About This Calculator

The Darzalex (daratumumab) Dosing Calculator is an educational resource designed to help healthcare professionals determine patient-specific dosing based on the formulation (IV or SC), approved indication, and treatment phase. This tool simplifies dose calculation for complex, multi-phase regimens used in multiple myeloma and light chain (AL) amyloidosis.

Understanding the Outputs

After inputting patient data, the calculator provides the following key information:

• Calculated Dose: For the IV formulation, it calculates a weight-based dose (16 mg/kg). For the SC formulation (Darzalex FASPRO), it displays the standard fixed dose of 1,800 mg.
• Dosing Schedule: It outlines the complete, multi-phase dosing schedule for the selected regimen, highlighting the current treatment phase (e.g., weekly induction, bi-weekly, or monthly maintenance).
• Administration Details: The tool provides a summary of standard administration instructions, including recommended infusion rates for IV Darzalex and injection time for Darzalex FASPRO.

How to Use the Calculator

To use the tool effectively, follow these four steps:

1. Enter Patient Weight: Input the patient’s weight and select the appropriate unit (kg or lbs). The tool will convert lbs to kg for calculations.
2. Select Formulation: Choose between Darzalex (IV) for intravenous infusion or Darzalex FASPRO (SC) for subcutaneous injection.
3. Choose Indication & Regimen: Select the appropriate disease (Multiple Myeloma or AL Amyloidosis) and the specific combination therapy regimen (e.g., D-VMP, D-Rd).
4. Select Treatment Phase: Indicate where the patient is in their treatment course (e.g., Weeks 1-8, Week 25 onwards) to see the relevant schedule details highlighted.

Dosing Overview

Daratumumab dosing varies significantly by formulation and treatment schedule.

• Darzalex (IV): The recommended dose is 16 mg/kg of actual body weight. The frequency of administration starts weekly, then typically transitions to every 2 weeks, and finally every 4 weeks.
• Darzalex FASPRO (SC): The recommended dose is a fixed 1,800 mg of daratumumab and 30,000 units of hyaluronidase, administered subcutaneously. The dosing schedule is similar to the IV formulation, starting weekly and decreasing in frequency over time.

Switching Between Formulations

Patients currently receiving Darzalex IV can be switched to Darzalex FASPRO (SC). The first SC dose should be given at the time the next scheduled IV dose was due. Switching maintains the same dosing schedule established during the IV treatment course.

Missed Dose Guidance

If a planned dose of daratumumab is missed, it should be administered as soon as possible. The dosing schedule should then be adjusted accordingly to maintain the prescribed treatment interval. Always refer to the official prescribing information for specific instructions.

Key Safety Alerts

A critical aspect of daratumumab administration is the management of infusion-related reactions (IRRs). Pre-medication and post-medication are required to reduce this risk.

• Pre-medication: Patients should receive a corticosteroid, antipyretic, and antihistamine 1-3 hours before every dose to minimize IRRs.
• Post-medication: An oral corticosteroid is typically required for 2 days following IV infusions. Post-injection medication for the SC formulation may not be necessary after the first dose if no major reactions occur.

Frequently Asked Questions

1. Does this calculator work for both Darzalex and Darzalex FASPRO?
Yes, you can select either the intravenous (IV) or subcutaneous (SC) formulation to get the appropriate dosing information.

2. Why is the Darzalex FASPRO (SC) dose always 1,800 mg?
The subcutaneous formulation is a fixed-dose product co-formulated with hyaluronidase. This allows for a standard dose to be administered to all adult patients regardless of their weight.

3. What happens if I enter a patient’s weight in pounds (lbs)?
The calculator automatically converts the weight from lbs to kg to perform the IV dose calculation, as the standard dosing is 16 mg/kg.

4. Does the calculator recommend dose adjustments for side effects or organ impairment?
No. This tool is for calculating standard doses only. It does not provide guidance on dose reductions or adjustments for toxicity, renal, or hepatic impairment. Consult the full prescribing information for such cases.

5. Why does the calculator show a warning for very high or low weights?
A warning appears for clinically uncommon weights (e.g., <30 kg or >200 kg) to prompt the user to double-check their input for accuracy, preventing potential data entry errors.

6. Where is the administration and rate information sourced from?
The infusion rate guidance and injection instructions are based on the recommendations found in the FDA-approved prescribing information for each formulation.

7. Can I use this calculator for pediatric patients?
No. The safety and effectiveness of daratumumab have not been established in pediatric patients.

8. What are the key differences between the dosing schedules (Standard, VMP, VTd)?
The schedules differ in the duration of each phase. For example, the “VMP” schedule has a 6-week weekly induction phase, while the “Standard” schedule has an 8-week weekly induction. The calculator automatically applies the correct schedule based on the selected regimen.

References

• DARZALEX® (daratumumab) injection, for intravenous use – Prescribing Information. Janssen Biotech, Inc. U.S. Food and Drug Administration. Revised: 01/2022.
• DARZALEX FASPRO® (daratumumab and hyaluronidase-fihj) injection, for subcutaneous use – Prescribing Information. Janssen Biotech, Inc. U.S. Food and Drug Administration. Revised: 01/2022.
• Darzalex (daratumumab) Official Healthcare Professional Site. Janssen Medical Information.
• NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Multiple Myeloma. National Comprehensive Cancer Network. Version 3.2024.
• Mateos MV, Cavo M, Blade J, et al. Overall survival with daratumumab, bortezomib, melphalan, and prednisone in newly diagnosed multiple myeloma (ALCYONE): a randomised, open-label, phase 3 trial. Lancet. 2018;391(10116):132-141.