Short-chain fatty acid derivatives induce fetal globin expression and erythropoiesis in vivo

Abstract

Orally bioactive compounds that induce ␥ globin gene expression at tolerable doses are needed for optimal treatment of the ␤-hemoglobinopathies. Short-chain fatty acids (SCFAs) of 2 to 6 carbons in length induce ␥ globin expression in animal models, and butyrate, phenylbutyrate, and valproate induce ␥ globin in human patients. The usefulness of these compounds, however, is limited by requirements for large doses because of their rapid metabolism and their tendency to inhibit cell proliferation, which limits the pool of erythroid progenitors in which ␥ globin can be induced. Selected shortchain fatty acid derivatives (SCFADs) were recently found to induce ␥ globin and to stimulate the proliferation of hematopoietic cells in vitro. These SCFADs are now evaluated in vivo in nonanemic transgenic mice containing the human ␤ globin gene locus and in anemic phlebotomized baboons. In mice treated with a SCFAD once daily for 5 days, ␥ globin mRNA increased 2-fold, reticulocytes increased 3-to 7-fold, and hematocrit levels increased by 27%. Administration of 3 SCFADs in anemic baboons increased F-reticulocytes 2-to 15-fold over baseline and increased total hemoglobin levels by 1 to 2 g/dL per week despite ongoing significant daily phlebotomy. Pharmacokinetic studies demonstrated 90% oral bioavailability of 2 SCFADs, and targeted plasma levels were maintained for several hours after single oral doses equivalent to 10% to 20% of doses required for butyrate. These findings identify SCFADs that stimulate ␥ globin gene expression and erythropoiesis in vivo, activities that are synergistically beneficial for treatment of the ␤ hemoglobinopathies and useful for the oral treatment of other anemias. (Blood. 2002;100:4640-4648)

Short-term Toxicity Study of ST-20 (NSC-741804) by Oral Gavage in Sprague-Dawley Rats

“…To stimulate fetal globin expression, short chain fatty acids (SCFADs) have been used in many experimental therapeutics such as reporter gene assays, transgenic murine, and nonhuman primate models; and in clinical trials (Pace et al 2002;Steinberg and Rodgers 2001;Perrine 2005;Perrine et al 1993;Collins et al 1995;Ikuta et al 1998;Dover, Brusilow, and Charache 1994;Boosalis et al 2001;Vadolas et al 2004;Atweh, Sutton, and Nassif 1999). Sodium phenylbutyrate and arginine butyrate increase total hemoglobin in beta thalassemia patients (Perrine et al 1993;Collins et al 1995;Ikuta et al 1998;Atweh, Sutton, and Nassif 1999;Perrine et al 2005).…”

“…These dual beneficial effects of ST-20, enhanced erythroid survival and fetal globin gene induction, are likely to be of potential benefit in the treatment of beta thalassemia. In addition, ST-20 has also shown a favorable PK profile after oral administration to baboons (Pace et al 2002) and was chosen for further preclinical development. A toxicity study was conducted for safety evaluation of ST-20 in rat following once-daily gavage administration for up to 15 days.…”

Liquid chromatography–mass spectrometric assay for quantitation of the short-chain fatty acid, 2,2-dimethylbutyrate (NSC 741804), in rat plasma

“…One approach to treating these diseases is reactivating expression of developmentally silenced fetal globin genes, which can functionally substitute for deficient β-globin in β-thalassemia and inhibit sickling in the sickle syndromes [2][3][4][5][6][7]. Short-chain fatty acids, such as butyric acid, stimulate fetal globin gene expression in experimental models, including patients' cultured cells, transgenic mice, and baboons [8][9][10][11][12][13][14][15][16]. In clinical trials, short-chain fatty acids have induced fetal hemoglobin and improved total hemoglobin levels, thereby demonstrating proofof-concept of such an approach to the treatment of hemoglobinopathies [17][18][19][20][21][22].…”

“…Short-chain fatty acids, such as butyric acid, stimulate fetal globin gene expression in experimental models, including patients' cultured cells, transgenic mice, and baboons [8][9][10][11][12][13][14][15][16]. In clinical trials, short-chain fatty acids have induced fetal hemoglobin and improved total hemoglobin levels, thereby demonstrating proofof-concept of such an approach to the treatment of hemoglobinopathies [17][18][19][20][21][22]. However, short-chain fatty acids are: 1)rapidly metabolized, necessitating prolonged intravenous infusions or large oral doses; and 2) exhibit unwanted anti-proliferative effects on erythroid cells [22].…”

“…Development of an orally active, short-chain fatty acid with more favorable pharmacologic properties would be a major advance in the treatment of hemoglobinopathies. 2,2-Dimethylbutyrate (DMB) has such favorable properties; it stimulates fetal globin production, prolongs erythroid cell survival, lacks antiproliferative properties and increases cell proliferation by altering the balance of Bcl-family proteins [14][15][16]. Because preliminary studies have suggested that DMB has favorable pharmacokinetic properties, such as a longer half-life, and an acceptable safety profile [14][15][16], it has been selected for clinical development.…”