Discovery of the Oxadiazine FRM-024: A Potent CNS-Penetrant Gamma Secretase Modulator.

The recent approval of aducanumab for Alzheimer's disease has heightened the interest in therapies targeting the amyloid hypothesis. Our research has focused on identification of novel compounds to improve amyloid processing by modulating gamma secretase activity, thereby addressing a significant biological deficit known to plague the familial form of the disease. Herein, we describe the design, synthesis, and optimization of new gamma secretase modulators (GSMs) based on previously reported oxadiazine 1. Potency improvements with a focus on predicted and measured properties afforded high-quality compounds further differentiated via robust Aß42 reductions in both rodents and nonhuman primates. Extensive preclinical profiling, efficacy studies, and safety studies resulted in the nomination of FRM-024, (+)-cis-5-(4-chlorophenyl)-6-cyclopropyl-3-(6-methoxy-5-(4-methyl-1H-imidazole-1-yl)pyridin-2-yl)-5,6-dihydro-4H-1,2,4-oxadiazine, as a GSM preclinical candidate for familial Alzheimer's disease.

LX2761, a Sodium/Glucose Cotransporter 1 Inhibitor Restricted to the Intestine, Improves Glycemic Control in Mice.

LX2761 is a potent sodium/glucose cotransporter 1 inhibitor restricted to the intestinal lumen after oral administration. Studies presented here evaluated the effect of orally administered LX2761 on glycemic control in preclinical models. In healthy mice and rats treated with LX2761, blood glucose excursions were lower and plasma total glucagon-like peptide-1 (GLP-1) levels higher after an oral glucose challenge; these decreased glucose excursions persisted even when the glucose challenge occurred 15 hours after LX2761 dosing in ad lib-fed mice. Further, treating mice with LX2761 and the dipeptidyl-peptidase 4 inhibitor sitagliptin synergistically increased active GLP-1 levels, suggesting increased LX2761-mediated release of GLP-1 into the portal circulation. LX2761 also lowered postprandial glucose, fasting glucose, and hemoglobin A1C, and increased plasma total GLP-1, during long-term treatment of mice with either early- or late-onset streptozotocin-diabetes; in the late-onset cohort, LX2761 treatment improved survival. Mice and rats treated with LX2761 occasionally had diarrhea; this dose-dependent side effect decreased in severity and frequency over time, and LX2761 doses were identified that decreased postprandial glucose excursions without causing diarrhea. Further, the frequency of LX2761-associated diarrhea was greatly decreased in mice either by gradual dose escalation or by pretreatment with resistant starch 4, which is slowly digested to glucose in the colon, a process that primes the colon for glucose metabolism by selecting for glucose-fermenting bacterial species. These data suggest that clinical trials are warranted to determine if LX2761 doses and dosing strategies exist that provide improved glycemic control combined with adequate gastrointestinal tolerability in people living with diabetes.

Design, Synthesis, and Evaluation of a Novel Series of Oxadiazine Gamma Secretase Modulators for Familial Alzheimer's Disease.

Herein we describe the design, synthesis, and evaluation of a novel series of oxadiazine-based gamma secretase modulators obtained via isosteric amide replacement and critical consideration of conformational restriction. Oxadiazine lead 47 possesses good in vitro potency with excellent predicted CNS drug-like properties and desirable ADME/PK profile. This lead compound demonstrated robust Aß42 reductions and subsequent Aß37 increases in both rodent brain and CSF at 30 mg/kg dosed orally.

Discovery of LX2761, a Sodium-Dependent Glucose Cotransporter 1 (SGLT1) Inhibitor Restricted to the Intestinal Lumen, for the Treatment of Diabetes.

The increasing number of people afflicted with diabetes throughout the world is a major health issue. Inhibitors of the sodium-dependent glucose cotransporters (SGLT) have appeared as viable therapeutics to control blood glucose levels in diabetic patents. Herein we report the discovery of LX2761, a locally acting SGLT1 inhibitor that is highly potent in vitro and delays intestinal glucose absorption in vivo to improve glycemic control.

Characterization of FRM-36143 as a new γ-secretase modulator for the potential treatment of familial Alzheimer's disease.

BACKGROUND: Familial Alzheimer's disease (FAD) is caused by mutations in the amyloid precursor protein (APP) or presenilin (PS). Most PS mutations, which account for the majority of FAD cases, lead to an increased ratio of longer to shorter forms of the amyloid beta (Aß) peptide. The therapeutic rationale of γ-secretase modulators (GSMs) for Alzheimer's disease is based on this genetic evidence as well as on enzyme kinetics measurements showing changes in the processivity of the γ-secretase complex. This analysis suggests that GSMs could potentially offset some of the effects of PS mutations on APP processing, thereby addressing the root cause of early onset FAD. Unfortunately, the field has generated few, if any, molecules with good central nervous system (CNS) drug-like properties to enable proof-of-mechanism studies. METHOD: We characterized the novel GSM FRM-36143 using multiple cellular assays to determine its in vitro potency and off-target activity as well as its potential to reverse the effect of PS mutations. We also tested its efficacy in vivo in wild-type mice and rats. RESULTS: FRM-36143 has much improved CNS drug-like properties compared to published GSMs. It has an in vitro EC50 for Aß42 of 35 nM in H4 cells, can reduce Aß42 to 58 % of the baseline in rat cerebrospinal fluid, and also increases the non-amyloidogenic peptides Aß37 and Aß38. It does not inhibit Notch processing, nor does it inhibit 24-dehydrocholesterol reductase (DHCR24) activity. Most interestingly, it can reverse the effects of presenilin mutations on APP processing in vitro. CONCLUSIONS: FRM-36143 possesses all the characteristics of a GSM in terms of Aß modulation Because FRM-36143 was able to reverse the effect of PS mutations, we suggest that targeting patients with this genetic defect would be the best approach at testing the efficacy of a GSM in the clinic. While the amyloid hypothesis is still being tested with ß-site APP-cleaving enzyme inhibitors and monoclonal antibodies in sporadic AD, we believe it is not a hypothesis for FAD. Since GSMs can correct the molecular defect caused by PS mutations, they have the promise to provide benefits to the patients when treated early enough in the course of the disease.

Gamma Secretase Modulators: New Alzheimer's Drugs on the Horizon?

The rapidly aging population desperately requires new therapies for Alzheimer's disease. Despite years of pharmaceutical research, limited clinical success has been realized, with several failed disease modification therapies in recent years. On the basis of compelling genetic evidence, the pharmaceutical industry has put a large emphasis on brain beta amyloid (Aß) either through its removal via antibodies or by targeting the proteases responsible for its production. In this Perspective, we focus on the development of small molecules that improve the activity of one such protease, gamma secretase, through an allosteric binding site to preferentially increase the concentration of the shorter non-amyloidogenic Aß species. After a few early failures due to poor drug-like properties, the industry is now on the cusp of delivering gamma secretase modulators for clinical proof-of-mechanism studies that combine potency and efficacy with improved drug-like properties such as lower cLogP, high central nervous system multiparameter optimization scores, and high sp(3) character.

Discovery and Development of LX7101, a Dual LIM-Kinase and ROCK Inhibitor for the Treatment of Glaucoma.

The structure of LX7101, a dual LIM-kinase and ROCK inhibitor for the treatment of ocular hypertension and associated glaucoma, is disclosed. Previously reported LIM kinase inhibitors suffered from poor aqueous stability due to solvolysis of the central urea. Replacement of the urea with a hindered amide resulted in aqueous stable compounds, and addition of solubilizing groups resulted in a set of compounds with good properties for topical dosing in the eye and good efficacy in a mouse model of ocular hypertension. LX7101 was selected as a clinical candidate from this group based on superior efficacy in lowering intraocular pressure and a good safety profile. LX7101 completed IND enabling studies and was tested in a Phase 1 clinical trial in glaucoma patients, where it showed efficacy in lowering intraocular pressure.

Novel class of LIM-kinase 2 inhibitors for the treatment of ocular hypertension and associated glaucoma.

The discovery of a pyrrolopyrimidine class of LIM-kinase 2 (LIMK2) inhibitors is reported. These LIMK2 inhibitors show good potency in enzymatic and cellular assays and good selectivity against ROCK. After topical dosing to the eye in a steroid induced mouse model of ocular hypertension, the compounds reduce intraocular pressure to baseline levels. The compounds also increase outflow facility in a pig eye perfusion assay. These results suggest LIMK2 may be an effective target for treating ocular hypertension and associated glaucoma.

Novel L-xylose derivatives as selective sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors for the treatment of type 2 diabetes.

The prevalence of diabetes throughout the world continues to increase and has become a major health issue. Recently there have been several reports of inhibitors directed toward the sodium-dependent glucose cotransporter 2 (SGLT2) as a method of maintaining glucose homeostasis in diabetic patients. Herein we report the discovery of the novel O-xyloside 7c that inhibits SGLT2 in vitro and urinary glucose reabsorption in vivo.

Unpredictable stereochemical preferences for mu opioid receptor activity in an exhaustively stereodiversified library of 1,4-enediols.

Using olefin cross-metathesis, we synthesized a novel stereodiversified library of compounds 3 containing a trans-1,4-enediol. Screening this library for mu opioid receptor (MOR) affinity identified multiple high-affinity ligands and revealed that the stereochemical configuration varied widely among those ligands having the highest affinity. It was not possible to predict the configurations of the most active compounds 3 on the basis of the configuration of endomorphin-2, a known MOR peptide ligand, validating the diversity-based approach to ligand discovery.

2,6-Dimethyltyrosine analogues of a stereodiversified ligand library: highly potent, selective, non-peptidic mu opioid receptor agonists.

We recently reported the use of an exhaustively stereodiversified library based on endomorphin-2 (1) to discover mu opioid receptor (MOR) ligands of type 2-4. Here, we report the synthesis and evaluation of 2,6-dimethyltyrosine analogues 5-10. These analogues showed improved affinity for MOR relative to 2-4. In the cases of 5 and 6, we synthesized and evaluated five stereoisomers of each, thereby discovering stereoisomers with unexpected potency, selectivity, and efficacy. These results illustrate the utility of acyclic, stereodiverse libraries.

High-affinity mu opioid receptor ligands discovered by the screening of an exhaustively stereodiversified library of 1,5-enediols.

In this communication, we report the synthesis of an exhaustively stereodiversified library of 16 1,5-enediols (2) and the screening of these compounds for mu opioid receptor (MOR) binding. The stereochemical configuration of 2 strongly impacted the binding affinity, and (S,S,S,R)-2 exhibited a Ki of 8.8 nM for MOR, comparable to that of endomorphin-2 (Ki = 1.2 nM). Moreover, compounds 2 exhibited 5-86-fold selectivity for MOR over delta opioid receptor (DOR) and 16-150-fold selectivity for MOR over kappa opioid receptor (KOR). Additionally, analogues of 2 were synthesized which showed the importance of the trans olefin for receptor binding but that modifications of the C-terminal amino acid were well tolerated. Ligand 11 is noteworthy because it retains only one of the amide bonds present in 1, but binds MOR with an affinity of 10 nM and 110- and 600-fold selectivity for MOR over DOR and KOR. These results demonstrate the utility of stereochemical diversity in the discovery of bioactive small molecules.