The orally active melanocortin-4 receptor antagonist BL-6020/979: a promising candidate for the treatment of cancer cachexia.

BACKGROUND: Under physiological conditions, the melanocortin system is a crucial part of the complex network regulating food intake and energy expenditure. In pathological states, like cachexia, these two parameters are deregulated, i.e., food intake is decreased and energy expenditure is increased-a vicious combination leading to catabolism. Agouti-related protein (AgRP), the endogenous antagonist at the melanocortin-4 receptor (MC-4R), was found to increase food intake and to reduce energy expenditure. This qualifies MC-4R blockade as an attractive mode of action for the treatment of cachexia. Based on this rationale, a novel series of small-molecule MC-4R antagonists was designed, from which the orally active compound BL-6020/979 (formerly known as SNT207979) emerged as the first promising development candidate showing encouraging pre-clinical efficacy and safety properties which are presented here. METHODS AND RESULTS: BL-6020/979 is an orally available, selective and potent MC-4R antagonist with a drug-like profile. It increased food intake and decreased energy expenditure in healthy wild-type but not in MC-4R deficient mice. More importantly, it ameliorated cachexia-like symptoms in the murine C26 adenocarcinoma model; with an effect on body mass and body composition and on the expression of catabolic genes. Moreover, BL-6020/979 showed antidepressant-like properties in the chronic mild stress model in rats and exhibits a favorable safety profile. CONCLUSION: The properties of BL-6020/979 demonstrated in animal models and presented here make it a promising candidate suitable for further development towards a first-in-class treatment option for cachexia that potentially opens up the opportunity to treat two hallmarks of the disease, i.e., decreased food intake and increased energy expenditure, with one drug.

Synthesis and structure-activity relationship of N-arylrolipram derivatives as inhibitors of PDE4 isozymes.

Structure activity studies of N-phenylrolipram derivatives have led to the identification of highly potent PDE4 inhibitors. The potential of these inhibitors for cellular activity was routinely assessed in an assay of fMLP induced oxidative burst in human eosinophils. Since first generation PDE4 inhibitors have been plagued with a number of unwanted side effects, parallel structure activity studies for competition with the [3H]-rolipram binding site in rat brain were performed. In this fashion 5-[4-(3-cyclopentyloxy-4-methoxyphenyl)-2-oxo-pyrrolidin-1-yl]-3-(3-methoxybenzyloxy)benzoic acid N',N'-dimethylhydrazide (22) was identified as a potent inhibitor of PDE4 which exhibits >1000 fold selectivity versus PDE3, and is a nanomolar inhibitor in all the cellular assays tested. Studies on the stereoselectivity of PDE4 inhibition of this class of rolipram based compounds revealed, that for example (S)-11 is a more potent inhibitor than (R)-11. This effect can also be observed in primary human cells where the (S)-enantiomer is about 10 fold more potent than the corresponding (R)-enantiomer.

Palladium-catalyzed cross-coupling reactions for the synthesis of 6, 8-disubstituted 1,7-naphthyridines: a novel class of potent and selective phosphodiesterase type 4D inhibitors.

Recently, four subtypes of the human phosphodiesterase type 4 (PDE4A-D) enzyme have been described. So far, only very few PDE4 subtype-selective inhibitors are known. Herein, we describe the synthesis of 6,8-disubstituted 1,7-naphthyridines and their characterization as potent and selective inhibitors of PDE4D which suppress the oxidative burst in human eosinophils with IC(50) values as low as 0.7 nM. SAR development and the extended use of palladium-catalyzed cross-coupling reactions led to compound 11 which inhibited human PDE4D with an IC(50) value of 1 nM. Thus, compound 11 was 55, 175, and 1000 times more potent in inhibiting PDE4D over PDE4B, PDE4A, and PDE4C. In a Brown Norway rat model of allergic asthma, compound 11 when given by the oral route (1 mg/kg) reduced by more than 50% the influx of eosinophils, T-cells, and neutrophils into bronchoalveolar lavage fluid (BALF) samples obtained from antigen-challenged animals. Thus, PDE4D-selective inhibitors of the 1,7-naphthyridine class have the potential as an oral therapy for treating asthma.

N-arylrolipram derivatives as potent and selective PDE4 inhibitors.

Derivatization of rolipram led to the identification of 3-[4-(3-cyclopentyloxy-4-methoxyphenyl)-2-oxo-pyrrolidin-1-yl]-5-( 3- methoxybenzyloxy)-benzoic acid N',N'-dimethylhydrazide (4), a potent and selective inhibitor of PDE4, which inhibits the activation of human leukocytes with pIC50 values in the range of 7.3-7.8, and blocks antigen induced eosinophilia in Brown Norway rats at a dose of 1 mg/kg (i.t.).