Computationally designed liver-specific transcriptional modules and hyperactive factor IX improve hepatic gene therapy

• Published in: Blood Vol. 123; no. 20; pp. 3195 - 3199
• Main Authors: Nair, Nisha, Rincon, Melvin Y., Evens, Hanneke, Sarcar, Shilpita, Dastidar, Sumitava, Samara-Kuko, Emira, Ghandeharian, Omid, Man Viecelli, Hiu, Thöny, Beat, De Bleser, Pieter, VandenDriessche, Thierry, Chuah, Marinee K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.05.2014; American Society of Hematology
• Subjects: Animals; Base Sequence; Brief Report; Computational Biology; Dependovirus - genetics; Factor IX - genetics; Genetic Therapy; Genetic Vectors - genetics; Genetic Vectors - therapeutic use; Hemophilia B - genetics; Hemophilia B - therapy; Hepatocytes - metabolism; Humans; Liver - metabolism; Mice; Molecular Sequence Data; Regulatory Elements, Transcriptional; Thrombosis and Hemostasis; Transgenes
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2013-10-534032

The development of the next-generation gene therapy vectors for hemophilia requires using lower and thus potentially safer vector doses and augmenting their therapeutic efficacy. We have identified hepatocyte-specific transcriptional cis-regulatory modules (CRMs) by using a computational strategy that increased factor IX (FIX) levels 11- to 15-fold. Vector efficacy could be enhanced by combining these hepatocyte-specific CRMs with a synthetic codon-optimized hyperfunctional FIX-R338LPadua transgene. This Padua mutation boosted FIX activity up to sevenfold, with no apparent increase in thrombotic risk. We then validated this combination approach using self-complementary adenoassociated virus serotype 9 (scAAV9) vectors in hemophilia B mice. This resulted in sustained supraphysiologic FIX activity (400%), correction of the bleeding diathesis at clinically relevant, low vector doses (5 × 1010 vector genomes [vg]/kg) that are considered safe in patients undergoing gene therapy. Moreover, immune tolerance could be induced that precluded induction of inhibitory antibodies to FIX upon immunization with recombinant FIX protein. •Liver-targeted gene therapy for hemophilia can be improved by using computational promoter design in conjunction with hyperfunctional FIX.•Low and safe vector doses allow for stable supraphysiologic FIX that result in the induction of immune tolerance.