Ontruzant Dosage

Generic name: trastuzumab 150mg
Dosage form: injection, powder, lyophilized, for solution
Drug class: HER2 inhibitors

Medically reviewed by Drugs.com. Last updated on Mar 1, 2024.

Patient Selection

Select patients based on HER2 protein overexpression or HER2 gene amplification in tumor specimens. Assessment of HER2 protein overexpression and HER2 gene amplification should be performed using FDA-approved tests specific for breast or gastric cancers by laboratories with demonstrated proficiency. Information on the FDA-approved tests for the detection of HER2 protein overexpression and HER2 gene amplification is available at: http://www.fda.gov/CompanionDiagnostics.

Assessment of HER2 protein overexpression and HER2 gene amplification in metastatic gastric cancer should be performed using FDA-approved tests specifically for gastric cancers due to differences in gastric vs. breast histopathology, including incomplete membrane staining and more frequent heterogeneous expression of HER2 seen in gastric cancers.

Improper assay performance, including use of suboptimally fixed tissue, failure to utilize specified reagents, deviation from specific assay instructions, and failure to include appropriate controls for assay validation, can lead to unreliable results.

Recommended Doses and Schedules

Do not administer as an intravenous push or bolus. Do not mix Ontruzant with other drugs.
Do not substitute Ontruzant (trastuzumab-dttb) for or with ado-trastuzumab emtansine.

Adjuvant Treatment, Breast Cancer:

Administer according to one of the following doses and schedules for a total of 52 weeks of Ontruzant therapy:

During and following paclitaxel, docetaxel, or docetaxel and carboplatin:

Initial dose of 4 mg/kg as an intravenous infusion over 90 minutes then at 2 mg/kg as an intravenous infusion over 30 minutes weekly during chemotherapy for the first 12 weeks (paclitaxel or docetaxel) or 18 weeks (docetaxel and carboplatin).
One week following the last weekly dose of Ontruzant, administer Ontruzant at 6 mg/kg as an intravenous infusion over 30 to 90 minutes every three weeks.

As a single agent within three weeks following completion of multi-modality, anthracycline-based chemotherapy regimens:

Initial dose at 8 mg/kg as an intravenous infusion over 90 minutes
Subsequent doses at 6 mg/kg as an intravenous infusion over 30 to 90 minutes every three weeks.
Extending adjuvant treatment beyond one year is not recommended.

Metastatic Treatment, Breast Cancer:

Administer Ontruzant, alone or in combination with paclitaxel, at an initial dose of 4 mg/kg as a 90-minute intravenous infusion followed by subsequent once weekly doses of 2 mg/kg as 30-minute intravenous infusions until disease progression.

Metastatic Gastric Cancer:

Administer Ontruzant at an initial dose of 8 mg/kg as a 90-minute intravenous infusion followed by subsequent doses of 6 mg/kg as an intravenous infusion over 30 to 90 minutes every three weeks until disease progression.

Important Dosing Considerations

If the patient has missed a dose of Ontruzant by one week or less, then the usual maintenance dose (weekly schedule: 2 mg/kg; three-weekly schedule: 6 mg/kg) should be administered as soon as possible. Do not wait until the next planned cycle. Subsequent Ontruzant maintenance doses should be administered 7 days or 21 days later according to the weekly or three-weekly schedules, respectively.

If the patient has missed a dose of Ontruzant by more than one week, a re-loading dose of Ontruzant should be administered over approximately 90 minutes (weekly schedule: 4 mg/kg; three-weekly schedule: 8 mg/kg) as soon as possible. Subsequent Ontruzant maintenance doses (weekly schedule: 2 mg/kg; three-weekly schedule 6 mg/kg) should be administered 7 days or 21 days later according to the weekly or three-weekly schedules, respectively.

Infusion Reactions

Decrease the rate of infusion for mild or moderate infusion reactions
Interrupt the infusion in patients with dyspnea or clinically significant hypotension
Discontinue Ontruzant for severe or life-threatening infusion reactions.

Cardiomyopathy

Assess left ventricular ejection fraction (LVEF) prior to initiation of Ontruzant and at regular intervals during treatment. Withhold Ontruzant dosing for at least 4 weeks for either of the following:

≥ 16% absolute decrease in LVEF from pre-treatment values
LVEF below institutional limits of normal and ≥ 10% absolute decrease in LVEF from pretreatment values.

Ontruzant may be resumed if, within 4 to 8 weeks, the LVEF returns to normal limits and the absolute decrease from baseline is ≤15%.

Permanently discontinue Ontruzant for a persistent (> 8 weeks) LVEF decline or for suspension of Ontruzant dosing on more than 3 occasions for cardiomyopathy.

Preparation for Administration

To prevent medication errors, it is important to check the vial labels to ensure that the drug being prepared and administered is Ontruzant (trastuzumab-dttb) and not ado-trastuzumab emtansine.

420 mg Multiple-dose vial

Reconstitution: Reconstitute each 420 mg vial of Ontruzant with 20 mL of Bacteriostatic Water for Injection (BWFI), USP, containing 1.1% benzyl alcohol as a preservative to yield a multiple-dose solution containing 21 mg/mL trastuzumab-dttb that delivers 20 mL (420 mg trastuzumab-dttb). In patients with known hypersensitivity to benzyl alcohol, reconstitute with 20 mL of Sterile Water for Injection (SWFI) without preservative to yield a single use solution.

Use appropriate aseptic technique when performing the following reconstitution steps:

Using a sterile syringe, slowly inject the 20 mL of diluent into the vial containing the lyophilized powder of Ontruzant, which has a cake-like appearance. The stream of diluent should be directed into the cake. The reconstituted vial yields a solution for multiple-dose use, containing 21 mg/mL trastuzumab-dttb.
Swirl the vial gently to aid reconstitution. DO NOT SHAKE.
Slight foaming of the product may be present upon reconstitution. Allow the vial to stand undisturbed for approximately 5 minutes.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Inspect visually for particulates and discoloration. The solution should be free of visible particulates, clear to slightly opalescent and colorless to pale yellow.
Store reconstituted Ontruzant in the refrigerator at 2° to 8°C (36° to 46°F); discard unused Ontruzant after 28 days. If Ontruzant is reconstituted with SWFI without preservative, use immediately and discard any unused portion. Do not freeze.

Dilution:

Determine the dose (mg) of Ontruzant. Calculate the volume of the 21 mg/mL reconstituted Ontruzant solution needed, withdraw this amount from the vial and add it to an infusion bag containing 250 mL of 0.9% Sodium Chloride Injection, USP. DO NOT USE DEXTROSE (5%) SOLUTION.
Gently invert the bag to mix the solution.
The solution of Ontruzant for infusion diluted in polyvinylchloride or polyethylene bags containing 0.9% Sodium Chloride Injection, USP, should be stored at 2° to 8°C (36° to 46°F) for no more than 24 hours prior to use. Do not freeze.

150 mg Single-dose vial

Reconstitution: Reconstitute each 150 mg vial of Ontruzant with 7.4 mL of Sterile Water for Injection (SWFI) (not supplied) to yield a single-dose solution containing 21 mg/mL trastuzumab-dttb that delivers 7.15 mL (150 mg trastuzumab-dttb).

Use appropriate aseptic technique when performing the following reconstitution steps:

Using a sterile syringe, slowly inject 7.4 mL of SWFI (not supplied) into the vial containing the lyophilized powder of Ontruzant, which has a cake-like appearance. The stream of diluent should be directed into the cake. The reconstituted vial yields a solution for single-dose use, containing 21 mg/mL trastuzumab-dttb.
Gently swirl and invert the vial to aid reconstitution. DO NOT SHAKE.
Slight foaming of the product may be present upon reconstitution. Allow the vial to stand undisturbed for approximately 5 minutes.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Inspect visually for particulates and discoloration. The solution should be free of visible particulates, clear to slightly opalescent and colorless to pale yellow.
Use the Ontruzant solution immediately following reconstitution with SWFI, as it contains no preservative and is intended for single-dose only. If not used immediately, store the reconstituted Ontruzant solution for up to 24 hours at 2° to 8°C (36° to 46°F); discard any unused Ontruzant after 24 hours. Do not freeze.

Dilution:

Determine the dose (mg) of Ontruzant.
Calculate the volume of the 21 mg/mL reconstituted Ontruzant solution needed
Withdraw this amount from the vial and add it to an infusion bag containing 250 mL of 0.9% Sodium Chloride Injection, USP. DO NOT USE DEXTROSE (5%) SOLUTION.
Gently invert the bag to mix the solution.
The solution of Ontruzant for infusion diluted in polyvinylchloride or polyethylene bags containing 0.9% Sodium Chloride Injection, USP, should be stored at 2° to 8°C (36° to 46°F) for no more than 24 hours prior to use. Discard after 24 hours. This storage time is additional to the time allowed for the reconstituted vials. Do not freeze.