Safety and pharmacokinetics of subcutaneously administered recombinant activated factor VII (rFVIIa)

Subcutaneous Marzeptacog Alfa (Activated) for On-Demand Treatment of Bleeding Events in Subjects With Hemophilia A or B With Inhibitors

Marzeptacog alfa (MarzAA) is under development for subcutaneous treatment of episodic bleeds in patients with hemophilia A/B and was studied in a phase III trial evaluating MarzAA compared with standard-of-care (SoC) for on-demand use. The work presented here aimed to evaluate MarzAA and SoC treatment of bleeding events on a standardized four-point efficacy scale (poor, fair, good, and excellent). Two continuous-time Markov modeling approaches were explored; a four-state model analyzing all four categories of bleeding improvement and a two-state model analyzing a binarized outcome (treatment failure (poor/fair), and treatment success (good/excellent)). Different covariates impacting improvement of bleeding episodes as well as a putative relationship between MarzAA exposure and improvement of bleeding episodes were evaluated. In the final four-state model, higher baseline diastolic blood pressure and higher age (> 33 years of age) were found to negatively and positively impact improvement of bleeding condition, respectively. Bleeding events occurring in knees and ankles were found to improve faster than bleeding events at other locations. The covariate effects had most impact on early treatment success (≤ 3 hours) whereas at later timepoints (> 12 hours), treatment success was similar for all patients indicating that these covariates might be clinically relevant for early treatment response. A statistically significant relationship between MarzAA zero-order absorption and improvement of bleedings (P < 0.05) were identified albeit with low precision. No statistically significant difference in treatment response between MarzAA and intravenous SoC was identified, indicating the potential of MarzAA for treatment of episodic bleeding events with a favorable subcutaneous administration route.

Pharmacokinetics, immunogenicity, safety, and preliminary efficacy of subcutaneous turoctocog alfa pegol in previously treated patients with severe hemophilia A (alleviate 1)

BACKGROUND

The current standard of care for patients with hemophilia A is regular prophylaxis with factor VIII (FVIII) administered intravenously. Interest in subcutaneous (s.c.) administration, to potentially increase convenience, reduce the treatment burden and improve compliance, is increasing.

OBJECTIVES

Evaluate the pharmacokinetics (PK), immunogenicity, safety, and preliminary efficacy of s.c. administration of turoctocog alfa pegol (s.c. N8-GP) in adult or adolescent previously treated patients (PTPs) with severe hemophilia A (alleviate 1; NCT02994407).

PATIENTS/METHODS

In part A, 24 PTPs received a single dose of s.c. N8-GP (12.5, 25, 50, or 100 IU/kg) with 6 patients per cohort. PK modelling of data from part A supported a suitable dose for part B. Part B comprised a multiple dose trial in 26 PTPs; patients <60 kg received 2000 IU and patients ≥60 kg received 4000 IU s.c. N8-GP daily for 3 months.

RESULTS

Single-dose s.c. N8-GP supported dose linearity. Daily prophylaxis with s.c. N8-GP appeared well tolerated and efficacious, achieving a mean trough FVIII activity close to 10% at steady state. Five patients developed anti-N8-GP binding antibodies after 42 to 91 exposure days, one of whom developed an inhibitor to FVIII. Anti-N8-GP antibody appearance was associated with a decline in FVIII plasma activity in four of the five patients. Five patients reported a total of nine treatment-requiring bleeding episodes during prophylaxis.

CONCLUSIONS

Subcutaneous administration of N8-GP is associated with a high incidence of antibodies in PTPs with severe hemophilia A. Further clinical development of s.c. N8-GP has been suspended.

Establishment of an HPLC-based method to identify key proteases of proteins in vitro

Given that the biological functions of proteins may decrease or even be lost due to degradation by proteases, it is of great significance to identify potential proteases that degrade protein drugs during systemic circulation. In this work, we describe a method based on high-performance liquid chromatography (HPLC) to identify key proteases that degrade therapeutic proteins in blood, including endopeptidases and exopeptidases. Here, the degradation of proteins was detected by competition with standard substrates of proteases and is shown as the relative residue rate. Four protein drugs were subjected to this method, and the results suggested that growth hormone was degraded by aminopeptidase N and kallikrein-related peptidase 5, pertuzumab was hardly degraded by the proteases, factor VII was degraded by carboxypeptidase B, neprilysin, dipeptidyl peptidase-4 and peptidyl dipeptidase A, and fibrinogen was degraded by carboxypeptidase B and kallikrein-related peptidase 5, findings consistent with the literature. The results were confirmed by microscale thermophoresis; additionally, activity detection in vitro substantiated that the degradation of factor VII decreased its activity. We demonstrate that this method can be used to identify key proteases of proteins with high accuracy, precision and durability.

Challenges and Opportunities for the Subcutaneous Delivery of Therapeutic Proteins

Biotherapeutics is a rapidly growing drug class, and over 200 biotherapeutics have already obtained approval, with about 50 of these being approved in 2015 and 2016 alone. Several hundred protein therapeutic products are still in the pipeline, including interesting new approaches to treatment. Owing to patients' convenience of at home administration and reduced number of hospital visits as well as the reduction in treatment costs, subcutaneous (SC) administration of biologics is of increasing interest. Although several avenues for treatment using biotherapeutics are being explored, there is still a sufficient gap in knowledge regarding the interplay of formulation conditions, immunogenicity, and pharmacokinetics (PK) of the absorption of these compounds when they are given SC. This review seeks to highlight the major concerns and important factors governing this route of administration and suggest a holistic approach for effective SC delivery.

Sustained pro-haemostatic activity of rFVIIa in plasma and platelets in non-bleeding pigs may explain the efficacy of a once-daily prophylaxis in humans

Recombinant factor VIIa (rFVIIa) is registered for treatment of inhibitor-complicated haemophilia, and a once-daily prophylactic administration of rFVIIa is successful in reducing the number of bleeding events. This suggests that a single rFVIIa dose has a pro-haemostatic effect up to 24 hours (h), which is difficult to explain given its half-life of 2 h. In this study, six pigs received a 90 µg/kg rFVIIa bolus. Plasma was collected and platelets were isolated at various time points up to 48 h, and analysed for FVIIa levels and associated haemostatic activity. Elevated plasma FVIIa levels were detected up to 24 h post-administration (36 (32–56) mU/ml [median (interquartile range [IQR]), 24 h] vs 2 (2–14) mU/ml [baseline]). Corresponding prothrombin time (PT) values remained shortened compared to baseline until 24 h post-administration (9.4 (9.3–9.9) seconds (s) [24 h] vs 10.5 (10.2–11.0) s [baseline], p ≤0.01). The lag time in thrombin generation testing as well as clotting times in plasma-based assays were shortened up to 12 or 24 h post-administration, respectively (lag times 1.8 (1.7–2.1) minutes (min) [12 h] vs 2.3 (2.3–2.6) min [baseline], p ≤0.01 and clotting times 3.8 (3.2–3.9) min [24 h] vs 5.2 (4.6–5.5) min [baseline], p ≤0.001). Platelet FVIIa levels were elevated up to 48 h (7.7 (3.4–9.0) ng VIIa/mg actin [48 h] vs 2.5 (0.7–4.8) ng VIIa/mg actin [baseline]). In conclusion, elevated and haemostatically active plasma and platelet FVIIa levels are detectable up to 24–48 h following rFVIIa administration in pigs. This prolonged pro-haemostatic effect of FVIIa may explain the prophylactic efficacy of a once-daily rFVIIa treatment.

Changes in the amino acid sequence of the recombinant human factor VIIa analog, vatreptacog alfa, are associated with clinical immunogenicity

BACKGROUND

Vatreptacog alfa, a recombinant human factor VIIa (rFVIIa) analog developed to improve the treatment of bleeds in hemophilia patients with inhibitors, differs from native FVIIa by three amino acid substitutions. In a randomized, double-blind, crossover, confirmatory phase III trial (adept(™) 2), 8/72 (11%) hemophilia A or B patients with inhibitors treated for acute bleeds developed anti-drug antibodies (ADAs) to vatreptacog alfa.

OBJECTIVES

To characterize the formation of anti-vatreptacog alfa ADAs in hemophilia patients with inhibitors.

METHODS/PATIENTS

This was a post hoc analysis of adept(™) 2. Immunoglobulin isotype determination, specificity analysis of rFVIIa cross-reactive antibodies, epitope mapping of rFVIIa single mutant analogs and pharmacokinetic (PK) profiling were performed to characterize the ADAs.

RESULTS

Immunoglobulin isotyping indicated that the ADAs were of the immunoglobulin G subtype. In epitope mapping, none of the rFVIIa single mutant analogs (V158D, E296V or M298Q) contained the complete antibody epitope, confirming that the antibodies were specific for vatreptacog alfa. In two patients, for whom PK profiling was performed both before and after the development of ADAs, vatreptacog alfa showed a prolonged elimination phase following ADA development. During the follow-up evaluation, the rFVIIa cross-reactivity disappeared after the last vatreptacog alfa exposure, despite continued exposure to rFVIIa as part of standard care.

CONCLUSIONS

Results from the vatreptacog alfa phase III trial demonstrate that the specific changes made, albeit relatively small, to the FVIIa molecule alter its clinical immunogenicity.

Recombinant factor VIIa analog in the management of hemophilia with inhibitors: results from a multicenter, randomized, controlled trial of vatreptacog alfa

BACKGROUND

Vatreptacog alfa, a recombinant factor VIIa (rFVIIa) analog with three amino acid substitutions and 99% identity to native FVIIa, was developed to improve the treatment of hemophilic patients with inhibitors.

OBJECTIVES

To confirm the safety and assess the efficacy of vatreptacog alfa in treating bleeding episodes in hemophilic patients with inhibitors.

PATIENTS AND METHODS

In this international, multicenter, randomized, double-blind, active-controlled, crossover, confirmatory phase III trial (adept(™) 2) in patients with hemophilia A or B and inhibitors, bleeds were randomized 3 : 2 to treatment with vatreptacog alfa (one to three doses at 80 μg kg(-1) ) or rFVIIa (one to three doses at 90 μg kg(-1) ). Treatment failures after three doses of trial product (TP) were managed according to the local standard of care.

RESULTS

In the 72 patients enrolled, 567 bleeds were treated with TP. Both vatreptacog alfa and rFVIIa gave 93% effective bleeding control at 12 h. Vatreptacog alfa was superior to rFVIIa in secondary efficacy outcomes, including the number of doses used to treat a bleed and sustained bleeding control 24-48 h after the first dose. Eight patients (11%) developed antibodies against vatreptacog alfa, including four with cross-reactivity against rFVIIa and one with an in vitro neutralizing effect to vatreptacog alfa.

CONCLUSIONS

This large randomized controlled trial confirmed the well-established efficacy and safety profile of rFVIIa, and showed that vatreptacog alfa had similar or better efficacy than rFVIIa. However, because of the development of anti-drug antibodies, a positive benefit-risk profile is unlikely to be achieved with vatreptacog alfa.

Immunogenicity of subcutaneously administered therapeutic proteins--a mechanistic perspective

The administration of therapeutic proteins via the subcutaneous route (sc) is desired for compliance and convenience, but could be challenging due to perceived immunogenic potential or unwanted immune responses. There are clinical and preclinical data supporting as well as refuting the generalized notion that sc is more immunogenic. We provide a mechanistic perspective of immunogenicity of therapeutic proteins administered via the sc route and discuss strategies and opportunities for novel therapeutic approaches to mitigate immunogenicity.

Surgery in patients with congenital factor VII deficiency: A single center experience

Background

Congenital factor VII (FVII) deficiency is a rare hemorrhagic disorder that can cause excessive bleeding during and after surgery in affected patients. The recombinant form of activated factor VII (rFVIIa, NovoSeven® from Novo Nordisk, Bagsvaerd, Denmark), which was developed as a second-generation bypassing agent, has recently been used in the management of bleeding for patients with congenital FVII deficiency.

Methods

We reviewed the results of 8 surgical procedures in 5 patients with congenital FVII deficiency at the Kyung Hee University Hospital, Gangdong, Seoul, Korea, between January 2008 and June 2010. We administrated rFVIIa preoperatively in six patients and postoperatively in five patients.

Results

Between January 2008 and June 2010 at our center, 8 operations were performed successfully and no complications were observed in the 5 patients with congenital FVII deficiency. The median level of FVII activity was 2% (range, 0.6-7%). Four orthopedic procedures, 1 tonsillectomy, and 3 dental extractions were performed. The median duration of hospitalization was 8.5 days (range, 0-15 days). rFVIIa was administered at all procedures, except the dental extraction that was performed using only antifibrinolytic agents without any replacement. No bleeding or thrombogenic complications were observed in any case.

Conclusion

Patients with congenital FVII deficiency who require surgery can be treated efficiently and safely with rFVIIa or antifibrinolytic agents. rFVIIa was well tolerated and maintained effective hemostasis and showed good clinical outcome after the major surgery.