Traceability
In order to improve the traceability of biological medicinal products, the name and the batch number of the administered product should be clearly recorded.
Initiation of treatment with Hemgenix
Patients with pre-existing antibodies to the AAV5 vector capsid
Prior to the treatment with Hemgenix, patients should be assessed for the titre of pre-existing neutralising anti-AAV5 antibodies.
Pre-existing neutralising anti-AAV5 antibodies above a titre of 1:898, based on the neutralising anti-AAV5 antibody assay with extended measuring range (equivalent to 1:678 titre based on the previous clinical study assay), may impede transgene expression at desired therapeutic levels and thus reduce the efficacy of Hemgenix therapy (see section 5.1).
There is limited data in patients with neutralising anti-AAV5 antibodies above 1:898 (equivalent to the 1:678 titre based on the clinical study assay). In the clinical studies with etranacogene dezaparvovec, in 1 patient with a pre-existing neutralising anti-AAV5 antibody titre of 1:3212 (tested using the clinical study assay equivalent to 1:4417 titre based on the neutralising anti-AAV5 antibody assay with extended measuring range), no Factor IX expression was observed and restarting of exogenous Factor IX prophylaxis was needed (see section 5.1).
In the clinical studies with etranacogene dezaparvovec, for the patient sub-group with detectable pre-existing neutralising anti-AAV5 antibodies up to a titre of 1:678 (tested using the clinical study assay, equivalent to 1:898 titre based on the neutralising anti-AAV5 antibody assay with extended measuring range), mean Factor IX activity levels were within the same range but numerically lower compared to those of the patient sub-group without detectable pre-existing neutralising anti-AAV5 antibodies. However, both patient groups, with and without detectable pre-existing neutralising anti-AAV5 antibodies, demonstrated an improved haemostatic protection compared to the standard of care Factor IX prophylaxis after etranacogene dezaparvovec administration (see section 5.1).
Baseline hepatic function
Prior to the treatment with Hemgenix, patient's liver transaminases should be assessed and liver ultrasound and elastography performed, along with laboratory tests to evaluate for active Hepatitis B and C. This includes:
• Enzyme testing (alanine aminotransferase (ALT), aspartate aminotransferase (AST) alkaline phosphatase (ALP) and total bilirubin). ALT test results no later than within 3 months prior to treatment should be obtained, and ALT testing repeated at least once prior to Hemgenix administration to establish patient's ALT baseline.
• Hepatic ultrasound and elastography assessment obtained no later than within 6 months before Hemgenix administration.
In case of radiological liver abnormalities and/or sustained liver enzyme elevations, consideration of a consultation with a hepatologist is recommended to assess eligibility for Hemgenix administration (see information on hepatic function and Factor IX monitoring below). In patients with active Hepatitis B or C, etranacogene dezaparvovec treatment must be postponed until the infection is no longer active (see section 4.3).
Infusion-related reactions – During or shortly after Hemgenix infusion Infusion reactions, including hypersensitivity reactions and anaphylaxis, are possible (see section 4.8). Patients should be closely monitored for infusion reactions throughout the infusion period and at least for 3 hours after end of infusion.
The recommended infusion rate provided in section 4.2 should be closely adhered to ensure patient tolerability.
Suspicion of an infusion reaction requires slowing or stopping of the infusion (see section 4.2). Based on clinical judgement, treatment with e.g. a corticosteroid or antihistamine may be considered for management of an infusion reaction.
Monitoring after the treatment with Hemgenix
Hepatotoxicity
Intravenous administration of a liver-directed AAV vector may potentially lead to liver transaminase elevations (transaminitis). The transaminitis is presumed to occur due to immune-mediated injury of transduced hepatocytes and may reduce the therapeutic efficacy of the gene therapy.
In clinical studies with etranacogene dezaparvovec, transient, asymptomatic, and predominantly mild liver transaminase elevations were observed, most often in the first 3 months after etranacogene dezaparvovec administration. These transaminase elevations resolved either spontaneously or with corticosteroid treatment (see section 4.8).
To mitigate the risk of potential hepatotoxicity, patient`s liver transaminases should be evaluated and liver ultrasound and elastography performed before treatment (see section 4.2). After Hemgenix administration, transaminases should be closely monitored, e.g. once per week for at least 3 months. A course of corticosteroid taper should be considered in the event of ALT increase to above the upper limit of normal or to double the patient's baseline levels, along with human Factor IX activity examinations (see section 4.4 “Hepatic function and Factor IX monitoring”). Follow-up monitoring of transaminases in all patients who developed liver enzyme elevations is recommended on a regular basis until liver enzymes return to baseline values.
The safety of etranacogene dezaparvovec in patients with severe hepatic impairment, including cirrhosis, severe liver fibrosis (e.g. suggestive of or equal to METAVIR [Meta-analysis of Histological Data in Viral Hepatitis] Stage 3 disease or a liver elastography (FibroScan) score of ≥9 kPa), or uncontrolled Hepatitis B and C, have not been studied (see sections 4.3 and 5.2).
Factor IX assays
The results of Factor IX activity tests are lower if measured with chromogenic substrate assay (CSA) compared to one-stage clotting assay (OSA).
In clinical studies, the post-dose Factor IX activity measured with CSA returned lower values with the mean CSA to OSA Factor IX activity ratio ranging from 0.408 to 0.547 (see section 5.1).
Hepatic function and Factor IX monitoring
In the first 3 months after Hemgenix administration, the purpose of hepatic and Factor IX monitoring is to detect increases in ALT, which may be accompanied by decreased Factor IX activity and may indicate the need to initiate corticosteroid treatment (see sections 4.2 and 4.8). After the first 3 months of administration, hepatic and Factor IX monitoring is intended to routinely assess liver health and bleeding risk, respectively.
A baseline assessment of liver health (including liver function tests within 3 months and recent fibrosis assessment using either imaging modalities, such as ultrasound elastography, or laboratory assessments, within 6 months) should be obtained before administration of Hemgenix. Consider obtaining at least two ALT measurements prior to administration, or use an average of prior ALT measurements (for example within 4 months) to establish patient's baseline ALT. It is recommended that the hepatic function is evaluated through a multidisciplinary approach with involvement of a hepatologist to best adjust the monitoring to the patient's individual condition.
It is recommended (where possible) to use the same laboratory for hepatic testing at baseline and monitoring over time, particularly during the timeframe for corticosteroid treatment decision making, to minimise the impact of inter‑laboratory variability.
After administration, the patient's ALT and Factor IX activity levels should be monitored according to Table 1. To assist in the interpretation of ALT results, monitoring of ALT should be accompanied by monitoring of AST and creatine phosphokinase (CPK) to help rule out alternative causes for ALT elevations (including potentially hepatotoxic medicinal products or agents, alcohol consumption, or strenuous exercise). Based on patient's ALT elevations, corticosteroid treatment may be indicated (see Corticosteroid regimen). Weekly monitoring is recommended, and as clinically indicated, during corticosteroid tapering.
Treating physicians should ensure the availability of patients for frequent monitoring of hepatic laboratory parameters and Factor IX activity after administration.
Table 1: Hepatic function and Factor IX activity monitoring
| | Measurements | Timeframe | Monitoring frequencya |
| Before administration | Liver function tests | Within 3 months prior to infusion | Baseline measurement |
| Recent fibrosis assessment | Within 6 months prior to infusion |
| After administration | ALTb and Factor IX activity | First 3 months | Weekly |
| Months 4 to 12 (Year 1) | Every 3 months |
| Year 2 | • Every 6 months for patients with Factor IX activity levels > 5 IU/dL (see Factor IX assays) • Consider more frequent monitoring in patients with Factor IX activity levels ≤ 5 IU/dL and consider the stability of Factor IX levels and evidence of bleeding. |
| | | After Year 2 | • Every 12 months for patients with Factor IX activity levels > 5 IU/dL (see Factor IX assays) • Consider more frequent monitoring in patients with Factor IX activity levels ≤ 5 IU/dL and consider the stability of Factor IX levels and evidence of bleeding. |
a Weekly monitoring is recommended, or as clinically indicated, during corticosteroid tapering. Adjustment of the monitoring frequency may also be indicated depending on the individual situation.
b Monitoring of ALT should be accompanied by monitoring of AST and CPK, to rule out alternative causes for ALT elevations (including potentially hepatotoxic medications or agents, alcohol consumption, or strenuous exercise).
If a patient returns to prophylactic use of Factor IX concentrates/haemostatic agents for haemostatic control, consider following monitoring and management consistent with instructions for those agents. An annual health check‑up should include liver function tests.
Corticosteroid regimen
An immune response to the AAV5 capsid protein will occur after administration of etranacogene dezaparvovec. This may in some cases lead to elevation in liver transaminases (transaminitis) (see above and section 4.8). In case of elevated ALT levels above the upper limit of normal or doubling of the patient's baseline within the first 3 months post-dose, a corticosteroid treatment should be considered to dampen the immune response, e.g. starting with oral 60 mg/day prednisolone or prednisone (see Table 2).
It is further recommended to assess possible alternative causes of the ALT elevation including administration of potentially hepatotoxic medicinal products or agents, alcohol consumption, or strenuous exercise. Retesting of ALT levels within 24 to 48 hours and, if clinically indicated, performing additional tests to exclude alternative aetiologies should be considered.
Table 2. Recommended prednisolone treatment in response to ALT elevations:
| Timeline | Prednisolone oral dose (mg/day)* |
| Week 1 | 60 |
| Week 2 | 40 |
| Week 3 | 30 |
| Week 4 | 30 |
| Maintenance dose until ALT level returns to baseline level | 20 |
| Taper dose after baseline level has been reached | Reduce daily dose by 5 mg/week |
*Medicinal products equivalent to prednisolone may also be used. A combined immunosuppressant regimen or the use of other immunosuppressive therapy can also be considered in case of prednisolone treatment failure or contraindication (see section 4.5). It is further recommended to set a multidisciplinary consultation involving a hepatologist, to best adjust the alternative to corticosteroids and the monitoring to the patient's individual condition.
Risk of thromboembolic events
Patients with Haemophilia B have, compared to the general population, a reduced potential for thromboembolic events (e.g. pulmonary thromboembolism or deep venous thrombosis) due to inborn deficiency in the clotting cascade. Alleviating symptoms of Haemophilia B by restoring Factor IX activity may expose patients to the potential risk of thromboembolism, as observed in the general non-haemophilic population.
In patients with Haemophilia B with pre-existing risk factors for thromboembolic events, such as a history of cardiovascular or cardiometabolic disease, arteriosclerosis, hypertension, diabetes, advanced age, the potential risk of thrombogenicity may be higher.
In the clinical studies with etranacogene dezaparvovec, treatment-related thromboembolic events were not reported (see section 5.1). In addition, no supraphysiological Factor IX activity levels were observed.
Contraceptive measures in relation to transgene DNA shedding in semen
Male patients should be informed on the need for contraceptive measures for them or their female partners of child bearing potential (see section 4.6).
Blood, organ, tissue and cell donation
Patients treated with Hemgenix must not donate blood, organs, tissues and cells for transplantation. This information is provided in the Patient Card which must be given to the patient after treatment.
Immunocompromised patients
No immunocompromised patients, including patients undergoing immunosuppressive treatment within 30 days before etranacogene dezaparvovec infusion, were enrolled in clinical studies with etranacogene dezaparvovec. Safety and efficacy of this medicinal product in these patients have not been established. Use in immunocompromised patients is based on healthcare professional`s judgment, taking into account the patient's general health and potential for corticosteroid use post-etranacogene dezaparvovec treatment.
HIV positive patients
Limited clinical data are available in patients with controlled HIV infection treated with etranacogene dezaparvovec (see sections 4.2 and 5.1).
The safety and efficacy in patients with HIV infection not controlled with anti-viral therapy, as shown by CD4+ counts ≤200/μL, was not established in clinical studies with etranacogene dezaparvovec (see section 4.3).
Patients with active or uncontrolled chronic infections
There is no clinical experience with administration of etranacogene dezaparvovec in patients with acute infections (such as acute respiratory infections or acute hepatitis) or uncontrolled chronic infections (such as active chronic Hepatitis B or Hepatitis C). It is possible that such acute or uncontrolled infections may affect the response to Hemgenix and reduce its efficacy and/or cause adverse reactions. In patients with such infections, Hemgenix treatment is contraindicated (see section 4.3).
If there are signs or symptoms of acute or uncontrolled chronic active infections, Hemgenix treatment must be postponed until the infection has resolved or is controlled.
Patients with Factor IX inhibitors, Monitoring for Factor IX inhibitor development
There is no clinical experience with administration of etranacogene dezaparvovec in patients who have or had inhibitors to Factor IX. It is not known whether or to what extent such pre-existing Factor IX inhibitors may affect the safety or efficacy of Hemgenix. In patients with a history of Factor IX inhibitors, Hemgenix treatment is not indicated (see section 4.1).
In the clinical studies with etranacogene dezaparvovec, patients had no detectable Factor IX inhibitors at baseline, and formation of inhibitors to etranacogene dezaparvovec was not observed after treatment (see section 5.1).
Patients should be monitored through appropriate clinical observations and laboratory tests for the development of inhibitors to Factor IX after Hemgenix administration.
Use of Factor IX concentrates or haemostatic agents after treatment with etranacogene dezaparvovec
Following administration of etranacogene dezaparvovec:
• Factor IX concentrates/haemostatic agents may be used in case of invasive procedures, surgery, trauma, or bleeds, consistent with current treatment guidelines for the management of Haemophilia, and based on the patient's current Factor IX activity levels.
• If the patient's Factor IX activity levels are consistently below 5 IU/dL and the patient has experienced recurrent spontaneous bleeding episodes, physicians should consider the use of Factor IX concentrates to minimise such episodes, consistent with current treatment guidelines for the management of Haemophilia. Target joints should be treated in accordance with relevant treatment guidelines.
Repeated treatment and impact to other AAV-mediated therapies
It is not yet known whether or under what conditions Hemgenix therapy may be repeated, and to what extent developed endogenous cross-reacting antibodies could interact with the capsids of AAV vectors used by other gene therapies, potentially impacting their treatment efficacy (see section 4.4 further above).
Risk of malignancy as a result of vector integration
Integration site analysis was performed on liver samples from one patient treated with Hemgenix in clinical studies. Samples were collected one year post-dose. Vector integration into human genomic DNA was observed in all samples.
The clinical relevance of individual integration events is not known to date, but it is acknowledged that individual integration into human genome could potentially contribute to a risk of malignancy.
In the clinical studies, no malignancies were identified in relation to treatment with etranacogene dezaparvovec (see sections 5.1 and 5.3). In the event that a malignancy occurs, the marketing authorisation holder should be contacted by the treating healthcare professional to obtain instructions on collecting patient samples for potential vector integration examination and integration site analysis.
It is recommended that patients with preexisting risk factors for hepatocellular carcinoma (such as hepatic fibrosis, hepatitis C or B disease, non-alcoholic fatty liver disease) undergo regular liver ultrasound screenings and are regularly monitored for alpha-fetoprotein (AFP) elevations (e.g. annually) for at least 5 years after Hemgenix administration (see also section 4.3).
Long-term follow up
Patients are expected to be enrolled in a follow-up study to follow Haemophilia patients for 15 years, to substantiate the long-term safety and efficacy of Hemgenix gene therapy.
Sodium and potassium content
This medicinal product contains 35.2 mg sodium per vial, equivalent to 1.8% of the WHO recommended maximum daily intake of 2 g sodium for an adult.
This medicinal product contains potassium, less than 1 mmol (39 mg) per vial, that is to say essentially potassium-free.