Kisqali (Ribociclib)

• Kisqali is a CDK4/6 inhibitor used in the management of hormone‑receptor‑positive breast cancer pathways.
• Hormone receptor‑positive, HER2‑negative advanced breast cancer: improves progression‑free survival when combined with endocrine therapy.
• Premenopausal women with HR+/HER2‑negative advanced breast cancer: used together with ovarian suppression and endocrine agents.
• Postmenopausal women with HR+/HER2‑negative metastatic breast cancer: administered alongside aromatase inhibitors for disease control.

• Ribociclib selectively inhibits cyclin‑dependent kinases 4 and 6, preventing phosphorylation of the retinoblastoma protein. This blockade halts cell‑cycle progression from the G1 to S phase, leading to growth arrest of tumor cells that depend on CDK4/6 signaling, particularly in hormone‑receptor‑positive breast cancer.

Ribociclib may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Neutropenia: reduced neutrophil count, increasing infection risk.
• Nausea: mild to moderate upset stomach.
• Fatigue: persistent tiredness.
• Diarrhea: loose stools.
• Alopecia: hair thinning or loss.
• Vomiting: occasional episodes.

Serious or Rare Side Effects

• QT interval prolongation: potential cardiac rhythm disturbances.
• Severe neutropenia: marked drop in neutrophils requiring medical attention.
• Hepatotoxicity: elevated liver enzymes or liver injury.
• Interstitial lung disease: rare pulmonary inflammation.
• Severe infections: opportunistic bacterial or fungal infections.
• Thromboembolic events: rare blood clot formation.

• Before initiating ribociclib therapy, several safety considerations should be addressed.
• Monitor blood counts: perform regular CBC to detect neutropenia.
• Assess cardiac function: obtain baseline ECG and monitor QT interval.
• Evaluate liver function: check hepatic enzymes prior to and during treatment.
• Avoid strong CYP3A4 inhibitors: these can increase ribociclib exposure.
• Pregnancy and lactation: contraindicated; advise effective contraception.
• Store at ambient temperature: keep tablets in the original container, protect from moisture and direct sunlight.

Ribociclib may interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): can raise ribociclib levels.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce therapeutic effect.
• QT‑prolonging agents (e.g., certain antiarrhythmics): increase risk of cardiac arrhythmias.

Moderate Interactions (Monitor Closely)

• Moderate CYP3A4 inhibitors (e.g., erythromycin, fluconazole): may modestly increase exposure.
• Moderate CYP3A4 inducers (e.g., phenytoin, St. John’s wort): could lower drug concentrations.
• Endocrine therapies (e.g., aromatase inhibitors): monitor for additive toxicities.
• Antacids containing multivalent cations: may affect absorption; separate dosing times.