Ghrelin Signaling Via GOAT Inhibition in Alcohol Use Disorder

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Background and Objective: Acyl-ghrelin is a 28-amino acid peptide that stimulates appetite and food intake. It is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R1a). Preclinical studies suggest that acyl-ghrelin increases alcohol intake (Szulc, Mikolajczak et al. 2013, Cepko...

Background and Objective: Acyl-ghrelin is a 28-amino acid peptide that stimulates appetite and food intake. It is an endogenous ligand for the growth hormone secretagogue receptor (GHS-R1a). Preclinical studies suggest that acyl-ghrelin increases alcohol intake (Szulc, Mikolajczak et al. 2013, Cepko et al. 2014) and decreases in acyl-ghrelin and GHS-R1a function suppresses alcohol consumption (Kaur and Ryabinin 2010, Landgren et al. 2012, Bahi et al. 2013, Suchankova et al. 2013, Gomez and Ryabinin 2014, Suchankova, Engel et al. 2016 Furthermore, previous human studies indicate a positive correlation between endogenous ghrelin levels and alcohol craving and drinking (Addolorato, Capristo et al.2006). In clinical studies conducted by our group with individuals with AUD, intravenous (IV) acyl-ghrelin administration, versus placebo 1) increased alcohol craving during alcohol cue-exposure and 2) increased IV alcohol self-administration as well as decreased latency to first infusion of alcohol and 3) increased brain activation in the amygdala in anticipation of alcohol reward. Together, this preclinical and human data suggest that manipulating the ghrelin signal may be a novel and potentially effective pharmacological approach to treat individuals with alcohol use disorder. After the discoveries of GHS-R1a and acyl-ghrelin, a next step was identifying ghrelin O-acyltransferase (GOAT) the enzyme that catalyzes the conversion of des-acyl-ghrelin (DAG) to acyl-ghrelin via octanoylation. GOAT is thus the master switch for the ghrelin system , as acyl-ghrelin, not DAG, is biologically active at the GHSR-1a. GOAT s structure is highly conserved, is produced by endocrine cells in the stomach and is co-expressed with ghrelin. Therefore, GOAT is a promising target for manipulating the ghrelin system by altering the peripheral acyl-to-total ghrelin ratio (where total ghrelin = acyl-ghrelin + DAG). Recently, the ghrelin system has been investigated as a potential treatment target for AUDs. As such, an oral bioavailable GOAT inhibitor offers encouraging potential as a treatment for alcohol use disorder. GLWL-01 is an existing GOAT inhibitor for which GLWL Research Inc. has recently and successfully completed a first-in-human safety clinical trial. The goal of this protocol is to conduct a proof-of-concept human laboratory study to assess a potential early signal of efficacy of GLWL-01 in relation to alcohol-related outcomes. Study population: Males and females (N = 43) with alcohol use disorder. Study Design: A within-subject, counterbalanced, double-blind, placebo-controlled study. Participants will take GLWL-01 450 mg b.i.d. or matched placebo for a minimum of 4 days (Stage I). After a wash-out window, Stage II will take place during which the counterbalanced study drug will be administered for a minimum of 4 days. Primary outcome measure: The co-primary aims will be to determine whether: 1) the number of adverse events (AEs) experienced differ in the GLWL-01 condition, compared to placebo; and 2) GLWL-01, compared to placebo, reduces alcohol cue-elicited craving using a validated alcohol cue-reactivity procedure. Secondary outcome measures: The main secondary aim will be the effects of GLWL-01 on food choices using a virtual buffet experimental procedure. We will also monitor a wide range of behavioral measures including e.g., pain, anxiety, depression, alcohol craving and withdrawal, and smoking.

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