Hypoxia‐inducible factor stabilizers and other small‐molecule erythropoiesis‐stimulating agents in current and preventive doping analysis

Abstract

Increasing the blood's capacity for oxygen transport by erythropoiesis‐stimulating agents (ESAs) constitutes a prohibited procedure of performance enhancement according to the World Anti‐Doping Agency (WADA). The advent of orally bio‐available small‐molecule ESAs such as hypoxia‐inducible factor (HIF) stabilizers in the development of novel anti‐anaemia therapies expands the list of potential ESA doping techniques. Here, the erythropoiesis‐stimulating properties and doping relevance of experimental HIF‐stabilizers, such as cobaltous chloride, 3,4‐dihydroxybenzoic acid or GSK360A, amongst others, are discussed. The stage of clinical trials is reviewed for the anti‐anaemia drug candidates FG‐2216, FG‐4592, GSK1278863, AKB‐6548, and BAY85‐3934. Currently available methods and strategies for the determination of selected HIF stabilizers in sports drug testing are based on liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS). For the support of further analytical assay development, patents claiming distinct compounds for the use in HIF‐mediated therapies are evaluated and exemplary molecular structures of HIF stabilizers presented. Moreover, data concerning the erythropoiesis‐enhancing effects of the GATA inhibitors K7174 and K11706 as well as the lipidic small‐molecule ESA PBI‐1402 are elucidated the context of doping analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Maternal intestinal HIF-2α is necessary for sensing iron demands of lactation in mice

“…Therefore, alternative strategies aimed at increasing maternal dietary iron absorption will be highly beneficial in patients who are refractory to iron supplementation. The present work provides evidence that the PHD inhibitor FG-4592 that is currently under phase III clinical trial for treatment of anemia could effectively stabilize intestinal HIF-2α and improve milk iron levels and ameliorate neonatal anemia (43). In this work, for the first time to our knowledge we demonstrate a molecular mechanism in which maternal HIF-2α plays a central role in milk quality and neonatal iron homeostasis.…”

“…To test whether activation of HIF-2α by pharmacological intervention could improve milk iron, lactating mothers were treated with a HIF prolyl hydroxylase (PHD) inhibitor, FG-4592. Currently FG-4592 is under phase III clinical trial to treat anemia in patients with chronic renal failure (43). Whether FG-4592 could stabilize intestinal HIF signaling was assessed using highly sensitive HIF reporter mice.…”

Erythropoietin

“…Hypoxia-Inducible Factor Stabilizers α-Ketoglutarate competitors and Fe 2+ chelators inhibit the degradation of HIF-α proteins, because α-ketoglutarate and Fe 2+ are required for HIF-α prolyl-and asparaginyl-hydroxylation [15] . Such HIF-stabilizing substances promote the transcription of HIF-dependent genes even under normoxic conditions.…”

Prolyl hydroxylation by EglN2 destabilizes FOXO3a by blocking its interaction with the USP9x deubiquitinase

“…In particular, our work predicts that EglN2 inhibitors would promote the accumulation of FOXO3a and in turn down-regulate Cyclin D1, leading to impaired cancer cell proliferation. In this regard, it has already been established that EglN family members can be inhibited with drug-like small organic molecules in humans (Nwogu et al 2001;Ivan et al 2002;Fraisl et al 2009;Beuck et al 2012). It will be important to determine whether small molecule EglN2 inhibitors display anti-cancer activity either alone or when combined with other agents such as cytotoxics, Cdk4 inhibitors, or PI3K/AKT inhibitors.…”