From the Guidelines
Osimertinib therapy requires monitoring of QTc interval and cardiac function.
Key Monitoring Parameters
- QTc interval: due to the dose-dependent increase in QTc interval associated with osimertinib therapy 1
- Cardiac function: particularly in patients with baseline cardiac compromise, as they may be at increased risk of cardiac adverse events 1
Rationale
Osimertinib's effect on the QTc interval is a significant concern, and patients with pre-existing cardiac conditions may be more susceptible to cardiac adverse events 1. As such, regular cardiac monitoring is recommended, especially in metastatic patients.
Clinical Considerations
In patients with baseline cardiac compromise, the benefits of osimertinib therapy should be carefully weighed against the potential risks, and additional safety monitoring may be necessary 1. This may involve adjusting concurrent medications that could exacerbate QTc interval prolongation.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Laboratory Monitoring for Osimertinib Therapy
To monitor patients on osimertinib therapy, several laboratory tests can be considered:
- Complete Blood Count (CBC) to monitor for potential hematologic adverse effects such as anemia, neutrophil count decrease, and thrombocytopenia 2
- Electrolyte panel to monitor for hyponatremia 2
- Liver function tests (LFTs) to monitor for increased alanine aminotransferase (ALT) 2
- Electrocardiogram (ECG) to monitor for QT interval prolongation 2
- Plasma concentrations of osimertinib and its metabolites to ensure adequate drug levels and to adjust dosing as needed 3, 4, 5
Therapeutic Drug Monitoring (TDM)
TDM can be used to monitor osimertinib levels in patients, which can help optimize dosing and minimize adverse effects:
- Osimertinib concentrations can be measured in plasma or dried blood spots (DBS) 4
- A validated liquid chromatography-mass spectrometry (LC-MS) assay or ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method can be used to quantify osimertinib and its metabolites in human plasma 4, 5
- TDM can help identify patients who may require dose adjustments due to variability in drug metabolism or other factors 4