Perioperative haemostasis with full‐length, PEGylated, recombinant factor VIII with extended half‐life (rurioctocog alfa pegol) in patients with haemophilia A: Final results of a multicentre, single‐arm phase III trial

Abstract Introduction Rurioctocog alfa pegol (BAX 855, TAK‐660) is a PEGylated, full‐length, recombinant factor VIII (rFVIII) with extended half‐life developed from unmodified rFVIII (antihaemophilic factor [recombinant]). Aim To determine the perioperative haemostatic efficacy and safety of rurioctocog alfa pegol in male previously treated patients (PTPs) with severe haemophilia A. Methods This multicentre, single‐arm, phase III study included PTPs who were to undergo major or minor elective or minor emergency surgical, dental or other invasive procedures. Rurioctocog alfa pegol dose and frequency were individualized based on patients’ pharmacokinetic profiles for major surgeries and by rurioctocog alfa pegol incremental recovery for minor surgeries. Haemostatic efficacy was assessed using the Global Haemostatic Efficacy Assessment score. Results Twenty‐one patients aged 16‐61 years underwent 21 major and five minor surgeries. For all 24 evaluable surgeries, overall haemostatic efficacy was rated as excellent and blood loss comparable to that expected in non‐haemophilic patients. No blood transfusions were required intraoperatively but were administered postoperatively for four surgeries in three patients. Five injury‐related postoperative bleeding episodes occurred in five patients, of which two required additional rurioctocog alfa pegol treatment. Two non‐serious adverse events of mild severity (increased ALT level and headache) were considered possibly related to rurioctocog alfa pegol. There were no deaths or treatment‐related serious adverse events. No patients developed inhibitory antibodies to FVIII or persistent IgG‐ or IgM‐binding antibodies to FVIII, PEG‐FVIII or PEG. Conclusion Rurioctocog alfa pegol was well tolerated and effective for perioperative use in patients with haemophilia A and showed no signs of immunogenicity.


| INTRODUC TI ON
Haemophilia A is a deficiency in clotting factor VIII (FVIII) inherited in an X-linked manner, almost invariably presenting in males. It increases the risk of acute bleeding within joints leading to arthropathy 1 and also increases healing time after surgery or trauma. 2 As a result of improvements in treatment, life expectancy among patients with haemophilia in developed countries is approaching that of the general population. 3 This has resulted in an increase in age-related conditions including requirement for surgery in this population. [4][5][6][7] In addition, joint surgery is frequently required for pain or disability arising from haemophilic arthropathy. 4 Intensified FVIII replacement therapy is required in patients with severe haemophilia A (FVIII <1%) during and after surgery until healing is complete, for up to 7 days or more following major surgery. 8 Because of their relatively short half-life (approximately 12 hours), standard FVIII formulations require administration twice or three times daily to maintain haemostatic FVIII levels in the postoperative period. An extended half-life FVIII may offer less frequent dosing and the possibility of earlier hospital discharge and attendant cost savings. [9][10][11] Rurioctocog alfa pegol (BAX 855, TAK-660; ADYNOVATE ® , ADYNOVI™, Baxalta US Inc., a Takeda company, Lexington, MA, USA) is a PEGylated, full-length, recombinant FVIII (rFVIII) with extended half-life, developed from unmodified rFVIII (antihaemophilic factor [recombinant]; ADVATE ® , Baxalta US Inc., a Takeda company, Lexington, MA, USA). 12,13 Mean half-life of rurioctocog alfa pegol is 1.3-to 1.5-fold longer in children aged <12 years and 1.4-to 1.5-fold longer in adolescents and adults aged ≥12 years compared with its non-PEGylated parent rFVIII. 12,14 Rurioctocog alfa pegol has been shown to be effective and well tolerated in the prevention and control of bleeding in previously treated paediatric and adult patients with severe haemophilia A. 12,14 The aim of our study was to determine the perioperative haemostatic efficacy and safety of rurioctocog alfa pegol in male previously treated patients (PTPs) with severe haemophilia A. Interim results from a prospectively planned analysis have been published 15 ; here, we report the final results of this study.

| MATERIAL S AND ME THODS
The study was performed in accordance with Good Clinical Practice and ethical principles consistent with the Declaration of Helsinki and was registered at clini caltr ials.gov (NCT01913405) and at clini caltr ialsr egist er.eu (2013-001359-11). The protocol was approved by the independent review boards at each participating centre. Written informed consent was provided by each patient before recruitment.

| Objectives
The primary objective of the study was to determine the perioperative haemostatic efficacy of rurioctocog alfa pegol in male PTPs (≥150 prior exposure days) with severe haemophilia A undergoing major or minor elective or minor emergency surgical, dental or other invasive procedures, as determined by the Global Haemostatic Efficacy Assessment (GHEA) score. Secondary objectives included intra-and postoperative blood loss; volume of blood, red blood cells, platelets, and other blood products transfused; occurrence of bleeding episodes and additional need for surgical intervention; daily and total weight-adjusted consumption of rurioctocog alfa pegol; and safety, as previously detailed. 15

| Study design
This was a phase III, prospective, open-label, single-group, multicentre study to evaluate the efficacy and safety of rurioctocog alfa pegol in PTPs undergoing major or minor elective or minor emergency surgical, dental or other invasive procedures. Surgical procedures were prospectively defined as major or minor by the investigator/surgeon based on protocol guidance as previously detailed 15 in accordance with international guidelines. 8,16 Adjunct antifibrinolytic agents, for example tranexamic acid, or topical haemostatic agents were permitted. Mechanical thromboprophylaxis was allowed, and pharmacological thromboprophylaxis was permitted for certain surgical interventions at the investigator's discretion.

| Patients
The study included male patients with severe haemophilia A. Eligible patients could transition from another rurioctocog alfa pegol study or were newly recruited. If newly recruited, patients were to be ≥12-75 years of age, receiving prophylaxis or on-demand treatment with FVIII at study entry, had a documented exposure to FVIII of ≥150 days and had no detectable FVIII inhibitory antibodies (≥0.4 Bethesda units using the Nijmegen-modified Bethesda assay).
Major exclusion criteria were need for major emergency surgery; detectable or a history of FVIII inhibitory antibodies; platelet count <100 × 10 9 /L; ongoing or recent thrombotic disease; diagnosis of an inherited or acquired haemostatic defect other than haemophilia A; recent use of another PEGylated product; and incremental recovery (IR) <1.5 IU/dL:IU/kg determined during participation in another rurioctocog alfa pegol study or after screening in this surgery study.

| Pharmacokinetic assessment
Presurgical pharmacokinetics of rurioctocog alfa pegol were determined after a 60 IU/kg dose and included IR; area under the plasma concentration time curve from time 0 to ∞ and from time 0 to 96 hours; mean residence time; clearance; terminal half-life (t 1/2 ); and volume of distribution at steady state. IR was also assessed following the initial preoperative bolus infusion, and throughout the study. The pharmacokinetic parameters were determined using non-compartmental methods, except for t 1/2 . Blood samples were taken for pharmacokinetic evaluation of FVIII levels and activated partial thromboplastin time within 30 minutes preinfusion and 15 ± 5 minutes postinfusion. Additional blood samples were taken for FVIII activity levels at 3 hours ± 30 minutes, 9 hours ± 30 minutes, 32 hours ± 2 hours, 56 hours ± 4 hours and 96 hours ± 4 hours.

| Treatment
Details of perioperative treatment with rurioctocog alfa pegol have been previously published. 15 Briefly, the dose and frequency of rurioctocog alfa pegol were individualized based on patients' pharmacokinetic parameters for major surgeries and the most recent IR value for minor surgeries. A loading dose was administered within 60 minutes before surgery to achieve FVIII target levels of 80%-100% of normal for major surgery, and FVIII target levels of 30%-60% of normal for minor procedures. 17 For major surgery, FVIII trough levels were required to be maintained ≥80% for the first 72 hours and at least 50% on postoperative days 4-7. From day 8 until discharge, the FVIII levels were to remain above 30% (at the discretion of the investigator, depending on the postoperative course). For minor surgery, FVIII trough levels were targeted postoperatively at 30%-60% for the first 24 hours (or longer if deemed necessary by the investigator). For all surgeries, FVIII levels were not to exceed supraphysiological peak FVIII levels of 180%.

| Assessment of haemostatic efficacy
The primary outcome measure used (ie the GHEA score), comprised three assessments of haemostatic efficacy: intraoperative performed by the operating surgeon on day 0, postoperative by the operating surgeon on postoperative day 1 and perioperative performed by the investigator at discharge or on postoperative day 14.
Each assessment was scored on a 4-point scale (0 = none, 1 = fair, 2 = good, 3 = excellent). Detailed criteria for the GHEA score have been previously published. 15 Actual intraoperative and postoperative blood loss was compared with that estimated by the surgeon/investigator for the same surgical intervention in a haemostatically normal individual of the same sex, age and stature as the study patient. Estimates took into account all relevant variables, for example the use of a tourniquet, the placement of a postoperative drain and the use of suction.

| Safety assessment
Safety outcomes assessed included thrombotic events, severe allergic reactions, other treatment-related adverse events (AEs), and clinically significant changes in vital signs and laboratory parameters.
Samples were investigated for inhibitory antibodies to FVIII, and F I G U R E 1 Patient disposition. Note: The numbers outside the parentheses are counted on surgical enrolments and those inside the parentheses are based on unique patients. One subject underwent both orthopaedic and non-orthopaedic major surgery, which is therefore counted twice in the flowchart. PK, pharmacokinetics development of binding antibodies to FVIII, rurioctocog alfa pegol, PEG and Chinese hamster ovary (CHO) proteins.

| Statistics
The target sample size of approximately 50 major and minor surgeries in approximately 40 patients was based on regulatory guidance to evaluate a minimum of 10 major surgical procedures in at least five patients 18 and was not based on statistical considerations. The results were summarized by descriptive statistics. Median values are reported with their range throughout.

| Demographics and patient disposition
The study was conducted between 20 December 2013 and 23 September 2016. Figure 1 shows the disposition of the patients and surgeries performed during the study. Twenty-two patients were treated with rurioctocog alfa pegol and comprised the safety set.
Patients' demographic and clinical characteristics are summarized in Table 1; all were male, most were white (91%) and adult (96%), and had a history of haemophilic arthropathy (91%). Patients were recruited at 12 study sites in the United States (n = 4), Spain (n = 3), Bulgaria, Lithuania, Russia, Switzerland and the United Kingdom (each n = 1). One patient withdrew before surgery after receiving rurioctocog alfa pegol infusions for pharmacokinetic assessment.
Twenty-six surgeries (14 major orthopaedic, seven major non-orthopaedic and five minor) were performed in 21 unique patients. Seven of the 14 major orthopaedic surgeries were arthroplasties. Among these, one patient underwent surgery but discontinued before study completion. Of the 21 unique patients, six patients (who underwent four minor and four major surgeries) were transitioned from another rurioctocog alfa pegol study 12 and 15 patients (who underwent one minor and 17 major surgeries) were newly recruited. Seven patients received pharmacologic thromboprophylaxis after nine surgeries (three bemiparin plus rivaroxaban, two bemiparin, one enoxaparin and one heparin). Four patients undergoing four oral surgeries (three major, one minor) received antifibrinolytic therapy during surgery; two with tranexamic acid and one each with aminocaproic acid, and etamsylate plus tranexamic acid.

| Primary efficacy outcome
Haemostatic efficacy for all 24 surgeries (21 major, three minor) with available GHEA scores was rated as excellent (

| Secondary efficacy outcomes
Data for median intra-and postoperative blood loss are summarized in Table 3. Actual intraoperative blood loss for major orthopaedic surgeries was substantially less than the average volume predicted by the investigators (median, 125 mL less). Actual intraoperative blood loss was similar to the predicted average volumes for  Note: Full analysis set. N is number of surgical enrolments. Data presented as median (range). a Actual blood loss determined by drainage volume, if applicable, and the estimated blood loss into swabs and towels during the procedure. Surgeries for which estimates of actual blood loss were available: intraoperative period 14 (major orthopaedic), six (major non-orthopaedic), five (minor), 25 (all); postoperative period nine (major orthopaedic), four (major non-orthopaedic), three (minor), 16 (all). b Preoperative prediction by surgeon/investigator (data available for all surgeries). c From completion of procedure until 24 h postsurgery. non-orthopaedic major (median, 1.5 mL less) and minor (no difference) surgeries. Actual postoperative blood loss was higher than the average volume predicted for orthopaedic major surgeries (median, 50 mL more) but lower than the maximum volume predicted (median, 100 mL less). Actual postoperative blood loss was similar to the average volume predicted for non-orthopaedic major (median, 4.0 mL less) and minor (no difference) surgeries.
No blood transfusions were required intraoperatively. Five

| Rurioctocog alfa pegol dosage and consumption
The median (range) preoperative loading dose of rurioctocog Daily weight-adjusted consumption of rurioctocog alfa pegol before discharge from hospital across all surgeries is displayed in Figure 2A.
The median daily weight-adjusted consumption of rurioctocog alfa pegol was generally similar for major orthopaedic and non-orthopaedic surgeries pre-, intra-and postoperatively. FVIII activity levels 30 minutes preinfusion (trough) and 15 minutes after infusion (peak) for all surgeries are shown in Figure 2B and 2C, and generally declined from postoperative day 1 through to day 7, in keeping with weight-adjusted consumption.

| Pharmacokinetics
Presurgical pharmacokinetics were determined for the 25 surgeries in 20 unique patients for whom data were available, following a median rurioctocog alfa pegol dose of 60 (range, 51-67) IU/kg [ Table 4]).

| Safety
Eighteen treatment-emergent AEs were reported for eight (36%) unique patients: all but two of these AEs were considered unrelated to rurioctocog alfa pegol by the investigators. Two non-serious AEs of mild severity (one increased alanine aminotransferase [ALT] level, one headache) were considered possibly related to rurioctocog alfa pegol. There were no AEs considered to be thrombotic events or related AEs considered to be allergic reactions. There were no treatment-related serious AEs (SAEs) and no deaths.  With regard to sample size, regulatory guidance recommends that a minimum of 10 major surgical procedures in at least five patients are evaluated, 18 and this requirement was surpassed in the current study with the enrolment of only 21 unique patients. Thus, further enrolment was unnecessary, and the target sample size was not reached.
In conclusion, rurioctocog alfa pegol was considered well tolerated and effective for perioperative use in PTPs with severe haemophilia A. The efficacy and safety results of rurioctocog alfa pegol in this study in the operative setting confirm those found in studies of rurioctocog alfa pegol in prophylactic and on-demand settings 12,14 and were consistent with those for unmodified, non-PEGylated rFVIII 19 (from which rurioctocog alfa pegol was derived) in the perioperative setting.

ACK N OWLED G EM ENTS
The authors thank the following individuals for their contributions to the conduct of the trial at the investigative sites: Pratima Chowdary, ST is an employee of Baxalta US Inc., a Takeda company, and a stock owner in Takeda. *A Takeda company.

AUTH O R CO NTR I B UTI O N S
MFLF and TTW performed the research and acquisition of data. RG participated in the research and analysis of data. WE, MS and ST designed the study and analysed the data. All authors critically reviewed the manuscript and approved the final version.

DATA AVA I L A B I L I T Y
The datasets, including redacted study protocol, redacted statistical analysis plan and individual participants data behind the results reported in this article, will be available 3 months after the submission of a request to researchers who provide a methodologically sound proposal after de-identification, in compliance with applicable privacy laws, data protection and requirements for consent and anonymization. Data requests should follow the process outlined in the Data Sharing section on Shire's website: http://www. shire trials.com/en/our-commi tment-to-trans paren cy/data-shari ng-with-resea rchers and should be directed to clini caltr ialda ta@ shire.com.