Long-term safety and efficacy outcomes of valoctocogene roxaparvovec gene transfer up to 6 years post-treatment.

INTRODUCTION: Valoctocogene roxaparvovec uses an adeno-associated virus serotype 5 (AAV5) vector to transfer a factor VIII (FVIII) coding sequence to individuals with severe haemophilia A, providing bleeding protection. AIM: To assess safety and efficacy of valoctocogene roxaparvovec 5-6 years post-treatment. METHODS: In a phase 1/2 trial, adult male participants with severe haemophilia A (FVIII ≤1 IU/dL) without FVIII inhibitors or anti-AAV5 antibodies received valoctocogene roxaparvovec and were followed for 6 (6 × 1013 vg/kg; n = 7) and 5 (4 × 1013 vg/kg; n = 6) years. Safety, including investigation of potential associations between a malignancy and gene therapy, and efficacy are reported. RESULTS: No new treatment-related safety signals emerged. During year 6, a participant in the 6 × 1013  vg/kg cohort was diagnosed with grade 2 parotid gland acinar cell carcinoma; definitive treatment was uncomplicated parotidectomy with lymph node dissection. Target enrichment sequencing of tumour and adjacent healthy tissue revealed low vector integration (8.25 × 10-5 per diploid cell). Integrations were not elevated in tumour samples, no insertions appeared to drive tumorigenesis, and no clonal expansion of integration-containing cells occurred. During all follow-ups, >90% decreases from baseline in annualised treated bleeds and FVIII infusion rates were maintained. At the end of years 6 and 5, mean FVIII activity (chromogenic assay) was 9.8 IU/dL (median, 5.6 IU/dL) and 7.6 IU/dL (median, 7.1 IU/dL) for the 6 × 1013 and 4 × 1013 vg/kg cohorts, respectively, representing proportionally smaller year-over-year declines than earlier timepoints. CONCLUSIONS: Valoctocogene roxaparvovec safety and efficacy profiles remain largely unchanged; genomic investigations showed no association with a parotid tumour.

Health-related quality of life following valoctocogene roxaparvovec gene therapy for severe hemophilia A in the phase 3 trial GENEr8-1.

BACKGROUND: Severe hemophilia A (HA) negatively impacts health-related quality of life (HRQOL). OBJECTIVES: We aimed to analyze HRQOL in adult men with severe HA without inhibitors after valoctocogene roxaparvovec gene transfer in the phase 3 trial GENEr8-1. METHODS: Participant-reported outcomes were the hemophilia-specific quality of life questionnaire for adults (Haemo-QOL-A), the EQ-5D-5L instrument, the Hemophilia Activities List (HAL), and the Work Productivity and Activity Impairment Questionnaire: Hemophilia Specific (WPAI+CIQ:HS). Participants completed the questionnaires at baseline and through 104 weeks postinfusion with 6 × 1013 vg/kg of valoctocogene roxaparvovec. Scores were analyzed per participant characteristics and outcomes. RESULTS: For 132 HIV-negative participants, mean change from baseline in Haemo-QOL-A Total Score met the anchor-based clinically important difference (CID: 5.5) by week 12; the mean (SD) increase was 7.0 (12.6) at week 104. At week 104, improvement in Consequences of Bleeding, Treatment Concern, Worry, and Role Functioning domain scores exceeded the CID (6). EQ-5D-5L Utility Index scores improved above the CID at week 52, but not at week 104. EQ-5D-5L visual analog scale and HAL scores increased from baseline to week 104. Participants reported less activity and work impairment at week 104 than baseline. Participants with problem joints had lower mean baseline Haemo-QOL-A Total and domain scores than those without them, but improved over 104 weeks, except for 11 participants with ≥3 problem joints. Participants with 0 bleeds during the baseline prophylaxis period reported Haemo-QOL-A score improvements above the CID, including in the Consequences of Bleeding domain. CONCLUSION: Valoctocogene roxaparvovec provided clinically meaningful HRQOL improvement for men with severe HA.

Two-Year Outcomes of Valoctocogene Roxaparvovec Therapy for Hemophilia A.

BACKGROUND: Valoctocogene roxaparvovec delivers a B-domain-deleted factor VIII coding sequence with an adeno-associated virus vector to prevent bleeding in persons with severe hemophilia A. The findings of a phase 3 study of the efficacy and safety of valoctocogene roxaparvovec therapy evaluated after 52 weeks in men with severe hemophilia A have been published previously. METHODS: We conducted an open-label, single-group, multicenter, phase 3 trial in which 134 men with severe hemophilia A who were receiving factor VIII prophylaxis received a single infusion of 6×1013 vector genomes of valoctocogene roxaparvovec per kilogram of body weight. The primary end point was the change from baseline in the annualized rate of treated bleeding events at week 104 after receipt of the infusion. The pharmacokinetics of valoctocogene roxaparvovec were modeled to estimate the bleeding risk relative to the activity of transgene-derived factor VIII. RESULTS: At week 104, a total of 132 participants, including 112 with data that were prospectively collected at baseline, remained in the study. The mean annualized treated bleeding rate decreased by 84.5% from baseline (P<0.001) among the participants. From week 76 onward, the trajectory of the transgene-derived factor VIII activity showed first-order elimination kinetics; the model-estimated typical half-life of the transgene-derived factor VIII production system was 123 weeks (95% confidence interval, 84 to 232). The risk of joint bleeding was estimated among the trial participants; at a transgene-derived factor VIII level of 5 IU per deciliter measured with chromogenic assay, we expected that participants would have 1.0 episode of joint bleeding per year. At 2 years postinfusion, no new safety signals had emerged and no new serious adverse events related to treatment had occurred. CONCLUSIONS: The study data show the durability of factor VIII activity and bleeding reduction and the safety profile of valoctocogene roxaparvovec at least 2 years after the gene transfer. Models of the risk of joint bleeding suggest that the relationship between transgene-derived factor VIII activity and bleeding episodes is similar to that reported with the use of epidemiologic data for persons with mild-to-moderate hemophilia A. (Funded by BioMarin Pharmaceutical; GENEr8-1 ClinicalTrials.gov number, NCT03370913.).

Psychometric Validation of the Haemo-QOL-A in Participants with Hemophilia A Treated with Gene Therapy.

Purpose: The hemophilia-specific health-related quality of life (HRQOL) questionnaire (Haemo-QOL-A) is validated for detecting QOL changes following standard therapy for hemophilia A, but has not been rigorously evaluated after gene therapy. This post hoc analysis evaluated the psychometric properties of Haemo-QOL-A in adult people with severe hemophilia A (PWSHA) receiving valoctocogene roxaparvovec (AAV5-hFVIII-SQ) in 2 clinical trials (phase 1/2, NCT02576795; phase 3, NCT03370913). Patients and Methods: Adult PWSHA (factor VIII levels ≤1 IU/dL) received 1 AAV5-hFVIII-SQ infusion (6×1013 vg/kg). Participants were assessed using the Haemo-QOL-A and the EuroQOL (EQ)-5D-5L and visual analog scale (VAS) questionnaires pre- and post-infusion. Psychometric analyses included convergent and discriminant validity, internal consistency, and reliability. Clinically important difference (CID) was estimated using 3-point change in EQ-5D-5L VAS as anchor. Results: Haemo-QOL-A data were analyzed from 7 (phase 1/2, 3-year follow-up) and 16 participants (phase 3, 26-week analysis). Change in Haemo-QOL-A Total Scores correlated with EQ-5D-5L VAS score change at 26 weeks (Pearson's correlation 0.77). At 26 weeks, increased Haemo-QOL-A Physical Functioning was associated with decreased EQ-5D-5L Pain and Discomfort and decreased Anxiety and Depression (Spearman's Rank correlations -0.73 and -0.62, respectively, P <0.01). Internal consistency analysis showed good reliability for all domains (Cronbach's alpha >0.7) except Treatment Concern (Cronbach's alpha = 0.31). Anchor-based CID estimates were met for Haemo-QOL-A Total Score (≥5.5) and domain scores (≥6) for Consequences of Bleeding, Physical Functioning, Role Functioning, and Worry. Conclusion: Our preliminary results suggest that the Haemo-QOL-A is a valid, reliable instrument for HRQOL assessment in PWSHA undergoing gene therapy. Future research should be undertaken to confirm these findings in a larger number of participants.

Interindividual variability in transgene mRNA and protein production following adeno-associated virus gene therapy for hemophilia A.

Factor VIII gene transfer with a single intravenous infusion of valoctocogene roxaparvovec (AAV5-hFVIII-SQ) has demonstrated clinical benefits lasting 5 years to date in people with severe hemophilia A. Molecular mechanisms underlying sustained AAV5-hFVIII-SQ-derived FVIII expression have not been studied in humans. In a substudy of the phase 1/2 clinical trial ( NCT02576795 ), liver biopsy samples were collected 2.6-4.1 years after gene transfer from five participants. Primary objectives were to examine effects on liver histopathology, determine the transduction pattern and percentage of hepatocytes transduced with AAV5-hFVIII-SQ genomes, characterize and quantify episomal forms of vector DNA and quantify transgene expression (hFVIII-SQ RNA and hFVIII-SQ protein). Histopathology revealed no dysplasia, architectural distortion, fibrosis or chronic inflammation, and no endoplasmic reticulum stress was detected in hepatocytes expressing hFVIII-SQ protein. Hepatocytes stained positive for vector genomes, showing a trend for more cells transduced with higher doses. Molecular analysis demonstrated the presence of full-length, inverted terminal repeat-fused, circular episomal genomes, which are associated with long-term expression. Interindividual differences in transgene expression were noted despite similar successful transduction, possibly influenced by host-mediated post-transduction mechanisms of vector transcription, hFVIII-SQ protein translation and secretion. Overall, these results demonstrate persistent episomal vector structures following AAV5-hFVIII-SQ administration and begin to elucidate potential mechanisms mediating interindividual variability.

Global Seroprevalence of Pre-existing Immunity Against AAV5 and Other AAV Serotypes in People with Hemophilia A.

Adeno-associated virus (AAV)-mediated gene therapy may provide durable protection from bleeding events and reduce treatment burden for people with hemophilia A (HA). However, pre-existing immunity against AAV may limit transduction efficiency and hence treatment success. Global data on the prevalence of AAV serotypes are limited. In this global, prospective, noninterventional study, we determined the prevalence of pre-existing immunity against AAV2, AAV5, AAV6, AAV8, and AAVrh10 among people ≥12 years of age with HA and residual FVIII levels ≤2 IU/dL. Antibodies against each serotype were detected using validated, electrochemiluminescent-based enzyme-linked immunosorbent assays. To evaluate changes in antibody titers over time, 20% of participants were retested at 3 and 6 months. In total, 546 participants with HA were enrolled at 19 sites in 9 countries. Mean (standard deviation) age at enrollment was 36.0 (14.87) years, including 12.5% younger than 18 years, and 20.0% 50 years of age and older. On day 1, global seroprevalence was 58.5% for AAV2, 34.8% for AAV5, 48.7% for AAV6, 45.6% for AAV8, and 46.0% for AAVrh10. Considerable geographic variability was observed in the prevalence of pre-existing antibodies against each serotype, but AAV5 consistently had the lowest seroprevalence across the countries studied. AAV5 seropositivity rates were 51.8% in South Africa (n = 56), 46.2% in Russia (n = 91), 40% in Italy (n = 20), 37.2% in France (n = 86), 26.8% in the United States (n = 71), 26.9% in Brazil (n = 26), 28.1% in Germany (n = 89), 29.8% in Japan (n = 84), and 5.9% in the United Kingdom (n = 17). For all serotypes, seropositivity tended to increase with age. Serostatus and antibody titer were generally stable over the 6-month sampling period. As clinical trials of AAV-mediated gene therapies progress, data on the natural prevalence of antibodies against various AAV serotypes may become increasingly important.

Persistence of haemostatic response following gene therapy with valoctocogene roxaparvovec in severe haemophilia A.

INTRODUCTION: Valoctocogene roxaparvovec is an investigational AAV5-based factor VIII (FVIII) gene therapy that has demonstrated sustained clinical benefit in people with severe haemophilia A. AIM: To report safety, tolerability, efficacy, and quality of life (QOL) among participants who received valoctocogene roxaparvovec in a phase 1/2 clinical study (NCT02576795). METHODS: Men ≥18 years of age with severe haemophilia A (FVIII ≤1 IU/dl) without history of FVIII inhibitors or anti-AAV5 antibodies received a single infusion of valoctocogene roxaparvovec and were followed for 5 years (6 × 1013 vg/kg dose, n = 7) and 4 years (4 × 1013 vg/kg dose, n = 6). RESULTS: Over the past 2 years, few adverse events and no FVIII inhibitors were reported. Per chromogenic substrate (CSA) assay at years 5 and 4, four of seven and three of six participants in the 6 × 1013 and 4 × 1013 vg/kg cohorts, respectively, maintained median FVIII levels >5 IU/dl, corresponding to mild haemophilia. By regression analysis, rate of change in FVIII activity was -0.14 (95% confidence interval [CI]: -.32 to .03) IU/dl/wk in the 6 × 1013 vg/kg cohort in year 5 and -.06 (95% CI: -.14 to .01) IU/dl/wk in the 4 × 1013 vg/kg cohort in year 4. No participants resumed FVIII prophylaxis, and eight of 13 participants reported zero bleeds in the past 2 years. Improved QOL from baseline persisted in the 6 × 1013 vg/kg cohort; all six Haemo-QOL-A domain scores increased. For the 4 × 1013 vg/kg cohort, high baseline Haemo-QOL-A scores persisted. CONCLUSION: These results demonstrate transgene expression and haemostatic response for up to 5 years in individuals with haemophilia A.

Early Phase Clinical Immunogenicity of Valoctocogene Roxaparvovec, an AAV5-Mediated Gene Therapy for Hemophilia A.

Evaluation of immune responses to adeno-associated virus (AAV)-mediated gene therapies prior to and following dose administration plays a key role in determining therapeutic safety and efficacy. This report describes up to 3 years of immunogenicity data following administration of valoctocogene roxaparvovec (BMN 270), an AAV5-mediated gene therapy encoding human B domain-deleted FVIII (hFVIII-SQ) in a phase 1/2 clinical study of adult males with severe hemophilia A. Patients with pre-existing humoral immunity to AAV5 or with a history of FVIII inhibitors were excluded from the trial. Blood plasma and peripheral blood mononuclear cell (PBMC) samples were collected at regular intervals following dose administration for assessment of humoral and cellular immune responses to both the AAV5 vector and transgene-expressed hFVIII-SQ. The predominant immune response elicited by BMN 270 administration was largely limited to the development of antibodies against the AAV5 capsid that were cross-reactive with other common AAV serotypes. No FVIII inhibitor responses were observed within 3 years following dose administration. In a context of prophylactic or on-demand corticosteroid immunosuppression given after vector infusion, AAV5 and hFVIII-SQ peptide-specific cellular immune responses were intermittently detected by an interferon (IFN)-γ and tumor necrosis factor (TNF)-α FluoroSpot assay, but they were not clearly associated with detrimental safety events or changes in efficacy measures.

Pharmacokinetics and safety of a novel recombinant human von Willebrand factor manufactured with a plasma-free method: a prospective clinical trial.

Safety and pharmacokinetics (PK) of recombinant von Willebrand factor (rVWF) combined at a fixed ratio with recombinant factor VIII (rFVIII) were investigated in 32 subjects with type 3 or severe type 1 von Willebrand disease (VWD) in a prospective phase 1, multicenter, randomized clinical trial. rVWF was well tolerated and no thrombotic events, inhibitors, or serious adverse events were observed. The PK of rVWF ristocetin cofactor activity, VWF antigen, and collagen-binding activity were similar to those of the comparator plasma-derived (pd) VWF-pdFVIII. In vivo cleavage of ultra-large molecular-weight rVWF multimers by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; the endogenous VWF protease) and generation of characteristic satellite bands were demonstrated. In 2 subjects with specific nonneutralizing anti-VWF-binding antibodies already detectable before rVWF infusion, a reduction in VWF multimers and VWF activity was observed. Stabilization of endogenous FVIII was enhanced following post-rVWF-rFVIII infusion as shown by the difference in area under the plasma concentration curve compared with pdVWF-pdFVIII (AUC0-∞) (P < .01). These data support the concept of administering rVWF alone once a therapeutic level of endogenous FVIII is achieved.

Pediatric patients with intravascular devices: polymicrobial bloodstream infections and risk factors.

A retrospective study was conducted, including 61 patients with long-term intravascular devices (IVDs) admitted to the Childrens Hospital Los Angeles with diverse underlying diseases, different types of catheters, and culture-proven catheter-related bloodstream infections (BSIs). Within these patients, 125 catheter-related BSIs occurred, and the incidence of monomicrobial and polymicrobial BSIs was evaluated. Risk factors for polymicrobial BSIs were determined. Forty-two BSIs contained more than one pathogen. These polymicrobial BSIs were observed more often in younger patients (<4.1 years versus ≥4.1 years) and less in patients using venous implanted ports. No other associations were found between the occurrences of polymicrobial BSIs and underlying diseases, other types of catheters, host defense status, parenteral nutrition, recurrences, or catheter removal. Patients with long-term IVDs at a younger age have a higher risk of developing a polymicrobial BSI. Future prospective studies should address the issue of polymicrobial infection in IVDs in more detail.

Severe congenital protein C deficiency: description of a new mutation and prophylactic protein C therapy and in vivo pharmacokinetics.

Severe congenital protein C deficiency is a rare life-threatening disorder that presents with purpura fulminans, disseminated intravascular coagulation, and thrombotic complications during the neonatal period. Affected children require acute replacement therapy with fresh frozen plasma or protein C concentrate, for example, Ceprotin (Baxter AG, Vienna). Long-term management and outcome is dependent on effective anticoagulation with warfarin, low-molecular weight heparin, or protein C concentrate. We describe the successful use of intravenous protein C concentrate for thrombotic prophylaxis in 2 sisters with severe type I protein C deficiency. Individualized long-term prophylactic regimens were developed based on clinical response. In vivo pharmacokinetic analyses of protein C concentrate were performed in each patient. Analysis of the protein C gene coding sequences identified 2 mutations in both patients, the previously described Arg169 to Trp mutation, and a novel mutation that changes Cys17 into a stop codon.

Overt and incomplete (silent) cerebral infarction in sickle cell anemia: diagnosis and management.

Cerebral vasculopathy in sickle cell anemia (HbSS) is manifest clinically as cerebral infarction and intracranial hemorrhage. The type of stroke, ischemic or hemorrhagic, is age specific with distinct differences in outcomes. Cerebral infarction with or without clinical stroke begins during early childhood and rarely causes death immediately.

Ethanol-lock technique for persistent bacteremia of long-term intravascular devices in pediatric patients.

OBJECTIVES: To use the ethanol-lock technique (in conjunction with systemic antibiotics) to salvage central lines from removal and to prevent persistence of catheter-related infections among pediatric patients with long-term intravascular devices. DESIGN: Medical records of patients treated with ethanol locks were retrospectively reviewed from June 1, 2004, through June 22, 2005. SETTING: Childrens Hospital Los Angeles, Los Angeles, Calif, a tertiary care pediatric hospital. Patients Forty children with diverse underlying disorders were treated for 51 catheter-related infections using the Childrens Hospital Los Angeles ethanol-lock technique. INTERVENTIONS: Eligible infected central lines were instilled with a dose volume of 0.8 to 1.4 mL of 70% ethanol into the catheter lumen during 12 to 24 hours and then withdrawn. The volume of ethanol used was based on the type of intravascular device. MAIN OUTCOME MEASURES: Clearance of infection and incidence of recurrence. RESULTS: Of the 51 ethanol-lock treatments in 40 children, no catheters were removed because of persistent infection. Eighty-eight percent (45/51) of the treated episodes cleared without recurrence (defined as a relapse within 30 days with the same pathogen). Twelve (75%) of 16 polymicrobial isolates and 33 (94%) of 35 monomicrobial isolates were successfully treated. There were no adverse reactions or adverse effects reported. CONCLUSION: This retrospective study supports the use of the ethanol-lock technique in conjunction with systemic antibiotics as an effective and safe method to retain the use of a previously infected central venous catheter, decrease the need for line removal, and eradicate persistent pathogens in catheter-related infections.

The next generation of hemophilia treatment specialists.

We currently are witnessing a serious attrition of physicians specializing in hemophilia treatment in Europe and the United States while most physicians who complete training in hematology-oncology choose oncology practice as their career. Nevertheless, recent therapeutic developments, including advances in prophylaxis and inhibitor management, have renewed the demand for experts in hemophilia and related disorders. To meet this demand, several specialty training programs have been developed in the United States and Europe, specifically the International Course in Hemophilia in Malmö, Sweden, the Children's Hospital of Los Angeles International Pediatric Hemostasis and Thrombosis Program, and the Baxter/National Hemophilia Foundation Fellowship Programs. The purpose of these programs is to enhance the clinical expertise and further the professional development of individuals dedicated to treating patients with coagulation disorders.

Overt and incomplete (silent) cerebral infarction in sickle cell anemia: diagnosis and management.

Regional complete infarctions in children with sickle cell anemia (HbSS) are often associated with stenosis of the large intracranial arteries and result in lifetime disability. Incomplete infarction occurs more frequently than previously recognized and has far-reaching effects on neurocognitive development and the risk for overt secondary strokes into adulthood. Clinical and neuroimaging modalities have been highlighted in an algorithmic approach, with the studies giving the highest yield in results and most likely to be available listed in sequential order. The recognition of an emerging "second peak" incidence in the third decade of life is worrisome and warrants more intense scrutiny and diagnosis of subtle findings of stroke in this young adult population.

Invasive pneumococcal infections in children with sickle cell disease in the era of penicillin prophylaxis, antibiotic resistance, and 23-valent pneumococcal polysaccharide vaccination.

Rates and severity of pneumococcal infections in children with sickle cell disease were examined before licensure of pneumococcal-conjugated vaccine (PVC). Rates of peak invasive infection rates in 1-year-old children with hemoglobin SS and mortality in those 0 to 10 years of age were 36.5 to 63.4 and 1.4 to 2.8 per 1000 person-years, respectively (>10 and 100 times as frequent as in the general population). Overall, 71% of serotyped isolates (n=80) were PVC serotypes and 71% of nonvaccine serotype strains were penicillin-sensitive. Clinical presentation in children with hemoglobin SS (n=71; more with hypotension) and hemoglobin SC (n=18; more with acute chest syndrome, otitis media) differed. Penicillin nonsusceptibility (38% of isolates) varied between geographic study sites. Penicillin prophylaxis appeared less effective against intermediate and resistant strains. Of all infected children, meningitis developed in 20% and 15% died (hemoglobin SS, n=15 and 11; hemoglobin SC, n=1 each). Factors associated with death included age >4 years (58%), serotype 19F, and not being followed by a hematologist (42% each). The pneumococcal-polysaccharide vaccine was 80.4% effective within 3 years after vaccination (95% CI, 39.7, 93.6). Children with sickle cell disease of all ages may benefit from PVC boosted with polysaccharide vaccination.

Cardiac abnormalities in children with sickle cell anemia.

Sickle cell anemia (SCA) results in chronic volume overload of the heart due to hemodilution. Previous echocardiographic studies of cardiac function in children with SCA have not accounted for these abnormal loading conditions. The objectives of this study were to (1) determine how the degree of anemia and transfusion status relate to cardiac findings and (2) evaluate cardiac function using load-independent parameters of function. We evaluated 77 patients with SCA, ages 2 to 22 years (mean +/- SD = 11.7 +/- 4.7), using physical examination, electrocardiography, and echocardiography. We compared two groups of patients. Group 1 consisted of 57 non-transfused patients, and Group 2 consisted of 20 patients on a chronic transfusion protocol. Group 1 patients exhibited a significantly lower hemoglobin, higher cardiac output, and larger left ventricular (LV) end-diastolic dimension and LV mass than groups 2 (P < 0.05). However, the velocity of circumferential fiber shortening-wall stress index (a load-independent measure of systolic function) was normal and not statistically different between the two groups. Conversely, the LV myocardial performance index (a measure of combined systolic and diastolic function) was significantly higher in Group 2 (P < 0.001), possibly indicating impaired myocardial diastolic function. SCA in children results in a volume-overloaded heart with a significant increase in LV dimensions and mass, both proportional to the degree of anemia. Despite these abnormal loading conditions, systolic function is preserved. Patients on a chronic transfusion protocol may develop diastolic dysfunction despite iron chelation therapy.