Results of genetic analysis of 11 341 participants enrolled in the My Life, Our Future hemophilia genotyping initiative in the United States.

BACKGROUND: Hemophilia A (HA) and hemophilia B (HB) are rare inherited bleeding disorders. Although causative genetic variants are clinically relevant, in 2012 only 20% of US patients had been genotyped. OBJECTIVES: My Life, Our Future (MLOF) was a multisector cross-sectional US initiative to improve our understanding of hemophilia through widespread genotyping. METHODS: Subjects and potential genetic carriers were enrolled at US hemophilia treatment centers (HTCs). Bloodworks performed genotyping and returned results to providers. Clinical data were abstracted from the American Thrombosis and Hemostasis Network dataset. Community education was provided by the National Hemophilia Foundation. RESULTS: From 2013 to 2017, 107 HTCs enrolled 11 341 subjects (68.8% male, 31.2% female) for testing for HA (n = 8976), HB (n = 2358), HA/HB (n = 3), and hemophilia not otherwise specified (n = 4). Variants were detected in most male patients (98.2%% HA, 98.1% HB). 1914 unique variants were found (1482 F8, 431 F9); 744 were novel (610 F8, 134 F9). Inhibitor data were available for 6986 subjects (5583 HA; 1403 HB). In severe HA, genotypes with the highest inhibitor rates were large deletions (77/80), complex intron 22 inversions (9/17), and no variant found (7/14). In severe HB, the highest rates were large deletions (24/42). Inhibitors were reported in 27.3% of Black versus 16.2% of White patients. CONCLUSIONS: The findings of MLOF are reported, the largest hemophilia genotyping project performed to date. The results support the need for comprehensive genetic approaches in hemophilia. This effort has contributed significantly towards better understanding variation in the F8 and F9 genes in hemophilia and risks of inhibitor formation.

BAX 335 hemophilia B gene therapy clinical trial results: potential impact of CpG sequences on gene expression.

Gene therapy has the potential to maintain therapeutic blood clotting factor IX (FIX) levels in patients with hemophilia B by delivering a functional human F9 gene into liver cells. This phase 1/2, open-label dose-escalation study investigated BAX 335 (AskBio009, AAV8.sc-TTR-FIXR338Lopt), an adeno-associated virus serotype 8 (AAV8)-based FIX Padua gene therapy, in patients with hemophilia B. This report focuses on 12-month interim analyses of safety, pharmacokinetic variables, effects on FIX activity, and immune responses for dosed participants. Eight adult male participants (aged 20-69 years; range FIX activity, 0.5% to 2.0%) received 1 of 3 BAX 335 IV doses: 2.0 × 1011; 1.0 × 1012; or 3.0 × 1012 vector genomes/kg. Three (37.5%) participants had 4 serious adverse events, all considered unrelated to BAX 335. No serious adverse event led to death. No clinical thrombosis, inhibitors, or other FIX Padua-directed immunity was reported. FIX expression was measurable in 7 of 8 participants; peak FIX activity displayed dose dependence (32.0% to 58.5% in cohort 3). One participant achieved sustained therapeutic FIX activity of ∼20%, without bleeding or replacement therapy, for 4 years; in others, FIX activity was not sustained beyond 5 to 11 weeks. In contrast to some previous studies, corticosteroid treatment did not stabilize FIX activity loss. We hypothesize that the loss of transgene expression could have been caused by stimulation of innate immune responses, including CpG oligodeoxynucleotides introduced into the BAX 335 coding sequence by codon optimization. This trial was registered at www.clinicaltrials.gov as #NCT01687608.

Cost-effectiveness of brentuximab vedotin plus chemotherapy as frontline treatment of stage III or IV classical Hodgkin lymphoma.

OBJECTIVE: The ECHELON-1 trial demonstrated efficacy and safety of brentuximab vedotin plus doxorubicin, vinblastine, and dacarbazine (A + AVD) vs doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) as frontline therapy for stage III/IV classical Hodgkin lymphoma. This analysis evaluated the cost-effectiveness of A + AVD from a US healthcare payer perspective. METHODS: The incremental cost-effectiveness ratio (ICER), defined as the incremental costs per quality-adjusted life year (QALY) gained, was estimated using a non-homogenous semi-Markov cohort model with health states defined on progression following frontline treatment, and for those with progression, receipt of autologous stem-cell transplant (ASCT), and progression after ASCT. Patients undergoing ASCT were classified as refractory or relapsed based on timing of progression. Probabilities of progression/death with frontline therapy were based on parametric survival distributions fit to data on modified progression-free survival (mPFS) from ECHELON-1. Duration of frontline treatment and incidence of adverse events were from ECHELON-1. Utility values for patients in the frontline mPFS state were based on EQ-5D data from ECHELON-1. Other inputs were from published sources. A lifetime time horizon was used. Costs and QALYs were discounted at 3%. Analyses were conducted alternately using data on mPFS for the overall and North American populations of ECHELON-1. RESULTS: The ICER for A + AVD vs ABVD was $172,074/QALY gained in the analysis using data on mPFS for the overall population and $69,442/QALY gained in the analysis using data on mPFS for the North American population of ECHELON-1. The ICER is sensitive to estimated costs of ASCT and frontline failure. CONCLUSION: The ICER for A + AVD vs ABVD based on ECHELON-1 is within the range of threshold values for cost-effectiveness in the US. A + AVD is, therefore, likely to be a cost-effective frontline therapy for patients with stage III/IV classical Hodgkin lymphoma from a US healthcare payer perspective.

Brentuximab vedotin plus bendamustine: a highly active first salvage regimen for relapsed or refractory Hodgkin lymphoma.

Autologous stem cell transplantation (ASCT) is standard of care for patients with Hodgkin lymphoma (HL) who have relapsed/refractory disease after frontline chemotherapy. Achievement of complete remission (CR) with pre-ASCT salvage chemotherapy predicts favorable outcomes post-ASCT. This phase 1/2 study evaluated the combination of brentuximab vedotin (BV) plus bendamustine as a first salvage regimen in relapsed/refractory HL. A total of 55 patients (28 primary refractory and 27 relapsed) were enrolled. Patients received BV (1.8 mg/kg) on day 1 and bendamustine (90 mg/m2) on days 1 and 2 of a 21-day cycle for up to 6 cycles. Patients could undergo ASCT any time after cycle 2. Following ASCT or completion of combination therapy if not proceeding to ASCT, patients could receive BV monotherapy for up to 16 cycles of total therapy. After a median of 2 cycles of combination therapy (range, 1-6), the objective response rate among 53 efficacy-evaluable patients was 92.5%, with 39 patients (73.6%) achieving CR. Forty patients underwent ASCT. Thirty-one patients (25 of whom underwent ASCT) received BV monotherapy (median, 10 cycles; range, 1-14). After a median of 20.9 months of follow-up, the estimated 2-year progression-free survival was 69.8% and 62.6% for patients who received ASCT and all patients, respectively. Thirty-one patients (56.4%) experienced infusion-related reactions (IRRs), with a majority occurring during cycle 2 of combination therapy. A protocol amendment requiring premedication reduced IRR severity. BV plus bendamustine as first salvage therapy in relapsed/refractory HL is highly active with a manageable toxicity profile. This trial was registered at www.clinicaltrials.gov as #NCT01874054.

Treatment of CD30-Expressing Germ Cell Tumors and Sex Cord Stromal Tumors with Brentuximab Vedotin: Identification and Report of Seven Cases.

BACKGROUND: Cytotoxic therapy for relapsed and refractory germ cell tumors or metastatic sex cord stromal tumors is rarely effective and is often accompanied by high adverse event rates. Expression of CD30 has been observed in testicular cancers, and patients with CD30-expressing embryonal carcinomas have worse progression-free survival and overall survival than those with CD30-negative tumors. The objective of this study (NCT01461538) was to characterize the antitumor activity of brentuximab vedotin in patients with CD30-expressing nonlymphomatous malignancies. Enrolled patients included seven patients with relapsed or refractory germ cell tumors or metastatic sex cord stromal tumors described in this case series. MATERIALS AND METHODS: Forty patients with relapsed or refractory germ cell tumors, metastatic sex cord stromal tumors, or testicular tumors were screened for CD30 expression; 14 patients had tumors that expressed CD30. Seven patients with CD30-expressing testicular cancer were enrolled in the treatment study: five patients with germ cell tumors, one patient with a Leydig cell tumor, and one patient with a Sertoli cell tumor. Patients were treated with brentuximab vedotin at initial doses of 1.8 or 2.4 mg/kg every 3 weeks. Response assessments were performed at cycles 2 and 4 and every 4 cycles thereafter while the patient was receiving treatment. RESULTS: Two of seven patients achieved an objective response, including one durable complete response and one partial response at a single time point. Both responding patients had germ cell tumors. Treatment with brentuximab vedotin was generally well tolerated. CONCLUSION: Treatment of relapsed or refractory germ cell tumors with brentuximab vedotin can induce durable responses with a manageable toxicity profile. IMPLICATIONS FOR PRACTICE: This case series of seven patients with relapsed or refractory CD30-expressing germ cell tumors (GCTs) or sex cord stromal tumors demonstrates that brentuximab vedotin has activity against GCTs and is well tolerated in heavily pretreated patients with these aggressive tumor types. One patient achieved a complete response that has been durable for almost 4 years since the discontinuation of treatment with brentuximab vedotin. Therefore, brentuximab vedotin may be a valuable option for physicians who care for this difficult-to-treat patient population.

Brentuximab Vedotin with Chemotherapy for Stage III or IV Hodgkin's Lymphoma.

BACKGROUND: Brentuximab vedotin is an anti-CD30 antibody-drug conjugate that has been approved for relapsed and refractory Hodgkin's lymphoma. METHODS: We conducted an open-label, multicenter, randomized phase 3 trial involving patients with previously untreated stage III or IV classic Hodgkin's lymphoma, in which 664 were assigned to receive brentuximab vedotin, doxorubicin, vinblastine, and dacarbazine (A+AVD) and 670 were assigned to receive doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). The primary end point was modified progression-free survival (the time to progression, death, or noncomplete response and use of subsequent anticancer therapy) as adjudicated by an independent review committee. The key secondary end point was overall survival. RESULTS: At a median follow-up of 24.6 months, 2-year modified progression-free survival rates in the A+AVD and ABVD groups were 82.1% (95% confidence interval [CI], 78.8 to 85.0) and 77.2% (95% CI, 73.7 to 80.4), respectively, a difference of 4.9 percentage points (hazard ratio for an event of progression, death, or modified progression, 0.77; 95% CI, 0.60 to 0.98; P=0.04). There were 28 deaths with A+AVD and 39 with ABVD (hazard ratio for interim overall survival, 0.73 [95% CI, 0.45 to 1.18]; P=0.20) [corrected]. All secondary efficacy end points trended in favor of A+AVD. Neutropenia occurred in 58% of the patients receiving A+AVD and in 45% of those receiving ABVD; in the A+AVD group, the rate of febrile neutropenia was lower among the 83 patients who received primary prophylaxis with granulocyte colony-stimulating factor than among those who did not (11% vs. 21%). Peripheral neuropathy occurred in 67% of patients in the A+AVD group and in 43% of patients in the ABVD group; 67% of patients in the A+AVD group who had peripheral neuropathy had resolution or improvement at the last follow-up visit. Pulmonary toxicity of grade 3 or higher was reported in less than 1% of patients receiving A+AVD and in 3% of those receiving ABVD. Among the deaths that occurred during treatment, 7 of 9 in the A+AVD group were associated with neutropenia and 11 of 13 in the ABVD group were associated with pulmonary-related toxicity. CONCLUSIONS: A+AVD had superior efficacy to ABVD in the treatment of patients with advanced-stage Hodgkin's lymphoma, with a 4.9 percentage-point lower combined risk of progression, death, or noncomplete response and use of subsequent anticancer therapy at 2 years. (Funded by Millennium Pharmaceuticals and Seattle Genetics; ECHELON-1 ClinicalTrials.gov number, NCT01712490 ; EudraCT number, 2011-005450-60 .).

Real-world economic burden of hematopoietic cell transplantation among a large US commercially insured population with hematologic malignancies.

AIMS: Approximately 20,000 hematopoietic cell transplantation (HCT) procedures are performed in the US annually. This study aims to study the healthcare resource utilization and costs among commercially-insured patients with hematologic malignancies who received autologous HCT (auto-HCT) and allogeneic HCT (allo-HCT) in the US. MATERIALS AND METHODS: Adult patients with hematologic malignancies undergoing auto- or allo-HCT between January 1, 2011 and June 30, 2014 were identified in the Truven Health MarketScan Research Databases. Patients with 12 months of continuous pharmacy and medical enrollment pre- and post-HCT were included. Patients with prior HCT were excluded. Controls were selected from patients without any claims for HCT and matched with HCT recipients in a 3:1 ratio based on age, gender, insurance type, and Deyo-Charlson Comorbidity Index categories. Total healthcare resource uses and costs were compared between auto- or allo-HCT recipients and controls. RESULTS: In total, 10,527 patients (HCT, n = 2,672 vs control, n = 7,855) were included, with the majority of HCT recipients (63.6%) undergoing auto-HCT. During the 6-month pre-index and 12-month post-index period, auto-HCT recipients incurred $313,562 (p < .01) higher all-cause costs than controls, attributable to inpatient admission (54.1%), outpatient services (33.4%), and prescriptions (12.5%). The all-cause costs for allo-HCT recipients were $621,895 (p < .01) higher vs controls during the 18-month observation period, attributable to inpatient admissions (75.5%), outpatient services (22.1%), and prescriptions (2.4%). CONCLUSIONS: The use of HCT among patients with hematologic malignancies is associated with considerable economic burden in direct healthcare costs in a commercially insured population. Incremental costs for HCT recipients were mainly driven by costs related to hospitalization and other medical services.

Real-World Economic Burden Associated with Transplantation-Related Complications.

Approximately 20,000 hematopoietic cell transplantation (HCT) procedures are performed annually in the United States. Real-world data on the costs associated with post-transplantation complications are limited. Patients with hematologic malignancies aged ≥18 years undergoing autologous HCT (auto-HCT) or allogeneic HCT (allo-HCT) between January 1, 2011, and June 30, 2014, were identified in the Truven Health MarketScan Research Databases. Patients were required to have 12 months of continuous medical and pharmacy enrollment before and after HCT; patients who experience inpatient death within 12 months post-HCT were also included. Patients with previous HCT were excluded. Potential HCT-related complications were identified if they had a medical claim with a diagnosis code for relapse; infection; cardiovascular, renal, neurologic, pulmonary, hepatic, or gastrointestinal disease; secondary malignancy; thrombotic microangiopathy; or posterior reversible encephalopathy syndrome within 1 year post-HCT. Healthcare costs attributable to these complications were evaluated by comparing total costs in HCT recipients with complications and those without complications. The MarketScan Research Databases were further linked to the Social Security Administration's Master Death File to obtain patient death events in a subset of patients. A total of 2672 HCT recipients were included in the analysis. The mean ± SD age of recipients was 54.5 ± 11.6 years, and the majority of recipients (63.6%) underwent auto-HCT. Complications were identified in 81% of auto-HCT recipients and in 95.5% of allo-HCT recipients. Most complications occurred within 180 days post-HCT. Compared with Auto-HCT recipients without complications, those with complications incurred $51,475 higher adjusted total costs (P < .01). Compared with allo-HCT recipients without complications, those with complications incurred $181,473 higher adjusted total costs (P < .01). Among the patients with mortality data, auto-HCT recipients with complications had a higher mortality rate (13.4% vs 5.7%, P < .01) and a lower probability of survival (P < .01) compared with those without complications. In allo-HCT recipients, however, the mortality rate and probability of survival were not significantly different between those with complications and those without complications. HCT recipients with complications were associated with considerable economic burden in terms of direct healthcare costs in a commercially insured population, and in the case of auto-HCT, a higher mortality rate was observed in those with complications.

Novel approach to genetic analysis and results in 3000 hemophilia patients enrolled in the My Life, Our Future initiative.

Hemophilia A and B are rare, X-linked bleeding disorders. My Life, Our Future (MLOF) is a collaborative project established to genotype and study hemophilia. Patients were enrolled at US hemophilia treatment centers (HTCs). Genotyping was performed centrally using next-generation sequencing (NGS) with an approach that detected common F8 gene inversions simultaneously with F8 and F9 gene sequencing followed by confirmation using standard genotyping methods. Sixty-nine HTCs enrolled the first 3000 patients in under 3 years. Clinically reportable DNA variants were detected in 98.1% (2357/2401) of hemophilia A and 99.3% (595/599) of hemophilia B patients. Of the 924 unique variants found, 285 were novel. Predicted gene-disrupting variants were common in severe disease; missense variants predominated in mild-moderate disease. Novel DNA variants accounted for ∼30% of variants found and were detected continuously throughout the project, indicating that additional variation likely remains undiscovered. The NGS approach detected >1 reportable variants in 36 patients (10 females), a finding with potential clinical implications. NGS also detected incidental variants unlikely to cause disease, including 11 variants previously reported in hemophilia. Although these genes are thought to be conserved, our findings support caution in interpretation of new variants. In summary, MLOF has contributed significantly toward variant annotation in the F8 and F9 genes. In the near future, investigators will be able to access MLOF data and repository samples for research to advance our understanding of hemophilia.

Treatment of CD30-positive systemic mastocytosis with brentuximab vedotin.

Systemic mastocytosis is a myeloproliferative neoplasm with varying presentation that is caused by infiltration of neoplastic mast cells into extracutaneous tissues. Cytoreductive therapy is used to control organ dysfunction in aggressive systemic mastocytosis and is sometimes needed for control of severe refractory symptoms in patients with indolent disease. However, current standard cytoreductive agents are limited by their suboptimal degree and duration of response and associated significant toxicities, highlighting the need for novel treatments for systemic mastocytosis. Recent studies have identified CD30 as a therapeutic target in systemic mastocytosis, as CD30 is expressed on a majority of neoplastic mast cells. In this case series, the clinical outcomes of 4 patients with aggressive or indolent systemic mastocytosis treated with the anti-CD30 antibody-drug conjugate brentuximab vedotin are reported. Two patients showed evidence of a response to treatment with a reduction in disease burden, 1 of which has demonstrated a durable response with ongoing benefit for more than 3 years. Treatment with brentuximab vedotin was well-tolerated with side effects that were effectively managed by dose modifications. The results presented suggest that brentuximab vedotin is active in systemic mastocytosis and can induce durable responses with a manageable toxicity profile.

Recombinant factor VIII Fc (rFVIIIFc) fusion protein reduces immunogenicity and induces tolerance in hemophilia A mice.

Anti-factor VIII (FVIII) antibodies is a major complication of FVIII replacement therapy for hemophilia A. We investigated the immune response to recombinant human factor VIII Fc (rFVIIIFc) in comparison to BDD-rFVIII and full-length rFVIII (FL-rFVIII) in hemophilia A mice. Repeated administration of therapeutically relevant doses of rFVIIIFc in these mice resulted in significantly lower antibody responses to rFVIII compared to BDD-rFVIII and FL-rFVIII and reduced antibody production upon subsequent challenge with high doses of rFVIIIFc. The induction of a tolerogenic response by rFVIIIFc was associated with higher percentage of regulatory T-cells, a lower percentage of pro-inflammatory splenic T-cells, and up-regulation of tolerogenic cytokines and markers. Disruption of Fc interactions with either FcRn or Fcγ receptors diminished tolerance induction, suggesting the involvement of these pathways. These results indicate that rFVIIIFc reduces immunogenicity and imparts tolerance to rFVIII demonstrating that recombinant therapeutic proteins may be modified to influence immunogenicity and facilitate tolerance.

Preoperative management of factor XI deficiency with therapeutic plasma exchange: A case report and literature review.

Patients with factor XI deficiency may have bleeding complications during surgery. Because bleeding severity and factor levels correlate poorly, factor replacement needs to be personalized based on bleeding history and type of procedure. We report a 65-year-old male with factor XI deficiency (7 IU dL-1 ) who presented before scheduled hip arthroplasty. He had a history of total hip arthroplasty complicated by bleeding, delayed healing and prosthesis removal, despite receiving prophylactic treatment with plasma infusion. For the current surgery a factor XI ≥50 IU dL-1 level was targeted. The calculated plasma infusion needed to achieve this goal was 3100 mL (14 U). Because of concerns about circulatory overload and inability to achieve target by simple infusion, prophylactic treatment with therapeutic plasma exchange (TPE) was requested. TPE was performed the morning before the surgery, using 100% plasma as replacement fluid (3912 mL of plasma), and a positive fluid balance of 631 mL. Factor XI activity level was 51 IU dL-1 immediately post TPE. The patient received daily infusions of 3 U (∼ 660 mL) of plasma to maintain a factor XI level of 30 IU dL-1 until post-operative day 7. Aminocaproic acid was given during the surgery and until post-operative day 10. There were no bleeding or thrombotic complications. CONCLUSION: TPE was effective in increasing factor XI levels; it was well tolerated and did not result in circulatory overload. TPE can be considered when therapeutic factor levels cannot be achieved by simple plasma infusion, or when circulatory overload is a concern. J. Clin. Apheresis 31:579-583, 2016. © 2015 Wiley Periodicals, Inc.

Long-acting recombinant factor IX Fc fusion protein (rFIXFc) for perioperative management of subjects with haemophilia B in the phase 3 B-LONG study.

In the phase 3 B-LONG (Recombinant Factor IX Fc Fusion Protein [rFIXFc] in Subjects With Haemophilia B) study, rFIXFc demonstrated a prolonged half-life compared with recombinant factor IX (rFIX), and safety and efficacy for prophylaxis and treatment of bleeding in subjects with moderately-severe to severe haemophilia B. In this B-LONG sub-analysis, rFIXFc was evaluated for efficacy in subjects requiring major surgery. Dosing was investigator-determined. Assessments included dosing, consumption, bleeding, transfusions and haemostatic response. A population pharmacokinetics model of rFIXFc was used to predict FIX activity. Twelve subjects underwent 14 major surgeries (including 11 orthopaedic surgeries); most subjects (11/12) received rFIXFc prophylaxis before surgery (range, ~2 weeks-12 months). Investigators/surgeons rated haemostatic responses as excellent (n = 13) or good (n = 1). In most surgeries (85·7%), haemostasis from the pre-surgical dose until the end of surgery was maintained with a single rFIXFc infusion. Blood loss was consistent with similar surgeries in subjects without haemophilia. The strong correlation (R(2) = 0·9586, P < 0·001) between observed and population pharmacokinetic model-predicted FIX activity suggests surgery did not impact rFIXFc pharmacokinetics. No unique safety concerns or inhibitors were observed. In conclusion, rFIXFc was safe and efficacious, with prolonged dosing intervals and low consumption, when used perioperatively in haemophilia B. Surgery did not appear to alter rFIXFc pharmacokinetics.

Phase 3 study of recombinant factor VIII Fc fusion protein in severe hemophilia A.

This phase 3 pivotal study evaluated the safety, efficacy, and pharmacokinetics of a recombinant FVIII Fc fusion protein (rFVIIIFc) for prophylaxis, treatment of acute bleeding, and perioperative hemostatic control in 165 previously treated males aged ≥12 years with severe hemophilia A. The study had 3 treatment arms: arm 1, individualized prophylaxis (25-65 IU/kg every 3-5 days, n = 118); arm 2, weekly prophylaxis (65 IU/kg, n = 24); and arm 3, episodic treatment (10-50 IU/kg, n = 23). A subgroup compared recombinant FVIII (rFVIII) and rFVIIIFc pharmacokinetics. End points included annualized bleeding rate (ABR), inhibitor development, and adverse events. The terminal half-life of rFVIIIFc (19.0 hours) was extended 1.5-fold vs rFVIII (12.4 hours; P < .001). Median ABRs observed in arms 1, 2, and 3 were 1.6, 3.6, and 33.6, respectively. In arm 1, the median weekly dose was 77.9 IU/kg; approximately 30% of subjects achieved a 5-day dosing interval (last 3 months on study). Across arms, 87.3% of bleeding episodes resolved with 1 injection. Adverse events were consistent with those expected in this population; no subjects developed inhibitors. rFVIIIFc was well-tolerated, had a prolonged half-life compared with rFVIII, and resulted in low ABRs when dosed prophylactically 1 to 2 times per week.

Phase 3 study of recombinant factor IX Fc fusion protein in hemophilia B.

BACKGROUND: Prophylactic factor replacement in patients with hemophilia B improves outcomes but requires frequent injections. A recombinant factor IX Fc fusion protein (rFIXFc) with a prolonged half-life was developed to reduce the frequency of injections required. METHODS: We conducted a phase 3, nonrandomized, open-label study of the safety, efficacy, and pharmacokinetics of rFIXFc for prophylaxis, treatment of bleeding, and perioperative hemostasis in 123 previously treated male patients. All participants were 12 years of age or older and had severe hemophilia B (endogenous factor IX level of ≤2 IU per deciliter, or ≤2% of normal levels). The study included four treatment groups: group 1 received weekly dose-adjusted prophylaxis (50 IU of rFIXFc per kilogram of body weight to start), group 2 received interval-adjusted prophylaxis (100 IU per kilogram every 10 days to start), group 3 received treatment as needed for bleeding episodes (20 to 100 IU per kilogram), and group 4 received treatment in the perioperative period. A subgroup of group 1 underwent comparative sequential pharmacokinetic assessments of recombinant factor IX and rFIXFc. The primary efficacy end point was the annualized bleeding rate, and safety end points included the development of inhibitors and adverse events. RESULTS: As compared with recombinant factor IX, rFIXFc exhibited a prolonged terminal half-life (82.1 hours) (P<0.001). The median annualized bleeding rates in groups 1, 2, and 3 were 3.0, 1.4, and 17.7, respectively. In group 2, 53.8% of participants had dosing intervals of 14 days or more during the last 3 months of the study. In groups 1, 2 and 3, 90.4% of bleeding episodes resolved after one injection. Hemostasis was rated as excellent or good during all major surgeries. No inhibitors were detected in any participants receiving rFIXFc; in groups 1, 2, and 3, 73.9% of participants had at least one adverse event, and serious adverse events occurred in 10.9% of participants. These events were mostly consistent with those expected in the general population of patients with hemophilia. CONCLUSIONS: Prophylactic rFIXFc, administered every 1 to 2 weeks, resulted in low annualized bleeding rates in patients with hemophilia B. (Funded by Biogen Idec; ClinicalTrials.gov number, NCT01027364.).

The hemophilias and their clinical management.

Outcomes for patients with hemophilia have improved dramatically over the past 50 years. With the increased availability of safe clotting factor concentrates, the primary focus in clinical management is now the prevention of long-term complications, most notably the debilitating hemophilic arthropathy that is associated with severe disease. This article reviews evidence-based approaches for managing both children and adults with hemophilia. Definitive evidence of improved clinical results from primary prophylaxis started in young patients with severe hemophilia A and a minimal bleeding history is presented. Furthermore, recent studies showing benefits for initiating prophylaxis in older adolescents and adults with established joint disease are examined. Inhibitors to factor VIII are the most problematic complication of factor replacement therapy. Patient-specific and treatment-related factors that contribute to the risk of inhibitor formation are discussed and controversies and clinical evidence related to approaches for tolerance induction are reviewed.

Phenotypes of allo- and autoimmune antibody responses to FVIII characterized by surface plasmon resonance.

Evidence of antibody isotype/subtype switching may provide prognostic value regarding the state of immune responses to therapeutic proteins, e.g. anti-factor VIII (FVIII) antibodies that develop in many hemophilia A patients, clinically termed "inhibitors". A sensitive, high- information-content surface plasmon resonance (SPR) assay has been developed to quantify IgG subtype distributions and the domain specificity of anti-drug antibodies. Plasma samples from 22 subjects with an allo- or auto-immune reaction to FVIII were analyzed. Pre-analytical treatment protocols were developed to minimize non-specific binding and specific matrix interference due to von Willebrand factor-FVIII interactions. The dynamic range for IgG quantification was 0.2-5 µg/ml (∼1-33 nM), allowing characterization of inhibitor-positive samples. Subtype-specific monoclonal antibodies were used to quantify the IgG subtype distribution of FVIII-specific antibodies. Most samples obtained from multiply-infused inhibitor subjects contained IgG4 antibodies. Several distinct phenotypes were assigned based on the IgG subtype distribution: IgG1, IgG4, IgG1 & IgG4, and IgG1, IgG2 & IgG4. An IgG1-only response was found in mild/moderate HA subjects during early FVIII infusions, and analysis of serial samples followed antibody class switching as several subjects' immune responses developed. Competition studies utilizing a recombinant FVIII-C2 domain indicated 40-80% of FVIII-specific antibodies in most samples were directed against this domain.

Acquired von Willebrand syndrome in a patient with monoclonal gammopathy of undetermined significance.

Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that typically presents as mucocutaneous bleeding in individuals with no personal or family history of bleeding disorder. Here we present a case in which a patient presented with profound epistaxis and was found to have AVWS in the setting of monoclonal gammopathy of undetermined significance (MGUS).

Safety and prolonged activity of recombinant factor VIII Fc fusion protein in hemophilia A patients.

Current factor VIII (FVIII) products display a half-life (t(1/2)) of ∼ 8-12 hours, requiring frequent intravenous injections for prophylaxis and treatment of patients with hemophilia A. rFVIIIFc is a recombinant fusion protein composed of a single molecule of FVIII covalently linked to the Fc domain of human IgG(1) to extend circulating rFVIII t(1/2). This first-in-human study in previously treated subjects with severe hemophilia A investigated safety and pharmacokinetics of rFVIIIFc. Sixteen subjects received a single dose of rFVIII at 25 or 65 IU/kg followed by an equal dose of rFVIIIFc. Most adverse events were unrelated to study drug. None of the study subjects developed anti-rFVIIIFc antibodies or inhibitors. Across dose levels, compared with rFVIII, rFVIIIFc showed 1.54- to 1.70-fold longer elimination t(1/2), 1.49- to 1.56-fold lower clearance, and 1.48- to 1.56-fold higher total systemic exposure. rFVIII and rFVIIIFc had comparable dose-dependent peak plasma concentrations and recoveries. Time to 1% FVIII activity above baseline was ∼ 1.53- to 1.68-fold longer than rFVIII across dose levels. Each subject showed prolonged exposure to rFVIIIFc relative to rFVIII. Thus, rFVIIIFc may offer a viable therapeutic approach to achieve prolonged hemostatic protection and less frequent dosing in patients with hemophilia A. This trial was registered at www.clinicaltrials.gov as NCT01027377.