Abstract: Background: Etranacogene dezaparvovec is an investigational gene therapy for hemophilia B (HB) comprising an adeno-associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant human factor IX (FIX) gene with a liver specific promoter. In a Phase 2b study, a single dose of etranacogene dezaparvovec provided mean FIX activity of 41.0% sustained at 1yr post-dose in 3 participants (pts). Although most gene therapy clinical studies exclude pts with pre-existing neutralizing antibodies (NAbs) to the capsid serotype, early clinical studies and nonhuman primate data suggest that generally prevalent titers of anti-AAV5 NAbs may not preclude successful transduction with etranacogene dezaparvovec. Aims: A Phase 3, Health Outcomes with Padua gene; Evaluation in Hemophilia B (HOPE-B; NCT03569891) was established to further assess efficacy and safety of etranacogene dezaparvovec in adults with HB with a wide range of pre-existing NAbs to AAV5. Here we report outcomes at 26 weeks (wks). Methods: HOPE-B is a Phase 3, open-label, single-dose, single-arm, multi-national trial in adult males with severe or moderate-severe HB (FIX≤2%). All pts received routine FIX prophylaxis prior to study. Pts were not excluded based on pre-existing NAbs to AAV5. Pts entered a prospective lead-in period of at least 6 months during which bleeding/factor use was monitored, then received a single intravenous dose of etranacogene dezaparvovec (2x1013 gc/kg). Pts will be followed for 5yrs. Primary endpoints comprised FIX activity (one stage) at 26 and 52wks after dosing and 52wk annualized bleeding rate. For pts with no clean post-treatment FIX samples (≥10d post exogenous FIX), factor activity was imputed as baseline value based on historic disease severity. Secondary endpoints include factor replacement use, adverse events (AEs), and reactive use of corticosteroids. Results: 75 pts were screened, of whom 67 entered lead-in. 54 pts were dosed (44 severe, 10 moderately severe HB) and completed 26wks of follow-up. Mean age (±SD) was 41.5 (15.8) yrs. 38/54 pts (70.4%) had bleeds (n=123) during the lead-in despite prophylaxis, and 23/54 (42.6%) had NAbs to AAV5 at baseline (max titer: 3212.3). Following treatment, FIX activity increased rapidly to a mean (SD; min,max) of 37.2% (±19.6; 1.0, 97.1) at wk26, representing a mean (SD; min,max) change from baseline of 36.0% (±19.7; 0, 96.1 p & lt;0.0001, confirmed by per-protocol sensitivity analysis). No correlation of pre-existing NAbs with FIX activity was identified up to a titer of 678.2; n=52, R2 = 0.078); a single pt had a NAb titer of 3212.3 and did not respond. In addition to this pt, one other pt received a partial dose and remained on prophylaxis; all other pts (96.3%) successfully discontinued routine prophylaxis. 39/54 (72.2%) pts reported 0 bleeds in the first 26wks post-treatment; 15 pts reported a total of 21 bleeds. Mean (SD) annualized FIX consumption (IU/yr/pt) was 292,304 (±171,079) during lead-in, decreasing to 12,622 (±36,466) at wk26 (96.0% reduction, N=54). Overall, 37/54 (68.5%) pts had any treatment-related AE post-treatment, the majority of which were mild (81.5%). No deaths occurred and no treatment-related SAEs were reported. 7 pts had infusion-related reactions; the infusion was discontinued in 1 pt. Treatment-related elevations in liver enzymes were reported in 9 pts and received steroids per protocol. All discontinued steroid use prior to wk26 and FIX activity was preserved in the mild range. In addition to these, the most frequent treatment-related AEs were headache (13.0%) and influenza-like illness (13.0%). No inhibitors to FIX were reported. No relationship between safety and NAbs was observed. Conclusions: The first co-primary endpoint of this study was met. This is the first report of a Phase 3 study in HB and the largest gene therapy trial cohort to date. Following a single dose of etranacogene dezaparvovec, FIX activity increased, without the need for prophylactic immunosuppression, into the mild-to-normal range at 26wks in pts with severe/moderately severe HB. Importantly, this included pts with titers of pre-existing anti-AAV5 NAbs. Pts were able to discontinue prophylaxis and bleeding was abolished in the majority. The safety profile was consistent with early phase AAV5 studies and together these data support a favorable safety and efficacy profile for etranacogene dezaparvovec Disclosures Pipe: HEMA Biologics: Consultancy, Other; Catalyst Biosciences: Consultancy; CSL Behring: Consultancy; ApcinteX: Consultancy; Bayer: Consultancy, Other: Contracted Research; BioMarin: Consultancy, Other: Contracted Research; Takeda: Consultancy; uniQure: Consultancy, Other; Siemens: Other; Pfizer: Consultancy; Freeline Therapeutics: Consultancy, Other: Contracted Research; Novo Nordisk: Consultancy, Other: Contracted Research; Roche/Genentech: Consultancy, Other: Contracted Research; Sangamo Therapeutics: Consultancy; Sanofi Genzyme: Consultancy, Other; Spark Therapeutics: Consultancy. Recht:CSL Behring: Consultancy, Other: personal fees; Genentech: Consultancy, Other: personal fees, Research Funding; Pfizer: Consultancy, Other: personal fees, Research Funding; BioMarin: Research Funding; Takeda: Consultancy, Other: personal fees, Research Funding; uniQure: Consultancy, Other: personal fees, Research Funding; Novo Nordisk: Consultancy, Other: personal fees, Research Funding; Spark: Research Funding; Bayer: Research Funding; Grifols: Research Funding; Hema Biologics: Consultancy, Research Funding; LFB: Research Funding; Octapharma: Research Funding; Catalyst Biosciences: Consultancy; Kedrion: Consultancy; Sanofi: Consultancy, Research Funding. Key:Uniqure: Consultancy; Grifols: Research Funding; Takeda: Research Funding; Novo Nordisk: Other: Chair of Grants Committee. Leebeek:Shire/Takeda: Research Funding; uniQure: Consultancy; Shire/Takeda: Consultancy; BioMarin: Consultancy; SOBI: Other: Travel grant; Roche: Other: DSMB member for a study; CSL Behring: Research Funding. Castaman:Bayer, Roche, Sobi, Grifols, Novo Nordick, Werfen, Kedrion: Consultancy, Honoraria, Speakers Bureau; CSL Behring, Pfizer, Sobi: Research Funding; Ablynx, Alexion, Bayer, Takeda, CSL Behring, Novo Nordisk, Pfizer, Roche,Sanofi, SOBI, uniQure: Membership on an entity's Board of Directors or advisory committees. Lattimore:uniQure: Other: Study Steering Committee member. Van Der Valk:Baxalta: Research Funding. Peerlinck:Bayer: Consultancy, Research Funding; CSL Behring: Consultancy, Research Funding; NovoNordisk: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Roche: Research Funding; Sobi: Consultancy; Takeda: Consultancy, Research Funding. Coppens:Roche: Research Funding; Portola/Alexion: Research Funding; Sanquin Blood Supply: Research Funding; uniQure: Research Funding; NovoNordisk: Consultancy; Pfizer: Consultancy; Sobi: Consultancy; Medcon International: Consultancy; MEDtalks: Consultancy; Bayer: Consultancy, Research Funding; CSL Behring: Consultancy, Research Funding; Daiichi Sankyo: Research Funding. O'Connell:uniQure: Consultancy; F. Hoffmann-La Roche Ltd, Novo Nordisk, SOBI: Speakers Bureau; SOBI: Research Funding. Pasi:Sanofi: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia, Research Funding; BioMarin: Consultancy, Honoraria, Other: Grants, personal fees, and nonfinancial support; honoraria as member of scientific advisory boards and symposia, Research Funding; uniQure: Other: Grants and nonfinancial support , Research Funding; ApcinteX: Consultancy, Other: Personal fees ; Takeda: Consultancy, Honoraria, Other: Personal fees; honoraria as member of scientific advisory boards and symposia ; Biotest: Consultancy, Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Catalyst Biosciences: Consultancy, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia; Novo Nordisk: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia ; Octapharma: Honoraria, Other: Personal fees and nonfinancial support; honoraria as member of scientific advisory boards and symposia , Speakers Bureau; Roche: Honoraria, Other; Sobi: Consultancy, Honoraria, Other; Tremeau: Consultancy. Kampmann:Uniqure: Research Funding, Speakers Bureau; Shire Pharmaceuticals: Speakers Bureau. Meijer:Pfizer: Research Funding; Sanquin: Speakers Bureau; Bayer: Speakers Bureau; Sanquin: Research Funding; Bayer: Research Funding; Boehringer Ingelheim: Speakers Bureau; BMS: Speakers Bureau; Aspen: Speakers Bureau; Uniqure: Consultancy. von Drygalski:Biomarin: Consultancy; Bioverativ/Sanofi Genzyme: Consultancy; NovoNordisk: Consultancy; Pfizer: Consultancy; uniQure: Consultancy; Hematherix Inc.: Membership on an entity's Board of Directors or advisory committees. Young:Genentech/Roche, Grifols, and Takeda: Research Funding; BioMarin, Freeline, Genentech/Roche, Grifols, Kedrion, Novo Nordisk, Sanofi Genzyme, Spark, Takeda, and UniQure: Honoraria; Bayer, CSL Behring, Freeline, UniQure: Consultancy. Hermans:WFH: Other; EAHAD: Other; LFB: Consultancy, Speakers Bureau; CSL Behring: Consultancy, Speakers Bureau; CAF-DCF: Consultancy, Speakers Bureau; Biogen: Consultancy, Speakers Bureau; Sobi: Consultancy, Research Funding, Speakers Bureau; Shire, a Takeda company: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau; Octapharma: Consultancy, Speakers Bureau; Kedrion: Speakers Bureau. Astermark:Bayer, CSL Behring, Novo Nordisk, Octapharma, Roche, Sobi, Spark, Takeda, uniQure: Consultancy; uniQure: Research Funding. Klamroth:Bayer: Consultancy, Research Funding, Speakers Bureau; Biomarin: Consultancy, Research Funding, Speakers Bureau; CSL Behring: Research Funding, Speakers Bureau; Novo Nordisk: Consultancy, Research Funding, Speakers Bureau; Octapharma: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Roche/Chugai: Consultancy, Speakers Bureau; Takeda/Shire: Consultancy, Research Funding, Speakers Bureau; Sobi: Consultancy, Speakers Bureau; Biotest: Speakers Bureau; LEO: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Lemons:uniQure: Research Funding. Visweshwar:Biogen Idec: Membership on an entity's Board of Directors or advisory committees. Escobar:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; National Hemophilia Foundation: Consultancy, Membership on an entity's Board of Directors or advisory committees; Biomarin, Genetech/Roche, CSL Behring, Kedrion, Magellan Healthcare: Honoraria. Gomez:Global Blood Therapeutics: Speakers Bureau. Kruse-Jarres:CSL Behring, Genentech, Inc., Spark: Research Funding; Biomarin, Chugai Pharmaceutical Co., CSL Behring, CRISPR Therapeutics, Genentech, Inc.: Honoraria; F. Hoffmann-La Roche Ltd: Speakers Bureau; Biomarin, Chugai Pharmaceutical Co., CSL Behring, CRISPR Therapeutics, Genentech, Inc.: Consultancy. Kotowski:uniQure: Research Funding. Quon:Orthopaedic Institute for Children: Current Employment; Bayer: Honoraria; Biomarin: Honoraria, Speakers Bureau; Bioverativ/Sanofi: Honoraria, Speakers Bureau; Genentech, Inc./F. Hoffmann-La Roche Ltd: Honoraria, Speakers Bureau; Novo Nordisk: Honoraria, Speakers Bureau; Octapharma: Honoraria; Shire/Takeda: Speakers Bureau. Wang:Bayer: Honoraria; Takeda: Honoraria; Genentech: Honoraria; Biomarin: Honoraria; CSL Behring: Honoraria; Bioverativ Inc: Honoraria; Catalyst Biologics: Consultancy; NovoNordisk: Consultancy; Hema biologics / LFB: Consultancy. Wheeler:Takeda: Membership on an entity's Board of Directors or advisory committees; uniQure: Membership on an entity's Board of Directors or advisory committees; Biomarin: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees. Sawyer:uniQure: Current Employment, Current equity holder in publicly-traded company. Verweij:uniQure: Current Employment. Colletta:uniQure: Current Employment. Bajma:uniQure: Current Employment. Gut:uniQure: Current Employment. Miesbach:Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biomarin: Consultancy, Membership on an entity's Board of Directors or advisory committees; Freeline: Consultancy, Membership on an entity's Board of Directors or advisory committees; LFB: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Consultancy; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; uniQure: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotest: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: Etranacogene dezaparvovec is an investigational gene therapy

Abstract: Etranacogene dezaparvovec (AMT-061) is a recombinant adeno-associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant human factor IX (FIX) transgene with a liver-specific promoter. Here, we report 3-year outcomes from a phase 2b, open-label, single-dose, single-arm, multicenter trial conducted among adults with severe or moderately severe hemophilia B (FIX ≤2%). All participants (n = 3) received a single intravenous dose (2 × 1013 gene copies per kg) and will be followed up for 5 years. The primary end point of FIX activity ≥5% at 6 weeks was met. Secondary end points included bleed frequency, FIX concentrate use, joint health, and adverse events (AEs). All participants required routine FIX prophylaxis and had neutralizing antibodies to AAV5 before etranacogene dezaparvovec treatment. After administration, FIX activity rose to a mean of 40.8% in year 1 and was sustained in year 3 at 36.9%. All participants discontinued FIX prophylaxis. Bleeding was completely eliminated in 2 out of 3 participants. One participant required on-demand FIX replacement therapy per protocol because of elective surgical procedures, for 2 reported bleeding episodes, and twice for a single self-administered infusion because of an unreported reason. One participant experienced 2 mild, self-limiting AEs shortly after dosing. During the 3-year study period, there were no clinically significant elevations in liver enzymes, no requirement for steroids, no FIX inhibitor development, and no late-emergent safety events in any participant. Etranacogene dezaparvovec was safe and effective in adults with hemophilia B over 3 years after administration. This trial was registered at www.clinicaltrials.gov as #NCT03489291.

Abstract: Background: Gene therapy for hemophilia offers the possibility to ameliorate disease severity to a mild or functionally curative state through a single administration. Etranacogene dezaparvovec (AMT-061) is an investigational gene therapy for hemophilia B comprising an adeno associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant human factor IX (FIX) gene with liver specific promoter. Aims: We have previously shown a single dose of etranacogene dezaparvovec to provide sustained FIX activity into the mild-to normal range for up to 52 weeks post-dose in participants with severe or moderate-severe hemophilia B. This time, 2 years of follow-up data will be presented for the first time. Methods: A Phase 2b, open-label, single-dose, single-arm, multi-center trial (NCT03489291) in adult hemophilia B subjects. Interestingly, participants were not excluded based on neutralizing antibodies to AAV5. All subjects received a single intravenous dose of etranacogene dezaparvovec (2x1013 gc/kg) and will be followed for 5-years. The primary endpoint was FIX activity at Week 6. Secondary endpoints include e-diary recordings of bleeds and FIX concentrate use, laboratory parameters, joint health, patient reported outcomes, and adverse events (AEs). Results: All participants had FIX ≤1% (severe or moderately-severe FIX deficiency), required routine FIX prophylaxis, and had neutralizing activity to AAV5 at baseline. Following AMT-061 treatment, FIX activity increased rapidly to a mean of 31% at Week 6. At Week 52, mean FIX activity increased further to 41% with FIX activity levels of 50%, 31% and 41% in participants 1-3 respectively. There was no relationship between the presence of anti-AAV5 NAbs and response to etranacogene dezaparvovec. As of 52 weeks, there were no bleeds post-treatment and no requirement for FIX replacement aside from protocol-specified use for perioperative management in participant 3. There were no clinically significant elevations in liver enzymes and no participants required steroids related to the treatment. One participant experienced 2 mild AEs possibly related to treatment shortly after dosing (self-limiting headache and slightly elevated CRP). One patient had hip surgery due to worsening of pre-existing avascular necrosis deemed unrelated by investigator to etranacogene dezaparvovec and received FIX per protocol according to standard clinical practice. No participant developed inhibitors to FIX. Updated results to 2 years of follow-up will be presented with the main focus on FIX activity, FIX replacement therapy use and reported bleeds. Conclusions: Patients with AAV5 NAbs were included in the Phase 2b etranacogene dezaparvovec trial and have shown sustained FIX activity into the mild-to normal range. All participants were able to discontinue routine prophylaxis, and there have been no bleeds post-treatment with etranacogene dezaparvovec. Disclosures Giermasz: BioMarin: Consultancy, Research Funding, Speakers Bureau; Genentech/Roche: Consultancy, Research Funding, Speakers Bureau; uniQure: Consultancy, Research Funding; Sangamo Therapeutics: Research Funding; Bioverativ/Sanofi: Consultancy, Research Funding, Speakers Bureau. Castaman:Alexion: Honoraria; Roche: Consultancy, Honoraria, Speakers Bureau; CSL Behring: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Ablynx: Honoraria; Baxalta/Shire: Honoraria; Bayer: Honoraria; Uniqure: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kedrion: Speakers Bureau; Werfen: Speakers Bureau; Sobi: Honoraria, Research Funding, Speakers Bureau; Novo Nordisk: Honoraria, Speakers Bureau. Key:Novo Nordisk: Other: Chair of Grants Committee; Takeda: Research Funding; Grifols: Research Funding; Uniqure: Consultancy. Miesbach:Bayer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BioMarin Pharmaceutical Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; UniQure: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Recht:Spark: Research Funding; Novo Nordisk: Consultancy, Other: personal fees, Research Funding; uniQure: Consultancy, Other: personal fees, Research Funding; Takeda: Consultancy, Other: personal fees, Research Funding; BioMarin: Research Funding; Pfizer: Consultancy, Other: personal fees; Genentech: Consultancy, Other: personal fees, Research Funding; CSL Behring: Consultancy, Other: personal fees. Gomez:Global Blood Therapeutics: Speakers Bureau. Gut:uniQure: Current Employment. Pipe:Siemens: Research Funding; Medical and Scientific Advisory Council to the National Hemophilia Foundation; Medical Advisory Board to World Federation of Hemophilia: Membership on an entity's Board of Directors or advisory committees; Apcintex, Bayer, BioMarin, Catalyst Biosciences, CSL Behring, HEMA Biologics, Freeline, Novo Nordisk, Pfizer, F. Hoffmann-La Roche Ltd/Genentech, Inc., Sangamo Therapeutics, Sanofi, Takeda, Spark Therapeutics, uniQure: Consultancy. OffLabel Disclosure: Etranacogene dezaparvovec (AMT-061) is an investigational gene therapy for hemophilia B comprising an adeno associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant human factor IX (FIX) gene with liver specific promoter.