Gene Therapy in Hemophilia: An Assessment of Hematologists' Knowledge Gaps and Attitudes

BACKGROUND: Currently available treatments for hemophilia A and B require frequent intravenous infusions. Gene therapy, by contrast, offers the hope of a functional cure through endogenous expression of the factor VIII or factor IX genes. To identify and address practice gaps among healthcare providers who manage patients with hemophilia, a collaboration between the National Hemophilia Foundation (NHF), European Haemophilia Consortium (EHC), World Federation of Hemophilia (WFH), and Medscape Education was established. The objective of the current study is to assess clinicians' needs with regard to understanding the science and mechanism for gene therapy, the different technologies being proposed, identifying candidates for gene therapy, disease areas for which gene therapy is being explored, and the latest data on the potential role of gene therapy in hemophilia A and B.

METHODS: A continuing medical education (CME)-certified clinical practice assessment comprising 25 multiple choice questions that measured knowledge, attitudes, and perspectives about gene therapy was developed. The survey instrument was made available online to physicians without monetary compensation or charge. Respondent confidentiality was maintained and responses were de-identified and aggregated prior to analyses. The activity launched on March 03, 2018; data through July 27, 2018 are presented, but data collection is ongoing.

RESULTS: At the time of this analysis, 194 physician participants indicated that they actively manage patients with hemophilia. Demographics are presented in Table 1; confidence and attitudes about gene therapy in Table 2. Among hematologists/oncologists (n=54; hem/onc), identified knowledge gaps include,

• 46% could not identify the liver as the tissue/cell type that is the primary target for gene therapy in hemophilia

• 46% thought that current approaches to gene therapy in hemophilia involved some form of host gene editing

• 39% did not realize that gene therapy strategies only affect somatic cells and not the germline

• 22% thought current gene therapy strategies would prevent or reduce the severity of hemophilia in subsequent generations of patients

• 33% were unable to correctly identify adeno-associated virus (AAV) as the viral vector that is the current basis for the majority of gene therapy trials in hemophilia

• 81% had misconceptions regarding the key characteristics of the AAV vector

• 56% did not recognize that the AAV vector does not routinely integrate into the host genome

• 19% were unfamiliar with the maximum gene cassette capacity of AAV

• 57% were unfamiliar with the results from the pivotal University College London (UCL)/St Jude trial of scAAV2/8-LP1-hFIXcovector in patients with hemophilia B

• 63% were unfamiliar with the clinical trial data for SPK-8011 in hemophilia A

• 67% were unfamiliar with the results at the 12 month time-point for valoctocogene roxaparvovec in hemophilia A trials

• 57% had misconceptions with regard to the causes for and treatment of ALT elevations seen in hemophilia AAV gene therapy trials

CONCLUSIONS: Gene therapy has the potential to fundamentally alter the management of hemophilia. This educational activity identified clear deficits about - and attitudes toward - gene therapy among healthcare providers who currently care for patients with hemophilia. Furthermore, the great majority of healthcare providers lacked confidence in their understanding of gene therapy for hemophilia A. These findings will be used to inform the development of educational programs and to prepare providers for anticipated changes to the hemophilia treatment landscape.

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