Hemgenix Shortage: What Providers and Prescribers Need to Know in 2026

In March 2026, CSL Behring issued a formal notice to the hemophilia B community disclosing a temporary global stockout of Hemgenix (etranacogene dezaparvovec-drlb). For hematologists, HTCs, and other prescribing providers, this announcement has immediate implications for patient care planning, treatment scheduling, and clinical conversations.

This guide provides a clinical overview of the shortage situation and practical recommendations for providers managing patients who are awaiting or considering Hemgenix.

Current Shortage Status: What CSL Behring Has Communicated

CSL Behring's March 2026 communication was clear on several key points:

The stockout is temporary and not related to any safety, efficacy, or regulatory concern regarding the product itself.

It reflects the complexity of manufacturing gene therapies and adherence to the highest regulatory and quality standards.

CSL Behring is working with regulatory authorities on strategies to ensure stable ongoing supply while preserving quality standards.

Patients in countries with established commercial access may experience treatment delays.

Providers should contact their CSL Behring representative directly for region-specific supply timelines and to discuss individual patient situations.

Understanding Why Hemgenix Supply Is Structurally Fragile

Hemgenix is manufactured as a patient-specific kit based on body weight. The recommended dose is 2 × 10¹³ genome copies per kg (2 mL/kg), meaning each kit must match the patient's weight category. For patients in the 126–130 kg range, this translates to approximately 252–260 mL of product, dispensed from 10–48 individual vials depending on the weight-tier kit configuration.

This weight-specific production model — combined with the labor-intensive AAV5 vector manufacturing process, multi-stage batch testing, and FDA/EMA batch release requirements — means there is no simple way to quickly scale production in response to a supply gap. The small patient population (approximately 7,250 in the U.S.) also limits the economic incentive to build excess manufacturing redundancy.

Clinical Implications for Patients in the Pipeline

Providers should identify which patients are at various stages of the Hemgenix treatment pathway and communicate proactively:

Patients with insurance authorization approved: Confirm authorization expiration dates. Many authorizations are time-limited (commonly 12 months). If approval may expire before supply is restored, request renewal proactively.

Patients with pre-treatment screening completed: Review validity windows. Factor IX inhibitor tests, liver function panels, and AAV5 NAb titers may need to be repeated if too much time passes. Track and rebook as needed.

Patients who had treatment dates cancelled: Provide written communication noting the supply-related cancellation. Reassure patients that the delay is not related to their eligibility or the drug's safety profile.

Patients early in evaluation: Encourage them to continue the workup — completing eligibility testing and insurance authorization now maximizes readiness for when supply returns.

Bridge Therapy Recommendations During the Shortage

Patients who were on active Factor IX prophylaxis prior to beginning the Hemgenix evaluation should be maintained on their existing regimen. For patients experiencing inadequate bleed control on their current Factor IX product, consider transitioning to an extended half-life (EHL) product:

Alprolix (eftrenonacog alfa): EHL FIX Fc fusion protein; once-weekly prophylaxis in most patients; FDA-approved for adults and children.

Idelvion (albutrepenonacog alfa): Albumin-FIX fusion protein; once-weekly or every 10–14 day dosing possible; also from CSL Behring.

Rebinyn (nonacog beta pegol): PEGylated FIX; once-weekly dosing for adults and adolescents ≥12 years.

For patients with inhibitors, or those who cannot tolerate IV infusions, non-factor therapies such as Alhemo (concizumab), Hympavzi (marstacimab), or Qfitlia (fitusiran) are appropriate considerations per current MASAC guidelines.

How Providers Can Help Patients Navigate the Shortage

Several practical steps can help your patients during this period:

Enroll patients in HEMGENIX Connect (1-833-436-0021) so their assigned Case Manager can track supply status and notify them directly.

Ensure all pre-treatment paperwork and insurance authorizations are in place so patients can be treated as soon as supply is confirmed.

Recommend medfinder to patients who want help checking availability across multiple treatment centers. medfinder contacts centers on their behalf and reports results by text, reducing the burden on both patients and HTC staff.

For a step-by-step provider guide on helping patients find Hemgenix, see How to Help Your Patients Find Hemgenix in Stock. Providers can also visit medfinder.com/providers to learn how medfinder supports the hemophilia care team.