Loading Dose of Herceptin (Trastuzumab)
The recommended loading dose of trastuzumab for adults with HER2-positive breast cancer is 8 mg/kg IV, followed by maintenance doses of 6 mg/kg IV every 3 weeks, or alternatively 4 mg/kg IV loading dose followed by 2 mg/kg IV weekly. 1, 2, 3
Standard Dosing Regimens
Every-3-Week Schedule
- Administer an initial loading dose of 8 mg/kg IV on day 1, followed by maintenance doses of 6 mg/kg IV every 3 weeks. This is the preferred regimen for most patients and is supported by multiple guidelines including NCCN and ASCO. 1, 2, 3
- This schedule is pharmacokinetically equivalent to weekly dosing and offers greater convenience for patients. 1
Weekly Schedule
- Administer an initial loading dose of 4 mg/kg IV on day 1, followed by maintenance doses of 2 mg/kg IV weekly. 1, 2, 3
- This weekly regimen is particularly useful when trastuzumab is given concurrently with weekly chemotherapy regimens such as weekly paclitaxel. 1
Treatment Duration
- The total duration of adjuvant trastuzumab therapy should be 1 year (52 weeks), which includes both neoadjuvant and adjuvant cycles if applicable. 1, 2, 3
- For patients receiving neoadjuvant therapy, continue trastuzumab after surgery to complete the full year of treatment. 1
Critical Timing Considerations
Concurrent vs. Sequential Administration
- Trastuzumab must NOT be administered concurrently with anthracyclines (doxorubicin, epirubicin) due to significantly increased risk of cardiotoxicity. 1, 2
- Trastuzumab should be administered concurrently (not sequentially) with taxane-based chemotherapy for optimal efficacy. 1
- When using anthracycline-containing regimens, administer the anthracycline component first, then start trastuzumab with the taxane phase. 1, 2
Cardiac Monitoring Requirements
- Assess left ventricular ejection fraction (LVEF) at baseline before initiating trastuzumab; patients with LVEF <50% should not receive trastuzumab. 1, 2
- Monitor cardiac function every 3 months during trastuzumab therapy. 1, 2
- Discontinue trastuzumab if LVEF falls below institutional thresholds or if symptomatic heart failure develops. 1
Alternative Formulation
Subcutaneous Administration
- A subcutaneous formulation of trastuzumab (600 mg fixed dose every 3 weeks) is available and demonstrates non-inferior efficacy to IV administration, with the advantage of 5-minute administration time versus 30-90 minutes for IV infusion. 4, 5, 6, 7
- The subcutaneous formulation achieves 33% higher trough concentrations than IV dosing while maintaining equivalent efficacy and safety. 4
- Patient preference studies show 91.5% of patients prefer subcutaneous over IV administration. 6
Common Pitfalls to Avoid
- Do not reduce the loading dose based on age alone; use the standard 8 mg/kg loading dose unless specific contraindications exist. 1
- Do not give trastuzumab with anthracyclines concurrently; this combination dramatically increases cardiotoxicity risk from approximately 2-4% to 16-27%. 1
- Do not omit cardiac monitoring; asymptomatic cardiac dysfunction can occur and requires dose interruption or discontinuation. 1, 2
- Do not stop trastuzumab prematurely; the full 1-year duration is required for optimal disease-free and overall survival benefit. 1, 3, 8