Severe bradycardia after amivantamab administration in a patient with epidermal growth factor receptor-positive non-small cell lung cancer: A case report

Amivantamab, a bispecific antibody targeting epidermal growth factor receptor (EGFR) and mesenchymal–epithelial transition factor, has shown clinical efficacy in patients with EGFR-mutated non-small cell lung cancer. Although infusion-related reactions (IRRs) are common adverse events associated with this drug, cardiac events such as bradycardia have rarely been reported. We report the case of a 53-year-old Japanese man with advanced EGFR exon 19-deleted lung adenocarcinoma who was treated with amivantamab plus lazertinib as eighth-line therapy. On the first day, he experienced dyspnea, chills, and headache 30 min after amivantamab administration, so the infusion flow was reduced to 25 mL/h. After the symptoms resolved, the flow rate was set to 50 mL/h. On the second day, 2 h after initiating amivantamab infusion (700 mg) at 50 mL/h, his heart rate decreased to <50 beats per minute (bpm) and subsequently to <40 bpm. His blood pressure remained stable and he had no symptoms. The infusion was interrupted and intravenous methylprednisolone, chlorpheniramine, and atropine were administered. Bradycardia persisted for approximately 24 h but gradually resolved. On rechallenge with amivantamab 10 days later, bradycardia did not recur, suggesting that bradycardia is an IRR. Clinicians should be aware of this potential reaction and closely monitor cardiac rhythm during and after amivantamab infusion.