Positive Initial Clinical Data from the B-LIEVE Dose-Confirmation Trial for FLT180a in Hemophilia B Presented at the International Society on Thrombosis and Haemostasis Congress
Freeline Therapeutics
Freeline Therapeutics

FLT180a generated protective FIX levels with no bleeding or need for FIX replacement

The treatment was well tolerated with a good safety profile

LONDON, July 10, 2022 (GLOBE NEWSWIRE) -- Freeline Therapeutics Holdings plc (Nasdaq: FRLN) today announced the presentation of safety and initial efficacy data from the first cohort of the Phase 1/2 dose-confirmation B-LIEVE trial for FLT180a, the company’s AAVS3-based gene therapy candidate for people with hemophilia B, at the International Society on Thrombosis and Haemostasis (ISTH) Congress being held in London, July 9-13, 2022.

As of the data cut-off of May 23, 2022, a one-time FLT180a dose of 7.7e11 vg/kg generated a rapid increase of coagulation factor IX (FIX), reaching levels in the normal range (93, 92 and 80 IU/dL) for the three patients in cohort 1 through days 77, 56 and 36, respectively. Patients stopped FIX prophylaxis and did not require FIX replacement or experience bleeding following treatment with FLT180a.

The treatment and the prophylactic immune management regimen were well tolerated. No serious adverse events or infusion reactions were observed, and there has been no evidence of FIX inhibitors. All adverse events (AEs) were mild, and most were transient. AEs related to immune management were consistent with the known profiles of corticosteroids and tacrolimus.

Dosing of cohort two was completed in June, with early results showing a similar initial response to FLT180a. Based on the data from cohort one and consistent with the advice of the independent Data Monitoring Committee of the B-LIEVE trial, patients in cohort two received the same dose of FLT180a and prophylactic immune management regimen that were used in the first cohort.

As the data continue to evolve since the data cut-off for cohort one, two patients have experienced a decrease in FIX expression together with a mild and transient increase in liver enzymes. All patients continue to have expression levels above baseline, and no patient has experienced a bleed or required FIX supplementation.

“The initial data show that FLT180a provides rapid and consistent elevations in FIX to normal levels, which can prevent bleeding and the need for regular FIX replacement in people with hemophilia B,” said Pamela Foulds, MD, Chief Medical Officer of Freeline. “Emerging data suggest that while FIX expression was maintained at protective levels, a further refined immune management regimen may be required to avoid mild and transient transaminitis and to sustain FIX levels in the normal range. Potential adjustments in cohort two and forthcoming results from that cohort will help us interpret this further.”