Recombinant factor VIII Fc fusion protein for the prevention and treatment of bleeding in children with severe hemophilia A

BACKGROUND

Prophylactic factor replacement, which prevents hemarthroses and thereby reduces the musculoskeletal disease burden in children with hemophilia A, requires frequent intravenous infusions (three to four times weekly).

OBJECTIVE

Kids A-LONG was a phase 3 open-label study evaluating the safety, efficacy and pharmacokinetics of a longer-acting factor, recombinant factor VIII Fc fusion protein (rFVIIIFc), in previously treated children with severe hemophilia A (endogenous FVIII level of < 1 IU dL(-1) [< 1%]).

METHODS

The study enrolled 71 subjects. The starting rFVIIIFc regimen was twice-weekly prophylaxis (Day 1, 25 IU kg(-1) ; Day 4, 50 IU kg(-1) ); dose (≤ 80 IU kg(-1) ) and dosing interval (≥ 2 days) were adjusted as needed. A subset of subjects had sequential pharmacokinetic evaluations of FVIII and rFVIIIFc. The primary endpoint was development of inhibitors (neutralizing antibodies). Secondary endpoints included pharmacokinetics, annualized bleeding rate (ABR), and number of infusions required to control a bleed.

RESULTS

No subject developed an inhibitor to rFVIIIFc. Adverse events were typical of a pediatric hemophilic population. The rFVIIIFc half-life was prolonged relative to that of FVIII, consistent with observations in adults and adolescents. The median ABR was 1.96 overall, and 0.00 for spontaneous bleeds; 46.4% of subjects reported no bleeding episodes on study. Ninety-three per cent of bleeding episodes were controlled with one to two infusions. The median average weekly rFVIIIFc prophylactic dose was 88.11 IU kg(-1) . At study end, 62 of 69 subjects (90%) were infusing twice weekly. Among subjects who had been previously receiving FVIII prophylaxis, 74% reduced their dosing frequency with rFVIIIFc.

CONCLUSION

Twice-weekly infusions with rFVIIIFc were well tolerated and yielded low bleeding rates in children with severe hemophilia A.

Public health concerns about lung cancer: a case report

An illustrative clinical case is presented and important features are highlighted regarding public health concerns about risk factors for lung cancer, lung cancer in women, and lung cancer screening.

Effect of chest wall vibration on dyspnea during hypercapnia and exercise in chronic obstructive pulmonary disease

Vibration of chest wall inspiratory muscles during inspiration (in-phase) reduces breathlessness associated with hypercapnia and resistive loading in normal subjects and in patients with chronic obstructive pulmonary disease (COPD) at rest. To evaluate further the effect of chest wall vibration on breathlessness ("breathing discomfort") in patients, we studied 10 subjects 52 to 79 yr of age with severe dyspnea (mean FEV1, 0.75 L, 27% predicted). On a single day, we used two separate stimuli to produce mild to moderate breathlessness (BR): Protocol 1, steady-state hypercapnia; Protocol 2, exercise with a lower extremity ergometer. During each protocol, we applied in-phase chest wall vibration (CW) randomly alternating with one of two controls: deltoid vibration (DV) or no vibration (NV). During hypercapnia, CW significantly reduced BR (DV, 2.9 +/- 2.1; CW, 2.3 +/- 1.4; p < 0.05; NV, 3.3 +/- 2.1; CW, 2.6 +/- 2.0; p < 0.01) without significant changes in ventilation. During exercise, CW did not significantly alter BR relative to controls. These findings may be explained by the effect of vibration on the sense of respiratory effort and/or by improvement of the match between efferent motor commands and afferent information from the respiratory system. The lack of effect during exercise on BR suggests there may be a "therapeutic window" or range of conditions within which CW is effective in reducing dyspnea in patients with COPD.

Air trapping in the lungs during cardiopulmonary resuscitation in dogs. A mechanism for generating changes in intrathoracic pressure

To test the hypothesis that during cardiopulmonary resuscitation, chest compression with an unobstructed trachea raises and maintains intrathoracic pressure by collapsing airways and trapping air in the lung, we studied 11 dogs (20-32 kg). An inflatable vest compressed the thorax after induction of ventricular fibrillation. First, tracheal airflow was measured by a pneumotachometer during vest inflation and deflation in nine of the dogs. As expected, during the initial phase of vest inflation of cycles after ventilation, air moved out of the lungs, but then airflow stopped. After vest deflation, however, more air moved out of the lungs in eight of the nine dogs; this occurrence indicated that a portion of the inspired tidal volume was trapped during vest inflation. During cycles without prior ventilation, the amount of air expired by chest compression decreased, paradoxically, at higher peak vest pressure (p less than 0.002); this occurrence indicated that air was trapped at the higher vest pressures. The change in right atrial pressure was higher on cycles after ventilation than on cycles without prior ventilation (79 +/- 12 vs. 67 +/- 12 mm Hg [mean +/- SEM], p less than 0.005), and lung volume was higher on cycles after ventilation (p less than 0.001). Next, a 5-Fr micromanometer was advanced down the airway in eight of the dogs. With the tip of the micromanometer 5-8 cm distal to the carina, a zone of high pressure was noted in seven dogs; this high pressure suggested a zone of airway collapse distal to the carina.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute non-dilating obstructive renal failure in a patient with AIDS

A 30-year-old male who presented with acute renal failure was found to have acquired immunodeficiency syndrome (AIDS). Although sonography and computerized tomography did not show urinary tract dilatation, obstructive renal failure was demonstrated by retrograde pyelography. Relief of obstruction(s) due to encasement of the renal pelves and ureters with histiocytic lymphoma led to immediate return of normal renal function. Although the etiology of renal failure in this patient is highly unusual, the high incidence of lymphoma in patients with AIDS should make tumor-related renal disease a consideration in all such patients with renal dysfunction.