Kisqali (Ribociclib)
ribociclib succinate
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Adjuvant early breast cancer — stage II/III at high risk | HR+/HER2− adults | Combination (+ aromatase inhibitor) | FDA Approved |
| Advanced/metastatic — initial endocrine therapy | HR+/HER2− adults | Combination (+ AI or fulvestrant) | FDA Approved |
| Advanced/metastatic — after endocrine progression | HR+/HER2− adults | Combination (+ fulvestrant) | FDA Approved |
Ribociclib is the only CDK4/6 inhibitor with demonstrated overall survival benefit across all three phase III advanced breast cancer trials. MONALEESA-2 (postmenopausal, 1st line + letrozole) showed median OS 63.9 vs 51.4 months (HR 0.76; P=0.008). MONALEESA-3 (postmenopausal, + fulvestrant, 1st/2nd line) demonstrated significant OS benefit. MONALEESA-7 (pre/perimenopausal, + NSAI/tamoxifen) showed significant OS benefit (HR 0.71; P=0.01). In September 2024, ribociclib received adjuvant approval based on NATALEE (iDFS 90.7% vs 87.6% at 3 years). Pre/perimenopausal women and men should receive concurrent LHRH agonist therapy.
Ribociclib is the only CDK4/6 inhibitor with statistically significant OS benefit across all three pivotal advanced breast cancer trials (MONALEESA-2, -3, -7). In contrast, palbociclib did not demonstrate significant OS in PALOMA-2 or PALOMA-3 (ITT), and abemaciclib showed OS benefit only in MONARCH 2. NCCN guidelines recognize ribociclib as the only CDK4/6 inhibitor with first-line OS data in postmenopausal HR+/HER2− advanced breast cancer.
Dosing
Adult Dosing by Clinical Scenario
| Clinical Scenario | Starting Dose | Schedule | Duration | Notes |
|---|---|---|---|---|
| Adjuvant early breast cancer (NATALEE) | 400 mg (2×200 mg) PO once daily | 21 days on / 7 days off (28-day cycle) | 3 years (or until recurrence/intolerable toxicity) | With or without food; with NSAI Pre/perimenopausal or male: add LHRH agonist |
| Advanced/metastatic — 1st line with AI | 600 mg (3×200 mg) PO once daily | 21 days on / 7 days off (28-day cycle) | Until progression or intolerable toxicity | With or without food Pre/perimenopausal or male: add LHRH agonist |
| Advanced/metastatic — with fulvestrant | 600 mg (3×200 mg) PO once daily | 21 days on / 7 days off (28-day cycle) | Until progression or intolerable toxicity | Fulvestrant 500 mg Days 1, 15, 29, then monthly Pre/perimenopausal or male: add LHRH agonist |
| With strong CYP3A inhibitor — early BC | 200 mg PO once daily | 21/7 schedule | Per indication | Resume prior dose after ≥5 half-lives of inhibitor upon stopping |
| With strong CYP3A inhibitor — advanced BC | 400 mg PO once daily | 21/7 schedule | Per indication | Resume prior dose after ≥5 half-lives of inhibitor upon stopping |
| Moderate/severe hepatic impairment — advanced BC | 400 mg PO once daily | 21/7 schedule | Per indication | No adjustment for early BC or mild hepatic impairment |
| Severe renal impairment (all indications) | 200 mg PO once daily | 21/7 schedule | Per indication | eGFR 15 to <30 mL/min/1.73 m² |
Dose Reductions for Toxicity
| Setting | Starting | 1st Reduction | 2nd Reduction | If Further Needed |
|---|---|---|---|---|
| Early breast cancer | 400 mg | 200 mg | Discontinue if <200 mg needed | |
| Advanced/metastatic | 600 mg | 400 mg | 200 mg | Discontinue if <200 mg needed |
Ribociclib requires more intensive monitoring than palbociclib due to QTc and hepatotoxicity risks. Perform ECG before starting, at Day 14 of cycle 1, and as indicated. Monitor LFTs every 2 weeks for first 2 cycles, then at the beginning of each subsequent 4 cycles. Monitor CBC every 2 weeks for first 2 cycles, then at the beginning of each subsequent 4 cycles. Monitor electrolytes (K+, Ca2+, Mg2+, PO4) before starting and at the beginning of each cycle for 6 cycles. Take dose preferably in the morning at the same time each day.
Pharmacology
Mechanism of Action
Ribociclib is a selective, reversible inhibitor of CDK4/6. Like palbociclib, it blocks Rb phosphorylation and arrests the cell cycle at G1. However, ribociclib has distinct pharmacological properties including concentration-dependent QTc prolongation (estimated mean QTcF increase of ~22 ms at steady-state Cmax at 600 mg with AI), more potent CYP3A4 inhibition (midazolam AUC increased 5.2-fold vs palbociclib's 61%), and a different dose-reduction strategy owing to its 200 mg tablet formulation. Ribociclib is a strong CYP3A inhibitor in vivo, contrasting with palbociclib which is a weak time-dependent inhibitor. The combination with endocrine therapy provides synergistic anti-tumor activity in ER-positive breast cancer models.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Bioavailability ~66%; Tmax 1–4 h; no food effect; dose-proportionality is over-proportional across 50–1200 mg range; accumulation ratio 2.5 | Can be taken with or without food; PPIs have no effect; no acid-suppression interaction |
| Distribution | Vss/F = 1,090 L; protein binding ~70% (concentration-independent); blood-to-plasma ratio 1.04 | Extensive tissue distribution; lower protein binding than palbociclib (~85%) |
| Metabolism | CYP3A4 (primary, ~74% of oxidative metabolism) and FMO3 (~26%); parent = 44% of circulating drug; major metabolites M13, M4, M1 (all clinically inactive) | Strong CYP3A inhibitor in vivo (ritonavir increases AUC 3.2-fold; rifampin decreases AUC 89%); ribociclib increases midazolam AUC 5.2-fold |
| Elimination | Effective t½ 32 h; feces 69% (17% unchanged), urine 23% (12% unchanged); total recovery 92% by day 22; CL/F 25.5 L/h (600 mg steady state) | Once-daily dosing; 21/7 schedule for hematologic recovery; CL/F higher at 400 mg dose (38.4 L/h) due to over-proportional PK |
Side Effects
Data from FDA prescribing information (Sept 2025). MONALEESA-2 (N=334, ribociclib + letrozole) provides first-line advanced data. NATALEE (N=2526, ribociclib + NSAI) provides adjuvant data. Ribociclib has unique toxicities vs palbociclib: QTc prolongation, more prominent hepatotoxicity, and SCARs.
Leukocytes decreased 93% (Gr3-4: 34%), neutrophils decreased 93% (Gr3-4: 60%), hemoglobin decreased 57% (Gr3-4: 1.8%), lymphocytes decreased 51% (Gr3-4: 14%), ALT increased 46% (Gr3-4: 10%), AST increased 44% (Gr3-4: 7%), platelets decreased 29% (Gr3-4: 0.9%), creatinine increased 20% (Gr3-4: 0.6%), phosphorous decreased 13% (Gr3-4: 5%), potassium decreased 11% (Gr3-4: 1.2%).
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Nausea | 52% | Grade 3: 2.4%; higher incidence than palbociclib (35%); antiemetics as needed |
| Fatigue | 37% | Grade 3: 2.4%; comparable to palbociclib |
| Diarrhea | 35% | Grade 3: 1.2%; higher than palbociclib (26%) |
| Alopecia | 33% | Non-graded; comparable to palbociclib; typically non-total, reversible |
| Vomiting | 29% | Grade 3: 3.6%; higher than palbociclib (16%); antiemetics may be needed |
| Constipation | 25% | Grade 3: 1.2%; manage supportively |
| Headache | 22% | Grade 3: 0.3% |
| Back pain | 20% | Grade 3: 2.1% |
| Decreased appetite | 19% | Grade 3: 1.5% |
| Rash | 17% | Grade 3: 0.6%; monitor for SCARs progression |
| Pruritus | 14% | Grade 3: 0.6% |
| Pyrexia | 13% | Grade 3: 0.3%; rule out febrile neutropenia |
| Stomatitis | 12% | Grade 3: 0.3% |
| Peripheral edema | 12% | No grade 3–4 events |
| Dyspnea | 12% | Grade 3: 1.2%; evaluate for ILD if new onset |
| Insomnia | 12% | Grade 3: 0.3% |
| UTI | 11% | Grade 3: 0.6% |
| Abdominal pain | 11% | Grade 3: 1.2% |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Dry skin | ~9% (MONALEESA-7) | Emollients recommended |
| Thrombocytopenia (clinical) | ~9% (MONALEESA-7) | Lab-based platelets decreased in 26–29%; clinical events less common |
| Lacrimation increased | ~4% (MONALEESA-7) | Usually mild; no grade 3–4 |
| Dry eye | ~4% (MONALEESA-7) | Lubricating eye drops; ophthalmologic referral if persistent |
| Febrile neutropenia | 1.2% (MONALEESA-2); 1.7% (pooled advanced) | See Serious tier; requires hospitalization and IV antibiotics |
| ILD / Pneumonitis | 0.3–0.6% (MONALEESA-2) | Includes ILD, lung infiltration, pneumonitis, pulmonary fibrosis; see Serious tier |
| Adverse Effect | Estimated Frequency | Details | Required Action |
|---|---|---|---|
| QTc Prolongation | QTcF >500 ms: 1.4% (advanced); 0.3% (early). >60 ms increase: 6% (advanced); 2% (early) | Concentration-dependent; mean QTcF increase ~22 ms at Cmax. Most occurs within first 4 weeks. No Torsades de Pointes in trials. | ECG at baseline, Day 14 cycle 1, and as indicated. Dose interruption/reduction per QTcF thresholds (Table 4 of PI). Correct electrolytes before starting. One sudden death reported (MONALEESA-2). |
| Hepatotoxicity | ALT Gr3-4: 8–11%; AST Gr3-4: 5–8%. Hy’s Law: 1% (advanced); 0.3% (early) | Median onset of Gr≥3 ALT/AST: ~92 days; median resolution to Gr≤2: ~21 days | LFTs every 2 weeks × 2 cycles, then every 4 cycles. Discontinue if ALT/AST >3× ULN with bilirubin >2× ULN (Hy’s Law). Drug-induced liver injury reported in 0.4% (NATALEE). |
| Grade ≥3 Neutropenia | 60–63% (advanced); 45% (early) | Median onset Gr≥2: 17–18 days; median Gr≥3 resolution: 10–12 days | CBC every 2 weeks × 2 cycles, then every 4 cycles. Febrile neutropenia: 0.3% (early), 1.7% (advanced). Dose modification per PI Table 6. |
| ILD / Pneumonitis | 1.5% Gr 1-2 (early); 1.6% any grade (advanced, 0.4% Gr 3-4, 0.1% fatal) | Variable | Interrupt immediately if suspected; permanently discontinue for severe or recurrent symptomatic ILD. Fatal postmarketing cases reported. |
| SCARs (SJS/TEN/DRESS) | Postmarketing reports | Variable | Permanently discontinue if confirmed SCAR. Do not rechallenge. Early dermatology consultation recommended. Unique to ribociclib among CDK4/6 inhibitors. |
Ribociclib causes concentration-dependent QTc prolongation with an estimated mean QTcF increase of ~22 ms at steady-state Cmax. This is not seen with palbociclib or abemaciclib at approved doses. Avoid ribociclib in patients with congenital long QT syndrome, significant cardiac disease, or uncontrolled electrolyte abnormalities. Do not combine with tamoxifen (QTcF increase >10 ms higher with tamoxifen + placebo vs NSAI + placebo; QTcF >60 ms increase seen in 16% with ribociclib + tamoxifen vs 7% with ribociclib + NSAI). Avoid concurrent use of drugs known to prolong QT. ECG monitoring is mandatory before initiation, at Day 14 of cycle 1, and as clinically indicated.
Drug Interactions
Ribociclib is metabolized primarily by CYP3A4. It is a strong CYP3A inhibitor in vivo (midazolam AUC increased 5.2-fold), a substantially greater effect than palbociclib (61%). This creates significant interaction potential with co-administered narrow-TI CYP3A substrates. Ribociclib also carries a unique QT interaction risk.
Monitoring
- ECGBaseline, Day 14 of cycle 1, then as indicated
RoutineQTcF must be <450 ms to start. Repeat more frequently if QTcF prolongation occurs. Assess at any dose change. QTcF >500 ms or >60 ms change with arrhythmia symptoms → permanently discontinue. - Serum ElectrolytesBaseline, beginning of each cycle ×6, then as indicated
RoutineK+, Ca2+, Mg2+, PO4. Correct abnormalities before starting ribociclib. Hypokalemia increases QTc risk. - Liver Function TestsBaseline, every 2 weeks ×2 cycles, then every 4 cycles
RoutineALT increased Gr3-4 in 8–11%; Hy’s Law in 0.3–1%. More frequent monitoring if Gr≥2 abnormalities. Discontinue if ALT/AST >3× ULN + bilirubin >2× ULN. - CBC with DifferentialBaseline, every 2 weeks ×2 cycles, then every 4 cycles
RoutineNeutrophils decreased Gr3-4 in 45–63%. Febrile neutropenia 0.3–1.7%. Dose modification per PI Table 6. - Pregnancy TestBefore initiation
RoutineVerify pregnancy status in females of reproductive potential. - Skin AssessmentEvery visit
Trigger-basedMonitor for rash progression, blistering, mucosal involvement suggestive of SJS/TEN/DRESS. Prompt dermatology referral if suspected. - Respiratory SymptomsEvery visit
Trigger-basedILD in 1.5–1.6% of patients. Interrupt immediately if suspected; permanently discontinue for severe/recurrent symptomatic ILD.
Contraindications & Cautions
Absolute Contraindications
- The FDA prescribing information lists no formal absolute contraindications.
- Congenital long QT syndrome — PI 5.3 states to avoid ribociclib in these patients.
- Confirmed SCAR on prior ribociclib — do not rechallenge.
Relative Contraindications (Specialist Input Recommended)
- Baseline QTcF ≥450 ms — do not initiate ribociclib.
- Uncontrolled cardiac disease — including recent MI, heart failure, unstable angina, bradyarrhythmias.
- Severe hepatic impairment for advanced BC — dose reduce to 400 mg; Hy’s Law cases reported.
- Concurrent tamoxifen — ribociclib is not indicated for use with tamoxifen due to additive QTc prolongation.
Use with Caution
- Concurrent strong CYP3A inhibitors — dose reduce and increase QTc/ECG monitoring.
- Concurrent QT-prolonging drugs — avoid if possible.
- Patients on narrow-TI CYP3A substrates — ribociclib increases their exposure 5.2-fold (midazolam); dose reduction of substrate may be needed.
- Electrolyte abnormalities — correct K+, Ca2+, Mg2+ before and during treatment.
Ribociclib can cause fetal harm. In animal studies, embryo-fetal toxicities occurred at exposures 0.6–1.5 times human clinical exposure. Females of reproductive potential must use effective contraception during treatment and for at least 3 weeks after the last dose. Verify pregnancy status before initiation. Advise not to breastfeed during treatment or for 3 weeks after the last dose.
Patient Counselling
Purpose of Therapy
Ribociclib is a targeted cancer therapy that blocks proteins called CDK4 and CDK6. It is always used alongside hormone therapy. The treatment follows a 3-weeks-on, 1-week-off cycle. For early breast cancer, treatment continues for 3 years.
How to Take
Ribociclib can be taken with or without food, preferably in the morning at the same time each day. Swallow tablets whole. If a dose is missed or vomiting occurs, do not take an extra dose.
Sources
- KISQALI (ribociclib) [prescribing information]. East Hanover, NJ: Novartis Pharmaceuticals Corporation; revised September 2025. Novartis LabelingPrimary source for all dosing, adverse reaction incidence rates, pharmacokinetics, warnings, dose modification tables, and QTc data.
- FDA approves Kisqali with an aromatase inhibitor and Kisqali Femara co-pack for early high-risk breast cancer. FDA News Release, September 17, 2024. FDA.govOfficial FDA announcement of adjuvant indication based on NATALEE trial.
- Hortobagyi GN, Stemmer SM, Burris HA, et al. Ribociclib as first-line therapy for HR-positive, advanced breast cancer. N Engl J Med. 2016;375(18):1738-1748. doi:10.1056/NEJMoa1609709MONALEESA-2 primary PFS analysis: ribociclib + letrozole significantly improved PFS (HR 0.56; P<0.001).
- Hortobagyi GN, Stemmer SM, Burris HA, et al. Overall survival with ribociclib plus letrozole in advanced breast cancer. N Engl J Med. 2022;386(10):942-950. doi:10.1056/NEJMoa2114663MONALEESA-2 final OS: median 63.9 vs 51.4 months (HR 0.76; P=0.008); longest median OS reported in HR+/HER2− advanced BC.
- Slamon DJ, Neven P, Chia S, et al. Overall survival with ribociclib plus fulvestrant in advanced breast cancer. N Engl J Med. 2020;382(6):514-524. doi:10.1056/NEJMoa1911149MONALEESA-3 OS: significant OS benefit with ribociclib + fulvestrant in 1st/2nd-line postmenopausal patients.
- Slamon DJ, Neven P, Chia S, et al. Phase III randomized study of ribociclib and fulvestrant in HR+, HER2− advanced breast cancer: MONALEESA-3. J Clin Oncol. 2018;36(24):2465-2472. doi:10.1200/JCO.2018.78.9909MONALEESA-3 primary PFS analysis: ribociclib + fulvestrant improved PFS (HR 0.593; P<0.001) in 1st/2nd-line postmenopausal patients.
- Im SA, Lu YS, Bardia A, et al. Overall survival with ribociclib plus endocrine therapy in breast cancer. N Engl J Med. 2019;381(4):307-316. doi:10.1056/NEJMoa1903765MONALEESA-7 OS: significant OS benefit in pre/perimenopausal patients (HR 0.71; P=0.00973).
- Slamon DJ, Fasching PA, Patel R, et al. Ribociclib plus endocrine therapy in early breast cancer. N Engl J Med. 2024;390(12):1080-1091. doi:10.1056/NEJMoa2305942NATALEE trial: ribociclib 400 mg + NSAI improved iDFS at 3 years (90.7% vs 87.6%) in stage II-III high-risk early BC.
- National Comprehensive Cancer Network (NCCN). Clinical Practice Guidelines in Oncology: Breast Cancer. Version 1.2025. NCCN.orgRecognizes ribociclib as the only CDK4/6 inhibitor with first-line OS benefit in postmenopausal HR+/HER2− advanced BC.
- Samant TS, Dhuria S, Lu Y, et al. Use of pharmacokinetic and pharmacodynamic data to develop the CDK4/6 inhibitor ribociclib for patients with advanced breast cancer. Clin Pharmacol Ther. 2024;115(2):201-215. doi:10.1002/cpt.3094Comprehensive PK/PD review: bioavailability 65.8%, Vss/F 1,090 L, CL/F 25.5 L/h, t½ 32 h, CYP3A4 metabolism, QTc-exposure relationship.