About This Tool

The Perjeta (pertuzumab) Dosing Calculator is designed for healthcare professionals to quickly determine the correct intravenous dosage for patients with HER2-positive breast cancer. It provides information for both the initial loading dose and subsequent maintenance doses, aligning with the standard, fixed-dose administration protocol. This tool simplifies dose verification and helps ensure adherence to the approved prescribing information.

Outputs

The calculator provides specific details for the selected dosing scenario:

• Loading Dose: Outputs the standard initial dose of 840 mg, recommended to be administered as a 60-minute IV infusion, with a subsequent 60-minute observation period.
• Maintenance Dose: Outputs the standard subsequent dose of 420 mg, recommended to be administered as a 30 to 60-minute IV infusion every 3 weeks, with a 30 to 60-minute observation period.

An optional patient identifier can be added to the output for documentation purposes, such as printing or saving to an electronic health record.

How to Use

To use the calculator, follow these simple steps:

1. Select the appropriate “Dosing Scenario”: choose “Initiating Perjeta” for the one-time loading dose or “Continuing Perjeta” for the recurring maintenance dose.
2. Optionally, enter a patient identifier (e.g., medical record number or initials) for reference. This information is not stored or transmitted.
3. Click the “Calculate Dose” button to generate the detailed dosing and administration instructions.

Dosing Overview

Perjeta is administered intravenously and does not require dose calculation based on patient weight. The dosing regimen is fixed:

• Initial (Loading) Dose: 840 mg IV infusion over 60 minutes.
• Subsequent (Maintenance) Dose: 420 mg IV infusion over 30-60 minutes, administered every 3 weeks.

It is administered in combination with trastuzumab and chemotherapy for HER2-positive breast cancer. Perjeta and trastuzumab should be administered sequentially, and can be given in any order.

Switching

There is no specific guidance for switching from other anti-cancer therapies to a Perjeta-containing regimen within the prescribing information. Decisions regarding treatment changes should be based on a comprehensive clinical evaluation, disease status, and the patient’s treatment history. Always consult the full prescribing information for all agents involved in the treatment regimen.

Missed Dose

Management of a missed dose depends on the time elapsed:

• If the time between two sequential maintenance infusions (420 mg) is less than 6 weeks, the scheduled 420 mg dose should be administered as soon as possible. Do not wait until the next planned dose. The schedule should be maintained at 3-week intervals thereafter.
• If the time between two sequential infusions is 6 weeks or more, a re-loading dose of 840 mg should be administered, followed by the standard 420 mg maintenance dose every 3 weeks.

Safety Alerts

Frequently Asked Questions (FAQ)

Is patient weight required for the Perjeta dose calculation?
No, Perjeta is administered as a fixed dose (840 mg loading, 420 mg maintenance) and is not based on patient body weight.

Does this calculator adjust for renal or hepatic impairment?
No dose adjustments are recommended for patients with mild to moderate renal impairment or mild hepatic impairment. The calculator reflects the standard fixed dose, as there is insufficient data for severe impairment.

Can Perjeta be given as an IV push or bolus?
No. Perjeta must be administered as an intravenous infusion over the recommended duration (60 minutes for loading, 30-60 minutes for maintenance). It should never be given as an IV push or bolus.

How should Perjeta be prepared for infusion?
Perjeta must be diluted into a 250 mL 0.9% Sodium Chloride Injection PVC or non-PVC polyolefin infusion bag by a healthcare professional using aseptic technique. Do not use dextrose (5%) solutions.

What is the recommended observation period after infusion?
Patients should be observed for 60 minutes after the initial loading dose and for 30-60 minutes after each maintenance dose for signs of infusion-related reactions.

Does the calculator provide dosing for pediatric patients?
No. The safety and effectiveness of Perjeta have not been established in pediatric patients. The calculator is intended for adult dosing only.

How are Perjeta and trastuzumab administered when given on the same day?
They can be given sequentially in any order. The chemotherapy agent (e.g., docetaxel) should be administered after both Perjeta and trastuzumab.

What if an infusion-related reaction occurs?
The infusion rate should be slowed or interrupted, and appropriate medical therapies should be administered. The infusion should be discontinued immediately if the patient experiences a serious hypersensitivity reaction.

References

1. PERJETA® (pertuzumab) Prescribing Information. Genentech, Inc. March 2024.
2. Perjeta for Healthcare Professionals. Genentech, Inc.
3. Swain SM, Baselga J, Kim SB, et al; CLEOPATRA Study Group. Pertuzumab, trastuzumab, and docetaxel in HER2-positive metastatic breast cancer. N Engl J Med. 2015;372(8):724-734. doi:10.1056/NEJMoa1413513
4. NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. National Comprehensive Cancer Network. (Requires free registration to view).