Management of acute infusion-related reactions in AAV gene therapy guided by mechanistic insight.

Infusion-related reactions (IRRs), serious immune events that occur either during or within six hours of an infusion, can occur with adeno-associated virus (AAV) gene therapy. IRRs may be attributed to IgE-mediated hypersensitivity, leading to treatment discontinuation due to concern about progressive, life-threatening allergic reactions. IRRs were observed in two participants who received an AAV8 gene therapy (DTX401) for glycogen storage disease type Ia and in one participant who received an AAV9 gene therapy (UX701) for Wilson's disease. All of these IRRs were associated with a rapid infusion rate, despite the second and third participants receiving antipyretic and antihistamine pre-medication. In both participants with DTX401-related IRRs, the infusion was terminated and not restarted. The DTX401 study protocol was amended to require both pre-medication and a slow, staged infusion; no additional IRRs were reported. Due to a medical error, a UX701-treated participant received a very rapid initial infusion rate, resulting in an IRR. After symptoms resolved, administration was restarted using a slow, staged infusion and was completed uneventfully. AAV gene therapy IRRs may be rate related and possibly driven by complement activation. In our studies, IRRs were mitigated by a slow, staged infusion.