Freeline Therapeutics Holdings plc announced the upcoming presentation of new and important clinical data for its AAVS3-based gene therapy candidate FLT180a at the International Society on Thrombosis and Haemostasis (ISTH) Congress to be held in London, July 9-13, 2022. The presentation will provide safety and initial efficacy data from the first cohort of the Phase 1/2 B-LIEVE trial, which aims to confirm the FLT180a dose and immune management regimen for the pivotal Phase 3 trial planned for 2023. The goal of treatment with FLT180a is to provide a functional cure for people with hemophilia B by delivering predictable and sustained normalization of coagulation Factor IX levels with a good safety profile.

The poster (PB0213) will be presented between 6:30pm-7:30pm BST on Sunday, July 10, 2022. The abstract has been published on the ISTH website: Young G et al. Results from B-LIEVE, a Phase 1/2 Dose-Confirmation Study of FLT180a AAV Gene Therapy in Patients with Hemophilia B. The poster presentation will be available on the Investors section of Freeline's website following presentation at the ISTH Congress.

B-LIEVE is a Phase 1/2 dose confirmation trial of FLT180a using a short course of prophylactic immune management with the goal of normalizing FIX levels in patients with severe and moderately severe hemophilia B. The starting dose of 7.7e11 vg/kg was selected based on the results of the Phase 1/2 B-AMAZE dose-finding trial and multiple modeling approaches. Freeline expects the B-LIEVE trial to finalize a dose for the pivotal Phase 3 trial intended to consistently enable predictable and sustained Factor IX (FIX) expression in the normal range for people with hemophilia B. Freeline's FLT180a candidate uses a potent, rationally designed AAVS3 capsid containing an expression cassette encoding a gain of function Padua variant of human Factor IX (FIX). FLT180a has been studied in B-AMAZE, a Phase 1/2 dose-finding trial in patients with severe and moderately severe hemophilia B with the goal of normalizing FIX activity in patients with moderate and severe hemophilia B. Patients treated in B-AMAZE are being followed in a long-term follow-up study.

A Phase 1/2 dose-confirmation trial of FLT180a called B-LIEVE to finalize a dose for a Phase 3 pivotal trial is in progress.