What is the standard dosage of Abemaciclib (Verzenio)?

Standard Dosage of Abemaciclib (Verzenio)

The standard dosage of abemaciclib (Verzenio) is 150 mg taken orally twice daily, which is the established therapeutic dose for both metastatic breast cancer and adjuvant treatment of early breast cancer. 1, 2

Dosing Details by Indication

For Early Breast Cancer (Adjuvant Setting)

• Dose: 150 mg twice daily
• Duration: 2 years
• Administration: Taken with endocrine therapy
• Patient Population: Hormone receptor-positive, HER2-negative, node-positive early breast cancer at high risk of recurrence 1

For Metastatic Breast Cancer

• Dose: 150 mg twice daily
• Administration: Can be given as monotherapy or in combination with endocrine therapy
• Duration: Until disease progression or unacceptable toxicity 2

Dose Modifications

Dose adjustments may be necessary based on individual tolerability:

• First dose reduction: 100 mg twice daily
• Second dose reduction: 50 mg twice daily
• If further reduction needed: Discontinuation should be considered 2, 3

Common Adverse Events Requiring Dose Adjustments

1. Diarrhea (most common adverse event):

   • Occurs in up to 83.5% of patients
   • Grade ≥2 diarrhea reported in 42.8% of patients
   • Typically begins within 1 week of starting treatment
   • Managed with:
     • Antidiarrheal medications (72.8% of cases)
     • Dose omissions (17.3%)
     • Dose reductions (16.7%) 3

2. Neutropenia:

   • Grade ≥3 neutropenia occurs in approximately 25.4% of patients
   • Managed with:
     • Dose omissions (16.8%)
     • Dose reductions (11.2%)
   • Febrile neutropenia is rare (0.7%) 3

3. Other significant adverse events:

   • Thromboembolic events (5.3%)
   • Interstitial lung disease (3.4%) 1, 3

Important Clinical Considerations

• Abemaciclib is available in 50 mg, 100 mg, 150 mg, and 200 mg tablet strengths 2
• The pharmacokinetic profile shows slow absorption with maximum concentrations achieved after approximately 6 hours and an elimination half-life of about 24 hours 4
• Dose reductions due to adverse events do not appear to negatively impact progression-free survival 3
• Fatal adverse events occurred in 0.8% of patients taking abemaciclib plus endocrine therapy in clinical trials 1

Special Populations

In the monarchE trial, abemaciclib demonstrated significant improvement in invasive disease-free survival with a hazard ratio of 0.664 (95% CI 0.578-0.762) at 42 months median follow-up, with an absolute difference of 6.4% at 4 years between abemaciclib plus endocrine therapy versus endocrine therapy alone 5

Pitfalls to Avoid

1. Not providing adequate antidiarrheal prophylaxis: Diarrhea is the most common adverse event and typically occurs early in treatment. Proactive management is essential.

2. Overlooking drug interactions: As a CYP metabolized drug, potential interactions should be monitored.

3. Failure to monitor complete blood counts: Regular monitoring is needed due to the risk of neutropenia.

4. Not recognizing the importance of dose adjustments: Proper dose modifications can allow patients to continue therapy while managing adverse events effectively.