Yes, patients can safely receive Enhertu (trastuzumab deruxtecan) and Zofran (ondansetron) concurrently.
Ondansetron is explicitly recommended as prophylactic antiemetic therapy for patients receiving Enhertu, as the drug is classified as highly emetogenic. 1
Antiemetic Prophylaxis Requirements
The FDA label for Enhertu specifically mandates premedication for nausea and vomiting management:
- Enhertu is highly emetogenic, causing both immediate and delayed nausea/vomiting 1
- Prophylactic antiemetic medications must be administered per local institutional guidelines for prevention of chemotherapy-induced nausea and vomiting 1
- Ondansetron (Zofran), as a 5-HT3 antagonist, is a standard first-line antiemetic for highly emetogenic chemotherapy
Clinical Practice Evidence
Real-world experience confirms the safety and necessity of this combination:
- Nausea and vomiting are among the most common treatment-related adverse events with trastuzumab deruxtecan 2, 3
- Gastrointestinal disorders are frequently reported, making antiemetic prophylaxis essential 3
- Multidisciplinary oncology teams routinely use antiemetics including ondansetron as part of standard supportive care protocols for T-DXd 2
Important Caveat About Drug Interactions
While there is no contraindication to using ondansetron with Enhertu, be aware of one theoretical concern from older literature: fluoxetine (a 5-HT reuptake inhibitor) may reduce ondansetron's antiemetic efficacy by increasing synaptic 5-HT concentrations that compete with ondansetron at receptors 4. However, this interaction involves SSRIs, not Enhertu, and should not affect the Enhertu-ondansetron combination.
Practical Management
- Administer ondansetron prophylactically before each Enhertu infusion
- Consider multi-drug antiemetic regimens (NK1 antagonists, corticosteroids) given Enhertu's high emetogenic potential
- Monitor for breakthrough nausea/vomiting and adjust antiemetic regimen as needed
- Continue antiemetics for several days post-infusion to address delayed emesis
The combination is not only safe but required for optimal patient care and treatment tolerability.