Dosing, efficacy, and safety of recombinant factor VIIa (rFVIIa) in pediatric versus adult patients: the experience of the Hemostasis and Thrombosis Research Society (HTRS) Registry (2004-2008)

Bleeding in patients with hemophilia who have inhibitors: Modeling US medical system utilization and cost avoidance between recombinant factor VIIa products with different clinical dosing requirements

BACKGROUND: A mainstay of treatment in patients with hemophilia with inhibitors (PWIs) is the use of a recombinant factor VIIa (rFVIIa) bypassing agent. A new rFVIIa product may allow reduced rFVIIa utilization for on-demand treatment of bleeding episodes (BEs). OBJECTIVE: A decision analytic health economic model was developed to compare the utilization and consequent need for bleed-related clinical encounters of 2 rFVIIa products, with the International Nomenclature Name of eptacog alfa (EA) and eptacog beta (EB). METHODS: This study uses recent, peer-reviewed, and published data from clinical trials with similar endpoints for 1 million insured male lives in the United States. rFVIIa product utilization was modeled in hemophilia (A and B) PWI for on-demand treatment of BEs with rFVIIa treatment. Estimated annual BE rates were modeled to include prophylaxis and on-demand management. The clinical encounter avoidance estimates are based on refractory bleeding through 24 hours. RESULTS: In a cohort of 1 million insured, 5-6 patients with hemophilia A or B with inhibitors annually receive on-demand treatment for a total of 59 mild/moderate BEs. The model suggests that EB requires less unit utilization per BE (13,125 μg and 17,850 μg for the 75μg/kg and 225μg/kg dose regimens, respectively) than EA 90 μg/kg dosing (20,178μg), with wholesale acquisition costs expanding the difference. Further, both EB initial dose regimens would permit decreased total nonmedication health plan spending for the acute treatment of BEs by reducing the need for clinical encounters arising from BEs that fail to respond within 24 hours. CONCLUSIONS: With reduced infusion requirements, the model consistently shows that EB could generate lower insured-cohort drug utilization, as well as reduce costly clinical encounters by keeping mild and moderate BEs amenable to home bypassing agent management. DISCLOSURES: The article was funded by HEMA Biologic, LLC. The authors approved all content and results in this article without being subject to sponsor censorship. Mr Jensen, Mr Cyr, and Ms Hathway are employees of PRECISIONheor, which provides consulting services to the pharmaceutical industry, including HEMA Biologics, LLC. Dr Batt is an advisor to PRECISIONheor. Dr Alexander is a former employee of HEMA Biologics, LLC, and provides consulting services to the pharmaceutical industry.

Thrombotic events with recombinant activated factor VII (rFVIIa) in approved indications are rare and associated with older age, cardiovascular disease, and concomitant use of activated prothrombin complex concentrates (aPCC)

Purpose

Recombinant activated factor VII (rFVIIa; NovoSeven^® RT; Novo Nordisk A/S, Bagsvaerd, Denmark) is approved in the United States for the treatment of bleeding and perioperative management in congenital hemophilia with inhibitors (CHwI), acquired hemophilia (AH), congenital factor VII (FVII) deficiency, and Glanzmann’s thrombasthenia (GT) with refractoriness to platelets. The aim of the current analysis was to review clinical trials and registries pre- and post-licensure for each indication to establish the estimated rate of thrombosis and then to establish the association of all reported thrombotic events (TEs) with certain risk factors listed for many years in the prescribing information (PI).

Patients and methods

A retrospective safety assessment of both clinical trials and registries used to support licensure and postmarketing surveillance was performed. The rate of thrombosis was calculated in the 4 indicated disorders and an assessment of TE risk factors was conducted through a review of all narratives within those indications in the safety database.

Results

In clinical trials and registries used to support licensure and in postmarketing surveillance, the overall rate of thrombosis was 0.17% of 12,288 bleeding and surgical episodes. The specific risk by indication was 0.11% for CHwI, 0.82% for FVII deficiency, 0.19% for GT, and 1.77% for AH. The most common associated risk factor—“elderly” (29%), defined in the PI as age ≥65 years—was particularly prevalent in patients with AH. TE was also frequently reported with concomitant cardiac or vascular disease (18%) and use of activated prothrombin complex concentrates (18%).

Conclusion

Data show that the rate of TEs within the 4 licensed indications is low, as was originally described in the US PI from 1999 to 2009. It has remained stable over time during postapproval surveillance in multiple US and global registries with active surveillance for safety information across the 4 approved indications.

Safety and efficacy of recombinant activated coagulation factor VII in congenital hemophilia with inhibitors in the home treatment setting: A review of clinical studies and registries

Self-administration of factor and bypassing agents by persons with hemophilia in the home setting is recommended to facilitate earlier intervention after bleeding episodes. The objective of this review was to summarize recombinant activated coagulation factor VII (rFVIIa) safety and efficacy data from clinical trials and patient registries documenting use in the home treatment setting in people with congenital hemophilia with inhibitors (CHwI). A total of 16 studies and registries were identified for inclusion; 14 evaluated on-demand treatment of acute bleeding episodes (865 patients, 9024 bleeding episodes) and 2 evaluated use for secondary prophylaxis (108 patients, 42,861 prophylaxis days). In the on-demand studies, efficacy was consistently high (81%-96%), and thrombotic events were uncommon (n = 3). In the secondary prophylaxis studies, rFVIIa was associated with a 45% to 59% reduction in bleeding episodes and no thrombotic events. These data support the clinical practice of administering rFVIIa in patients in the home treatment setting after initiation under a physician's care.

The role of recombinant activated factor VII in the haematological management of elective orthopaedic surgery in haemophilia A patients with inhibitors

The clinical profile and expectations of haemophilic patients with inhibitors have changed over the last three decades, mainly because of the prolongation of life-expectancy, often resulting in an increase of the orthopaedic burden. Recombinant activated factor VII (rFVIIa) is the most frequently used bypassing agent in haemophilia patients with inhibitors during elective orthopaedic surgery. For nearly 30 years, rFVIIa has been successfully used to control haemostasis in several major and minor surgical procedures. Clinical trials, case series, reports and surveys were progressively aimed at optimising rFVIIa usage in very demanding conditions managed in highly specialised centres. Recommendations from consensus opinions and guidelines have been provided on the basis of this clinical experience.

Safety and efficacy of recombinant factor VIIa by pediatric age cohort: reassessment of compassionate use and trial data supporting US label

BACKGROUND

The relative safety and efficacy of recombinant activated coagulation factor VII (rFVIIa, NovoSeven® RT) across pediatric age cohorts is poorly defined. The objective of this analysis was to assess the safety and efficacy of rFVIIa in pediatric patients with congenital hemophilia with inhibitors (CHwI) in the clinical studies supporting the U.S. labeling.

PROCEDURE

Pediatric data were derived from seven studies (five acute and two perioperative treatments) and pooled. All data were stratified by age (<2, 2 to <6, 6 to <12, and 12-16 years) and study category (acute treatment of bleeding episodes or surgery).

RESULTS

The pediatric dataset included 172 patients; 144 received rFVIIa for the treatment of bleeding episodes and 28 for the control of bleeding perioperatively. Recombinant FVIIa was effective for 95.4% (1,026/1,076) of the evaluable bleeding episodes and had similar treatment effectiveness across pediatric age groups (range, 94.1-97.2%). The majority received doses of 90 mcg/kg. rFVIIa was effective in achieving perioperative hemostasis across pediatric age groups (range, 91-100%), with greater efficacy observed with the recommended (90 mcg/kg) versus lower dose (35 mcg/kg). A total of 88 pediatric patients experienced a total of 285 adverse drug reactions, similar in type to those reported among adult patients. A total of seven thrombotic events were recorded in seven pediatric patients; only one was confirmed related to rFVIIa upon individual case review.

CONCLUSIONS

rFVIIa is safe and effective in the treatment of bleeding episodes and prevention of periprocedure bleeding in CHwI with no apparent differences observed among pediatric age groups.

A Budget Impact Model of Hemophilia Bypassing Agent Prophylaxis Relative to Recombinant Factor VIIa On-Demand

BACKGROUND

Hemophilia patients use factor-clotting concentrates (factor VIII for hemophilia A and factor IX for hemophilia B) for improved blood clotting. These products are used to prevent or stop bleeding episodes. However, some hemophilia patients develop inhibitors (i.e., the patient's immune system develops antibodies against these factor concentrates). Hence, these patients do not respond well to the factor concentrates. A majority of hemophilia patients with inhibitors are managed on-demand with the following bypassing agents: recombinant factor VIIa (rFVIIa) and activated prothrombin complex concentrate (aPCC). The recently published U.S. registries Dosing Observational Study in Hemophilia (DOSE) and Hemostasis and Thrombosis Research Society (HTRS) reported higher rFVIIa on-demand use for bleed management than previously described.

OBJECTIVE

To estimate aPCC and rFVIIa prophylaxis costs relative to rFVIIa on-demand treatment cost based on rFVIIa doses reported in U.S. registries.

METHODS

A literature-based cost model was developed assuming a base case on-demand annual bleed rate (ABR) of 28.7 per inhibitor patient, which was taken from a randomized phase 3 clinical trial. The doses for rFVIIa on-demand were taken from the median dose per bleed reported by the DOSE and HTRS registries. Model inputs for aPCC and rFVIIa prophylaxis (i.e., dosing and efficacy) were derived from respective randomized clinical trials. Cost analysis was from the U.S. payer perspective, and only direct drug costs were considered. The drug cost was based on the Medicare Part B 2014 average sale price (ASP). Two-way sensitivity and threshold analyses were performed by simultaneously varying on-demand ABR, prophylaxis efficacy, and unit drug cost. In addition to studying relative costs associated with on-demand and prophylaxis treatments, relative cost per bleeding episode avoided were also calculated for aPCC and rFVIIa prophylaxis treatments. The prophylaxis efficacy reported in the trials were used to determine the number of bleeding episodes avoided.

RESULTS

Based on the median on-demand dose of 695 mcg per kg per bleed, reported by the DOSE registry, the annual rFVIIa on-demand cost was $34,009 per kg of body weight. The annual rFVIIa on-demand cost was $22,020 per kg of body weight when the median dose of 450 mcg per kg per bleed reported by the HTRS registry was considered. The annual cost rose to $38,461 per kg of body weight when the rFVIIa on-demand dose of 786 mcg per kg per bleed among patients infusing an initial dose ≥ 250 mcg per kg was considered. The aPCC (85 units per kg per every other day) and rFVIIa (90 mcg per kg per every day) annual prophylaxis costs were $26,536 and $60,700, respectively. Also, aPCC and rFVIIa prophyaxis treatments were estimated to prevent a total of 20.8 and 12.9 annual bleeding episodes, respectively. When compared with the on-demand dose of 695 mcg per kg per bleed (DOSE registry), the annual aPCC and rFVIIa prophylaxis costs were 21.9% lower and 78.4% higher, respectively. Additionally, aPCC prophylaxis saved $360 per kg for each bleeding episode avoided. rFVIIa prophylaxis cost $2,066 per kg for each bleeding episode avoided. Compared with the on-demand dose of 450 mcg per kg per bleed (HTRS registry), aPCC and rFVIIa prophylaxis costs were 20.5% and 174.9% higher, respectively. In this case, aPCC and rFVIIa prophylaxis treatment costs were $217 per kg and $2,995 per kg, respectively, for each bleeding episode avoided. aPCC and rFVIIa prophylaxis costs were 31.0% lower and 57.8% higher, respectively, when compared with the rFVIIa on-demand dose of 786 mcg per kg per bleed, among patients infusing an initial dose ≥ 250 mcg per kg (HTRS registry). In this case, aPCC prophylaxis saved $573 per kg for each bleeding episode avoided, while rFVIIa prophylaxis costs $1,724 per kg for each bleeding episode avoided. Results of the 2-way sensitivity analyses were robust in the majority of the scenarios considered.

CONCLUSIONS

aPCC prophylaxis may be cost saving for managing hemophilia patients with inhibitors who bleed frequently and infuse significant quantities of rFVIIa on-demand.