A 49-Year-Old Woman With Trastuzumab-Deruxtecan-Induced Pneumonitis Responsive to IV Immunoglobulin Therapy After Failed Steroid Treatment.

Abstract

Trastuzumab-deruxtecan (T-DXd) is an antibody-drug conjugate associated with interstitial pneumonitis, affecting over 15% of patients receiving treatment. Initial management for grade 3/4 pneumonitis includes stopping the drug and administering high-dose steroids, but there is minimal guidance on additional treatment for steroid-refractory cases. We present a case of a 49-year-old woman with metastatic breast cancer who developed grade 4 pneumonitis after T-DXd treatment, who responded well to IV immunoglobulin (IVIG) after failing to respond to high-dose IV methylprednisolone. Most case reports and retrospective analyses to date have been done in pneumonitis associated with checkpoint inhibitors. To our knowledge, this is the first case report of a patient with steroid-refractory T-DXd pneumonitis positively responding to IVIG treatment. IVIG represents an attractive option as adjunctive therapy, given its minimal side effect profile compared with intensive immunosuppression. Further evidence is needed to help guide clinicians in managing drug-induced pneumonitis, including with T-DXd.