for Palbociclib?

Palbociclib labeling lists contraindications including: None. None.. Always consult the full prescribing information and a clinician.