Evaluation of AMG 076, a potent and selective MCHR1 antagonist, in rodent and primate obesity models

Abstract

Melanin-concentrating hormone (MCH) regulates food intake through activation of the receptor, MCHR1. We have identified AMG 076 as an orally bioavailable potent and selective small molecule antagonist of MCHR1. In mouse models of obesity, AMG 076 caused a reduction in body weight gain in wild-type (MCHR1+/+) but not in knockout (MCHR1-/-) mice. The body weight reduction was associated with decreases in food intake and increases in energy expenditure. Importantly, we show that these MCHR1-dependent effects of AMG 076 were also reflected in improved metabolic phenotypes, increased glucose tolerance and insulin sensitivity. Preliminary data on effects of AMG 076 in obese cynomolgus monkeys are also presented.

Keywords: Antagonist; MCHR1; diabetes; obesity.

Figure 1

Binding affinity and functional antagonism of AMG 076 to MCHR1. (A) Binding affinity of AMG 076 to MCHR1 was determined by [¹²⁵I]-MCH displacement membrane-binding assay. The human MCHR1 membrane was prepared from HEK293 cells stably expressing human MCHR1 (HEK293-MCHR1). Unlabeled MCH was included as a reference. (B) Functional antagonism was determined by FLIPR Ca²⁺ mobilization assay. MCH at EC₅₀ (12 nmol/L) was used to stimulate Ca²⁺ response in the presence of AMG 076 at the concentrations as indicated. RFU, relative fluorescence unit.

Figure 2

AMG 076 reduced body weight gain in male and female mice fed a high-fat diet. (A) Body weight. (B) Food intake. AMG 076 (3, 10, and 100 mg kg⁻¹ day⁻¹) was prepared as an admixture high-fat diet and administered ad libitum to C57BL/6 mice with wide-type (WT) MCHR1(+/+) or inactivated (KO) allele of MCHR1 (MCHR1(−/−)). Doses are indicated in mg kg⁻¹ day⁻¹. Responses are indicated as mean ± SEM of n = 7–9 mice per group. *P < 0.05 versus Vehicle (WT). #P < 0.05 versus Vehicle (WT); NS, not significant versus Vehicle (KO).

Figure 3

AMG 076 increased oxygen consumption in mice. Energy expenditure in a sample population of AMG 076-treated C57BL/6 female mice from the study in Fig. 2 was measured as described in Materials and Methods. AMG 076 and sibutramine were suspended in vehicle and administered by oral gavage (5–10 mL/kg) at the doses indicated, once daily approximately 90–120 min prior to initiation of the dark cycle (6 pm to 6 am). Doses are indicated in mg kg⁻¹ day⁻¹. Responses (after 20 weeks of dosing) are indicated as mean ± SEM of n = 8 mice per group. *P < 0.05 versus vehicle WT. #P < 0.05 versus vehicle WT. Values indicate percent change from respective vehicle genotype controls.

Figure 4

AMG 076 inhibited weight gain and food intake in DIO mice. Pair-housed, high-fat diet-induced obese (DIO) male C57BL/6 mice were maintained on a high-fat diet for 20–24 weeks prior to AMG 076 dosing. Test compounds were administered once daily by bolus oral gavage (5–10 mL/kg) at the indicated doses and body weight (A) and food intake (B) were monitored daily. (A) Sibutramine, P < 0.05 versus vehicle between day 2–34 and day 47–80. AMG 076 (3 mg/kg), P < 0.05 versus vehicle between day 7–144. AMG 076 (10 mg/kg), P < 0.05 between day 3–144. (B) *P < 0.05 versus vehicle. Values indicate percent change from Vehicle. Responses are indicated as mean ± SEM, n = 10 mice per group.

Figure 5

AMG 076 reduced fasted glucose and insulin levels and insulin levels in response to a glucose challenge. (A) Insulin levels. (B) Glucose levels. On day 130 of compound treatment the DIO male C57BL/6 mice were challenged with an oral glucose bolus (0.75 g/10 mL/kg) after an overnight fast. Blood was sampled from the tails of conscious mice. Responses are indicated as mean ± SEM, n = 6–8 mice per group. Values indicate percentage change from vehicle. Test material doses are indicated in mg kg⁻¹ day⁻¹. *P < 0.05 versus vehicle. AUC, area under the concentration curve over time course as indicated; Sibut, sibutramine.

Figure 6

AMG 076 increased the glucose-lowering response to a bolus of insulin. On day 95 of compound treatment the DIO male C57BL/6 mice were fasted for 4 h and then challenged with insulin (1.5 U/10 mL/kg) intraperitoneally. Blood was sampled at time points post insulin injection as indicated. (A) Whole blood glucose concentrations. (B) Areas under the whole blood glucose concentration curves (Glucose AUC). Responses are indicated as mean ± SEM, n = 6–8 mice per group. Test material doses are indicated in mg kg⁻¹ day⁻¹. Sibut, sibutramine. *P < 0.05 versus vehicle.

Figure 7

Effect of AMG 076 on body weight in obese cynomolgus monkeys. Spontaneously obese male cynomolgus monkeys received twice daily oral gavage of either vehicle or AMG 076 for 90 days. Body weight and BMI were measured weekly, food intake daily, intra-abdominal fat before and after the treatment. (A) Body weight and BMI are indicated as the mean ± SEM. *P < 0.05 versus vehicle; #P < 0.05 versus vehicle. (B) Intra-abdominal fat. ♢Vehicle treatment group; AMG 076 treatment groups: ■0.3 mg/kg, ▲1 mg/kg, ●3 mg/kg. (C) Daily chow intake. The percent change relative to pretreatment values calculated from individual measurements, n = 6 monkeys per group.