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The latest data reinforce the long-term efficacy and safety profile of HEMGENIX1
through 5 years post-administration
of HEMGENIX1
*Two patients experienced lack of efficacy. One patient had the highest NAb titer of 1:3212, and 1 patient received ~10% of the planned dose. One patient returned to factor IX prophylaxis at month 30 and their last factor IX activity levels were 3.6%. An additional patient required intermittent prophylaxis for approximately 20 weeks during months 7－18.
†Joint ABR during lead-in versus months 7–60 (2.34 vs 0.35; p<0.0001).
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No clinically meaningful correlation was identified between a subject’s AAV5 NAb titer at baseline (up to a titer of 1:678) and their factor IX activity at Year 5 postdose.
aPTT, activated partial thromboplastin time; M, Month; W, Week.
‡Baseline factor IX was imputed based on the subject’s historical hemophilia B severity documented on the Case Report Form. If the subject had documented severe factor IX deficiency (factor IX plasma level <1%), their baseline factor IX activity level was imputed as 1%. If the subject had documented moderately severe factor IX deficiency (factor IX plasma level ≥1% and ≤2%), their baseline factor IX activity level was imputed as 2%. Standard error was not provided at baseline.
Notes: Exogenous data from the central laboratory were used; "exogenous" meant that the blood sampling did not occur within 5 half-lives of exogenous FIX use. FIX levels beginning with the Week 3 assessment were used in the analysis. Both the date and time of exogenous FIX use (start) and blood sampling were considered in determining contamination. All efficacy data collected after liver transplants were excluded from the analysis. The lower and upper edges of the box correspond to the interquartile range, the 25th, and 75th percentile. The line at the middle of the box corresponds to the median. The "whiskers" (horizontal lines connected to vertical lines) show the lowest and highest observation within 1.5 times the interquartile range of the bottom and top of the box, respectively. The diamond is the arithmetic mean. Any points outside of the whiskers are plotted individually.
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ABR, annualized bleeding rate.
§ABR for all bleeds during Months 7–60 post-gene therapy was significantly reduced to 1.52 vs 4.16 during the lead-in period (rate ratio 0.37 [95% CI 0.18–0.76], p=0.0035).
| TRAEs by MedDRA PT|| | Up to Year 5 | |
|---|---|---|
| n (%) | No. of Events | |
| At least 1 TRAE¶ | 39 (72.2) | 100 |
| ALT increased | 10 (18.5) | 11 |
| Headache | 8 (14.8) | 9 |
| Influenza-like illness | 7 (13.0) | 8 |
| AST increased | 6 (11.1) | 7 |
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| TRAEs by MedDRA PT|| | Up to Year 5 | |
|---|---|---|
| n (%) | No. of Events | |
| At least 1 TRAE¶ | 39 (72.2) | 100 |
| ALT increased | 10 (18.5) | 11 |
| Headache | 8 (14.8) | 9 |
| Influenza-like illness | 7 (13.0) | 8 |
| AST increased | 6 (11.1) | 7 |
ALT, alanine aminotransferase; AST, aspartate aminotransferase; PT, Preferred Term.
||Medical Dictionary for Regulatory Archives (MedRA) Version 26.0 was used for coding.
¶Related=Possibly related or related.
#Infusion-related reactions were defined as any AEs related to the investigation medical product administration procedure or unexpected reactions. They were any treatment-emergent adverse event occurring within 24 hours of infusion, qualifying for special notification, assessed as related or possibly related by the investigator and considered as an infusion-related reaction during the safety assessment. They were infusion-site reaction, hypersensitivity (ie, urticaria), facial flushing, itching, headache, dizziness, etc.
References: 1. Pipe S, Miesbach W, Recht M, et al. End-of-study analysis of the HOPE-B trial confirms the durable efficacy and safety of etranacogene dezaparvovec hemophilia b gene therapy over 5 years. Paper presented at: 67th ASH Annual Meeting and Exposition; December 6-9, 2025; Orlando, FL. 2. Pipe S, Miesbach W, Recht M, et al. Hope-B Study Group Investigators. Final analysis of a study of etranacogene dezaparvovec for hemophilia B. N Engl J Med. 2025 Dec 7. doi:10.1056/ NEJMoa2514332. 3. Recht M, Leebeek FWG, Miesbach W, et al. Management of Infusion Reactions: Lessons from the from the Phase 3 HOPE-B Gene Therapy Trial of Etranacogene Dezaparvovec in Adults with Hemophila B. Poster presented at 62nd ISTH congress. July 2021.
Patient Selection
Perform baseline testing to select patients, including titer testing for Factor IX (FIX) inhibitor presence. Do not administer HEMGENIX®, etranacogene dezaparvovec-drlb, to patients with FIX inhibitors or a history of FIX inhibitors. Perform liver health assessments, consulting with a hepatologist if needed. Also perform laboratory tests to evaluate hepatitis B and C, and postpone treatment if patient has active infection, as this may reduce the efficacy of HEMGENIX and/or increase the risk of adverse reactions.
Warnings and Precautions
Hypersensitivity and Infusion Reactions
Infusion reactions, including hypersensitivity reactions and anaphylaxis, have occurred. Monitor during administration and for at least 3 hours after end of infusion. If symptoms occur, slow or interrupt administration. When symptoms have resolved, restart administration at a slower infusion rate.
Hepatotoxicity/Hepatocellular Carcinogenicity
Hepatotoxicity with elevated liver transaminase has occurred after HEMGENIX treatment. Monitor ALT levels once per week for 3 months and thereafter monthly up to 1 year after administration. Consider corticosteroid treatment should elevations occur and as clinically indicated.
The integration of liver-targeting AAV vector DNA into the genome may carry the theoretical risk of hepatocellular carcinoma development. For patients with preexisting risk factors for hepatocellular carcinogenicity, consider liver ultrasound and alpha-fetoprotein testing following administration, and monitor for hepatocellular carcinomas for five years following administration of HEMGENIX.
Immune-Mediated Neutralization of the AAV5 vector capsid
Preexisting neutralizing anti-AAV antibodies may impede transgene expression at desired therapeutic levels. Following treatment with HEMGENIX, all patients developed neutralizing anti-AAV5 antibodies to AAV5 vector capsid.
Monitoring Laboratory Tests
Monitor patients regularly for FIX activity (eg, weekly for 3 months), especially when exogenous FIX is administered, as it may take several weeks following HEMGENIX administration before hemostatic control becomes apparent. Hemostatic support may be needed for some patients. Monitor patients through appropriate clinical observations and laboratory tests for the development of inhibitors to FIX.
Adverse Reactions
The most common adverse reactions (incidence ≥5% in clinical trials) are elevated ALT, headache, blood creatine kinase elevations, flu-like symptoms, infusion-related reactions, fatigue, nausea, malaise, and elevated AST.
Indication
HEMGENIX is indicated for the treatment of adults with Hemophilia B (congenital Factor IX deficiency) who:
HEMGENIX is for single-use intravenous infusion only.
Please see full prescribing information for HEMGENIX.
To report SUSPECTED ADVERSE REACTIONS, contact the CSL Behring Pharmacovigilance Department at 1-866-915-6958 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
