Trisomy X conferring moderate hemophilia A by extremely skewed X-chromosome inactivation.

Background: Hemophilia carriers occasionally present with bleeding tendency due to skewed inactivation of normal F8 carrying X chromosome. Key Clinical Question: Can extreme skewing of X-chromosome inactivation (XCI) with trisomy X cause low factor (F) VIII activity and bleeding in a hemophilia carrier?. Clinical Approach: A young female with low FVIII activity (2 IU/dL), who presented with history of frequent bleeding and F8 variant, NP_000123.1:p.(Arg1800His), was identified. The mother was also confirmed genetically as hemophilia carrier. Karyotype was 47, XXX, multiplex ligation-dependent probe amplification for aneuploidy in the family identified trisomy X only in the index case. Digital polymerase chain reaction using leucocytes, urine, and oral mucosa identified one maternal F8 variant carrying and 2 wild-type F8 carrying X chromosomes, but it detected no somatic mosaicisms. Methylation-sensitive-HpaII-polymerase chain reaction assay showed predominantly activated maternal and 2 fully inactivated paternal X chromosomes. The XCI patterns using tissues of different developmental origins showed extremely skewed XCI. Conclusion: Extreme skewing of XCI can occur even in hemophilia carriers with trisomy X, conferring frequent bleeding and low FVIII activity.

Real-World Amount of Clotting Factor Concentrates Dispensed and Annual Medical Expenditures for Japanese Patients with Hemophilia B.

Introduction: Until extended half-life (EHL) factor IX (FIX) concentrates became available in Japan in 2010, patients with hemophilia B received intravenous FIX replacement therapy with standard half-life (SHL) FIX concentrates. Purpose: To investigate the amount of factor dispensed and the associated medical expenditures for the treatment of hemophilia B in the real-world clinical setting in Japan. Methods: This retrospective study comprised patients with hemophilia B (N=197) who had filled prescriptions for FIX concentrates reported in Japan's Medical Data Vision database from 2015 to 2019. Patients were included if they had 2 or more prescriptions for the same FIX concentrates within the first 6 months of the study period and the interval between prescriptions was at least 2 weeks. Results: Since 2015, there was a decrease in the proportion of patients using SHL FIX concentrates and a corresponding increase in international units of dispensed EHL FIX concentrates. Median annualized dispensed dosages (IU/kg body weight) of EHL FIX concentrates were lower than for SHL concentrates for outpatient use only. Annual total health care expenditures per patient and annual expenditures for prescribed FIX concentrates increased each year during the study period. Following a switch from an SHL to an EHL concentrate, the median amount of prescribed FIX concentrate decreased slightly, although median total health care expenditures and FIX concentrate expenditures increased. Conclusion: In the real-world setting in Japan, medical expenditures and the proportion of patients prescribed EHL FIX concentrates for the treatment of hemophilia B have increased.

Assessment of joint bleeding and target joints in patients with severe or moderately severe hemophilia B (factor IX ≤2%) receiving prophylaxis with rIX-FP in the PROLONG-9FP clinical trial program.

OBJECTIVE: To assess the impact of prophylaxis with rIX-FP, a fusion protein linking recombinant factor IX (FIX) with human albumin, on joint outcomes. METHODS: Joint outcomes were assessed in pediatric (<12 years) and adult/adolescent (≥12 years) patients receiving rIX-FP prophylaxis every 7, 10, or 14 days; patients (>18 years) well-controlled on a 14-day regimen could switch to a 21-day regimen. Target joints were defined as ≥3 spontaneous bleeds into a single joint within a 6-month period. RESULTS: For adult/adolescent (n = 63) and pediatric (n = 27) patients, median (Q1, Q3) annualized joint bleeding rate was 0.39 (0.00, 2.31), 0.80 (0.00, 2.85), 0.20 (0.00, 2.58), and 0.00 (0.00, 1.78) when treated with 7-, 10-, 14-, or 21-day prophylaxis. 50.0%, 38.9%, 45.5%, and 63.6% of adult/adolescent patients had no joint bleeds when treated with 7-, 10-, 14-, or 21-day prophylaxis, respectively, and 40.7%, 37.5%, and 37.5% of pediatric patients had no joint bleeds when treated with 7-, 10-, or 14-day prophylaxis. Ten adult and two pediatric patients developed target joints; all resolved by the end of the study. CONCLUSION: Prophylaxis with rIX-FP produced low joint bleeding rates and provided excellent hemostatic efficacy in the treatment of joint bleeds. All target joints reported resolved with rIX-FP prophylaxis.

The length of the sanitary napkins can be used as a handier index than pictorial blood loss assessment chart to predict the heavy menstrual bleeding.

AIM: Many women with inherited bleeding disorders are not diagnosed because of a lack of appropriate indicators. This study aimed to assess the predictability of the pictorial blood loss assessment chart (PBAC) as an indicator of menorrhagia and identify an easy indicator of menorrhagia resulting from bleeding disorders. METHODS: A multicenter study enrolled 9 patients with von Willebrand disease (VWD), 23 hemophilia carriers, and 71 controls aged 20-45 years who completed PBACs for two menstrual cycles as well as questionnaires. RESULTS: The PBAC scores of the VWD were significantly higher than those of other groups, even in multivariate analysis with age and sanitary item factors (p = 0.014). A PBAC score of 100 was not an appropriate cutoff because of its low specificity (VWD: sensitivity, 100; specificity, 29.5; hemophilia carriers: 74 and 29.5, respectively). In the ROC analysis, the cutoff of optimal PBAC for VWD was 171 (sensitivity, 66.7; specificity, 72.3; AUC, 0.7296). As the pad length increased, the total length of the pads used during one menstrual period could be a new and easy indicator. However, the cutoff for VWD was 735 cm (sensitivity, 42.9; specificity, 94.3; AUC 0.6837). A threshold could not be established for the hemophilia carrier. Therefore, we multiplied the coefficient by the length of thick pads, which caused a lower PBAC. For the VWD, the sensitivity increased to 85.7 (specificity, 77.1). For the hemophilia carrier, sensitivity (66.7) and specificity (88.6) could be separated from the control. CONCLUSIONS: The total length of the pads with a thick-pad adjustment can be a simple method to identify bleeding disorders.

Real-World Use of Albutrepenonacog Alfa, A Recombinant Coagulation Factor IX Albumin Fusion Protein, for Personalized Prophylaxis in Japanese Individuals With Hemophilia B: A Case Series.

Currently, the mainstay of disease management for hemophilia B, a hemorrhagic disease caused by a congenital deficiency or molecular abnormalities of blood coagulation factor IX (FIX), is prophylaxis using FIX concentrate. On-demand injections of FIX concentrate may also be required, even during prophylaxis, when a patient with hemophilia B is bleeding. Albutrepenonacog alfa (rFIX-FP) is a human albumin fusion gene recombinant FIX, which is administered once every seven, 14, or 21 days, depending on patient preferences and symptoms. Studies have demonstrated its efficacy and safety in a range of patients; however, to date, reports of real-world experiences of the use of rFIX-FP in Japan are limited. We present a case series of three Japanese individuals with moderately severe (FIX activity 1 to <2%) or severe (FIX activity <1%) hemophilia B who benefited from prophylaxis using rFIX-FP in our clinical practice setting. We highlighted the good effectiveness of rFIX-FP in a patient with moderately severe hemophilia B who required prophylaxis due to joint bleeding, which was causing deterioration of his left ankle joint, as well as in a patient with severe hemophilia B and atherothrombotic cerebral infarction, whose trough level had to be ≥5% for concomitant use of an antiplatelet drug, and in a patient with severe hemophilia B who was working in nursing care, which involved heavy labor and night shifts, and who had previously been treated with on-demand FIX concentrate. In all three cases, rFIX-FP improved disease symptoms, and the patients were able to maintain steady states of therapy due to the treatment characteristics of rFIX-FP, which stabilizes FIX at high trough levels.

Clinical conditions and risk factors for inhibitor-development in patients with haemophilia: A decade-long prospective cohort study in Japan, J-HIS2 (Japan Hemophilia Inhibitor Study 2).

BACKGROUND: Inhibitor-development is a serious complication in patients with haemophilia (PwH). Previous studies reported that therapeutic and genetic factors could be associated with these alloantibodies. Relevant clinical features such as genetic-background and different treatment regimens in Japan remain unclear, however. AIMS: To analyse a nation-wide Japanese registry for PwH, and to examine risk factors for inhibitor-development. METHODS AND RESULTS: Newly diagnosed patients with haemophilia A (PwHA) or haemophilia B (PwHB) without inhibitors after 2007, and with treatment records traceable from 0 to 75 exposure days (ED), were enrolled in the Japan Hemophilia Inhibitor Study 2 (J-HIS2) initiated in 2008. Of 417 patients (340 PwHA, 77 PwHB) from 46 facilities, 83 (76 PwHA, 7 PwHB) were recorded with inhibitors by July 2020. Inhibitors were observed in 31.0% of severe PwHA, 8.0% moderate and 1.6% mild and in 17.1% of severe PwHB. The majority of inhibitors (89.7% in severe PwHA and 71.4% in severe PwHB) were detected on or before 25ED (median 12ED in PwHA and 19ED in PwHB). Genotyping in these severe patients identified an association between inhibitor-development and null variants of F8 (P < .01) or F9 (P < .05). A lower incidence of inhibitors was recorded in severe PwHA treated with prophylaxis than in those treated on-demand (P < .01). A past-history of intracranial-haemorrhage appeared to be associated with inhibitor-development, while FVIII-concentrates infusion and routine vaccination on the same day was not related to inhibitor-development. CONCLUSION: The J-HIS2 study has identified significant clinical variables associated with inhibitor-development in Japanese PwH, consistent with other global studies.

Combination therapy with von Willebrand factor concentrate plus recombinant factor VIII during cesarean section in a patient with type 3 von Willebrand disease and a low inhibitor titer: a case report.

Type 3 von Willebrand disease (VWD), a rare and severe subtype, can produce inhibitors in roughly 5% to 10% of cases. We present a case of type 3 VWD with inhibitors in late pregnancy, which was successfully managed with a combination of neutralization and factor (F)VIII replacement during cesarean delivery. The patient, a 30-year-old woman, had no history of inhibitors despite over 100 exposures to VWF/FVIII. She developed inhibitors after 28 weeks of weekly pd VWF/FVIII prophylaxis for recurrent urolithiasis-associated hematuria during pregnancy. Genetic analysis detected two novel frameshift mutations: VWF Exon7 c.777_784dup and Exon14 c.1625_1646del. Titers of inhibitors to factors VIII and VWF using the Bethesda assay were 1.2 and 1.1 BU/mL, respectively. Pharmacokinetics revealed significantly low in vivo recovery of FVIII:C and VWF:Rcof and shortened half-life. During cesarean delivery, a combination of bolus pd VWF/FVIII once daily for neutralizing inhibitors plus continuous infusion of recombinant FVIII Fc fusion protein resulted in minimal bleeding without allergic reactions. Both VWF:Rcof and FVIII:C levels increased transiently during the 7-h of combination therapy without thrombotic events. In conclusion, combination therapy with neutralization and continuous FVIII replacement was effective for hemostasis with a low VWD inhibitor titer, though further optimization is required.

Genetic analysis of carrier status in female members of Japanese hemophilia families.

BACKGROUND: Genetic characteristics and genetic carrier diagnosis in Japanese hemophilia female carriers have not been evaluated. OBJECTIVES: To provide genetic information on Japanese hemophilia female carriers and demonstrate the advantages of genetic testing in carrier diagnosis. METHODS: DNA sequencing combined with long polymerase chain reaction for inversion and multiplex ligation-dependent probe amplification for large mutations. RESULTS: Genetic analysis was performed in 69 male hemophiliac patients (48 hemophilia A [HA] and 21 hemophilia B [HB]) and 112 female family members (FFM) (80 from 50 families with HA and 32 from 22 families with HB). In 72 hemophiliac families, the identified F8 mutations were inversion (42%), missense (26%), and other variations (32%), while 74% of F9 mutations were point mutations. Among the 112 FFM, 53/80 (66%) with HA and 21/32 (66%) with HB were diagnosed genetically as carriers based on detection of heterozygous mutations. Low factor VIII activity (FVIII:C) levels (<50 IU/dL) were detected in only 10% of gene-confirmed carriers, suggesting that FVIII:C is not suitable for HA carrier prediction. Low FVIII/von Willebrand factor ratio (<0.9) was observed in 67% of gene-confirmed carriers. Half of the gene-confirmed HB carriers had low FIX:C (<60 IU/dL). Importantly, 32 mothers of 37 sporadic cases (86%) (24/27 [89%] HA and 8/10 [80%] HB) showed the relevant mutations, suggesting low incidence of de novo mutations in males. CONCLUSIONS: This study is the first to provide genetic information on Japanese hemophilia female carriers. Gene analysis is the gold standard for carrier diagnosis as it well identifies undetected female carriers based on pedigree information and hemostatic measurements.

Spectrum of F8 Genotype and Genetic Impact on Inhibitor Development in Patients with Hemophilia A from Multicenter Cohort Studies (J-HIS) in Japan.

Some genetic and treatment-related factors are risk factors for inhibitor development in patients with hemophilia A (PwHA). However, the genotype distribution of the factor VIII gene (F8) and genetic impact on inhibitor development in Japanese PwHA remain unknown. In 2007, the Japan Hemophilia Inhibitor Study 2 (J-HIS2) was organized to establish a nationwide registry system for hemophiliacs and to elucidate risk factors for inhibitor development, designed for prospective investigation following a retrospective study (J-HIS1) which had already finished. Patients, newly diagnosed after January 2007, were enrolled in J-HIS2 and followed up for inhibitor development and clinical environments since 2008 onward. In the present study, F8 genotypes of PwHA were investigated in the patients recruited from the J-HIS2 cohort as well as those with inhibitor from the J-HIS1 cohort. F8 variants identified in 59 PwHA with inhibitor in J-HIS1 were: 20 intron-22 inversions, 5 intron-1 inversions, 9 large deletions, 4 nonsense, 8 missense, 11 small in/del, and 2 splice-site variants. F8 variants identified in 267 (67 with inhibitor) PwHA in J-HIS2 were: 76(28) intron-22 inversions, 3(2) intron-1 inversion, 1(0) duplication, 8(5) large deletions, 21(7) nonsense, 109(7) missense, 40(11) small in/del, and 9(7) splice-site variants. Forty variants were novel. The cumulative inhibitor incidence rate in the severe group with null changes was 42.4% (95% confidence interval [CI]: 33.7-50.8), higher than that with nonnull changes (15.6% [95%CI: 6.8-27.8]), in J-HIS2. Relative risk for inhibitor development of null changes was 2.89. The spectrum of F8 genotype and genetic impact on inhibitor development in Japanese PwHA were consistent with the previous reports.

Pharmacometric modeling to explore 4F-PCC dosing strategies for VKA reversal in patients with INR below 2.

The indicated dose of 4-factor prothrombin complex concentrate (4F-PCC) for urgent vitamin K antagonist (VKA) reversal in patients with an international normalized ratio (INR) of 2 to 4 is 25 IU/kg, but there is no indicated dose for INR <2. We explored 4F-PCC dosing strategies for baseline INR <2. Clinical trial data were used to develop pharmacometric models for Factor X (FX) and FII, accounting for covariates including baseline INR. FX and FII levels over time were simulated for mean baseline INR levels of the clinical trial participants plus baseline INRs 3.1, 1.9, and 1.6. For each INR, 200 virtual male patients were simulated to evaluate 4F-PCC doses of 35, 25, 20, 15, 12.5, and 10 IU/kg. Given an elevated bleeding risk with VKA therapy in Japanese vs Western populations, results were stratified by Japanese and non-Japanese patients. Target levels of FX and FII were ≥50% activity at 30 minutes after dosing in ≥80% of patients. FX- and FII-time models were developed with 1088 FX observations from 193 patients and 1074 FII observations from 192 patients. Model-based simulations indicated that at baseline INR 3.1, ≥80% of patients achieved ≥50% FX and FII activity with 25 IU/kg and 20 IU/kg 4F-PCC, respectively; at baseline INR 1.9, corresponding doses were 20 IU/kg and 15 IU/kg 4F-PCC, and at baseline INR 1.6, corresponding doses were 15 IU/kg, and 10 IU/kg 4F-PCC. Trends in Japanese and non-Japanese patients were similar. In conclusion, low 4F-PCC doses (15-20 IU/kg) may be sufficient to achieve hemostatic levels of FX and FII in Japanese and non-Japanese patients with baseline INR <2.

Successful Management of Acquired Factor V Inhibitor by Monitoring Factor V Activity, Antigen, and Inhibitor Values during Immunosuppressive Therapy.

Acquired factor V inhibitor (AFVI) results from the formation of autoantibodies to coagulation factor V (FV), and the clinical phenotype can range from asymptomatic laboratory abnormalities to life-threatening bleeds. We describe a 74-year-old man who developed AFVI along with a massive subcutaneous hematoma. He was initially treated with prednisolone (PSL), but AFVI recurred when the dose was reduced after a short period. We subsequently increased the PSL dose and added cyclophosphamide (CY), which resulted in a complete response. We then gradually tapered PSL and stopped CY, and the patient has since remained free of recurrent AFVI symptoms. We monitored FV activity, antigen concentrations, and inhibitor titers of this patient throughout the clinical course. The ratio of FV activity to antigen concentration was low at diagnosis and gradually increased along with the patient's improvement. This ratio might be a useful parameter for evaluating the effects of immunosuppressive therapy in patients with AFVI.

Long-term administration of pegylated liposomal doxorubicin at almost twice the recommended lifetime dose in 10 years without cardiotoxicity in a Japanese patient with HIV-associated Kaposi sarcoma.

We report a Japanese patient with HIV-associated Kaposi sarcoma (KS) who had many cutaneous KS lesions with extensive bilateral groin edema. As the KS was refractory to antiretroviral therapy and pegylated liposomal doxorubicin (PLD), he was administered PLD up to a cumulative dose of 940 mg/m2 in 10 years, which exceeded the recommended lifetime dose (550 mg/m2). However, the patient showed no major adverse events, including cardiotoxicity, and he eventually died of pancreatic cancer.

Recombinant FIX Fc fusion protein activity assessment with the one-stage clotting assay: A multicenter, assessor-blinded, prospective study in Japan (J-Field Study).

INTRODUCTION: The one-stage clotting assay is used to measure factor IX (FIX) activity in patients' plasma samples and in FIX products for hemophilia treatment. However, the diversity of reagents and instruments has resulted in significant FIX assay variability. METHODS: The accuracy of the one-stage clotting assay to measure recombinant FIX Fc fusion protein (rFIXFc) activity was evaluated by major Japanese hemophilia treatment centers and commercial laboratories that measure factor IX activity for a majority of hemophilia B patients in Japan. Plasma-derived FIX (pdFIX) and recombinant FIX (rFIX) products were used as comparators. FIX-deficient plasma was spiked with four levels of FIX products based on label potency and measured under blinded conditions by routine one-stage clotting assay procedures in 19 participating laboratories. Interlaboratory coefficient of variation and spike recovery were calculated. RESULTS: Interlaboratory coefficient of variation of rFIXFc was not significantly different from that of rFIX, but appeared larger than that of pdFIX. Mean spike recovery for rFIXFc was generally comparable to rFIX and pdFIX. However, larger discrepancies between pdFIX and rFIX were observed in three of nine laboratories using ellagic acid-based activated partial thromboplastin time reagents. CONCLUSION: Recombinant FIX Fc fusion protein activity was found to be similar to that of rFIX or pdFIX by the one-stage clotting assay. However, minimizing interlaboratory variability is vital for optimizing future patient care.

[Undetectable anti-platelet factor 4/heparin antibodies with IgG-specific chemiluminescent immunoassays in a heparin-induced thrombocytopenia patient].

A 51-year-old man with a 9-month history of narrowing of visual fields and papilledema was admitted to the Department of Neurosurgery. Upon admission, glycerol was intravenously administered and heparin flushes were initiated to maintain intravenous access. Brain MRI revealed right transverse and sigmoid sinus thrombosis on hospital day 2, and the patient was treated with unfractionated heparin. On hospital day 9, the patient had a seizure and impaired mental status. Moreover, on hospital day 10, the platelet count decreased to less than half compared with that documented upon admission. The patient was then switched from heparin to argatroban because thrombosis exacerbation due to heparin-induced thrombocytopenia (HIT) was suspected. Despite negative IgG-specific chemiluminescent immunoassay for anti-platelet factor 4 (PF4) /heparin antibodies, positive functional assay led to the diagnosis of HIT. Warfarin was initiated and the platelet count was restored. Because maintaining the patient's PT-INR within the therapeutic range was difficult probably due to concomitant antimicrobial administration for complicating pneumonia, anticoagulation was switched to rivaroxaban. No bleeding or thrombotic complications developed. Thus, the presentation and clinical course should be considered for an accurate diagnosis of HIT. This is particularly important when the immunological assay is negative for anti-PF4/heparin antibodies. Furthermore, anticoagulation with rivaroxaban can be useful in the management of the subacute phase of HIT.

Postmarketing safety and effectiveness of recombinant factor IX (nonacog alfa) in Japanese patients with haemophilia B.

INTRODUCTION: In 2010, nonacog alfa became the first recombinant factor IX (rFIX) available in Japan for patients with haemophilia B. AIM: To determine real-world safety (adverse events, incidence of inhibitors) and effectiveness of nonacog alfa in Japan. METHODS: This multicentre, prospective, observational, postmarketing surveillance study enrolled previously treated and untreated patients (PTPs and PUPs, respectively) who were observed for 1 and 2 years, respectively, after initiating nonacog alfa therapy. Safety and effectiveness were assessed for each treatment type. Annualized bleeding rate (ABR) and incremental recovery of rFIX were also evaluated. RESULTS: Overall, 312 of 314 patients enrolled from 173 sites were eligible for the safety analysis set (PTPs, 281; PUPs, 28; other, 3). Mean age was 25.4 (PTPs) and 14.8 (PUPs) years. Haemophilic severity ranged from mild to severe, and 133 (42.6%) patients had haemophilic arthropathy. Of 285 patients (PTPs, 257; PUPs, 28) in the effectiveness set, 112 received on-demand treatment for 1161 bleeding episodes (effectiveness rate, 93.7%) and 185 received routine prophylaxis (effectiveness rate, 95.5%). No spontaneous bleeding was observed in 52.4% of patients during prophylactic treatment. Median ABR was lower during routine prophylaxis (2.0) vs the rest of the observation period (8.3). A weak negative correlation was found between body weight and the reciprocal of rFIX recovery. Eleven adverse drug reactions occurred in 7 PTPs (2.2% [7/312]); recurrence of inhibitor was observed in 1 patient, but no new inhibitor developed in PTPs or PUPs. CONCLUSION: Nonacog alfa therapy is safe and effective in the real-world scenario in Japan.

Ischaemic events are rare, and the prevalence of hypertension is not high in Japanese adults with haemophilia: First multicentre study in Asia.

INTRODUCTION: With the increasing life expectancy of patients with haemophilia (PWH), the number of PWH with age-related comorbidities, such as ischaemic events, is increasing. AIM: We conducted this multicentre observational study to identify the risk factors for major ischaemic events in PWH. METHODS: This study was the first multicentre observational study, conducted with the participation of five haemophilia treatment centres in Japan, conducted in ≥30-year-old adult PWH. The latest data recorded in the medical charts between 1 January and 31 December 2016 were reviewed. Healthcare data collected from the National Health and Nutrition Survey were used as the control data. RESULTS: Data of a total of 711 patients were collected. Only two PWH (0.3%) had a history of ischaemic events. Age-adjusted analysis indicated that the prevalence of hypertension defined as a blood pressure of 140/90 mm Hg or over was similar in the PWH to that in the males of the general population. However, when hypertension was defined more strictly (≥130/85 mm Hg), the prevalence was significantly lower in PWH than in the general male population. The hypertension in PWH was associated with the age, BMI, CKD, HIV infection and inhibitors. In particular, the odds ratio for the presence of inhibitors was high (odds ratio = 7.529). CONCLUSION: Whether the present results can be attributed to Japanese ethnicity or to the presence of haemophilia per se remains uncertain. We propose to initiate a prospective study for further investigation.

[Exhaustive analysis of genetic mutations associated with protein S deficiency utilizing next-generation sequencing analysis].

Protein S (PS) gene (PROS1) is found on chromosome 3 (3q11.1). To date, the reported detection rate of causative gene mutations in patients suspected of PS deficiency is only approximately 50%. To improve the detection rate of causative mutations, an exhaustive analysis of PROS1 was attempted using the next-generation sequencing method (NGS) to analyze the entire nucleotide sequence of PROS1 without analyzing those affected by pseudogenes. A total of 10 different mutations (three males and six females (52.9%) out of 17 patients (3 males and 14 females) with clinical PS deficiency were identified in this study. Remarkable improvements in the detection rate of causative mutations could not be obtained even with NGS analysis. These results suggested that the rate of diagnosis did not improve even after performing an exhaustive genetic analysis in patients clinically diagnosed with low PS antigen level and/or low PS activity. Although no reports were found on the gender gap in the rate of gene diagnosis for PS deficiency, the fluctuation of estrogen levels especially in women might cause a lower rate of diagnosis.

Efficacy, safety, and pharmacokinetics of emicizumab prophylaxis given every 4 weeks in people with haemophilia A (HAVEN 4): a multicentre, open-label, non-randomised phase 3 study.

BACKGROUND: Emicizumab, a subcutaneously administered, humanised, bispecific, monoclonal antibody, is approved to treat people with haemophilia A of all ages with and without coagulation factor VIII (FVIII) inhibitors. HAVEN 4 assessed emicizumab prophylaxis administered as one dose every 4 weeks in adults and adolescents with haemophilia A, regardless of FVIII inhibitor status. METHODS: In this phase 3, multicentre, open-label, two-stage study, patients aged 12 years and older with severe congenital haemophilia A (<1% of normal FVIII activity in blood) or haemophilia A with FVIII inhibitors, undergoing treatment with either FVIII concentrates or bypassing agents were recruited from three sites in Japan and Spain for a run-in cohort, and from 17 sites in Australia, Belgium, Japan, Poland, Spain, and the USA for a subsequent expansion cohort. Participants in the run-in and expansion cohorts were given emicizumab subcutaneously 6 mg/kg every 4 weeks for 24 weeks or more; for patients in the expansion cohort this regimen was preceded by four loading doses of 3 mg/kg once weekly. In the run-in cohort, we assessed pharmacokinetics after single and multiple (every 4 weeks) subcutaneous administration of 6 mg/kg emicizumab and safety. In the expansion cohort, the efficacy endpoint was efficacy of prophylactic emicizumab in maintaining adequate bleed prevention, assessed in all patients who received at least one dose of emicizumab and reported as annualised bleed rates for treated bleeds, all bleeds (treated and untreated), treated spontaneous bleeds, treated joint bleeds, and treated target joint bleeds. Safety was assessed in all participants given emicizumab. This study is registered with ClinicalTrials.gov, number NCT03020160, and is ongoing. FINDINGS: Between Jan 30, 2017, and Feb 27, 2017, seven patients were enrolled into the initial run-in cohort, which confirmed the expected pharmacokinetic profile and safety of the regimen based on model-based simulations, providing sufficient evidence for opening of the expansion cohort (n=41), which was recruited and enrolled between May 24, 2017, and June 30, 2017. The annualised rate of treated bleeds was 2·4 (95% CI 1·4-4·3). 23 (56·1%; 95% CI 39·7-71·5) of 41 reported no treated bleeds and 37 (90%; 76·9-97·3) reported zero to three treated bleeds. The annualised bleed rate was 4·5 (95% CI 3·1-6·6) for all bleeds, 0·6 (0·3-1·5), for treated spontaneous bleeds, 1·7 (0·8-3·7) for treated joint bleeds, and 1·0 (0·3-3·3) for treated target joint bleeds. The most frequent treatment-related adverse event was injection-site reaction (nine [22%] of 41 patients). We observed no thrombotic events or development of de-novo antidrug antibodies with neutralising potential or FVIII inhibitors. INTERPRETATION: Emicizumab given once every 4 weeks showed clinically meaningful bleed control while being well tolerated. This regimen could improve patient care by decreasing treatment burden and increasing adherence to effective prophylaxis, potentially decreasing the development of secondary complications for people with haemophilia A. FUNDING: F Hoffmann-La Roche and Chugai Pharmaceutical.