Characterization and Disease Management of Persons with Hemophilia A Treated with Emicizumab: A Survey Study of Hematologists in the US

Introduction Emicizumab (EMI) is a subcutaneously administered, bispecific, humanized monoclonal antibody that bridges activated factor IX (FIXa) and FX to restore the function of missing FVIIIa in persons with hemophilia A (PwHA). It was approved in the US for prophylaxis in PwHA with FVIII inhibitors in November 2017 and for PwHA without FVIII inhibitors in October 2018. In May 2019, an online survey of 50 board-certified hematologists (HEMs) was conducted with the objective of understanding the characteristics of PwHA who are being treated with EMI (PwHA-EMI) and assessing any changes in disease management of these individuals by HEMs. Methods Descriptive analysis was conducted on data collected from May 8 to May 20, 2019, through a 30-minute, online survey of 50 HEMs treating adult and pediatric PwHA with or without FVIII inhibitors in the US. These HEMs were required to have ≥2 years of experience post-residency and experience treating ≥3 PwHA per month with EMI. Results Of the 50 HEMs from 22 states who were surveyed in this study, 28% (n=14) primarily treated pediatric PwHA and 76% (n=38) practiced at federally funded hemophilia treatment centers. HEMs reported that the majority of their PwHA-EMI had severe HA, were previously treated, and did not have FVIII inhibitors. HEMs reported presence of inhibitors (40%, n=20) and high treatment burden with previous treatments (16%, n=8) as the top factors that were considered when initiating treatment with EMI. HEMs reported that they are testing less frequently for FVIII activity (52%, n=26) and inhibitors (28%, n=14) in PwHA-EMI. Most HEMs reported using multiple methods for breakthrough bleed recognition in their PwHA-EMI, such as advising them to call a healthcare provider (HCP) for diagnosis support (70%, n=35) and providing educational materials (68%, n=34). Further, 34% (n=17) reported a change in their guidance on bleed treatment in PwHA-EMI. Guidance varied by inhibitor status and type of bleed; these HEMs were more likely to recommend that their PwHA-EMI with FVIII inhibitors (65%, n=11/17) and without FVIII inhibitors (53%, n=9/17) call a HCP to discuss symptoms before treating the bleed. Also, 42% (n=21) of HEMs typically advised keeping 3-4 doses of bypassing agent or FVIII at hand in case of breakthrough bleed treatment in PwHA-EMI. A majority of HEMs (84%, n=42) reported that the recreational physical activity levels of their PwHA have remained the same or increased after starting EMI; 48% (n=24) of HEMs recommended that their patients have a gradual increase in these activities after starting EMI. Among HEMs who provided specific guidance on recreational physical activities (54%; n=27), most develop customized plans for their patients based on fitness goals (82%; n=22/27), disease severity (74%; n=20/27), and age (56%; n=15/27). For disease management support, 58% (n=29) of HEMs reported no change in the support they provide, even though EMI is a relatively new treatment. HEMs mainly attributed this to fewer bleeds in PwHA-EMI. For routine and follow-up care, 72% (n=36) and 56% (n=28) of HEMs, respectively, reported that their PwHA-EMI seek about the same levels of such care as they did prior to starting EMI, but 32% (n=16) of HEMs reported that their PwHA-EMI need less non-routine care after starting treatment with EMI. Breakthrough bleeds (22%, n=11) and trauma (20%, n=10) were reported as the top reasons for any non-routine care in PwHA-EMI. As for treatment adherence, 90% (n=45) of HEMs reported that their PwHA-EMI have similar or better adherence compared with those on other HA treatments. Lastly, 46% (n=23) of HEMs reported that their PwHA-EMI regularly experience insurance issues, including ones related to coverage for EMI and coverage for care and breakthrough bleed treatments while on EMI. Conclusions Based on the findings of this survey study, most HEMs have retained similar disease management support and practices for their PwHA-EMI. Although the frequency of routine care has not changed for most PwHA-EMI, HEMs indicated a reduction in the amount of non-routine care needed by these individuals. As EMI is prescribed and used over a longer period post approval, patient characteristics, treatment methods, and disease management practices should continue to be monitored to support HEMs' treatment and care of PwHA. Disclosures Owens: PRO Unlimited: Employment; Genentech, Inc.: Consultancy. Patel: Roche/Genentech: Equity Ownership; Genentech: Employment. Poulos: MedPanel, Inc.: Employment. Powers: MedPanel: Employment. Ko: Genentech, Inc.: Employment.