Key points
- Ribociclib is a targeted tablet used with a hormone tablet in hormone receptor-positive, HER2-negative breast cancer, both after surgery in high-risk patients and in advanced disease [1].
- In a large study of more than 5,000 patients with early breast cancer, adding ribociclib lowered the chance of the cancer coming back [1, 2].
- In advanced disease, it helped patients live longer in three large studies [3, 4, 5].
- 400 mg a day in early cancer and 600 mg a day in advanced disease (21 days on, 7 days off); after surgery it continues for 3 years [1].
- It can change the heart rhythm and raise liver enzymes; a heart tracing (ECG), liver tests and blood counts are needed before starting and in the first months [1].
What is this drug and how does it work?
For physicians
Ribociclib, brand name Kisqali, is a "kinase inhibitor" that blocks the enzymes cyclin-dependent kinases 4 and 6 (CDK4/6) [1]. These enzymes are activated when they bind to D-type cyclins and drive cell cycle progression and cell proliferation by phosphorylating the retinoblastoma protein (pRb) [1].
In laboratory studies, ribociclib reduced pRb phosphorylation and arrested breast cancer cells in the G1 phase of the cell cycle. In models of oestrogen receptor-positive breast cancer, combining it with anti-oestrogen drugs (such as letrozole or fulvestrant) inhibited tumour growth more than either drug alone [1]. Ribociclib was first approved in the United States in 2017 [1].
Which cancers is it used for?
Your doctor may prescribe this drug for:
- Early hormone receptor-positive, HER2-negative stage II and III breast cancer at high risk of coming back [1, 2]
- Advanced or spread hormone receptor-positive, HER2-negative breast cancer (postmenopausal women) [1, 3, 6]
- Advanced hormone receptor-positive, HER2-negative breast cancer (pre- or perimenopausal women) [1, 5, 7]
- Advanced hormone receptor-positive, HER2-negative breast cancer [1, 4, 8]
Whether it suits you depends on the type and stage of your cancer and your test results. Details of each use are in the section for doctors.
For physicians
| Cancer | Treatment setting | Key evidence |
|---|---|---|
| HR-positive / HER2-negative stage II and III early breast cancer at high risk of recurrence | Adjuvant treatment with an aromatase inhibitor for 3 years | NATALEE: in the final analysis, HR for invasive disease-free survival 0.749 and 36-month invasive disease-free survival 90.7% vs 87.6% [1, 2] |
| HR-positive / HER2-negative advanced or metastatic breast cancer (postmenopausal women) | With an aromatase inhibitor (letrozole) as initial endocrine-based therapy | MONALEESA-2 (668 patients): median overall survival 63.9 vs 51.4 months (HR 0.765) [1, 3, 6] |
| HR-positive / HER2-negative advanced breast cancer (pre- or perimenopausal women) | With an aromatase inhibitor and goserelin as initial endocrine-based therapy | MONALEESA-7, aromatase inhibitor subgroup: median progression-free survival 27.5 vs 13.8 months; HR for overall survival 0.699 [1, 5, 7] |
| HR-positive / HER2-negative advanced breast cancer | With fulvestrant as initial endocrine therapy or after progression on endocrine therapy | MONALEESA-3 (726 postmenopausal women): median progression-free survival 20.5 vs 12.8 months; HR for overall survival 0.724 [1, 4, 8] |
HR: hazard ratio; a value below 1 means a lower risk of the event. Ribociclib is not approved for use with tamoxifen [1].
How it is taken and dose
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Treatment regimens and doses: index3 regimens
Ribociclib comes as 200 mg tablets taken once a day, preferably in the morning and at about the same time each day, for 21 days in a row, followed by 7 days off [1]. You can take it with or without food. Swallow the tablets whole; do not chew, crush or split them, and do not take a broken or cracked tablet [1].
If you miss a dose or vomit after taking it, do not take an extra dose that day; take the next dose at your usual time [1]. In early breast cancer, treatment continues for 3 years (or until the cancer comes back or side effects become intolerable) [1]. Premenopausal women and men usually also receive an LHRH agonist [1]. Do not change the dose on your own or stop the medicine without talking to your doctor.
- Before starting: ECG in all patients, and start only with QTcF below 450 ms; electrolytes (potassium, calcium, phosphorus, magnesium) and correction of abnormalities; liver tests; CBC; pregnancy test [1].
- Dose levels: early disease 400 → 200 mg; advanced disease 600 → 400 → 200 mg; if less than 200 mg is needed: stop [1].
- Dose adjustment [1]:
- QTcF above 480 to 500: hold until 480 or below; in early disease resume at the same dose and in advanced disease at the next lower level; if it recurs, the next lower level. Above 500: hold until 480 or below and resume at the next lower level; recurrence above 500, stop. QTcF above 500 or an increase of more than 60 ms with torsade de pointes, polymorphic ventricular tachycardia, syncope or signs of serious arrhythmia: stop permanently.
- AST/ALT without bilirubin above 2 × ULN: grade 2 (baseline below grade 2) hold until baseline and resume at the same dose, if it recurs at the next lower level; grade 3 hold and resume at the next lower level, if it recurs stop; grade 4 stop. ALT/AST above 3 × ULN with bilirubin above 2 × ULN (without cholestasis): stop permanently.
- Grade 3 neutropenia: hold until grade 2 or below and resume at the same dose; recurrent grade 3 at the next lower level. Grade 3 febrile neutropenia or grade 4: hold until grade 2 or below and resume at the next lower level.
- Grade 2 ILD/pneumonitis: hold until grade 1 or below, then consider the next lower level; recurrent grade 2 or grade 3 to 4: stop. Grade 2 skin reaction: continue with treatment; grade 3: hold until the cause is clarified (confirmed SCAR: stop permanently); grade 4, SJS/TEN: stop permanently.
- Other grade 3 toxicities: hold until grade 1 or below and resume at the same dose, if it recurs at the next lower level; grade 4: stop.
- Interactions: avoid strong CYP3A inhibitors; if unavoidable, use 200 mg once daily in early disease and 400 mg in advanced disease, and return to the previous dose at least 5 half-lives after the inhibitor is stopped. Avoid strong CYP3A inducers, QT-prolonging drugs (such as antiarrhythmics) and tamoxifen; sensitive CYP3A substrates may need a dose reduction [1].
- Kidney and liver: severe renal impairment: start at 200 mg; mild to moderate, no adjustment. Liver: no adjustment in early disease; in advanced disease with Child-Pugh B or C, start at 400 mg [1].
- Monitoring: ECG around day 14 of the first cycle and then as needed (more often with a prolonged QT); electrolytes at the start of the first 6 cycles; liver tests and CBC every 2 weeks for the first 2 cycles, at the start of the next 4 cycles and then as needed [1].
For physicians
Standard doses (FDA label)
Early breast cancer, adjuvant treatment (NATALEE)
HR-positive/HER2-negative stage II and III at high risk of recurrenceEach drug’s schedule in the table
HR-positive/HER2-negative stage II and III at high risk of recurrence
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Ribociclib | 400 mg (2 × 200 mg tablets) | Oral, with or without food, preferably in the morning | Once daily, days 1 to 21, every 28 days |
| Letrozole or anastrozole | 2.5 mg or 1 mg | Oral | Daily, continuously |
| Pre- or perimenopausal women and men | |||
| Goserelin | 3.6 mg | Subcutaneous | Day 1, every 28 days |
Accompanying doses as described for NATALEE in the FDA label. The only dose reduction level: 200 mg a day [1, 2].
Evidence: NATALEE (2025), NATALEE (2024)
Advanced breast cancer + aromatase inhibitor
HR-positive/HER2-negative advanced or metastatic, initial endocrine-based therapyEach drug’s schedule in the table
HR-positive/HER2-negative advanced or metastatic, initial endocrine-based therapy
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Ribociclib | 600 mg (3 × 200 mg tablets) | Oral, with or without food, preferably in the morning | Once daily, days 1 to 21, every 28 days |
| Letrozole (or anastrozole) | 2.5 mg (or 1 mg) | Oral | Daily, continuously |
Pre- or perimenopausal women and men: a concurrent LHRH agonist (in MONALEESA-7, goserelin on day 1 of each cycle) [1].
Advanced breast cancer + fulvestrant
Initial endocrine-based therapy or after progression on endocrine therapyCycle length: Every 28 days
Initial endocrine-based therapy or after progression on endocrine therapy
Before prescribing: Prescribing notes| Drug | Dose | Route | Schedule |
|---|---|---|---|
| Ribociclib | 600 mg | Oral, with or without food, preferably in the morning | Once daily, days 1 to 21 |
| Fulvestrant | 500 mg | Intramuscular injection | Days 1, 15 and 29, then monthly |
As described for MONALEESA-3 in the FDA label [1].
Doses follow the trial protocol, guideline or official drug label (source given in the notes of each regimen). Before prescribing, check blood counts, renal and hepatic function, drug interactions and the patient’s condition, and adjust the dose according to the drug label.
Side effects
The most common side effects:
- Low white blood cells in almost all patients; it usually causes no symptoms and is followed with regular blood tests [1].
- Raised liver enzymes and anaemia, which show up on blood tests [1].
- Mild infections, nausea, headache and tiredness [1].
- In advanced disease (higher dose): diarrhoea, vomiting, mild hair thinning and skin rash are also common [1].
For physicians
The FDA label reports common side effects (20% or more, including laboratory findings) separately for early cancer (NATALEE, 2526 patients on 400 mg) and advanced disease (MONALEESA-2, -3 and -7 combined, 1065 patients on 600 mg) [1]. Many of these are blood test changes that the patient does not feel but the doctor monitors.
| Side effect | Early cancer (NATALEE) | Advanced disease (MONALEESA) |
|---|---|---|
| Low white blood cells (laboratory) | 95% | 95% |
| Low neutrophils (laboratory) | 94% | 93% |
| Low lymphocytes (laboratory) | 97% | 66% |
| Low haemoglobin | 47% | 68% |
| Raised ALT / AST (liver enzymes) | 45% / 44% | 52% / 55% |
| Infections | 37% | 47% |
| Raised creatinine | 33% | 42% |
| Nausea / vomiting | 23% / — | 47% / 29% |
| Headache | 23% | 27% |
| Tiredness | 22% | 35% |
| Diarrhoea | — | 33% |
| Hair loss / skin rash | — | 25% / 24% |
Source: FDA label, section 6.1 [1]. "—" means this side effect was not in the list of side effects in 20% or more of that population. In NATALEE, 20% of patients stopped ribociclib because of a side effect, most often raised liver enzymes (8%) [1].
Serious side effects
These side effects are less common but serious; if you notice any sign of them, tell your team early:
- A change in heart rhythm: palpitations, dizziness or fainting; mostly in the first four weeks. A heart tracing (ECG) is done before starting and in the first months. This medicine must not be taken with tamoxifen [1].
- Liver damage: yellowing of the skin or eyes, dark urine or pain on the right side of the abdomen [1].
- Fever or chills, because your white blood cells may be low [1].
- Lung inflammation (a new cough or shortness of breath), severe skin reactions and harm to an unborn baby [1].
For physicians
The FDA label has no boxed warning, but highlights these warnings [1]:
- QT interval prolongation: ribociclib prolongs the QT interval in a concentration-dependent way. In NATALEE, 0.3% of patients had a QTcF above 500 ms and 2% an increase of more than 60 ms; in the trials in advanced disease these figures were 1.4% and 6%. Most cases occurred in the first four weeks and were reversible on stopping the drug [1]. In MONALEESA-2, one sudden death was reported in a patient with severe hypokalaemia and QT prolongation [1].
- Use with tamoxifen: in MONALEESA-7, an increase of more than 60 ms in QTcF was seen in 16% of patients on ribociclib with tamoxifen and 7% on ribociclib with an aromatase inhibitor; this is why ribociclib must not be used with tamoxifen [1].
- Hepatotoxicity: in NATALEE, grade 3 or 4 ALT and AST increases occurred in 8% and 4.7% of patients respectively, and drug-induced liver injury was reported in 0.4%; in advanced disease these increases were 11% and 8%, with a median time to onset of 92 days [1].
- Neutropenia: grade 3 or 4 neutropenia (laboratory) occurred in 45% of NATALEE patients and 62% of patients with advanced disease; febrile neutropenia occurred in 0.3% and 1.7% respectively [1].
- Interstitial lung disease (ILD) and pneumonitis: 1.5% in NATALEE (grade 1 and 2 only) and 1.6% in advanced disease (0.4% grade 3 or 4 and 0.1% fatal) [1].
- Severe cutaneous adverse reactions: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) and DRESS have been reported [1].
- Embryo-fetal toxicity [1].
When should I call my doctor?
Contact your treatment team straight away if you have [1]:
- A fast or irregular heartbeat, dizziness or feeling faint
- Yellowing of the skin or the whites of the eyes, dark (tea-coloured) urine, severe tiredness, loss of appetite, pain in the upper right abdomen, or easy bleeding and bruising
- Fever, chills or signs of infection
- New or worsening shortness of breath, cough or chest pain
- A severe or spreading rash, blisters on the lips, eyes, mouth or skin, or peeling skin with flu-like symptoms
- A possible pregnancy
Interactions, pregnancy and precautions
- Other medicines: some medicines, such as antifungals and the antibiotic clarithromycin, raise the amount of ribociclib and increase the risk of heart rhythm problems; medicines such as rifampicin (a tuberculosis drug) weaken it. Do not take any of them with it without your doctor's advice [1]. Ribociclib also raises the amount of some other medicines [1].
- QT-prolonging medicines: avoid taking medicines that prolong the QT interval (such as antiarrhythmics) at the same time; if this cannot be avoided, the ECG should be monitored [1]. Before starting, tell your doctor about any history of heart disease, a slow heartbeat, uncontrolled high blood pressure, an underactive thyroid, or problems with potassium, calcium, phosphorus or magnesium [1].
- Pregnancy: pregnancy status is checked before starting. Women who could become pregnant should use effective contraception during treatment and for at least 3 weeks after the last dose [1].
- Breastfeeding: do not breastfeed during treatment and for at least 3 weeks after the last dose [1].
- Male fertility: based on animal studies, ribociclib may reduce male fertility [1].
- Before starting any new medicine, even over-the-counter and herbal ones, ask your doctor or pharmacist.
Frequently asked questions
Why do I need heart tracings (ECGs) before and during treatment?
Why is my dose in early cancer lower than in advanced disease?
The approved dose for adjuvant treatment of early cancer is 400 mg a day, which was used in a large study; in advanced disease the dose is 600 mg a day [1].
How long do I take ribociclib after surgery?
Can I take ribociclib with tamoxifen?
My liver test has gone up; should I be worried?
Raised liver enzymes are a known side effect of ribociclib, which is why liver tests are done every 2 weeks in the first months [1]. Depending on how high they are, your doctor may pause the medicine, lower the dose or stop it; severe increases usually improved in about 3 weeks [1]. If you have yellowing of the skin or dark urine, call straight away.
Scientific evidence
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Related cancer types
References
8 referencesShow all references, 7 with a study cardClose the reference list
Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1
- 2
- 3Overall Survival with Ribociclib plus Letrozole in Advanced Breast Cancer
- 4Overall Survival with Ribociclib plus Fulvestrant in Advanced Breast Cancer
- 5Overall Survival with Ribociclib plus Endocrine Therapy in Breast Cancer
- 6Ribociclib as First-Line Therapy for HR-Positive, Advanced Breast Cancer
- 7Ribociclib plus endocrine therapy for premenopausal women with hormone-receptor-positive, advanced breast cancer (MONALEESA-7): a randomised phase 3 trial
- 8Phase III Randomized Study of Ribociclib and Fulvestrant in Hormone Receptor–Positive, Human Epidermal Growth Factor Receptor 2–Negative Advanced Breast Cancer: MONALEESA-3
This page is based on reputable scientific sources and was last updated on 27 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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