Etranacogene dezaparvovec-drlb gene therapy for patients with hemophilia B (congenital factor IX deficiency)

INTRODUCTION

Congenital hemophilia B (HB) is an X-linked bleeding disorder resulting in Factor IX (FIX) deficiency and bleeding of variable severity. There is no cure for HB. Typical management consists of prophylactic intravenous (IV) recombinant or plasma-derived FIX infusions. Etranacogene dezaparvovec-drlb (Hemgenix, AMT-061) is an adeno-associated virus serotype 5 (AAV5) vector containing a codon-optimized Padua variant of the human F9 gene with a liver-specific promoter. Etranacogene dezaparvovec-drlb received FDA approval on 22 November 2022 for the treatment of HB in adult patients who use FIX prophylaxis therapy, have current or historical life-threatening hemorrhage, or have experienced repeated, serious spontaneous bleeding episodes.

AREAS COVERED

This drug profile discusses the safety and efficacy of etranacogene dezaparvovec-drlb in patients with HB.

EXPERT OPINION

Etranacogene dezaparvovec-drlb therapy results in stable and sustained expression of near-normal to normal FIX levels in patients with HB regardless of neutralizing antibodies to AAV5 up to a titer of 678. Its use has led to significant reduction in bleeding and FIX prophylaxis. Etranacogene dezaparvovec-drlb was well tolerated; however, 17% of patients required corticosteroid therapy for alanine aminotransferase (ALT) elevation. Etranacogene dezaparvovec-drlb therapy marks the beginning of an exciting era in HB treatment and opens questions regarding treatment longevity and long-term safety.

Emicizumab in children: bleeding episodes and outcome before and after transition to Emicizumab

PURPOSE

Real-world data and study data regarding therapy with Emicizumab in pediatric cohorts with haemophilia A is scarce. Especially, data on previously untreated pediatric patients (PUPs) and minimally treated patients (MTPs) are missing.

METHODS

Thirteen pediatric patients with haemophilia A and treatment with Emicizumab were retrospectively evaluated for Annual Bleeding Rates (ABR) pre-and post-Emicizumab treatment. Safety data and data on management of minor surgery as well as laboratory results were collected. Additionally, we describe the clinical features of two PUPs and one MTP that are included in our cohort.

RESULTS

Median age at initiation of Emicizumab was 5.3 (range: 0.26-17.5) years, three patients were younger than one year at initiation of treatment with Emicizumab. Median follow-up time on Emicizumab was 23.8 (range: 0.7-40) months. Total ABR (p = 0.009) as well as spontaneous (p = 0.018), traumatic (p = 0.018), and joint (p = 0.027) ABR reduced significantly post-Emicizumab transition. Safety profile was favourable as only one local site reaction occurred; no cessation of treatment was necessary. Surgery was successfully performed in three patients receiving rFVlla pre- and post-surgery. Emicizumab trough levels showed a median of 43.2 μg/ml (range: 23.9-56.8) after three doses of 3 mg/kg and 51.9 μg/ml (range: 30.4-75) at first follow-up with 1.5 mg/kg.

CONCLUSION

Emicizumab is safe and efficient in pediatric patients with and without inhibitors. More data on larger multicenter cohorts and especially on PUPs/MTPs are still needed.

Efficacy, safety and pharmacokinetic profiles of a plasma-derived VWF/FVIII concentrate (VONCENTO®) in subjects with haemophilia A (SWIFT-HA study)

INTRODUCTION

VONCENTO® (CSL Behring) is a plasma-derived, high-concentration, low-volume, high-purity concentrate,which contains a high level of von Willebrand factor (VWF) high-molecular-weight multimers and aVWF/factor VIII (FVIII) ratio of ~2.4:1, similar to Haemate® P (CSL Behring).

METHODS

The pharmacokinetic, efficacy and safety profiles of VONCENTO® were investigated in this multicentre,double-blind, randomised study. Subjects aged ≥ 12 years with haemophilia A who required treatment of nonsurgical bleeds, treatment during surgical events or who were receiving prophylaxis were included. Pharmacokinetics were investigated with a single dose of 50 IU FVIII/kg body weight of either VONCENTO® or BIOSTATE® reference product (Biostate-RP) (Day 1; Day 8 [n= 16], repeated on Day 180 [VONCENTO® only; n=15]). Efficacy and safety analyses were performed either during on-demand treatment (n=52) or prophylaxis (n=29)for ≥ 6 months and ≥ 50 exposure days, respectively.

RESULTS

Besides the confirmation of bioequivalence between VONCENTO® and Biostate-RP, which displayed comparable PK profiles, haemostatic efficacy was rated by the investigators as either 'excellent' or 'good' in 96.4% of all bleeding events (96.5% spontaneous, 96.6% traumatic, 96.9% joint bleeds) as well as in 80% of major and 100% of minor surgical procedures at discharge. The median number of annualised bleeding events per subject [range] was significantly lower in the prophylaxis group (2.0 [0.0-34.6]) than in the on-demand group (14.0 [0.0-87.8], p = 0.0013).VONCENTO® was well tolerated and no inhibitory antibodies were identified during the study period.

CONCLUSIONS

This study demonstrated the bioequivalence of VONCENTO® to Biostate-RP, and its excellent efficacy and safety profile in haemophilia A subjects.