FLT180a Shows Efficacy in Hemophilia B at High Doses

When administered at a high dose, the experimental gene therapy FLT180a restored activity of clotting factor IX (FIX) within normal ranges in men with hemophilia B, according to phase I/II data from the B-AMAZE study presented at the 13th European Association for Haemophilia and Allied Disorders (EAHAD) in the Netherlands.

FLT180a uses a capsid protein shell from an adeno-associated virus that can infect human cells to target and deliver the correct version of F9 to the patient’s liver cells, allowing the body to produce the missing clotting FIX.

Previous findings showed that FLT180a increased FIX levels and kept them stable over 1 year in the first 2 patients treated in the study. At the lowest dose tested (4.5×1011 vg/kg), FIX levels rose to approximately 40% of normal levels.

More recent results from the first 8 patients treated in the trial suggest that at the highest dose tested (9.75×1011 vg/kg), FLT180a may be able to increase and sustain FIX activity within normal ranges of 50 to 150%.

As the researchers look to determine the optimal dose of FLT180a for normal FIX activity, up to three different doses will be tested in up to 18 patients with severe hemophilia B. The B-AMAZE study, sponsored by University College London and Freeline, is currently recruiting participants.

Sources: ClinicalTrials.gov; Chowdary P. Phase 1/2 interim data from B-AMAZE study of adeno associated virus (AAV) gene therapy (FLT180a) confirms progress towards achieving Factor IX levels in the normal range for patients with severe or moderately severe haemophilia B. Presented at the 13th Annual Congress of the EAHAD, February 2, 2020; The Hague, Netherlands.