Purified poloxamer 188 for treatment of acute vaso-occlusive crisis of sickle cell disease: A randomized controlled trial

CONTEXT

Sickle cell disease (SCD) can cause severe painful episodes that are often thought to be caused by vaso-occlusion. The current therapy for these uncomplicated painful episodes includes hydration, oxygen, and analgesics. Purified poloxamer 188 may increase tissue oxygenation and thereby reduce inflammation, pain, and the overall duration of such painful episodes in patients with SCD.

OBJECTIVE

To compare the duration of painful episodes in patients with SCD treated with purified poloxamer 188 to that of similar episodes experienced by patients who receive a placebo.

DESIGN AND SETTING

Randomized, double-blind, placebo-controlled, intention-to-treat trial conducted between March 1998 and October 1999 in 40 medical centers in the United States.

PARTICIPANTS

Two hundred fifty-five patients with SCD (aged 9-53 years) who had a painful episode sufficiently severe to require hospitalization and narcotic analgesics.

INTERVENTION

Patients were randomly assigned to receive an intravenous infusion of purified poloxamer 188, 100 mg/kg for 1 hour followed by 30 mg/kg per hour for 47 hours (n = 127), or a matching volume of saline placebo (n = 128).

MAIN OUTCOME MEASURE

Duration of the painful episode, from randomization to crisis resolution.

RESULTS

Mean (SD) duration of the painful episodes was 141 (42) hours in the placebo group compared with 133 (41) hours in those treated with purified poloxamer 188, a 9-hour reduction (P =.04). Subset analyses indicated an even more pronounced purified poloxamer 188 effect in children aged 15 years or younger (21 hours; P =.01) and in patients who were receiving hydroxyurea (16 hours; P =.02). Finally, the proportion of patients achieving crisis resolution was increased by purified poloxamer 188 (65/126 [52%] vs 45/123 [37%]; P =.02). Similar results were observed in children aged 15 years or younger (22/37 [60%] vs 10/36 [28%]; P =.009) and in patients who were also receiving hydroxyurea (12/26 [46%] vs 4/28 [14%]; P =.02).

CONCLUSIONS

A decrease in the duration of painful episodes and an increase in the proportion of patients who achieved resolution of the symptoms were observed when the purified poloxamer 188-treated patients were compared with the patients receiving placebo. However, the difference between these groups was significant but relatively small. In subgroup analysis, a more significant effect on both parameters was observed in children and in patients who were receiving concomitant hydroxyurea. It is important to confirm both of these observations in further prospective trials.

Effect of zinc supplementation on incidence of infections and hospital admissions in sickle cell disease (SCD)

Zinc deficiency is a common nutritional problem in adult sickle-cell disease (SCD) patients. Hyperzincuria and increased requirement of zinc due to continued hemolysis in SCD are probable bases for zinc deficiency in these patients. Zinc deficiency affects adversely T-helper1 (TH1) functions and cell mediated immunity and interleukin (IL)-2 production is decreased in zinc deficient subjects. We hypothesized that zinc supplementation will improve T-helper1 function and decrease incidence of infections in patients with SCD. We tested this hypothesis in 32 SCD subjects who were divided in three groups (Grs A, B, and C). Grs A (n = 11) and B (n = 10) were zinc deficient based on cellular zinc criteria and Gr C (n = 11) were zinc sufficient. Gr A subjects were observed for 1 year (baseline), following which they received zinc acetate (50 to 75 mg of elemental zinc orally daily) for 3 years. Gr B subjects were observed for 1 year (baseline), following which they received placebo for 1 year and then switched to zinc supplementation (50 to 75 mg of elemental zinc orally daily) for 2 years. Gr C subjects did not receive any intervention inasmuch as they were zinc sufficient. Prolonged zinc supplementation resulted in an increase in lymphocyte and granulocyte zinc (P = 0.0001), and an increase in interleukin-2 production (P = 0.0001), decreased incidence of documented bacteriologically positive infections (P = 0.0026), decreased number of hospitalizations and decreased number of vaso-occlusive pain crisis (P = 0.0001). The predominant pathogens isolated were staphylococci and streptococci involving the respiratory tract and aerobic gram-negative bacteria, particularly Escherichia coli, involving the urinary tract. Further confirmation of our observations will require prospective studies of zinc supplementation in a larger number of SCD patients.

High-performance liquid chromatographic method for determination of vanillin and vanillic acid in human plasma, red blood cells and urine

A simple high-performance liquid chromatographic method was developed for the determination of vanillin and its vanillic acid metabolite in human plasma, red blood cells and urine. The mobile phase consisted of aqueous acetic acid (1%, v/v)-acetonitrile (85:15, v/v), pH 2.9 and was used with an octadecylsilane analytical column and ultraviolet absorbance detection. The plasma method demonstrated linearity from 2 to 100 microg/ml and the urine method was linear from 2 to 40 microg/ml. The method had a detection limit of 1 microg/ml for vanillin and vanillic acid using 5 microl of prepared plasma, red blood cells or urine. The method was utilized in a study evaluating the pharmacokinetic and pharmacodynamic effects of vanillin in patients undergoing treatment for sickle cell anemia.

Serum concentrations of laminin P1 and aminoterminal propeptide of type III procollagen in sickle cell disease

We determined serum levels of laminin and aminoterminal propeptide of type III procollagen (PIIINP) in 20 patients with sickle cell hemoglobinopathies. Elevated levels of soluble laminin and PIIINP were observed in the patients--1.5 +/- 0.3 U/ml (mean +/- SD) (range 1.1-1.9 U/ml) and 0.90 +/- 0.2 U/ml (range 0.6-1.4 U/ml), respectively, compared to normal controls, 1.3 +/- 0.1 U/ml (range 1.2-1.4 U/ml) for laminin and 0.7 +/- 0.1 U/ml (range 0.6-0.9 U/ml) for PIIINP. The serum laminin and PIIINP were significantly elevated (p < 0.02 and p < 0.001, respectively, in patients with sickle cell hemoglobinopathies). There was no correlation between serum laminin and PIIINP levels in the patient group. The study indicates that aminoterminal propeptide of type III procollagen and laminin can be utilized as valuable non-invasive markers of possible alterations in extracellular matrix in bone marrow, spleen, kidney or other tissues in sickle cell hemoglobinopathies.

Type I collagen as a marker of bone metabolism in sickle cell hemoglobinopathies

Avascular necrosis of the skeletal system is a complication of sickle cell hemoglobinopathies. Type I collagen, which is synthesized by osteoblasts, comprises about 90% of the total organic matrix of bone. This preliminary study of skeletal changes in sickle cell hemoglobinopathies measured type I collagen formation and degradation using specific radioimmunoassays to determine the plasma concentrations of carboxyterminal propeptide of type I procollagen (PICP) and carboxyterminal pyridinoline cross-linked telopeptide of type I collagen (ICTP), respectively. Plasma ICTP concentrations were increased significantly in sickle cell patients with no clinical or radiologic symptoms of bone complications than in controls. Mean plasma ICTP concentration was moderately high in all patients. Plasma PICP levels did not differ significantly between patients and controls. This preliminary results indicate that measurements of plasma ICTP might be helpful in predicting bone changes in sickle cell hemoglobinopathies and also useful in the early detection of skeletal complications of the disease.

Effects of thymidine and hydroxyurea on the metabolism and cytotoxicity of 1-B-D arabinofuranosylcytosine in highly resistant human leukemia cells

We have examined the effect of the ribonucleotide reductase inhibitors thymidine (dThd) and hydroxyurea (HU) on the metabolism and cytotoxicity of high concentrations (10 to 100 mumol/L) of cytosine arabinoside (Ara-C) in a deoxycytidine kinase-deficient, highly Ara-C-resistant human promyelocytic leukemic cell subline (HL-60/Ara-C). Administration of dThd or HU (0.5 to 3 mmol/L) in conjunction with high concentrations of Ara-C either sequentially or simultaneously lead to enhanced (and in some cases a supra-additive) inhibition of HL-60/Ara-C suspension culture growth and soft agar colony formation. In addition, exposure of cells to 0.5 mmol/L dThd or HU for 48 hours significantly increased the percentage of HL-60/Ara-C in S-phase. In contrast to previous studies involving low-dose Ara-C administration, we were unable to detect dThd- or HU-mediated increments in Ara-CTP formation in HL-60/Ara-C cells treated with high-dose Ara-C despite reductions in intracellular dCTP pools as great as 65%. However, dThd or HU did increase Ara-C incorporation into newly synthesized DNA. These studies show that administration of dThd or HU in conjunction with high concentrations of Ara-C results in an enhanced antiproliferative effect of Ara-C against Ara-C-resistant leukemic cells deficient in deoxycytidine kinase.

Stopping the biologic clock for globin gene switching

The developmental switch from production of fetal (gamma) to adult (beta) globin occurs on a normally set biologic clock which proceeds even if expression of the adult (beta) globin genes is defective and produces little or no protein, as in the beta-thalassemias. Preventing or reversing the globin gene switch could provide a way of keeping the abnormal globin genes "silent" and maintaining expression of the fetal globin gene. We have identified a class of agents which, when present in elevated plasma concentrations during gestation, inhibits the gamma----beta-globin gene switch in developing humans. Further investigation has shown that butyric acid and related compounds can increase gamma-globin and decrease beta-globin expression in cultured erythroid cells of patients with beta-thalassemia. Butyrate compounds were therefore infused in an in vivo fetal animal model, and the globin switch was inhibited and even reversed in some fetal lambs. Histone hyperacetylation, which maintains active chromatin structure, and an effect on the gamma-globin promoter appear to be mechanisms of action involved. These data suggest that inhibiting expression of abnormal beta-globin genes by pharmacologic means may in the future be possible for treatment of individuals with beta-globin disorders.

Butyric acid modulates developmental globin gene switching in man and sheep

The developmental switch from production of fetal (gamma) to adult (beta) globin occurs on a normally set biologic clock which proceeds even if the adult (beta) globin genes are defective. Preventing or reversing the globin gene switch would be beneficial for subjects with abnormal beta globin genes. We have now identified a class of agents which, when present in elevated plasma concentrations during gestation, appears to inhibit the gamma beta globin gene switch in developing humans. Further investigation has shown that butyric acid and related compounds can increase gamma globin and decrease beta globin expression in erythroid cells cultured from subjects with diseases of abnormal beta globin. Butyrate compounds were therefore infused in an in vivo fetal animal model, and the globin switch was inhibited in most and reversed in some fetal lambs. These data suggest that inhibiting expression of abnormal beta globin genes may be possible in future generations. Histone modification may be a mechanism of action involved. The developmental switch from production of gamma globin to beta globin results in significant morbidity when the beta globin genes are defective. The globin switch has therefore been extensively studied, appearing to be set on a biologic clock and proceeding despite the site of blood production and solely on the basis of gestational age. We previously found that this developmental gene switch is delayed in human fetuses developing in the presence of maternal diabetes. A number of metabolites present in abnormal concentrations in these infants were therefore tested for effects on globin expression.(ABSTRACT TRUNCATED AT 250 WORDS)