Here we apply state-of-the-art statistical genetic approaches toward investigating the genetic architecture of factor VIII (FVIII) inhibitor (FEI) development in Hemophilia A (HA). A total of 442 ...North American HA patients (237 Whites and 205 Blacks; 88% severely affected) enrolled in the PATH Study were: 1) ImmunoChip genotyped at ~167,000 single nucleotide polymorphisms (SNPs) in genes previously implicated in autoimmune disease risk; 2) Evaluated by DNA sequencing and assays for the recurrent intron (I)1 and I22 inversions to identify their causative F8 mutations; and 3) Tested with the Bethesda assay to determine their FEI status. The ImmunoChip genotypes were used to construct a genetic relationship matrix (GRM), denoted by K, following our previously published method,1 and the F8 sequence data along with results from the I1 and I22 inversion assays were used to construct a shared F8-mutation matrix, denoted by F. We analyzed a dichotomous FEI variable under the statistical genetic threshold/liability model (a probit regression in the fixed effects) in conjunction with a variance components model for the FEI liability phenotypic covariance matrix, denoted by P, to model potentially important random effects. For the latter, we specifically assumed independent additive genetic, F8-mutation, and residual environmental random effects. By the independence assumption, the covariance matrix is then decomposable as a sum of the additive genetic (Va), F8-mutation (Vf), and residual environmental (Ve) variances respectively structured by K, F, and the identity matrix I. The variance component model is given as: P = K*Va + F*Vf + I*Ve. Heritability, denoted by h2, is defined as the ratio of Va to the total phenotypic variance (Vp): h2 = Va / Vp. We can further speak of the total heritability given as: h2t = h2r + h2f + h2snp, where the subscripts t, r, f, and snp respectively denote total, residual additive genetic, F8-mutation-specific, and SNP heritabilities. Using eigenstructure methods,2 we can compute power under a simpler model in which Va and Vf are combined as a single variance component. We computed power to detect genetic association as measured by SNP-specific heritability for a set of 403 SNPs in or near 14 candidate immune response genes previously implicated in FEI risk. To account for multiple hypothesis testing, power was computed at the Bonferroni-adjusted significance level of 0.05/403 = 1.2 × 10-4. Under the simplified model, we computed the statistical power to detect causal SNPs for our sample and study design for the sample FEI prevalences, denoted by Kp, for Whites (22.5%) and Blacks (45%), across a range of total heritabilities, h2t = 15%, 35%, and 55%, where the lattermost total heritability was observed for FEI liability in the current study (Figure 1). It should be noted that because the liability heritability is known to be biased upward, we applied the Dempster-Lerner correction to both the total and SNP-specific heritabilities.3 Close inspection of Figure 1 reveals that varying h2t from 15% to 35% to 55% results in slight decreases in power due to the decreasing ratio of the SNP-specific heritability to the total heritability. However, as seen in all three panels, the more important determinant of power is clearly the FEI prevalence in that the power curve for a Kp of 45% is associated with greater power than the power curve for a Kp of 22.5% across the range of total heritabilities examined. As seen in Figure 1, we have adequate power to detect SNP heritabilities as low as 5% and 6%, respectively, for a Kp of 45% and 22.5%. As noted above, we observed a FEI liability total heritability of 55% consisting of a 47% residual additive genetic heritability (p = 0.019) and 8% F8-mutation specific heritability (p = 0.005). This is the first study to use a GRM based on genotype data and a shared causal F8 mutation matrix to model additive genetic and F8-mutation specific effects.Almeida M, Peralta J, Farook V, …, Blangero J. Pedigree-based random effect tests to screen gene pathways. BMC Proc. 2014; 8(Suppl 1 Genetic Analysis Workshop): S100.Blangero J, Diego VP, Dyer T, …, Göring H. A kernel of truth: statistical advances in polygenic variance component models for complex human pedigrees. Adv Genetics. 2013; 81: 1-31.Glahn D, Williams J, McKay D, …, Blangero J. Discovering schizophrenia endophenotypes in randomly ascertained pedigrees. Biol Psychiatry. 2015; 77(1): 75-83.
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Chitlur:Baxter, Bayer, Biogen Idec, and Pfizer: Honoraria; Novo Nordisk Inc: Consultancy. Dinh:Haplomics Biotechnology Corporation: Employment, Equity Ownership. Howard:Haplomics Biotechnology Corporation: Equity Ownership, Other: Chief Scientific Officer, Patents & Royalties: Patent applications and provisional patent applications ; CSL Behring: Research Funding.
The development of inhibitors against tFVIIIs represents a serious impediment to efficacious management of bleeding episodes in patients with hemophilia A (HA). It is therefore critical to understand ...the etiology of inhibitors to improve HA outcomes. Our group has recently presented evidence (Diego et al. Res Pract Thromb Haemost. 2019;3(Suppl. 1):50-51) on the validity of the Sequence Mismatch hypothesis, which posits that a sequence mismatch between the patient's endogenous FVIII sequence (i.e., due to the presence of a non-HA-causing non-synonymous single-nucleotide variation) and that underlying their tFVIII increases the risk that inhibitors will be induced during FVIII replacement therapy.
For our study, 442 North American HA patients (237 Whites & 205 Blacks; 88% severely affected) were: 1) Immuno-Chip genotyped at ~167,000 SNPs in genes implicated in autoimmune disease risk; 2) Evaluated by Sanger DNA sequencing and assays for the recurrent intron (I)1- and I22-inversions to identify their F8-causal-mutations; and 3) Tested with the Nijmegen-modified Bethesda assay to determine their inhibitor status. The Immuno-Chip genotypes were used to construct a genetic-relationship matrix (GRM), and the F8 sequence data along with results from the I1- and I22-inversion (I22I) assays were used to construct a shared F8-mutation matrix (FMM). These matrices were used to estimate the heritable genetic and shared F8-mutation effects. Importantly, modeling a F8-mutation effect has the added advantage of accounting for the mutational heterogeneity in F8-mutations. We found that heritability and F8-mutation effects respectively accounted for 50% and 23% of the phenotypic variance in inhibitor (both p < 0.0001).
Under the Sequence Mismatch hypothesis, it is assumed that tFVIII-derived peptides spanning the sequence mismatch must first be bound and presented on HLAcII molecules. In Diego et al. (2019), we reported a significant sequence mismatch effect but did not account for the effect of HLAcII binding. In a previous study of PATH data, it was shown using an area under the curve (AUC) estimate from receiver operator characteristic (ROC) curve analysis that HLAcII binding affinities estimated from the then-current version of NetMHCIIpan algorithm with respect to 15-mer peptides spanning sequence mismatches significantly predicted inhibitor status in a sample of 25 patients with the I22I mutation (Pandey et al. Nat Med. 2013;19(10): 1318-24). Here we adopt two strategies to extend this latter analysis to account for genetic relatedness and mutational heterogeneity. In the first strategy, we initially performed a Cholesky decomposition of the phenotypic covariance matrix expressed as a function of the GRM and FMM and their associated heritability and F8-mutation effect estimates, respectively. Following this, the derived Cholesky factor was used to decorrelate the HLAcII binding data, and then a bootstrap with replacement followed by ROC curve analysis each time (for 1,000 resampling's of the data) was used to generate an empirical distribution of the estimated AUC estimates. In the second strategy, we stratified the sample into the subset with the I22I mutation. We next performed a Cholesky decomposition of the GRM multiplied by the heritability and then used the resulting Cholesky factor to decorrelate the data for this subset. Finally, bootstrap with replacement followed by ROC curve analysis each time was used to generate an empirical distribution of the estimated AUC estimates. The p-values for both strategies are determined as the number of AUC estimates greater than that for the original transformed sample plus 1 divided by the total number of bootstraps plus 1.
For the first time, we report results on the validity of the sequence mismatch hypothesis while modeling the effects of genetic relatedness, mutational heterogeneity, and HLAcII binding affinity.
Luu:Haplogenics Corporation: Employment. Chitlur:CSL-Behring: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda/Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Research Funding; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bioveritiv/Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Octapharma: Consultancy, Membership on an entity's Board of Directors or advisory committees. Dinh:Haplogenics Corporation: Employment. Mead:CSL Behring: Employment. Powell:Haplogenics: Membership on an entity's Board of Directors or advisory committees. Escobar:Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; National Hemophilia Foundation: Consultancy, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Howard:Haplogenics Corporation: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.
Hemophilia A is an X-linked bleeding disorder caused by mutations in the gene encoding the Factor VIII coagulation protein (FVIII). Bleeding episodes in patients are reduced by prophylactic therapy ...or treated acutely using recombinant or plasma derived FVIII. These treatments have substantially improved the outcome of hemophilia. More recently long-acting recombinant FVIII concentrates have become available in the clinic, but hemophilia A patients still require the repeated intravenous injections frequently 2-3 times per week. Furthermore, the development of inhibitors which are associated with significant mortality and morbidity remains a serious complication for approximately 30% of patients with severe hemophilia A, highlighting the need for new FVIII products with reduced immunogenicity. The development of recombinant FVIII molecules with a lower inhibitor risk profile would present an important advance in the care of patients with hemophilia A. rVIII-SingleChain (AFSTYLATM), is the first and only single-chain molecule purposely designed to provide key features such as increased dosing intervals and high clinical efficacy. The present study has focused on evaluating the immunogenic profile of rVIII-SingleChain in comparison to other rFVIII products (both full length and B-domain-truncated/deleted). Several key characteristics have been identified: The highly pure and homogeneous rVIII-SingleChain with a covalently linked heavy chain and light chain is less likely to contain dissociated FVIII chains (or fragments thereof) that cannot bind to von Willebrand Factor (VWF) and are thus available for uptake by antigen presenting cells (APC). The high degree of sulphation of the predicted six tyrosine sulphation sites in rVIII-SingleChain (as compared to other rFVIII molecules) not only provides a basis for optimal functionality but also (with respect to Tyr1680) ensures maximal VWF binding of the majority of rVIII-SingleChain molecules. The improved binding of rVIII-SingleChain to VWF as compared to full-length rFVIII may more effectively reduce antigen uptake and processing by antigen-presenting cells. In this regard, rVIII-SingleChain pre-complexed with plasma-derived VWF, is less efficiently internalized by human monocyte-derived dendritic cells (MoDCs) as compared to several rFVIII products tested. Further, in a ProImmune ProPresent® antigen presentation assay to identify potentially immunogenic regions in rVIII-SingleChain as compared to full length rFVIII protein revealed a lower number of HLA-DR/DP/DQ-restricted epitopes derived from rVIII-SingleChain as compared to the full length rFVIII protein (33 c.f. 47 for DR; 24 c.f. 32 for DP and 26 c.f. 32 for DQ). In addition, when compared to BDD-rFVIII comparators in the ProImmune ProReveal® T cell stimulation assay, rVIII-SingleChain was found to contain fewer HLA-DR/DP/DQ-restricted epitopes derived from the linker region that triggered T-cell proliferation (15% as compared to 25-35% for the comparators). Collectively, these features should contribute to the reduced immunogenic potential of rVIII-SingleChain. Importantly, these pre-clinical studies are supported by findings from the completed rVIII-SingleChain clinical studies in previously treated patients (PTPs) in which no inhibitor development has been observed. In summary, the immunogenicity of rVIII-SingleChain has been extensively characterized in PTPs over 28,418 exposure days equivalent to more than 233 treatment years. As of 01 August 2016, no PTP subject has developed inhibitors after being exposed to rVIII-SingleChain. All available data support the hypothesis that the unique structural attributes of rVIII-SingleChain may translate into reduced immunogenicity when used for replacement therapy in patients with hemophilia A. The previously untreated patient (PUP) arm in the ongoing extension study is designed to generate data that are necessary to prove this significant clinical benefit. rVIII-SingleChain could potentially offer hemophilia A patients a recombinant product with an inhibitor risk profile that is more favorable than that of currently available products.
Maraskovsky:CSL Limited: Employment. Verhagen:CSL Limited: Employment. Huynh:CSL Limited: Employment. Baz Morelli:CSL Limited: Employment. Schmidbauer:CSL Behring: Employment. Zollner:CSL Behring: Employment. Powell:CSL Behring: Employment. St Ledger:CSL Behring: Employment. Veldman:CSL Behring: Employment. Hofmann:CSL Behring: Employment.
Background:
Hemophilia A (HA) is caused by F8 mutations and resultant plasma deficiencies in FVIII activity. While bleeding can be arrested by infusing therapeutic FVIII proteins (tFVIIIs), ~30% of ...severe HA patients will develop neutralizing tFVIII antibodies (inhibitors) and become resistant to treatment. For inhibitors to develop, foreign peptides must be liberated from a tFVIII and displayed on dendritic cells (DCs) in self HLAcII molecules. Little is known about the inhibitor risk attributable to distinct isomers of individual HLAcII repertoires and different tFVIII domains.
Aims:
Determine the contributions to FVIII immunogenicity risk of the distinct 1) HLAcII isomers DP, DQ and DR, and 2) tFVIII domains A1, A2, A3, B, C1 and C2.
Methods:
We analyzed HLAcII/tFVIII peptidomic data generated in DC-protein processing assays (PPAs) that used monocyte-derived DCs from 12 healthy donors to compare the immunogenicity of a full length (FL) and B-domain truncated (BDT) recombinant FVIII (FL- and BDT-FVIII) ± von Willebrand Factor (VWF) and a plasma derived (pd)FVIII + VWF. All tFVIIIs contain 3 small acidic-residue-rich peptides (a1, a2 and a3) that connect A1 to A2, A2 to B, and B to A3. To simplify our analysis, any LC-MS/MS individually sequenced peptide (ISP) with an N-terminal residue in either the (i) C-terminal portion of A1, A2 or B that extends into the adjacent a1, a2 or a3 region, respectively, was placed into that domain, or (ii) a1, a2 or a3 region, whether or not it extends into A3, C1 or C2, was placed into that domain. We then calculated the expected frequency of peptides from each FVIII domain (including, when appropriate, the adjacent acidic regions) based on residue number. Finally, we compared the observed and expected peptide proportions and performed a Z-test on the difference of proportions per domain. We performed this analysis for all ISP data in which the observed frequencies were obtained by a weighting scheme jointly taking into account contributions by tFVIII & by domain (All-data). We also performed this analysis by tFVIII.
Results:
For the All-data comparisons, we found that A3 had a higher observed than expected proportion (dP = 22%; p = 0.006). For the FL-FVIII comparisons, the B domain had a lower observed than expected proportion (dP = -12.1%; p < 0.001) and A3 had a higher observed than expected proportion (dP = 11.4% p < 0.001). There were no significant differences for the FL-FVIII + VWF comparisons. For pdFVIII + VWF, we found that A1 had a higher observed than expected proportion (dP = 24%; p = 0.001) while B had a lower observed than expected proportion (dP = -30.9%; p < 0.001). For BDT-FVIII, we found that A2 and A3 both exhibited higher observed than expected proportions (dP = 7.4% & 24.6%; p = 0.049 & p < 0.001), and, as expected, that the B domain had a lower observed than expected proportion (dP = -35.9%; p < 0.001). Regarding the BDT-FVIII + VWF comparisons, we found B had a lower observed than expected proportion (dP = -30.8; p = 0.004).
We also approached these data from the HLAcII perspective. We found that our 12 donors expressed 12 distinct DR molecules based on their DRB1 alleles. After tallying the per allele density of FVIII residues (for all 2332 residues) falling in the DR-bound fraction of peptides, we constructed FVIII residue-by-allele matrices of dimensions 2332 x 12 per tFVIII and performed singular value decompositions that yielded their respective matrices of right singular vectors also known as principal components (PCs). Such PCs are said to span or generate a corresponding vector subspace. Using matrix analytic methods, we can compare the therapeutic-specific subspaces to see if such contrasts reflect differences in their associated density profiles. To compare two subspaces, we compute their projection onto their intersection subspace, and use this projection to compute a subspace distance. We test the null hypothesis of a subspace distance equal to 0 (for statistically similar subspaces) by a permutation test. As an example, we compared the FL-FVIII + VWF and pdFVIII + VWF subspaces, and found that they are significantly different (subspace distance (SD) = 0.96; p < 0.001). We also compared the FL-FVIII with & without VWF subspaces, and found that they are significantly different (SD = 0.545; p < 0.001).
Conclusions:
Our findings demonstrate that the distinct domains of tFVIIIs and different alleles of individual HLAcII repertoires differentially contribute to inhibitor risk.
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Hofmann:CSL Behring: Employment. Escobar:Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Honoraria, Membership on an entity's Board of Directors or advisory committees; NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dinh:Haplomics: Employment. Powell:CSL Behring: Employment. Howard:CSL Behring: Honoraria, Research Funding; Haplomics: Employment, Equity Ownership, Patents & Royalties, Research Funding.
Background
Patients with congenital
F
actor
XIII
(
FXIII
) deficiency have impaired fibrin stabilization and are at high risk for surgical bleeding. Data regarding the use of
FXIII
concentrates ...before and during surgery are lacking. The objective of this study was to report the use of plasma‐derived
FXIII
concentrate (
C
orifact in the
U
nited
S
tates;
F
ibrogammin
P
in other countries) in patients with congenital
FXIII
deficiency undergoing surgical procedures.
Study Design and Methods
FXIII
concentrate at preoperative doses ranging from 25 to 40
U
/kg was administered to six patients with congenital
FXIII
deficiency undergoing major or minor surgeries.
Results
FXIII
concentrate was administered immediately before surgery for five surgical cases; three of these patients achieved excellent hemostasis during and after surgery, while two had intraoperative bleeding. In one surgical case, a regular prophylactic dose of
FXIII
concentrate was administered to the patient 1 week before minor surgery.
FXIII
concentrate provided rapid replacement of
FXIII
activity. In all but one of the patients given a dose of
FXIII
designed to increase
FXIII
levels more than 50%, there was satisfactory intraoperative and postoperative hemostasis. One patient undergoing aortic valve replacement on cardiopulmonary bypass (
CPB
) was the exception. Intraoperative bleeding in this patient was associated with lower‐than‐expected blood levels of
FXIII
.
Conclusion
Preoperative plasma‐derived
FXIII
concentrate allowed for sufficient hemostasis in most patients with
FXIII
deficiencies. Additional doses were necessary to achieve hemostasis in one patient who underwent a
CPB
procedure.
Prevention of spontaneous bleeding in patients with severe haemophilia A usually requires therapeutic infusions every 2–3 days because of the short half‐life of factor VIII (FVIII). Longer‐acting ...FVIII products that require less frequent infusions would be beneficial and might obviate the need for central catheters in most patients. Liposomal formulation can enhance the efficacy of some therapeutic products. The incorporation of high‐molecular weight polyethylene glycol (PEG) can extend the circulatory half‐life of the liposome. These combined approaches led to the development of BAY 79‐4980, a PEG‐containing liposomal version of Kogenate® FS (rFVIII‐FS). Results from preclinical models and early clinical trials have shown that BAY 79‐4980 prolongs the time to the next bleed. Further clinical evaluation of the efficacy and long‐term safety of BAY 79‐4980 are planned.
▪
Introduction: Prophylaxis with replacement factor IX (FIX) therapies can reduce the frequency of bleeding episodes in patients with severe hemophilia B. There is currently a lack of data on factor ...activity levels in patients that treat bleeding episodes while adhering to a prophylactic regimen. The phase 3 B-LONG study (Powell et al. NEJM 2013) demonstrated that recombinant factor IX Fc fusion protein (rFIXFc) had a prolonged half-life relative to recombinant FIX, and that rFIXFc was efficacious and safe for prophylaxis and treatment of bleeding in subjects with hemophilia B; previous reports have evaluated treatment of bleeding in all subjects in B-LONG, including those receiving episodic treatment with rFIXFc. The purpose of this analysis was to assess the efficacy of rFIXFc for the treatment of bleeding in patients that received rFIXFc prophylaxis in the B-LONG study. Additionally, FIX activity levels were predicted under scenarios where treatment of bleeding occurred in close proximity to prophylactic doses using a population pharmacokinetic (PK) modeling approach.
Methods: B-LONG included previously treated male subjects ≥12 years of age that had moderately-severe to severe hemophilia B (≤2 IU/dL endogenous FIX activity). Treatment of bleeding was assessed in subjects receiving weekly prophylaxis (Arm 1) and individualized interval prophylaxis (Arm 2). The number of bleeds, median dose per infusion to treat a bleed, and number of infusions to resolve bleeds were evaluated. Predicted activity levels were generated for 1000 hypothetical patients using a three-compartment population PK model that was developed using PK data from B-LONG (n=123) and a phase 1/2a study of rFIXFc (n=12). Factor activity was predicted assuming that bleeds were treated with 50 IU/kg rFIXFc either 24 hours before or 24 hours after a scheduled prophylactic dose for patients on regimens of 50 IU/kg weekly (at steady-state). The treatment of bleeding dose was selected because it was in the recommended range in the B-LONG study and was consistent with the median dose per infusion used in B-LONG. The 50 IU/kg weekly regimen was the most common starting prophylactic regimen in B-LONG; 24 hours was selected to approximate the shortest time interval between separate treatment of bleeding and prophylactic doses.
Results: In Arm 1 of B-LONG, bleeding episodes were reported in 47 of 61 subjects, and there were 167 episodes in total. In Arm 2, 67 episodes were reported in 15 of 26 subjects. The median annualized bleeding rate (ABR) was 2.95 in Arm 1 (median spontaneous ABR 1.04) and 1.38 in Arm 2 (median spontaneous ABR 0.88). In Arm 1, 85% of bleeding episodes resolved with 1 infusion and the median dose per infusion was 47.11 IU/kg (interquartile range IQR 31.75-56.03). In Arm 2, 85.1% of bleeding episodes resolved with 1 infusion and the median dose per infusion was 44.78 IU/kg (IQR 33.63-74.33). rFIXFc was generally well-tolerated, and there were no vascular thrombotic events reported in any arm of the B-LONG study. The predicted median Cmax from the population PK model was in the normal range for both scenarios (Table 1; Figure 1).
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Conclusions: Predictions of factor activity from a population PK model showed that the vast majority of patients maintained factor activity within the normal range when rFIXFc was dosed in close proximity for both prophylaxis and to treat a bleeding episode. These predictions also indicated that maximum plasma concentration was achieved rapidly. An analysis of bleeding episodes in subjects specifically from the prophylaxis arms of B-LONG showed that rFIXFc was a safe and efficacious treatment for bleeding in patients on prophylactic regimens.
Powell:Bayer: Research Funding; Baxter Healthcare: Research Funding; Biogen Idec: Research Funding; CSL Behring: Research Funding; Novo Nordisk: Research Funding. Ozelo:Bayer: Research Funding; Baxter: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Novo Nordisk: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; CSL Behring: Research Funding; Novo Nordisk Haemophilia Foundation: Research Funding. Ragni:Pfizer: Research Funding; Novo Nordisk: Research Funding; Novartis: Research Funding; Merck: Research Funding; CSL Behring: Research Funding; Bayer: Research Funding; Baxter: Research Funding; Tacere Benitec: Consultancy, Drug Safety Monitoring Board, Drug Safety Monitoring Board Other; GlaxoSmithKline: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Biogen Idec: Consultancy, Research Funding; Spark Therapeutics: Research Funding; Vascular Medicine Institute, PIttsburgh, PA: Research Funding. Pasi:Bayer: Membership on an entity’s Board of Directors or advisory committees; BPL: Membership on an entity’s Board of Directors or advisory committees; Biogen Idec: Educational Support and Travel Grants, Educational Support and Travel Grants Other, Membership on an entity’s Board of Directors or advisory committees; Novo Nordisk: Educational Support and Travel Grants, Educational Support and Travel Grants Other; OctaPharma: Educational Support and Travel Grants Other, Membership on an entity’s Board of Directors or advisory committees; Pfizer: Educational Support and Travel Grants Other, Membership on an entity’s Board of Directors or advisory committees. Perry:Biogen Idec: Consultancy, Research Funding; Novo Nordisk: Consultancy, Honoraria, Speakers Bureau; Baxter: Honoraria. Zhu:Biogen Idec: Employment, Equity Ownership. Mei:Biogen Idec: Employment, Equity Ownership. Pierce:Biogen Idec: Employment, Equity Ownership. Li:Biogen Idec: Employment, Equity Ownership. Robinson:Biogen Idec: Employment, Equity Ownership.
Smooth muscle cell (SMC) proliferation and formation of extracellular matrix in the intima of muscular arteries are major processes that can lead to vascular stenosis in arteriosclerosis or after ...coronary angioplasty. These processes are also seen in the proliferative response to balloon catheter-induced vascular injury of the rat carotid artery, and result in marked neointima formation by 14 days after catheterization. We have shown recently that the angiotensin-converting enzyme (ACE) inhibitor cilazapril strongly suppressed this development of neointima. In this report, we show that the beneficial effects on neointima formation persist for at least 8 weeks after stopping treatment with cilazapril, and that continuous treatment may have additional inhibitory effects during the late phases of vascular remodeling after injury. To investigate further the possible mechanisms, we examined several vasoactive compounds in this model. Another ACE inhibitor of a different chemical class, captopril, reduced neointima formation as strongly as cilazapril (67 and 78%, respectively), but the calcium antagonist verapamil was not active as an inhibitor of neointima formation, despite similar lowering of blood pressure. Hydralazine and a new calcium antagonist, Ro 40-5967, partially suppressed neointima formation (36%, p less than 0.005 and 33%, p less than 0.05, respectively). In vitro, neither cilazapril nor its active metabolite, cilazaprilate, had any effect on SMC proliferation in response to serum or PDGF. To characterize further the role of angiotensin II (Ang II), we tested in cell culture the effects of Ang II and cilazaprilate on mRNA levels of several proteins potentially involved in regulating the SMC response.
Prophylactic replacement of factor IX (FIX), the optimal treatment for patients with hemophilia B, requires intravenous injections up to 3 times per week. To reduce injection frequency, a long-acting ...recombinant factor IX Fc fusion protein (rFIXFc) consisting of one rFIX molecule covalently linked to the Fc domain of immunoglobulin G1 (IgG1) was developed. Fc fusion is an established technology that utilizes an endogenous IgG recycling pathway to prolong the half-life of therapeutic proteins. The results of a phase 3 study (B-LONG; NCT01027364) of the pharmacokinetics (PK), safety, and efficacy of rFIXFc in previously treated subjects with hemophilia B were previously presented (J Thromb Haemost. 2013; 112:241). It has been reported that age may affect the half-life of recombinant coagulation factors (Blood. 2012; 1192:612-618); thus, we examined whether age influences the PK, safety, and efficacy of rFIXFc. We report here a planned subgroup analysis comparing PK, safety, and efficacy of rFIXFc in adolescents with that of adults enrolled in the B-LONG study.
Male subjects aged ≥12 years with severe hemophilia B (≤2 IU/dL endogenous FIX), no inhibitors to FIX, and ≥100 exposure days (EDs) to FIX were assigned to one of 4 treatment arms: Arm 1, weekly prophylaxis (starting at 50 IU/kg; PK-driven dose adjustments); Arm 2, individualised interval prophylaxis (100 IU/kg every 10 days; PK-driven dosing interval adjustments); Arm 3, episodic treatment of bleeding episodes (20-100 IU/kg); and Arm 4, perioperative management. The study was stopped when pre-specified exposure was achieved and specified number of major surgical procedures had been completed, notably when 53 subjects completed ≥50 EDs with rFIXFc. rFIXFc PK parameters were estimated in all subjects by non-compartmental analysis based on the one-stage clotting assay; a sequential PK subgroup in Arm 1 compared the PK profile of rFIXFc with that of rFIX (BeneFIX ®). The primary endpoints were annualized bleeding rate (ABR), the incidence of adverse events (AEs), and inhibitor development. This subgroup analysis compared the PK, safety, and efficacy of adolescents (12-17 years of age) to adults (18-65 years of age). rFIXFc efficacy was assessed by comparing ABR of Arm 1 and Arm 2 with that of Arm 3 for adolescent and adult subgroups.
A total of 123 subjects were enrolled at 50 study centers in 17 countries. The median treatment duration was 51.4 weeks across all arms. Of 123 subjects, 120 were included in the PK analysis set; 3 subjects were excluded due to incomplete PK profile or noncompliance with the study treatment. There were 11 adolescent subjects enrolled in arms 1–3, and none in perioperative management arm (Arm 4). All adolescent subjects had evaluable rFIXFc PK profiles; however, as none of them participated in the sequential PK subgroup, comparative rFIX PK profiles were unavailable. The terminal half-life, clearance (CL), incremental recovery (IR), and volume of distribution at steady state (Vss) were similar between adolescents and adults (Table 1).
Table 1PK parameters of adolescents vs. adults, geometric mean 95% CIAdolescents (n=11)Adults (n=109)Half-life (hrs)82.22 (72.30, 93.50)76.36 (73.04,79.83)CL (mL/h/kg)3.39 (2.89, 3.98)3.08 (2.94, 3.23)IR (IU/dL per IU/kg)0.85 (0.68, 1.06)0.96 (0.91, 1.03)Vss (mL/kg)316.80 (267.40, 375.50)272.20 (258.30, 286.80)
The ABRs (median interquartile range) of adolescents were 2.57 (0.0, 3.13) in Arm 1, 3.12 (2.61, 7.56) in Arm 2, and 27.15 (20.37, 33.93) in Arm 3, comparable to the ABRs of adults (Arm 1, 2.95 1.01, 4.48; Arm 2, 0.72 0.0, 3.43; Arm 3, 16.27 10.77, 23.08). Both adolescent and adult subgroups in the prophylactic arms (Arms 1 and 2) had lower ABRs than those in the episodic treatment arm (Arm 3). No unique safety issues were observed in adolescents and their safety profile was similar to that of the adult population. Adverse events in these subgroups were consistent with those expected in the hemophilia B population. In addition, no inhibitors were detected in any subjects.
In this analysis, PK parameters, safety profiles, and ABRs with rFIXFc prophylaxis were observed to be similar across adults and adolescents. This analysis supports the primary results of the B-LONG study, showing that rFIXFc is well-tolerated and efficacious for the prevention of bleeding episodes in both adults and adolescents with hemophilia B.
Shapiro:Baxter: Consultancy, Global steering committees Other, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer: Global steering committees, Global steering committees Other, Membership on an entity's Board of Directors or advisory committees, Research Funding; Inspiration: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Research Funding; Biogen Idec: Research Funding. Pasi:Bayer: Membership on an entity's Board of Directors or advisory committees; Bio Products Laboratory Ltd: Membership on an entity's Board of Directors or advisory committees; OctaPharma : Membership on an entity's Board of Directors or advisory committees, Research Funding; Biogen Idec: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Research Funding. Mahlangu:Amgen: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees, Research Funding. Perry:Biogen Idec: Consultancy, Research Funding. Powell:Biogen Idec: Research Funding; OctaPharma: Research Funding; Baxter: Research Funding; Bayer: Research Funding; CSL Behring: Research Funding; Novo Nordisk: Research Funding. Ragni:Baxter: Research Funding; Tacere Benitec: Consultancy; Smith Kline Glaxo: Consultancy, Research Funding; Biogen Idec: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Bayer: Research Funding; CSL Behring: Research Funding; Merck: Research Funding; Novo Nordisk: Research Funding; Pfizer: Research Funding. Valentino:Baxter: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Biogen Idec: Consultancy, Membership on an entity's Board of Directors or advisory committees; GTC Biotherapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Inspiration: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees. Ozelo:Novo Nordisk: Speakers Bureau. Nugent:Biogen Idec: Employment, Equity Ownership. Li:Biogen Idec: Employment, Equity Ownership. Brennan:Biogen Idec: Employment, Equity Ownership. Pierce:Biogen Idec: Employment, Equity Ownership. Allen:Biogen Idec: Employment, Equity Ownership.
Smooth muscle cell proliferation and formation of extracellular matrix are parts of the repair process after vascular injury. Similar processes occur after coronary angioplasty and, in approximately ...33% of vessels, lead to intimal hyperplasia and vascular restenosis within 6 months after angioplasty. In a rat model of balloon catheterization, the proliferative response to balloon injury was reduced by 70% and the area of vascular wall covered by lesion formation was decreased by 45% in rats treated with the angiotensin-converting enzyme inhibitor cilazapril.
Other antihypertensive agents were much less active when tested for suppression of intimal hyperplasia after balloon injury: verapamil 0%, minoxidil 4% and hydralazine 34%. For cilazapril at the dose of 10 mg/kg per day, approximately 20% greater suppression of intimal hyperplasia was seen when the treatment was started 6 days before balloon injury. Treatment of rats fron the time of balloon catheterization with both cilazapril (10 mg/kg per day) and heparin infusion (0.3 mg/kg per h) resulted in essentially complete (> 90%) inhibition of intimal hyperplasia.
These data indicate that the angiotensin-converting enzyme inhibitor cilazapril specifically inhibits the proliferative response to balloon injury and that heparin and cilazapril inhibit intimal hyperplasia through different mechanisms. The data also suggest that the use of pharmacologic combinations may have therapeutic usefulness to prevent late restenosis after coronary angioplasty.
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