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HEMGENIX®-logo-bg HEMGENIX® (etranacogene dezaparvovec)

Safety Profile For Hemgenix

In clinical studies, HEMGENIX was safe and effective, with no treatment-related serious adverse events and no development of factor IX inhibitors reported.

Adverse Events With HEMGENIX

Adverse Reactions ≥5%
Subjects (%) (N=57)*

Alanine aminotransferase increased

24 (42%)


10 (18%)

Blood creatine kinase increased

24 (42%)

Flu-like symptoms

8 (14%)

Infusion-related reactions (see below)

19 (33%)


2 (4%)


7 (12%)

Aspartate aminotransferase increased

24 (42%)


4 (7%)


7 (12%)

*N=57 patients (N=3 patients from a Phase 2b and N=54 patients from a Phase 3 clinical study).

Infusion-related reaction: In 7 subjects, symptoms occurred during infusion; in 12 subjects, after infusion.
Symptoms occurring in ≥5% of subjects were: Dizziness, flu-like symptoms and headache. Symptoms occurring in <5% of subjects were: Abdominal pain, abdominal discomfort, chest discomfort, chills, eye
pruritus, fever (pyrexia), flushing, hives (urticaria), infusion site reaction, and tachycardia. Eleven subjects recovered on the day or day after infusion. Eight subjects recovered within 8 days after infusion.

One of 2 hypersensitivity reactions: 12 minutes after initiation of administration of HEMGENIX, the patient experienced high blood pressure, red eyes, feeling warm, dizziness, coughing, dyspnea, elevated heart rate, shivering, and leg cramps. Infusion was stopped and not restarted. Only 10% of the dose of HEMGENIX was administered. The patient recovered on the same day after treatment with intravenous diphenhydramine and intramuscular epinephrine.

2 of 2 hypersensitivity reactions: 10 minutes after initiation of administration of HEMGENIX, the patient experienced itching, tightness of throat, and swelling of the right side of the neck. The dose of HEMGENIX was not interrupted and administered in full. All symptoms resolved on the same day without treatment.

Safety Considerations



IV bag icon

Infusion-related reactions (IRRs) occurred in 19/57 (33%) of patients. The majority (58%) of patients recovered on the day of or one day after infusion.

In the event of an IRR during administration, the infusion may be slowed or temporarily stopped and restarted at a slower rate once the infusion reaction is resolved. Treatment with a corticosteroid or antihistamine may be considered for management of IRR.

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In the clinical studies, ALT elevation occurred in 24/57 (42%) of patients.

  • The onset of ALT elevations ranged from day 8–day 731 post-dose
  • Nine patients with ALT elevations received a tapered course of corticosteroid. The mean duration of corticosteroid treatment for the elevated ALT was 81.4 days
  • Prophylactic steroids to prevent ALT elevation were not required
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Warning and Precautions

Infusion Reactions

Infusion reactions, including hypersensitivity reactions and anaphylaxis, may occur. Monitor during administration and for at least 3 hours after end of infusion. If symptoms occur, slow or interrupt administration. Re-start administration at a slower infusion once resolved.

Hepatotoxicity/Hepatocellular Carcinoma

Post-dose, monitor for elevated transaminase levels. Consider corticosteroid treatment should elevations occur. 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, perform regular (eg, annual) abdominal ultrasound and alpha-fetoprotein testing following administration.

Immune-mediated neutralization of the AAV5 vector capsid

Preexisting neutralizing anti-AAV antibodies may impede transgene expression at desired levels.

Monitoring Laboratory Tests

In addition to monitoring liver function, monitor for Factor IX activity and Factor IX inhibitors after administration.

Adverse Reactions

The most common adverse reactions (incidence ≥5%) were elevated ALT, headache, blood creatine kinase elevations, flu-like symptoms, infusion-related reactions, fatigue, nausea, malaise, and elevated AST.


HEMGENIX®, etranacogene dezaparvovec-drlb, is an adeno-associated virus vector-based gene therapy indicated for the treatment of adults with Hemophilia B (congenital Factor IX deficiency) who:

  • Currently use Factor IX prophylaxis therapy, or
  • Have current or historical life-threatening hemorrhage, or
  • Have repeated, serious spontaneous bleeding episodes.

HEMGENIX is for single use intravenous infusion only.

Contraindications: None.

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