Pharmacotherapeutic group: antihaemorrhagics, blood coagulation factor VIII, ATC code: B02BD02.
The factor VIII/von Willebrand factor complex consists of two molecules (factor VIII and von Willebrand factor) with different physiological functions. When infused into a haemophilic patient, factor VIII binds to von Willebrand factor in the patient's circulation. Activated factor VIII acts as a cofactor for activated factor IX, accelerating the conversion of factor X to activated factor X. Activated factor X converts prothrombin into thrombin. Thrombin then converts fibrinogen into fibrin and a clot can be formed. Haemophilia A is a sex-linked hereditary disorder of blood coagulation due to decreased levels of factor VIII:C and results in profuse bleeding into joints, muscles or internal organs, either spontaneously or as results of accidental or surgical trauma. By replacement therapy the plasma levels of factor VIII are increased, thereby enabling a temporary correction of the factor deficiency and correction of the bleeding tendencies.
Rurioctocog alfa pegol, is a pegylated recombinant human factor VIII with an extended half‑life. Rurioctocog alfa pegol is a covalent conjugate of octocog alfa consisting of 2 332 amino acids with polyethylene glycol (PEG) reagent (MW 20 kDa). The therapeutic activity of rurioctocog alfa pegol is derived from octocog alfa, which is produced by recombinant DNA technology from a Chinese hamster ovary cell line. Octocog alfa is then covalently conjugated with the PEG reagent. The PEG moiety is conjugated to octocog alfa to increase the plasma half‑life.
Clinical efficacy and safety
The safety, efficacy, and pharmacokinetics of ADYNOVI were evaluated in a pivotal multi-centre, open‑label, prospective clinical trial that compared the efficacy of a twice weekly prophylactic treatment regimen to on‑demand treatment and determined haemostatic efficacy in the treatment of bleeding episodes. A total of 137 male PTPs (12 to 65 years of age) with severe haemophilia A received at least one infusion with ADYNOVI. Twenty‑five of the 137 subjects were adolescents (12 to less than 18 years of age).
Immunogenicity
None of the subjects who participated in one or more of 6 completed clinical trials in previously treated patients (PTPs) developed persistent neutralizing (inhibitory) antibodies against FVIII of ≥ 0.6 BU/mL (based on the Nijmegen modification of the Bethesda assay). One patient developed a transient FVIII inhibitor at the lowest limit of positivity (0.6 BU) during personalized prophylaxis targeting a FVIII level of 8-12%.
From an ongoing study in previously untreated patients < 6 years with severe hemophilia A, preliminary reports on 9 cases of FVIII inhibitor development associated with treatment with ADYNOVI were received.
Prophylactic treatment
Subjects received either prophylactic treatment (n = 120) with ADYNOVI at a dose of 40‑50 IU per kg twice weekly or on‑demand treatment (n = 17) with ADYNOVI at a dose of 10‑60 IU per kg for a 6‑month period. The median dosing interval was 3.6 days and the mean dose (SD) was 48.7 (4.4) IU/kg. One hundred eighteen of 120 (98%) prophylaxis subjects remained on the starting recommended regimen without dose adjustment, and 2 subjects increased their dose to 60 IU/kg during prophylaxis due to bleeding in target joints.
In the per‑protocol population, i.e. dosed according to the protocol specific dosing requirements, a total of 101 subjects received a twice a week regimen in the prophylaxis arm, and 17 subjects were treated episodically in the on‑demand arm. The median annualised bleed rate (ABR) in the on‑demand treatment arm was 41.5 compared to 1.9 while on a twice a week prophylaxis regimen. The median joint ABR (Q1 ; Q3) in the on‑demand arm was 38.1 (24.5 ; 44.6) compared to 0.0 (0.0 ; 2.0) while on prophylaxis, and the median spontaneous ABR was 21.6 (11.2 ; 33.2) on the on‑demand arm compared to 0.0 (0.0 ; 2.2) while on prophylaxis. Results for the full‑analysis population were similar to those for the per‑protocol population. Of note, ABR is not comparable between different factor concentrates and between different clinical trials.
Forty out of 101 subjects (40%) experienced no bleeding episodes, 58 out of 101 subjects (57%) experienced no joint bleeding episodes, and 58 out of 101 subjects (57%) experienced no spontaneous bleeding episodes in the prophylaxis arm. All subjects in the on‑demand arm experienced a bleeding episode, including a joint or spontaneous bleeding episode.
Treatment of bleeding episodes
A total of 518 bleeding episodes were treated with ADYNOVI in the per‑protocol population. Of these, 361 bleeding episodes (n=17 subjects) occurred in the on‑demand arm and 157 (n=61 subjects) occurred in the prophylaxis arm. The median dose per infusion to treat all bleeding episodes in the per‑protocol population was 32.0 (Interquartile Range (IQR): 21.5) IU per kg. Overall, 95.9% of bleeding episodes were controlled with 1 to 2 infusions and 85.5% were controlled with only 1 infusion. Of the 518 bleeding episodes, 96.1% were rated excellent (full relief of pain and cessation of objective signs of bleeding after a single infusion) or good (definite pain relief and/or improvement in signs of bleeding after a single infusion) in their response to treatment with ADYNOVI.
Paediatric population < 12 years of age
A total of 66 PTPs with severe haemophilia A were dosed (32 subjects aged < 6 years and 34 subjects aged 6 to < 12 years) in the paediatric study. The prophylactic regimen was 40 to 60 IU/kg of ADYNOVI twice a week. The mean dose (SD) was 54.3 (6.3) IU/kg and the median frequency of infusions per week was 1.87. The median overall ABR was 2.0 (IQR: 3.9) for the 65 subjects in the per‑protocol population and the median ABRs for spontaneous and joint bleeding episodes were both 0 (IQR: 1.9). Twenty four out of 65 subjects (37%) experienced no bleeding episodes, 47 out of 65 subjects (72%) experienced no joint bleeding episodes, and 43 out of 65 subjects (66%) experienced no spontaneous bleeding episodes on prophylaxis.
Of the 70 bleeding episodes observed during the paediatric study, 82.9% were controlled with 1 infusion and 91.4% were controlled with 1 or 2 infusions. Control of bleeding was rated excellent (full relief of pain and cessation of objective signs of bleeding after a single infusion) or good (definite pain relief and/or improvement in signs of bleeding after a single infusion) in 63 out of 70 (90.0%) bleeding episodes.
Perioperative management (surgical prophylaxis)
A total of 21 major surgical procedures and 5 additional minor surgeries were performed and assessed in 21 unique subjects in the surgery study. For major surgeries, the preoperative loading dose ranged from 36 IU/kg to 109 IU/kg (median: 63 IU/kg); and postoperative total dose ranged from 186 IU/kg to 1 320 IU/kg (median: 490 IU/kg). The median total dose for major surgeries was 553 IU/kg (range: 248-1 394 IU/kg) and the median total dose of minor surgeries was 106 IU/kg (range: 76-132 IU/kg).
Perioperative haemostatic efficacy was rated as excellent (blood loss less than or equal to that expected for the same type of procedure performed in a non‑haemophilic patient, and required blood components for transfusions less than or similar to that expected in non‑haemophilic population) for all 26 (21 major, 5 minor) procedures. The median (IQR) observed intraoperative blood loss (n = 14) was 10.0 (20.0) ml compared to the predicted average blood loss (n = 14) of 150.0 (140.0) ml for major orthopaedic surgeries.
The European Medicines Agency has deferred the obligation to submit results of studies with ADYNOVI in one or more subsets of the paediatric population in the treatment of congenital factor VIII deficiency. See 4.2 for information on paediatric use.
Long-term prophylaxis treatment in paediatric and adult subjects
The long-term safety and efficacy of ADYNOVI in prophylaxis and treatment of bleeding episodes was evaluated in 216 paediatric and adult PTPs with severe haemophilia A who had either previously participated in other ADYNOVI studies or were naïve to ADYNOVI. In the treated population, subjects received a fixed-dose twice-weekly regimen of 40 to 50 IU/kg if aged ≥ 12 years or of 40 to 60 IU/kg if aged < 12 years. The dose was adjusted up to 80 IU/kg twice weekly if required to maintain FVIII trough levels of > 1%. Subjects that opted for a personalized (pharmacokinetically-tailored) prophylactic regimen received doses up to 80 IU/kg per infusion that targeted FVIII trough levels of ≥ 3% at least twice weekly. ABR per prophylactic regimen, bleeding site and etiology are presented in Table 3.
Table 3: Annualized bleed rate (ABR) by prophylactic regimen (ITT population)
| Bleeding Site Etiology | Twice-Weekly (N=186) | Every 5 Days (N=56) | Every 7 Days (N=15) | PK- tailoreda (N=25) |
| Mean [Point Estimate- 95% Confidence Interval] |
| Overall | 2.2 [1.85 - 2.69] | 2.1 [1.54 - 2.86] | 2.7 [1.44 -5.20] | 2.6 [1.70 - 4.08] |
| Joint | 1.2 [0.96 - 1.58] | 1.1 [0.81 - 1.55] | 2.0 [0.90 - 4.62] | 1.4 [0.91 - 2.17] |
| Spontaneous | 1.2 [0.92 - 1.56] | 1.3 [0.87 - 2.01] | 1.8 [0.78- 4.06] | 1.0 [0.54 - 1.71] |
| Point estimates and 95% confidence intervals obtained from a generalized linear model fitting a negative binomial distribution with logarithmic link function. Subjects receiving doses in multiple regimens are included in summaries for multiple regimens. Includes all subjects in the study (adults and paediatric subjects < 18 years. For Twice Weekly and PK-tailored dosing no subjects < 12 years were included in Every 5 & 7 Days dosing. ITT = intent to treat; N = Number of subjects included in the analysis a Targeting FVIII activity trough levels of ≥3% of normal |
Of note, ABR is not comparable between different factor concentrates and between different clinical trials.
Long-term haemostatic efficacy was evaluated in 910 bleeding episodes treated with ADYNOVI and was rated excellent or good in 88.5% of bleeding episodes. Across age categories and for both the fixed-dose and the PK-tailored dose regimen, >85% of bleed treatments were rated excellent or good. The majority of bleeding episodes were treated with one (74.0%) or two (15.4%) infusions.
Personalized prophylaxis PROPEL clinical trial in adolescents and adult subjectsThe safety and efficacy of ADYNOVI was evaluated in a prospective, randomized, open-label multi‑centre study in 121 (115 randomized) adolescents (12-18 years old) and adult PTPs with severe haemophilia A for a 12-month treatment period. The study compared 2 PK-guided prophylactic dosing regimens of ADYNOVI that targeted Factor VIII trough levels of 1-3% dosed twice weekly (N=57) or 8-12% dosed every other day (N=58), by assessing the proportions of subjects achieving a total ABR of 0 in the second 6-month study period.
The average prophylactic doses administered in the 1-3% and 8-12 % trough arms were 3 866.1 IU/kg per year [mean (SD) infusions/week = 2.3 (0.58)] and 7 532.8 IU/kg per year [(mean (SD) infusions/week = 3.6 (1.18)], respectively. After dose adjustment during the first 6-month period of prophylaxis, median trough levels in the second 6-month period (based on the one-stage clotting assay and calculated to the end of the planned infusion interval) ranged from 2.10 IU/dL to 3.00 IU/dL in the 1-3% trough level arm and from 10.70 IU/dL to 11.70 IU/dL in the 8-12 % trough level arm, demonstrating that dosing in the 2 prophylaxis regimens was generally adequate to achieve and maintain the desired FVIII trough levels.
The primary endpoint of the study, proportion of subjects who had a total ABR of 0 during the second 6-month period, was not reached in the ITT patient population (p= 0.0545) but was reached in the per-protocol population (p = 0.0154). The proportions of randomized subjects with total ABRs, spontaneous ABRs and spontaneous annualized joint bleeding rates (AJBRs) of 0 during the second 6-month study period in the Per Protocol population are presented in Table 4.
Table 4: Annualized bleed rate (ABR) of 0, second 6-month study period
| | Proportion of Subjects Without Bleedings in 6 Months [Point Estimate- 95% Confidence Interval] |
| ITT Population |
| 1-3% Trough Level (N=57) | 8-12% Trough Level (N=58) |
| Total ABR of 0 | 0.421 [0.292; 0.549] | 0.621[0.491; 0.750] |
| Spontaneous ABR of 0 | 0.596 [0.469; 0.724] | 0.760 [0.645; 0.875] |
| Spontaneous AJBR of 0 | 0.649 [0.525; 0.773] | 0.850 [0.753; 0.947] |
| ABR = Annualized bleeding rate. AJBR = Annualized joint bleeding rate. Annualized bleeding rate determined by dividing the number of bleeds by observation period in years. |
| | Proportion of Subjects Without Bleedings in 6 Months [Point Estimate- 95% Confidence Interval] |
| Per Protocol Population |
| 1-3% Trough Level (N=52) | 8-12% Trough Level (N=43) |
| Total ABR of 0 | 0.404 [0.270; 0.549] | 0.674 [0.515; 0.809] |
| Spontaneous ABR of 0 | 0.596 [0.451; 0.730] | 0.814 [0.666; 0.916] |
| Spontaneous AJBR of 0 | 0.654 [0.509; 0.780] | 0.907 [0.779; 0.974] |
| ABR = Annualized bleeding rate. AJBR = Annualized joint bleeding rate. Per-protocol population = all subjects who completed the second 6 months of prophylactic treatment and had no major deviations from the protocol affecting the study results. Annualized bleeding rate determined by dividing the number of bleeds by observation period in years. |
Of note, ABR is not comparable between different factor concentrates and between different clinical trials.
Total ABRs, spontaneous ABRs and spontaneous AJBRs during the second 6-month study period are presented in Table 5.
Table 5: Annualized bleed rate (ABR) second 6-month study period
| | (ITT Population) |
| 1-3% Trough Level (N=57) | 8-12% Trough Level (N=53) |
| Median | Mean (SD) | Median | Mean (SD) |
| Total ABR | 2.0 | 3.6 (7.5) | 0.0 | 1.6 (3.4) |
| Spontaneous ABR | 0.0 | 2.5 (6.6) | 0.0 | 0.7 (1.7) |
| Spontaneous AJBR | 0.0 | 2.0 (6.4) | 0.0 | 0.5 (1.7) |
| ABR = Annualized bleeding rate. AJBR = Annualized joint bleeding rate. Annualized bleeding rate determined by dividing the number of bleeds by observation period in years. |
| | Per Protocol Population |
| 1-3% Trough Level (N=52) | 8-12% Trough Level (N=43) |
| Median | Mean (SD) | Median | Mean (SD) |
| Total ABR | 2.0 | 2.4 (3.2) | 0.0 | 2.1 (4.2) |
| Spontaneous ABR | 0.0 | 1.6 (2.6) | 0.0 | 0.8 (2.4) |
| Spontaneous AJBR | 0.0 | 1.0 (1.8) | 0.0 | 0.7 (2.2) |
| ABR = Annualized bleeding rate. AJBR = Annualized joint bleeding rate. Per-protocol population = all subjects who completed the second 6 months of prophylactic treatment and had no major deviations from the protocol affecting the study results. Annualized bleeding rate determined by dividing the number of bleeds by observation period in years. |
A total of 242 bleeding episodes in 66 subjects were treated with ADYNOVI; 155 bleeds in 40 subjects in the 1-3% trough level arm and 87 bleeds in 26 subjects in the 8-12% trough level arm. The majority of bleeds (86.0%, 208/242) were treated with 1 or 2 infusions; and bleed treatment at resolution of the bleeding episode was rated excellent or good in 84.7% (205/242) of bleeds.