Freeline Therapeutics Holdings plc announced dosing of the second patient in the ongoing Phase 1/2 MARVEL-1 clinical trial of FLT190, its liver-directed AAV gene therapy candidate for Fabry disease. MARVEL-1 is a multicenter, international, Phase 1/2 dose-finding trial in adult males with classic Fabry disease being conducted in two parts: in previously treated patients and in previously untreated patients. The study is evaluating the safety and efficacy of FLT190 across four dose levels in approximately 10 patients and monitoring patients for nine months after dosing. Patients will be eligible to participate in a long-term follow-up study for further evaluation of the safety and efficacy of FLT190. In addition to safety, efficacy endpoints include levels of aGLA production, clearance of globotriaosylceramide (“Gb3”) and globotriaosylsphingosine (“LysoGb3”) from the plasma, changes in renal and skin biopsies, renal and cardiac function, aGLA immune response, and quality of life. FLT190 is an investigational AAV gene therapy in development as a potential treatment for patients with Fabry disease that is currently being studied in a Phase 1/2 clinical trial. FLT190 consists of next generation potent AAVS3 engineered capsid, containing an expression cassette with a codon-optimized human GLA cDNA under the control of the liver-specific promoter FRE1. The treatment is administered by intravenous infusion that lasts approximately one hour and does not require the patient to undergo stem cell harvest or conditioning with chemotherapy.