Understanding the Enhertu Dosing Schedule
Enhertu, also known by its chemical name fam-trastuzumab deruxtecan, is an antibody-drug conjugate (ADC) used to treat specific types of cancer that express the HER2 protein. For most patients, the treatment is given once every three weeks, completing what is known as a 21-day treatment cycle. This consistent schedule is crucial for delivering a precise and effective dose of medication over time.
The infusions are administered intravenously (IV), meaning the medication is delivered directly into a patient's bloodstream. The process is conducted under medical supervision at an oncologist's office or an infusion center to ensure proper administration and to monitor for any immediate reactions. The duration of the infusion can vary, with the first dose typically taking longer than subsequent treatments.
What to Expect During an Infusion
Before each Enhertu infusion, patients are often given pre-medications to help prevent or reduce the common side effects of chemotherapy, particularly nausea and vomiting. The infusion itself follows a predictable timeline:
- First Infusion: The initial treatment is administered over approximately 90 minutes. This longer period allows healthcare providers to closely observe the patient for any potential infusion-related reactions.
- Subsequent Infusions: For subsequent infusions, the duration is typically reduced to about 30 minutes, provided the first dose was well-tolerated.
During the infusion, the healthcare team will monitor vital signs and watch for any signs of an adverse reaction. If a patient experiences symptoms, the infusion rate may be slowed or temporarily stopped.
Dosage Based on Cancer Type
The specific dosage of Enhertu is calculated based on a patient's body weight in kilograms, as well as the type of cancer being treated. This tailored approach ensures that each patient receives the optimal amount of medication.
Enhertu Dosage Comparison by Cancer Type
| Cancer Type | Recommended Starting Dose | First Dose Reduction | Second Dose Reduction |
|---|---|---|---|
| Breast Cancer (HER2-positive, HER2-low, HR+/HER2-ultralow) | Varies by individual and treatment plan | Varies by individual and treatment plan | Varies by individual and treatment plan |
| Non-Small Cell Lung Cancer (NSCLC) | Varies by individual and treatment plan | Varies by individual and treatment plan | Varies by individual and treatment plan |
| Stomach Cancer or Gastroesophageal Junction (GEJ) Cancer | Varies by individual and treatment plan | Varies by individual and treatment plan | Varies by individual and treatment plan |
| HER2-Positive Solid Tumors | Varies by individual and treatment plan | Varies by individual and treatment plan | Varies by individual and treatment plan |
It is important to note that after a dose reduction, the Enhertu dose cannot be re-escalated. Further dose reductions after the second may lead to treatment discontinuation.
How Dose Modifications Occur
While the 3-week schedule is standard, it may not always be static. A patient's healthcare provider might need to modify the dosage or the schedule based on several factors, including the occurrence and severity of side effects. Common reasons for dose interruption or reduction include:
- Neutropenia: A decrease in the white blood cell count (neutrophils), which can increase the risk of infection.
- Interstitial Lung Disease (ILD) or Pneumonitis: Inflammation of the lungs that can range in severity and requires close monitoring.
- Nausea and Vomiting: Severe or unmanageable side effects that impact a patient's quality of life.
- Other Adverse Reactions: Any other serious side effects that may be attributed to the medication.
What to Do for a Missed Dose
Keeping a consistent schedule is important for maintaining therapeutic efficacy. If a planned dose is missed or delayed for any reason, patients should contact their healthcare provider as soon as possible to reschedule. The provider will determine the best course of action and adjust the schedule to maintain the 3-week interval between doses. It is crucial not to wait until the next planned treatment cycle.
Treatment Duration
The duration of Enhertu treatment is not fixed and is determined by a patient's response to the therapy and tolerability of the side effects. Treatment is typically continued until either the cancer shows signs of progression or the patient experiences unacceptable toxicity that warrants discontinuation. Your oncologist will discuss the expected duration and monitor your progress throughout the course of treatment.
Conclusion
Enhertu is a powerful targeted therapy that is most commonly administered as an intravenous infusion once every three weeks. The specific dosage is weight-based and tailored to the patient's cancer type, with adjustments possible based on the management of side effects. This consistent dosing regimen is a cornerstone of the treatment plan, and adherence to the schedule is crucial for achieving the best possible outcome. For any questions regarding your specific treatment schedule or if a dose is missed, it is essential to communicate directly with your healthcare team.
An authoritative resource for further information on Enhertu can be found on the U.S. Food and Drug Administration's website.
