Pulsed-dosing with oral sodium phenylbutyrate increases hemoglobin F in a patient with sickle cell anemia

Gum Arabic as fetal hemoglobin inducing agent in sickle cell anemia; in vivo study

Background

High levels of fetal haemoglobin (HbF) decrease sickle cell anaemia (SCA) severity and leads to improved survival. According to in vivo and in vitro studies, butyrate increases HbF production. Its utilization in clinical practice is hampered, however, by its short half-life. Serum butyrate concentrations could be enhanced by colonic bacterial fermentation of Gum Arabic (GA), edible, dried, gummy exudates from Acacia Senegal tree. We hypothesized that regular intake of GA increases serum butyrate levels, thus inducing HbF production and ameliorating symptoms of sickle cell anemia.

Methods

Fourty seven patients (5–42 years) carrying hemoglobin SS were recruited from April 2014 to January 2015. Patients received 30 g/day GA for 12 weeks. HbF, blood count and erythropoietin level were measured. The main outcome of interest was the level of HbF after 12 weeks. The secondary outcomes were improvement in clinical and laboratory results. The study was ethically approved by Alneelain University IRB.

Results

The study revealed significant increase in HbF level P.V0.000 [95 % CI, 0.43–1.02], MCV P.V:000 [95 % CI, 2.312–6.058] and Hematocrit level P.V:0.026 [95 % CI, 0.124–1.902]. No significant difference was encountered in platelets count P.V: 0.346 [95 % CI,−25.76–71.94], and WBCs count P.V:0.194 [95 % CI,−8.035–1.68]. Thirty seven percent of patients experienced minor side effects which resolved within a week.

Conclusion

These findings reveal a novel effect of GA, which may be used to foster fetal hemoglobin production.

Trial registration

ClinicalTrials.gov Identifier: NCT02467257. Registered 3rd June 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s12878-015-0040-6) contains supplementary material, which is available to authorized users.

The LSD1 inhibitor RN-1 induces fetal hemoglobin synthesis and reduces disease pathology in sickle cell mice

Inhibition of lysine-specific demethylase 1 (LSD1) has been shown to induce fetal hemoglobin (HbF) levels in cultured human erythroid cells in vitro. Here we report the in vivo effects of LSD1 inactivation by a selective and more potent inhibitor, RN-1, in a sickle cell disease (SCD) mouse model. Compared with untreated animals, RN-1 administration leads to induced HbF synthesis and to increased frequencies of HbF-positive cells and mature erythrocytes, as well as fewer reticulocytes and sickle cells, in the peripheral blood of treated SCD mice. In keeping with these observations, histologic analyses of the liver and spleen of treated SCD mice verified that they do not exhibit the necrotic lesions that are usually associated with SCD. These data indicate that RN-1 can effectively induce HbF levels in red blood cells and reduce disease pathology in SCD mice, and may therefore offer new therapeutic possibilities for treating SCD.

A dose-escalation phase IIa study of 2,2-dimethylbutyrate (HQK-1001), an oral fetal globin inducer, in sickle cell disease

2,2-Dimethylbutyrate (HQK-1001), an orally-bioavailable promoter-targeted fetal globin gene-inducing agent, was evaluated in an open-label, randomized dose-escalation study in 52 subjects with hemoglobin SS or S/β(0) thalassemia. HQK-1001 was administered daily for 26 weeks at 30 mg/kg (n = 15), 40 mg/kg (n = 18) and 50 mg/kg (n = 19), either alone (n = 21) or with hydroxyurea (n = 31). The most common drug-related adverse events were usually mild or moderate and reversible. Gastritis was graded as severe in three subjects at 40 mg/kg and was considered the dose-limiting toxicity. Subsequently all subjects were switched to the maximum tolerated dose of 30 mg/kg. Due to early discontinuations for blood transfusions, adverse events or non-compliance, only 25 subjects (48%) completed the study. Drug plasma concentrations were sustained above targeted levels at 30 mg/kg. Increases in fetal hemoglobin (Hb F) were observed in 42 subjects (80%), and 12 (23%) had increases ≥4%. The mean increase in Hb F was 2% [95% confidence interval (CI), 0.8-3.2%] in 21 subjects receiving HQK-1001 alone and 2.7% (95% CI, 1.7-3.8%) in 31 subjects receiving HQK-1001 plus hydroxyurea. Total hemoglobin increased by a mean of 0.65 g/dL (95% CI, 0.5-1.0 g/dL), and 13 subjects (25%) had increases ≥1 g/dL. Future studies are warranted to evaluate the therapeutic potential of HQK-1001 in sickle cell disease. .

Current management of sickle cell anemia

Proper management of sickle cell anemia (SCA) begins with establishing the correct diagnosis early in life, ideally during the newborn period. The identification of affected infants by neonatal screening programs allows early initiation of prophylactic penicillin and pneumococcal immunizations, which help prevent overwhelming sepsis. Ongoing education of families promotes the early recognition of disease-released complications, which allows prompt and appropriate medical evaluation and therapeutic intervention. Periodic evaluation by trained specialists helps provide comprehensive care, including transcranial Doppler examinations to identify children at risk for primary stroke, plus assessments for other parenchymal organ damage as patients become teens and adults. Treatment approaches that previously highlighted acute vaso-occlusive events are now evolving to the concept of preventive therapy. Liberalized use of blood transfusions and early consideration of hydroxyurea treatment represent a new treatment paradigm for SCA management.

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profiles. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using (11)CO2 and the appropriate Grignard reagents. [(11)C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity were the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low (<0.006%ID/cc, BA>VPA>PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [(11)C]BA showed relatively high uptake in spleen and pancreas whereas [(11)C]PBA showed high uptake in liver and heart. Notably, [(11)C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects.

Histone deacetylase inhibitors for treating a spectrum of diseases not related to cancer

This issue of Molecular Medicine contains 14 original research reports and state-of-the-art reviews on histone deacetylase inhibitors (HDACi's), which are being studied in models of a broad range of diseases not related to the proapoptotic properties used to treat cancer. The spectrum of these diseases responsive to HDACi's is for the most part due to several antiinflammatory properties, often observed in vitro but importantly also in animal models. One unifying property is a reduction in cytokine production as well as inhibition of cytokine postreceptor signaling. Distinct from their use in cancer, the reduction in inflammation by HDACi's is consistently observed at low concentrations compared with the higher concentrations required for killing tumor cells. This characteristic makes HDACi's attractive candidates for treating chronic diseases, since low doses are well tolerated. For example, low oral doses of the HDACi givinostat have been used in children to reduce arthritis and are well tolerated. In addition to the antiinflammatory properties, HDACi's have shown promise in models of neurodegenerative disorders, and HDACi's also hold promise to drive HIV-1 out of latently infected cells. No one molecular mechanism accounts for the non-cancer-related properties of HDACi's, since there are 18 genes coding for histone deacetylases. Rather, there are mechanisms unique for the pathological process of specific cell types. In this overview, we summarize the preclinical data on HDACi's for therapy in a wide spectrum of diseases unrelated to the treatment of cancer. The data suggest the use of HDACi's in treating autoimmune as well as chronic inflammatory diseases.

The chemical chaperone 4-phenylbutyrate inhibits adipogenesis by modulating the unfolded protein response

Recent studies have shown a link between obesity and endoplasmic reticulum (ER) stress. Perturbations in ER homeostasis cause ER stress and activation of the unfolded protein response (UPR). Adipocyte differentiation contributes to weight gain, and we have shown that markers of ER stress/UPR activation, including GRP78, phospho-eIF2, and spliced XBP1, are upregulated during adipogenesis. Given these findings, the objective of this study was to determine whether attenuation of UPR activation by the chemical chaperone 4-phenylbutyrate (4-PBA) inhibits adipogenesis. Exposure of 3T3-L1 preadipocytes to 4-PBA in the presence of differentiation media decreased expression of ER stress markers. Concomitant with the suppression of UPR activation, 4-PBA resulted in attenuation of adipogenesis as measured by lipid accumulation and adiponectin secretion. Consistent with these in vitro findings, female C57BL/6 mice fed a high-fat diet supplemented with 4-PBA showed a significant reduction in weight gain and had reduced fat pad mass, as compared with the high-fat diet alone group. Furthermore, 4-PBA supplementation decreased GRP78 expression in the adipose tissue and lowered plasma triglyceride, glucose, leptin, and adiponectin levels without altering food intake. Taken together, these results suggest that UPR activation contributes to adipogenesis and that blocking its activation with 4-PBA prevents adipocyte differentiation and weight gain in mice.

Pharmacotherapy in sickle cell disease--state of the art and future prospects

In the last decade, the care of patients with sickle cell disease (SCD) has undergone important advances with better understanding of disease pathophysiology and improvement in standards of care, especially among paediatric patients. Although many new drugs are currently being investigated and are at different stages of development, the pace of drug discovery and utilization has been slow and suboptimal. Hydroxycarbamide (hydroxyurea) has been investigated and utilized for at least two decades. Hydroxycarbamide's efficacy has been demonstrated, albeit with different levels of evidence, in paediatric and adult populations, and yet clinician and patient acceptance and use have been far from ideal. In this review we discuss the current usage of hydroxycarbamide and its possible future indications in SCD, as well as the use of new compounds that have very different mechanisms of action, which may prove safe and efficacious when used alone or in combination in patients with SCD.

Novel therapies in sickle cell disease

Despite an increased understanding of the pathophysiology of sickle cell disease (SCD), there remains a paucity of available agents for the prevention and treatment of specific SCD-related complications. Recently, there has been significant progress in the development of novel drugs for this disease. These agents, which increase the production of fetal hemoglobin, improve red blood cell hydration, increase the availability of nitric oxide and possess anti-inflammatory effects, are in varying stages of clinical development. With the complex pathophysiology of SCD, it is unlikely that a single agent will prevent or treat all the sequelae of this disease. As a result, patients may benefit from treatment with a combination of agents that possess different mechanisms of action. This overview discusses selected novel agents that appear promising in SCD.

Novel therapies in sickle cell disease

Despite an increased understanding of the pathophysiology of sickle cell disease (SCD), there remains a paucity of available agents for the prevention and treatment of specific SCD-related complications. Recently, there has been significant progress in the development of novel drugs for this disease. These agents, which increase the production of fetal hemoglobin, improve red blood cell hydration, increase the availability of nitric oxide and possess anti-inflammatory effects, are in varying stages of clinical development. With the complex pathophysiology of SCD, it is unlikely that a single agent will prevent or treat all the sequelae of this disease. As a result, patients may benefit from treatment with a combination of agents that possess different mechanisms of action. This overview discusses selected novel agents that appear promising in SCD.

Haemoglobin F modulation in childhood sickle cell disease

While supportive care remains the best option for most well children with sickle cell disease (SCD), increasing awareness of early signs of chronic organ damage in childhood has focused attention on therapy which modulates the natural history of the disease. Since cure by stem cell transplantation is only feasible for a minority and gene therapy remains developmental, pharmacological modification by Haemoglobin F (HbF)-inducers, is the most widely used approach in SCD. Currently, the only HbF modulator with a clear place in the management of childhood SCD is hydroxycarbamide for which the main indications are frequent painful crises and recurrent acute chest syndrome. In the majority of SCD children treated with hydroxycarbamide there is clear evidence of clinical benefit and the drug is well tolerated. The main disadvantages are the need for frequent monitoring and uncertainity about long-term risks of carcinogenicity and impaired fertility, although these risks appear to be very low. The role of hydroxycarbamide in sickle-associated central nervous system disease remains to be established. Decitabine and butyrate derivatives show some promise although robust data in children with SCD are lacking. A number of other drugs are currently under investigation for their effects on HbF production including thalidomide and lenolidamide.

Adeno-associated virus vector genomes persist as episomal chromatin in primate muscle

Recombinant adeno-associated virus (rAAV) vectors are capable of mediating long-term gene expression following administration to skeletal muscle. In rodent muscle, the vector genomes persist in the nucleus in concatemeric episomal forms. Here, we demonstrate with nonhuman primates that rAAV vectors integrate inefficiently into the chromosomes of myocytes and reside predominantly as episomal monomeric and concatemeric circles. The episomal rAAV genomes assimilate into chromatin with a typical nucleosomal pattern. The persistence of the vector genomes and gene expression for years in quiescent tissues suggests that a bona fide chromatin structure is important for episomal maintenance and transgene expression. These findings were obtained from primate muscles transduced with rAAV1 and rAAV8 vectors for up to 22 months after intramuscular delivery of 5 x 10(12) viral genomes/kg. Because of this unique context, our data, which provide important insight into in situ vector biology, are highly relevant from a clinical standpoint.