Clinical evaluation of an advanced category antihaemophilic factor prepared using a plasma/albumin-free method: pharmacokinetics, efficacy, and safety in previously treated patients with haemophilia A.

The efficacy and safety of an advanced category recombinant antihaemophilic factor produced by a plasma- and albumin-free method (rAHF-PFM) was studied in 111 previously treated subjects with haemophilia A. The study comprised a randomized, double-blinded, crossover pharmacokinetic comparison of rAHF-PFM and RECOMBINATE rAHF (R-FVIII); prophylaxis (three to four times per week with 25-40 IU kg(-1) rAHF-PFM) for at least 75 exposure days; and treatment of episodic haemorrhagic events. Median age was 18 years, 96% of subjects had baseline factor VIII <1%, and 108 received study drug. Bioequivalence, based on area under the plasma concentration vs. time curve and adjusted in vivo recovery, was demonstrated for rAHF-PFM and R-FVIII. Mean (+/-SD) half-life for rAHF-PFM was 12.0 +/- 4.3 h. Among 510 bleeding events, 473 (93%) were managed with one or two infusions of rAHF-PFM and 439 (86%) had efficacy ratings of excellent or good. Subjects who were less adherent to the prophylactic regimen had a higher bleeding rate (9.9 episodes subject(-1) year(-1)) than subjects who were more adherent (4.4 episodes subject(-1) year(-1); P < 0.03). One subject developed a low titre, non-persistent inhibitor (2.0 BU) after 26 exposure days. These data demonstrate that rAHF-PFM is bioequivalent to R-FVIII, and suggest that rAHF-PFM is efficacious and safe, without increased immunogenicity, for the treatment of haemophilia A.

Relationship between factor VIII mutation type and inhibitor development in a cohort of previously untreated patients treated with recombinant factor VIII (Recombinate). Recombinate PUP Study Group.

A cohort of 79 previously untreated patients (PUPs) with moderate-severe haemophilia A (baseline Factor VIII < or =2%) were enrolled in a study to evaluate the safety, efficacy and immunogenicity of recombinant factor VIII (r-FVIII, Recombinate). Blood samples were obtained retrospectively from a total 55 PUPs who were investigated for the spectrum of FVIII gene mutations responsible for their haemophilia. FVIII gene inversion mutations were found in 27 (49%) patients. Two patients had partial gene deletions. The remaining 26 patients were then screened for mutations in the FVIII gene coding region using conformation sensitive gel electrophoresis. Point mutations were identified in 22 (85%) of the patients and 14 of these mutations were novel. Study subjects were monitored for the development of FVIII inhibitors throughout the study. A total of 23 of the 73 evaluable subjects (including one subject with a low inhibitor titer at baseline) demonstrated an inhibitor on one or more occasions; 11 (15%) were persistent. Inhibitors were detected in patients with partial gene deletions and inversions and in three of eight patients with missense mutations. No inhibitors were found in 11 patients with small insertions or deletions resulting in an alteration of the protein translation reading frame (frameshift mutations). The results corroborate the observation that mutation type is an important determinant of the propensity to develop inhibitory anti-FVIII antibody.

Incidence of inhibitors in haemophilia A patients--a review of recent studies of recombinant and plasma-derived factor VIII concentrates.

The development of inhibitors to factor VIII or IX is the most serious complication of haemophilia therapy. While early surveys revealed inhibitor prevalences of 3.6-25%, recent studies, especially those using recombinant DNA-derived products, have prompted speculation as to whether ultrapurified products may cause a higher incidence of inhibitors. Although studies of ultrapure rFVIII in previously treated patients have not shown an increased inhibitor risk, in previously untreated patients (PUPs) with severe haemophilia A (factor VIII < 2%), cumulative incidences of approximately 30% have been reported. The majority of these inhibitors are low responders; many have disappeared spontaneously despite continued treatment with the study product (i.e. transient inhibitors), and were most probably detected as a consequence of frequent inhibitor testing. The mutation causing haemophilia has recently been shown to be a significant risk factor for developing an inhibitor; mutations leading to the absence of endogenous factor VIII protein (for example, large multidomain deletions, nonsense mutations, isochromosomal intron 22 inversions) are associated with the highest risk of inhibitor development. Furthermore, recent prospective studies of plasma-derived products reveal inhibitor incidences (i.e. 21-52%) that are comparable to those obtained with recombinant products. When comparing the incidences of high-responder inhibitors (> 10 BU) among recent prospectively studied severe haemophilia A cohorts (i.e. 11-41%), differences between plasma-derived and recombinant products cannot be discerned. New studies of either recombinant or plasma-derived products should consider all known parameters influencing inhibitor formation, thereby facilitating meaningful comparisons of inhibitor risk.

Multicenter trial to evaluate the safety and potential efficacy of pooled human fibrin sealant for the treatment of burn wounds.

OBJECTIVE: The primary purpose of this multicenter study was to evaluate the safety and potential efficacy of a solvent/detergent-treated commercial fibrin sealant (human) for topical hemostasis in skin grafting. METHODS: The study involved a prospective evaluation of changes in viral titers in patients with burns less than 15% after treatment with fibrin sealant (human). Each patient served as his/her own control for an unblinded, randomized comparison of donor site hemostasis and healing. Preoperative serum was obtained to screen for viral titers. At autografting, the recipient site and one of two randomly chosen donor sites were treated with fibrin sealant (human). The use of other hemostatic agents, including epinephrine was prohibited. Each donor site was covered with gauze to collect blood for estimation of the relative amount of bleeding. The healing of the graft and donor sites was observed. Viral titers and wounds were checked monthly for 6 months, and at 9 and 12 months postoperatively. RESULTS: Viral titers for human immunodeficiency virus; hepatitis A, B, and C; Epstein-Barr virus; and cytomegalovirus were obtained before and after treatment. Of 47 patients, 34 completed the full year of observation. After treatment, there were no seroconversions to any of the aforementioned viruses. Bleeding at the recipient site appeared well controlled with fibrin sealant (human). Although investigators felt that fibrin sealant (human) improved donor site hemostasis, differences in hemoglobin measurements of blood-soaked dressings failed to reach significance. No differences were noted with regard to acceleration of donor site healing, graft take, or scar maturation at the two groups of donor sites. Anecdotally, the maturation of the recipient site appeared to be accelerated. CONCLUSION: Fibrin sealant (human) is safe for use during excision and grafting, and its topical hemostatic potential needs to be examined in patients with larger burns. Its role in scar maturation also needs to be investigated.

A multicenter study of recombinant factor VIII (Recombinate) in previously treated patients with hemophilia A. The Recombinate Previously Treated Patient Study Group.

A prospective, open-label multicenter investigation has been conducted to compare pharmacokinetic parameters of recombinant DNA-derived FVIII (rFVIII) and plasma-derived FVIII concentrate (pdFVIII) and to assess safety and efficacy of long-term home-treatment with rFVIII for subjects with hemophilia A. Following comparative in vivo pharmacokinetic studies, 69 patients with severe (n = 67) or moderate (n = 2) hemophilia A commenced a program of home treatment using rFVIII exclusively for prophylaxis and treatment of all bleeding episodes for a period of 1.0 to 5.7 years (median 3.7 years). The mean in vivo half-lives of rFVIII and pdFVIII were both 14.7 h. In vivo incremental recoveries at baseline were 2.40%/IU/kg and 2.47%/IU/kg, respectively (p = 0.59). The response to home treatment with rFVIII was categorized as good or excellent in 3,195 (91.2%) of 3,481 evaluated bleeding episodes. Thirteen patients received rFVIII for prophylaxis for twenty-four surgical procedures. In all cases, hemostasis was excellent. Adverse reactions were observed in only 13 of 13,591 (0.096%) infusions of rFVIII: none was serious. No patient developed an inhibitor to rFVIII.

A multicenter study of recombinant factor VIII (recombinate): safety, efficacy, and inhibitor risk in previously untreated patients with hemophilia A. The Recombinate Study Group.

In July 1990, the Recombinate Study Group initiated a prospective, open-labeled investigation of recombinant factor VIII (r-FVIII) to assess its safety and efficacy and to characterize the natural history of inhibitor development in previously untreated patients (PUPs) with hemophilia A. All study subjects have severe FVIII deficiency (baseline FVIII level < or = 2% of normal) and no history of blood product exposure before study entry. Following the first r-FVIII infusion, plasma was screened for inhibitors once every 3 months, and plasma recovery of r-FVIII at 30 minutes and 24 hours postinfusion was assayed at least once every 6 months. As of May 1993, 73 of 79 patients originally enrolled in the trial continue to participate. The median number of r-FVIII exposure-days for the 71 subjects who have received at least one r-FVIII infusion is 11. A total of 1,785 infusions have been administered to treat 810 bleeding events. Ninety-two percent of bleeding events responded as anticipated to one or two infusions. Two, nonrecurring, acute adverse reactions occurred coincident with r-FVIII infusion, one of which was unrelated and the other, possibly related to the infusion. Seventeen (23.9%) subjects have developed inhibitors: five with peak titers more than 10 Bethesda units (BU) and 12 with peak titers < or = 10 BU (range, 0.5 to 10). Survival analysis showed that the probability of remaining inhibitor-free in this group of patients with severe hemophilia A is 88.4% after 8, 73.6% after 10, and 61.6% after 25 r-FVIII exposure-days. Inhibitors disappeared in five (29.4%) subjects on retesting 2 to 16 months after the last positive inhibitor assay. r-FVIII is safe and effective in the treatment of hemophilia A-related bleeding. To date, the inhibitor risk associated with its use is comparable to that in patients treated with plasma-derived concentrates. The majority of inhibitors identified are low in titer and do not preclude continued on-demand therapy with r-FVIII.

Erythropoietin response to critical illness.

OBJECTIVE: To examine the endogenous erythropoietin response in critically ill children with acute anemia or acute hypoxemia. DESIGN: A prospective case study of critically ill acutely anemic, and acutely hypoxemic pediatric patients compared with control groups of critically ill nonanemic and nonhypoxemic patients and with a hemoglobin and age-matched, chronically anemic patient group. SETTING: Multidisciplinary, tertiary, pediatric intensive care unit (ICU). PATIENTS: Critically ill patients admitted to the pediatric ICU during an 11-month period between February 1992 and March 1993 with acute anemia (n = 21), acute hypoxemia (n = 18), or neither anemia nor hypoxemia (n = 10). Outpatients with chronic anemia (n = 21) and no acute illness were also studied as a comparison group. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Ages were equivalent among the groups and averaged 57.4 +/- 47.2 months (range 1 to 144). Acutely hypoxemic and critically ill control patients had normal hemoglobin levels. Acutely anemic patients had a hemoglobin level equivalent to chronically anemic outpatients, but lower (p < .001) hemoglobin levels than acutely hypoxemic and critically ill control patients. The serum erythropoietin concentrations in the acutely anemic group were significantly lower than erythropoietin values in the chronically anemic group (39.3 +/- 62.2 vs. 861 +/- 758 mU/mL, p < .001) and similar to erythropoietin concentrations in the critically ill control (13.5 +/- 10.5 mU/mL) and acutely hypoxemic (5.2 +/- 3.3 mU/mL) patient groups. Only ten of 49 critically ill patients had an erythropoietin concentration above normal, compared with 20 of 21 chronically anemic patients, whose erythropoietin concentrations were above normal. CONCLUSIONS: The erythropoietin response to known physiologic stimuli is blunted in critically ill children. This blunted erythropoietin response may result in increased transfusion requirements.

Assessing clinical severity in children with sickle cell disease. Preliminary results from a cooperative study.

PURPOSE: Although it is clear that sickle cell disease is curable with bone marrow transplantation, there are few objective criteria that are helpful in the identification of suitable candidates for this aggressive and potentially life-threatening procedure. This disease is characterized by a highly variable clinical course, and there is a need to intervene with marrow transplant before the onset of disease-mediated chronic organ damage. These factors high-light the need for a clinical severity index that can prospectively identify patients who are at high risk for a turbulent clinical course and a poor prognosis. PATIENTS AND METHODS: We used the Cooperative Study of Sickle Cell Disease data base to identify features of the disease in early childhood (i.e., < 2 years of age) that are associated either with significant morbidity later in childhood or early mortality. Our study population includes the 1,944 children who entered the study before 12 years of age. Univariate analysis showed that factors associated with the occurrence of cerebrovascular accident (51 patients) include hematocrit, rate of change of pocked red cell count, and polymer fraction at 40% oxygen saturation (PF40). Only low hematocrit was predictive of death in this pediatric cohort (45 disease-related deaths). RESULTS: Our ability to identify other potential factors that correlate with these outcome measures is limited by their small numbers. Hence, it was necessary to designate a different endpoint whose relationship with various clinical and laboratory parameters could be assessed. To accomplish this, a distribution of acute events, which were defined as any episode of pain or acute chest syndrome, was calculated. Also, the age-specific "expected" event rate, defined as the mean number of events per patient-year of observation, was determined. CONCLUSIONS: The relationship between various aspects of sickle cell disease and high positive deviance from the expected event rate will be assessed in a cohort of 519 children who entered the study prior to 7 months of age and were followed beyond their second birthday.

Failure to mobilize intracellular calcium in response to thrombin in a patient with familial thrombocytopathy characterized by macrothrombocytopenia and abnormal platelet membrane complexes.

We report a mother and son who were found to have macrothrombocytopenia, prolonged bleeding time, and abnormal platelet responses to thrombin. Transmission electron microscopy performed on the son's platelets demonstrated an unusual arrangement of membrane complexes formed by association of the open canalicular and dense tubular systems. Number and appearance of platelet alpha-granules, dense bodies, and mitochondria were normal. These platelets demonstrated normal agonist-induced Ca2+ flux in response to collagen and supranormal responses to arachidonic acid but displayed no increase in intracellular free Ca2+ in response to thrombin. Platelet surface glycoproteins IIb-IIIa, Ib, and granular membrane protein-140 measured by fluorescence-activated flow cytometry, along with platelet content of von Willebrand factor and fibrinogen, were normal. The von Willebrand factor binding function of GP-Ib on these platelets was also normal. We believe that this family demonstrates a unique macrothrombocytopenia syndrome characterized by deficient Ca2+ mobilization in response to thrombin that is not related to a defect in GP-Ib.

Loss of high-responder inhibitors in patients with severe hemophilia A and human immunodeficiency virus type 1 infection: a report from the Multi-Center Hemophilia Cohort Study.

To evaluate the effects of human immunodeficiency virus type 1 (HIV-1) infection on the loss of factor VIII alloantibodies, we identified 77 patients with a history of inhibitors from among a large cohort of HIV-1-infected participants enrolled in a natural history study of HIV-1 infection in hemophilia. Fifty-six patients were high responders with inhibitors titers greater than 5 Bethesda Units (BU) measured on at least one occasion. From May 1985 to December 1989, 13 of the high-responder patients were rechallenged with factor VIII concentrates after several years of treatment with other plasma products. All exhibited excellent hemostasis upon reinstitution of factor VIII. Seven of the 13 patients (11.3-46.3 years of age) were in the advanced stages of HIV-1 infection at the time of rechallenge. Inhibitor titers measured subsequent to the reinstitution of factor VIII were consistently less than 1 BU in five of these seven patients. The remaining six patients (6.1-57.5 years of age) had mild to moderate CD4+ lymphocyte depletion (absolute CD4+ cells: 262-935/mm3) at the time of factor VIII rechallenge. Follow-up inhibitor titers were negative 7-42 months after consistent factor VIII use in these six patients. The lack of anamnestic response to factor VIII in all 13 patients who were rechallenged indicates that HIV-1-infected patients who have a history of high-responder inhibitors frequently benefit from the reintroduction of factor VIII use for the control of bleeding, regardless of their stage of HIV-1 disease.

Comparison of the erythropoietin response in children with aplastic anemia, transient erythroblastopenia, and iron deficiency.

To assess the effects of decreased erythrocyte production on the levels of serum erythropoietin in children, we measured simultaneous hemoglobin concentrations and erythropoietin in 18 children with iron deficiency anemia, 17 children with transient erythroblastopenia of childhood (TEC), and 7 children with aplastic anemia. In all but two patients (one with TEC; one with aplastic anemia), erythropoietin was measured at diagnosis, before institution of specific therapy for the anemia. There was a statistically significant inverse linear correlation between log10 erythropoietin and hemoglobin values for all patient groups (r = 0.904 to 0.912; p less than 0.005). A comparison of the slopes of the regressions for each patient group by analysis of covariance revealed a significantly steeper slope for the iron deficiency group (-0.553) versus the TEC (-0.287) and aplastic anemia (-0.256) groups (p = 0.0001). The difference in erythropoietin levels appeared greatest in patients whose presenting hemoglobin level was greater than 5 gm/dl. Decline in serum erythropoietin levels was more precipitous in the less severely anemic patients with iron deficiency anemia than in the patients with TEC or aplastic anemia. These data reveal quantitative and qualitative differences in the relationship between serum erythropoietin and hemoglobin levels when children with severe iron deficiency anemia versus those with TEC or aplastic anemia are considered, even though all three conditions are characterized by hypoproliferation of erythrocytes.

Erythropoietin deficiency: a complication of cisplatin therapy and its treatment with recombinant human erythropoietin.

Cisplatin (CDDP) has been implicated in the development of anemia via several mechanisms of action, including shortening of red cell (RBC) survival and direct toxicity of the drug on RBC bone marrow precursors. Recent studies and case reports suggest an association between CDDP and the development of hyporegenerative anemia as a consequence of relative erythropoietin (EPO) deficiency. To study the effects of CDDP on the relationship between serum EPO and hemoglobin (Hb) concentration, we measured levels of EPO in 12 patients (1-21 years of age) who were treated with cumulative doses of CDDP ranging from 300 to 720 mg/m2 for a variety of pediatric malignancies. Post-CDDP glomerular filtration rates (GFR) varied from 29 to 143 ml/min/1.73 m2 for 11 of the 12 patients studied. At the completion of CDDP therapy, an inverse linear relationship between log(10) serum EPO and Hb was noted among those patients who retained at least 40-50% of their pre-CDDP therapy GFR. One patient with chronic renal failure at the completion of CDDP therapy (GFR 25-35 ml/min/1.73 m2) exhibited a chronic transfusion-dependent, hyporegenerative anemia that was due to persistently low levels of EPO. Institution of recombinant human (r-Hu) EPO therapy resulted in an abrupt cessation of this patient's RBC transfusion dependency. Additional studies are needed to further characterize the effects of CDDP on EPO production and secretion and to determine optimal dosing schedules for r-Hu EPO in pediatric patients who receive CDDP and other myelosuppressive chemotherapy.

Autoimmune thrombocytopenia in pediatric systemic lupus erythematosus: alternative therapeutic modalities.

Three patients with pediatric systemic lupus erythematosus (PSLE) and autoimmune thrombocytopenia (AT), who developed unacceptable side effects (pseudotumor cerebri, hypertension, excessive weight gain) from treatment with steroids, were treated successfully with vincristine (2 patients) or intravenous immunoglobulin (1 patient). All patients remained off steroids without any complications for 11 to 23 months.