Gene therapy with adeno-associated virus vector 5–human factor IX in adults with hemophilia B

Wolfgang Miesbach, Karina Meijer, Michiel Coppens, Peter Kampmann, Robert Klamroth, Roger Schutgens, Marco Tangelder, Giancarlo Castaman, Joachim Schwäble, Halvard Bonig, Erhard Seifried, Federica Cattaneo, Christian Meyer, Frank W.G. Leebeek*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

52 Citations (Scopus)

Abstract

Gene therapy for hemophilia B aims to ameliorate bleeding risk and provide endogenous factor IX (FIX) activity/synthesis through a single treatment, eliminating the requirement for FIX concentrate. AMT-060 combines an adeno-associated virus-5 (AAV5) vector with a liver-specific promoter driving expression of a codon-optimized wild-type human FIX gene. This multinational, open-label study included 10 adults with hemophilia B (FIX £2% of normal) and severe-bleeding phenotype. No participants tested positive for AAV5-neutralizing antibodies using a green-fluorescent protein-based assay, and all 10 were enrolled. A single dose of 5 3 10 12 or 2 3 10 13 genome copies of AMT-060/kilogram was administered to 5 participants each. In the low-dose cohort, mean endogenous FIX activity increased to 4.4 IU/dL. Annualized FIX use was reduced by 81%, and mean annualized spontaneous bleeding rate (ASBR) decreased from 9.8% to 4.6% (53%). In the higher-dose cohort, mean FIX activity increased to 6.9 IU/dL. Annualized FIX use decreased by 73%, and mean ASBR declined from 3.0 to 0.9 (70%). There was no reduction in traumatic bleeds. FIX activity was stable in both cohorts, and 8 of 9 participants receiving FIX at study entry stopped prophylaxis. Limited, asymptomatic, and transient alanine aminotransferase elevations in the low-dose (n 5 1) and higher-dose (n 5 2) cohorts were treated with prednisolone. No decrease in FIX activity or capsid-specific T-cell responses were detected during transaminase elevations. A single infusion of AMT-060 had a positive safety profile and resulted in stable and clinically important increases in FIX activity, a marked reduction in spontaneous bleeds and FIX concentrate use, without detectable cellular immune responses against capsids. This trial was registered at www.clinicaltrials.gov as #NCT02396342; EudraCT #2013-005579-42.

Original languageEnglish
Pages (from-to)1022-1031
Number of pages10
JournalBlood
Volume131
Issue number9
DOIs
Publication statusPublished - 1 Mar 2018

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