About this Guide

This guide provides supplementary information for the Sprycel (dasatinib) dose calculator, an educational tool designed to assist healthcare professionals. It outlines key considerations for dasatinib administration, including initial dosing schedules, modifications for toxicity, and adjustments for drug interactions, based on official prescribing information.

Outputs Explained

The calculator provides tailored recommendations based on the data entered. Outputs may include:

• Recommended Dose: A specific starting or adjusted dose in milligrams (mg) per day.
• Administration Instructions: Guidance on whether to hold, resume, reduce, or increase the current dose.
• Clinical Rationale: Notes explaining the reason for the recommendation, such as specific ANC/platelet thresholds, toxicity grades, or the type of drug interaction.
• Patient-Specific Factors: The output is contextualized based on patient type (adult vs. pediatric), body weight (for pediatrics), and specific cancer indication.

How to Use the Calculator

To receive a dosing recommendation, follow these steps:

1. Select Calculation Type: Choose ‘Initial Dose’, ‘Toxicity Adjustment’, or ‘Drug Interaction’ to begin.
2. Enter Patient Data: Provide all required information. For an ‘Initial Dose’, this includes patient type and indication or weight. For ‘Toxicity Adjustment’, input the current dose, indication, toxicity type, and relevant lab values (ANC/platelets) or CTCAE grade. For ‘Drug Interaction’, specify the current dose and type of concomitant CYP3A4 medication.
3. Calculate: The tool will process the inputs and display the recommended dosing action and important considerations.

Dosing Overview

Standard dasatinib dosing varies by indication and patient population. The tablets should be swallowed whole and may be taken with or without food.

• Adult CML (Chronic Phase): The typical starting dose is 100 mg once daily.
• Adult CML (Accelerated/Blast Phase) or Ph+ ALL: The typical starting dose is 140 mg once daily.
• Pediatric CML (Chronic Phase): Dosing is based on body weight, starting at 40 mg and increasing up to 100 mg once daily.

Switching Therapy

Switching a patient to or from dasatinib from another tyrosine kinase inhibitor (TKI) is a clinical decision that requires careful consideration of the prior treatment history, reason for switching (e.g., resistance, intolerance), and the patient’s overall health. This process should be managed by a clinician experienced in treating hematologic malignancies.

Missed Dose

If a patient misses a dose of Sprycel, they should take their next scheduled dose at its regular time. The patient should not take two doses at the same time to make up for a missed dose.

Safety Alerts

• Myelosuppression: Dasatinib can cause severe thrombocytopenia, neutropenia, and anemia. Perform complete blood counts weekly for the first 2 months and then monthly thereafter, or as clinically indicated. Dose holds and reductions are often required.
• Drug Interactions: Co-administration with strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) increases dasatinib exposure, requiring a dose reduction. Conversely, co-administration with strong CYP3A4 inducers (e.g., rifampin, St. John’s Wort) decreases exposure, requiring a dose increase.
• Fluid Retention: Dasatinib is associated with fluid retention, which can be severe. Patients should be monitored for signs and symptoms, including pleural effusion.

Frequently Asked Questions

What is the initial dose for an adult with CML in chronic phase?

The standard starting dose for an adult with newly diagnosed Chronic Myeloid Leukemia in the Chronic Phase (CML-CP) is 100 mg administered orally once daily.

How is the pediatric dose for Sprycel determined?

For pediatric patients with CML-CP, the initial dose is based on body weight. The calculator uses established weight bands to recommend a daily dose, typically ranging from 40 mg to 100 mg.

What action is recommended if a patient’s ANC drops below 0.5 x 10⁹/L?

For severe neutropenia (Absolute Neutrophil Count < 0.5 x 10⁹/L), therapy should be held. It can be resumed at the original or a reduced dose once the ANC recovers to ≥ 1.0 x 10⁹/L, depending on the indication and whether it is a recurrent event.

How do you adjust the dose for non-hematologic toxicity?

For moderate to severe (Grade ≥2) non-hematologic toxicity, Sprycel should be withheld until the event resolves to Grade 1 or baseline. Therapy can then be resumed at a reduced dose.

What is the dose adjustment for Sprycel when taking a strong CYP3A4 inhibitor?

Concomitant use requires a significant dose reduction. For example, a 100 mg daily dose should be reduced to 20 mg daily. If dose reduction is not feasible, an alternative medication should be considered.

How do you manage Sprycel dosing with a strong CYP3A4 inducer?

Concomitant use requires a dose increase to counteract the reduced drug exposure. For example, a 100 mg daily dose should be increased to 200 mg daily. The patient should be monitored closely for response.

The calculator recommended resuming at a ‘reduced dose’. What are the typical dose reduction steps?

For patients starting at 140 mg, dose reductions are typically to 100 mg, then 80 mg. For patients starting at 100 mg, reductions are typically to 80 mg, then 50 mg.

Can the calculator be used for pediatric patients weighing less than 10 kg?

No. As per prescribing information, the safety and efficacy of Sprycel have not been established in pediatric patients weighing less than 10 kg. The tool will indicate that dosing is not established for this group.

References

• 1. SPRYCEL® (dasatinib) tablets, for oral use. U.S. Prescribing Information. Bristol-Myers Squibb Company. Revised: 10/2020. Accessed via FDA.
• 2. Sprycel (dasatinib) European public assessment report (EPAR). European Medicines Agency.
• 3. Sprycel.com. Official manufacturer website for U.S. Healthcare Professionals. Bristol Myers Squibb.
• 4. NCCN Clinical Practice Guidelines in Oncology. Chronic Myeloid Leukemia. (Version updates may apply). National Comprehensive Cancer Network.