Enhertu Monitoring Plan
Patients receiving Enhertu (trastuzumab deruxtecan) require vigilant monitoring for interstitial lung disease/pneumonitis with CT scans every 6-12 weeks, complete blood counts before each dose, and cardiac function assessment at baseline and regular intervals during treatment.
Critical Monitoring Components
Interstitial Lung Disease/Pneumonitis Surveillance
ILD/pneumonitis is the most serious toxicity requiring the most intensive monitoring. 1
- Imaging: Obtain CT scans every 6-12 weeks routinely throughout treatment 1
- Clinical monitoring: Educate patients about respiratory symptoms (dyspnea, cough) and actively assess at each visit 1
- Baseline assessment: Exclude pre-existing ILD before initiating therapy 1
High-risk patients who should NOT receive Enhertu:
- History of noninfectious ILD requiring steroid treatment 1
- Prior clinically significant pneumonitis from immune checkpoint inhibitors or everolimus 1
- Evidence of ILD on baseline imaging 1
Patients requiring individualized risk-benefit discussion:
- Lung comorbidities present 1
- Moderate/severe baseline renal dysfunction 1
- Baseline oxygen saturation <95% 1
The ILD rate is approximately 12-15%, with grade 5 events occurring in ~1% of patients 1. More frequent imaging detection identifies subclinical events earlier 2.
Hematologic Monitoring
Complete blood counts must be obtained before each dose and as clinically indicated. 3
- Neutropenia occurs in 65-72% of patients, with grade 3-4 in 19-51% depending on dose 3
- Median time to onset: 16-22 days 3
- Febrile neutropenia: 1.2-4.8% of patients 3
- Management: Dose interruption or reduction for significant neutropenia 3
Other common hematologic toxicities include:
- Decreased hemoglobin (67%)
- Decreased lymphocyte count (60%)
- Decreased platelet count (48%) 3
Cardiac Function Assessment
Assess left ventricular ejection fraction (LVEF) at baseline and at regular intervals during treatment. 3
- Baseline requirement: Document LVEF before initiating therapy 3
- Monitoring frequency: Regular intervals as clinically indicated 3
- Optimal duration: Evidence suggests cardiac monitoring can be limited to 18 months from treatment start, as events beyond 19 months are statistical outliers 4
Discontinuation criteria:
- LVEF <40% (confirmed) 3
- Absolute decrease from baseline >20% (confirmed) 3
- Symptomatic congestive heart failure (permanent discontinuation) 3
LVEF decrease occurs in 4.6-8% of patients, with grade 3-4 events in 0.6% 3.
Gastrointestinal Toxicity Management
Prophylactic antiemetic regimen is mandatory given the highly emetogenic nature of Enhertu. 1
Required prophylaxis (three-drug regimen):
- 5-HT3 receptor antagonist
- Dexamethasone
- Neurokinin-1 receptor antagonist 1
Delayed prophylaxis: Dexamethasone on days 2-3 1
Additional option: Olanzapine per local guidelines 1
Nausea occurs in 72-73% and vomiting in 34-38% of patients 1, 3. For grade 3-4 nausea/vomiting, hold treatment until resolution to grade 1; if resolution takes >7 days, dose reduction is required 1.
Monitoring Schedule Summary
Before each infusion (every 3 weeks):
Every 6-12 weeks:
- CT scan for ILD surveillance 1
At baseline and regular intervals:
Throughout treatment:
Common Pitfalls to Avoid
- Do not skip routine CT imaging even in asymptomatic patients—subclinical ILD is common and requires early detection 1, 2
- Do not use two-drug antiemetic regimens—Enhertu requires three-drug prophylaxis due to high emetogenicity 1
- Do not continue treatment with confirmed LVEF <40% or symptomatic heart failure 3
- Do not delay dose interruption for grade 3-4 neutropenia or other significant toxicities 3