Palbociclib (palbociclib)
Palbociclib is a cdk4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor from Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc), marketed originally as Ibrance. This monograph covers approved indications, mechanism, dosing, side effects and the manufacturer landscape.
Overview
Palbociclib (Ibrance) is an oral CDK4/6 inhibitor used to treat hormone receptor (HR)-positive, HER2-negative breast cancer. It is not a chemotherapy: it belongs to a class of targeted agents called cyclin-dependent kinase inhibitors, which interrupt the molecular switch that drives cancer cells from the resting phase (G1) of the cell cycle into DNA synthesis (S phase). Because the growth of most HR-positive breast cancers depends on cyclin D1-CDK4/6 signalling downstream of the oestrogen receptor, adding a CDK4/6 inhibitor to endocrine therapy produces a large and durable improvement in how long patients stay in remission compared with hormone therapy alone. The standard schedule is 125 mg once daily with food for 21 consecutive days followed by 7 days off, comprising a 28-day cycle. Palbociclib is always given with an endocrine partner: an aromatase inhibitor such as letrozole or anastrozole as initial therapy, fulvestrant after progression on endocrine treatment, and, following a 2026 US approval, with trastuzumab with or without pertuzumab plus endocrine therapy as maintenance for HR-positive, HER2-positive disease. The most characteristic adverse effect is neutropenia, which occurs in roughly 80% of patients and is grade 3 or worse in about two thirds; unlike chemotherapy-induced neutropenia it is usually uncomplicated, but febrile neutropenia and infections still occur and require prompt attention. Fatigue, nausea, alopecia, stomatitis and diarrhoea are common but generally mild. Blood counts are checked at the start of each cycle and on day 15 of the first two cycles. Palbociclib is protected by patents in the United States and Europe, so no FDA- or EMA-approved generic exists. These products are nationally registered, not FDA- or EMA-approved generics, and no bioequivalence study against Ibrance has been published.
How it works
Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own.
Palbociclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are downstream of signalling pathways which lead to cellular proliferation. In vitro, palbociclib reduced cellular proliferation of estrogen receptor (ER)-positive breast cancer cell lines by blocking progression of the cell from G1 into S phase of the cell cycle. Treatment of breast cancer cell lines with the combination of palbociclib and antiestrogens leads to decreased retinoblastoma (Rb) protein phosphorylation and reduced expression of E2F target genes. (FDA label, section 12. 1)
Approved indications
- In combination with an aromatase inhibitor as initial endocrine-based therapy in postmenopausal women or in men with HR-positive, HER2-negative advanced or metastatic breast cancer
- In combination with fulvestrant in patients with HR-positive, HER2-negative advanced or metastatic breast cancer with disease progression following endocrine therapy
- In combination with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of adults with HR-positive, HER2-positive locally advanced or metastatic breast cancer following induction treatment (FDA approval, June 24, 2026)
Dosage & administration
125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
Dose adjustment
Starting dose 125 mg/day; first dose reduction 100 mg/day; second dose reduction 75 mg/day; discontinue if further reduction below 75 mg/day is required. With a strong CYP3A inhibitor that cannot be avoided, reduce to 75 mg once daily. No adjustment for mild or moderate hepatic impairment (Child-Pugh A/B); severe hepatic impairment (Child-Pugh C) starting dose is 75 mg once daily.
Side effects
Neutropenia (80% in PALOMA-2, 83% in PALOMA-3; Grade >=3 in about 66%) · Leukopenia (39%) · Infections (60%) · Fatigue (37%) · Nausea (35%) · Alopecia (33%) · Stomatitis (30%) · Anemia (24%) · Diarrhea (26%) · Rash (18%) · Decreased appetite (15%) · Vomiting (16%) · Pyrexia (12%) · Dysgeusia (10%)
- Thrombocytopenia (16%)
Monitoring
- Complete blood count (CBC) prior to start of therapy and at the beginning of each cycle, and on Day 15 of the first 2 cycles, and as clinically indicated
- For patients with only Grade 1-2 neutropenia in the first 6 cycles, CBC every 3 months for subsequent cycles
- Prompt reporting and evaluation of fever, chills or other signs of infection (febrile neutropenia risk)
- Liver function (ALT/AST) as clinically indicated (transaminase elevations observed)
Generic and biosimilar landscape
Bangladeshi 'generics' (Beacon Palker/Palbonix, Incepta Palbocent and others) are made locally under the TRIPS least-developed-country patent exemption rather than as licensed or FDA/EMA-approved generics; they are approved by Bangladesh's DGDA. No published US/EU bioequivalence study against Ibrance was found for these products, so they should not be assumed interchangeable with the originator.
Who makes it
| Manufacturer | Country | Brand | Strength | Notes |
|---|---|---|---|---|
| Beacon Pharmaceuticals PLC | Bangladesh | Palker (exported/marketed as Palbonix) | 125 mg capsule | 21's pot; Beacon lists Palbonix on its global site with full prescribing information |
| Incepta Pharmaceuticals Ltd. | Bangladesh | Palbocent | 125 mg capsule | Pack 3 x 7; pack information on MedEx |
| Everest Pharmaceuticals Ltd. | Bangladesh | Palboxen | 125 mg capsule | Listed on MedEx; pack 1 x 21 |
| Renata PLC | Bangladesh | Paltab | 125 mg tablet | Listed on MedEx (tablet rather than capsule) |
| Drug International Ltd. | Bangladesh | Palbo | 125 mg capsule | Listed on MedEx; pack 1 x 21 |
Availability in Southeast Asia
| Country | Status | Notes |
|---|---|---|
| Singapore | registered | Palbociclib products registered with HSA and listed in the Singapore National Drug Formulary (e. g. PALBONAT CAPSULES 75MG [SIN17422P]; palbociclib tablets 75/100/125 mg) |
| Malaysia | marketed | Palbociclib is named by NPRA in its CDK4/6 inhibitor safety alert as a CDK4/6 inhibitor used in Malaysia, indicating it is on the Malaysian market |
| Thailand | No public source confirming palbociclib registration found in this research | |
| Philippines | No public source confirming palbociclib registration found in this research | |
| Indonesia | No public source confirming palbociclib registration found in this research | |
| Vietnam | No public source confirming palbociclib registration found in this research |
Frequently asked questions
Is there a generic version of palbociclib available?
Bangladeshi 'generics' (Beacon Palker/Palbonix, Incepta Palbocent and others) are made locally under the TRIPS least-developed-country patent exemption rather than as licensed or FDA/EMA-approved generics; they are approved by Bangladesh's DGDA. No published US/EU bioequivalence study against Ibrance was found for these products, so they should not be assumed interchangeable with the originator. Manufacturers supplying palbociclib generic versions include Beacon Pharmaceuticals PLC, Drug International Ltd. , Everest Pharmaceuticals Ltd. , Incepta Pharmaceuticals Ltd. , Renata PLC. Brands registered in Bangladesh include Cykin, Palbo, Palbocent, Palbokin, Palbolib, Palboxen.
What is the difference between palbociclib and abemaciclib?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
How long can you stay on palbociclib for metastatic breast cancer?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
Does palbociclib cause hair loss?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
Why do I need blood tests every month while taking palbociclib?
Recommended monitoring for palbociclib: Complete blood count (CBC) prior to start of therapy and at the beginning of each cycle, and on Day 15 of the first 2 cycles, and as clinically indicated; For patients with only Grade 1-2 neutropenia in the first 6 cycles, CBC every 3 months for subsequent cycles; Prompt reporting and evaluation of fever, chills or other signs of infection (febrile neutropenia risk); Liver function (ALT/AST) as clinically indicated (transaminase elevations observed)
Is palbociclib available in Singapore or Malaysia?
Palbociclib is made by 5 suppliers tracked in this database, including Beacon Pharmaceuticals PLC, Drug International Ltd. , Everest Pharmaceuticals Ltd. , Incepta Pharmaceuticals Ltd. , Renata PLC. Bangladesh-registered brands: Cykin, Palbo, Palbocent, Palbokin, Palbolib, Palboxen, Palcigen, Palker, Paltab.
Can palbociclib be taken without hormone therapy?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
What should I avoid eating while taking palbociclib?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
What happens if neutropenia develops on palbociclib?
Palbociclib (CDK4/6 inhibitor (cyclin-dependent kinase 4/6 inhibitor); protein kinase inhibitor, originally Ibrance by Pfizer Inc. (Pfizer Laboratories Div Pfizer Inc)) Palbociclib blocks two proteins called CDK4 and CDK6 that cancer cells use to push themselves through the cell division cycle. By blocking them, it stops hormone-receptor-positive breast cancer cells from dividing and slows tumour growth. It is given together with hormone therapy (an aromatase inhibitor or fulvestrant), not on its own. 125 mg orally once daily with food for 21 consecutive days followed by 7 days off treatment, comprising a 28-day cycle. Administered in combination with an aromatase inhibitor or fulvestrant (fulvestrant 500 mg on Days 1, 15, 29 and once monthly thereafter).
Sources
- https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/207103s008lbl.pdf
- https://ibrance.pfizerpro.com/dosing/administration
- https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-palbociclib-trastuzumab-or-without-pertuzumab-and-endocrine-therapy-maintenance
- https://medex.com.bd/generics/1390/palbociclib
- https://medex.com.bd/generics/1390/palbociclib/brand-names
- https://global.beaconpharma.com.bd/product/palbonix
- https://everyone.org/ibrance-palbociclib
- https://www.ndf.gov.sg/about-drugs/active-ingredient/m01329
This page is an information resource for healthcare professionals, licensed importers and patients under medical care. It is not medical advice, not a prescription service, and not an offer to sell prescription medicines to the public.
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