The sodium-phosphate cotransporter NPT2a plays a key role in the reabsorption of filtered phosphate in proximal renal tubules, thereby critically contributing to phosphate homeostasis. Inadequate ...urinary phosphate excretion can lead to severe hyperphosphatemia as in tumoral calcinosis and chronic kidney disease (CKD). Pharmacological inhibition of NPT2a may therefore represent an attractive approach for treating hyperphosphatemic conditions. The NPT2a-selective small-molecule inhibitor PF-06869206 was previously shown to reduce phosphate uptake in human proximal tubular cells in vitro. Here, we investigated the acute and chronic effects of the inhibitor in rodents and report that administration of PF-06869206 was well tolerated and elicited a dose-dependent increase in fractional phosphate excretion. This phosphaturic effect lowered plasma phosphate levels in WT mice and in rats with CKD due to subtotal nephrectomy. PF-06869206 had no effect on Npt2a-null mice, but promoted phosphate excretion and reduced phosphate levels in normophophatemic mice lacking Npt2c and in hyperphosphatemic mice lacking Fgf23 or Galnt3. In CKD rats, once-daily administration of PF-06869206 for 8 weeks induced an unabated acute phosphaturic and hypophosphatemic effect, but had no statistically significant effect on FGF23 or PTH levels. Selective pharmacological inhibition of NPT2a thus holds promise as a therapeutic option for genetic and acquired hyperphosphatemic disorders.
Branched chain amino acid (BCAA) catabolic impairments have been implicated in several diseases. Branched chain ketoacid dehydrogenase (BCKDH) controls the rate limiting step in BCAA degradation, the ...activity of which is inhibited by BCKDH kinase (BDK)-mediated phosphorylation. Screening efforts to discover BDK inhibitors led to identification of thiophene PF-07208254, which improved cardiometabolic endpoints in mice. Structure-activity relationship studies led to identification of a thiazole series of BDK inhibitors; however, these inhibitors did not improve metabolism in mice upon chronic administration. While the thiophenes demonstrated sustained branched chain ketoacid (BCKA) lowering and reduced BDK protein levels, the thiazoles increased BCKAs and BDK protein levels. Thiazoles increased BDK proximity to BCKDH-E2, whereas thiophenes reduced BDK proximity to BCKDH-E2, which may promote BDK degradation. Thus, we describe two BDK inhibitor series that possess differing attributes regarding BDK degradation or stabilization and provide a mechanistic understanding of the desirable features of an effective BDK inhibitor.
Glucagon receptor antagonists (GCGRAs) have been an area of ongoing research in the pharmaceutical industry for more than two decades. Blocking the action of the glucagon peptide leads to repression ...of hepatic glucose production and reduced blood glucose. Small molecule GCGRAs continue to be pursued as a potential new treatment for diabetes.
The current review summarizes small molecule GCGRA patents and patent applications that first appeared during 2011 - 2014. The search term 'glucagon receptor' was used to find patents of the desired type.
Several companies have brought forward GCGRAs into human clinical trials with the most advanced to date being in Phase II. This field is mature and the number of patents has been decreasing in the last few years.
Glucokinase (GK) is a key regulator of glucose homeostasis, and development of small molecule activators of this enzyme represents a promising new approach for the treatment of type 2 diabetes ...mellitus.
This manuscript reviews small molecule patent disclosures between late 2011 and February 2014 for both GK activators (GKAs) and GK-glucokinase regulatory protein (GK-GKRP) disruptors. The review is organized by company and structural class.
The field of GKA research continues to progress, driven by research across many organizations. To date, > 20 candidates have entered clinical development with the most advanced in Phase II trials. Despite promising efficacy, a significant number of early candidates have been discontinued for various reasons including increased risk of hypoglycemia and lack of durability. Recent work in the field has focused on liver-selective activators, which have shown lower hypoglycemia risk, including the development of novel GK-GKRP disruptors that act to indirectly increase hepatic GK activity.
Branched chain amino acid (BCAA) catabolic defects are implicated to be causal determinates of multiple diseases. This work aimed to better understand how enhancing BCAA catabolism affected metabolic ...homeostasis as well as the mechanisms underlying these improvements.
The rate limiting step of BCAA catabolism is the irreversible decarboxylation by the branched chain ketoacid dehydrogenase (BCKDH) enzyme complex, which is post-translationally controlled through phosphorylation by BCKDH kinase (BDK). This study utilized BT2, a small molecule allosteric inhibitor of BDK, in multiple mouse models of metabolic dysfunction and NAFLD including the high fat diet (HFD) model with acute and chronic treatment paradigms, the choline deficient and methionine minimal high fat diet (CDAHFD) model, and the low-density lipoprotein receptor null mouse model (Ldlr−/−). shRNA was additionally used to knock down BDK in liver to elucidate liver-specific effects of BDK inhibition in HFD-fed mice.
A rapid improvement in insulin sensitivity was observed in HFD-fed and lean mice after BT2 treatment. Resistance to steatosis was assessed in HFD-fed mice, CDAHFD-fed mice, and Ldlr−/− mice. In all cases, BT2 treatment reduced steatosis and/or inflammation. Fasting and refeeding demonstrated a lack of response to feeding-induced changes in plasma metabolites including insulin and beta-hydroxybutyrate and hepatic gene changes in BT2-treated mice. Mechanistically, BT2 treatment acutely altered the expression of genes involved in fatty acid oxidation and lipogenesis in liver, and upstream regulator analysis suggested that BT2 treatment activated PPARα. However, BT2 did not directly activate PPARα in vitro. Conversely, shRNA-AAV-mediated knockdown of BDK specifically in liver in vivo did not demonstrate any effects on glycemia, steatosis, or PPARα-mediated gene expression in mice.
These data suggest that BT2 treatment acutely improves metabolism and liver steatosis in multiple mouse models. While many molecular changes occur in liver in BT2-treated mice, these changes were not observed in mice with AAV-mediated shRNA knockdown of BDK. All together, these data suggest that systemic BDK inhibition is required to improve metabolism and steatosis by prolonging a fasting signature in a paracrine manner. Therefore, BCAA may act as a “fed signal” to promote nutrient storage and reduced systemic BCAA levels as shown in this study via BDK inhibition may act as a “fasting signal” to prolong the catabolic state.
•Treatment of DIO mice with BDK inhibitor BT2 rapidly improved insulin sensitivity.•BT2 treatment improved liver pathology in multiple models of NALFD/NASH.•Feeding-induced hepatic gene changes were ameliorated in BT2-treated DIO mice.•BT2 treatment may improve metabolism by activating PPARα in a paracrine manner.•Liver-specific BDK knockdown with AAV did not improve metabolism nor activate PPARα.
The mammalian mitochondrial branched-chain ketoacid dehydrogenase (BCKD) complex is a multienzyme complex involved in the catabolism of branched-chain amino acids. BCKD is regulated by the BCKD ...kinase, or BCKDK, which binds to the E2 subunit of BCKD, phosphorylates its E1 subunit, and inhibits enzymatic activity. Inhibition of the BCKD complex results in increased levels of branched-chain amino acids and branched-chain ketoacids, and this buildup has been associated with heart failure, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. To find BCKDK inhibitors for potential treatment of these diseases, we performed both NMR and virtual fragment screening and identified tetrazole-bearing fragments that bind BCKDK at multiple sites. Through structure-based virtual screening expanding from these fragments, the angiotensin receptor blocker class antihypertension drugs and angiotensin receptor blocker–like compounds were discovered to be potent BCKDK inhibitors, suggesting potential new avenues for heart failure treatment combining BCKDK inhibition and antihypertension.
Unbound tissue-to-plasma partition coefficients (Kpuu) were determined for 56 structurally diverse compounds in rats following intravenous infusion. Five tissues were included in the study: white ...adipose, brain, heart, liver, and skeletal muscle. The rank ordering of the median tissue Kpuu values was: liver (4.5) > heart (1.8) > adipose (1.2) > skeletal muscle (0.6) > brain (0.05), with liver being most enriched and brain most impaired. The median Kpuu values of acids and zwitterions were lower than those of bases and neutrals in all tissues but liver. Selective tissue distribution was observed, dependent upon chemotype, which demonstrated the feasibility of targeting or restricting drug exposure in certain tissues through rational design. Physicochemical attributes for Kpuu were identified using recursive partitioning, which further classified compounds with enriched or impaired tissue distribution. The attributes identified provided valuable insight on design principles for asymmetric tissue distribution to improve efficacy or reduce toxicity.
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•Compounds demonstrate unique tissue distributions depending on structural characteristics.•It is feasible to achieve asymmetric tissue distribution through rational medicinal chemistry design.•Enriched tissue exposure has been observed for compounds in all ionization classes.•Transporters not only transport ionizable compounds, but also neutrals.•Liver is the most enriched tissue; brain, most impaired; and heart, most unimpaired.
Targeting drugs to the gastrointestinal tract has been and continues to be an active area of research. Gut-targeting is an effective means of increasing the local concentration of active substance at ...the desired site of action while minimizing concentrations elsewhere in the body that could lead to unwanted side-effects. Several approaches to intestinal targeting exist. Physicochemical property manipulation can drive molecules to large, polar, low absorption space or alternatively to lipophilic, high clearance space in order to minimize systemic exposure. Design of compounds that are substrates for transporters within the gastrointestinal tract, either uptake or efflux, or at the hepato-biliary interface, may help to increase intestinal concentration. Prodrug strategies have been shown to be effective particularly for colon targeting, and several different technology formulation approaches are currently being researched. This review provides examples of various approaches to intestinal targeting, and discusses challenges and areas in need of future scientific advances.
Diacylglycerol O-acyltransferase 2 (DGAT2) inhibitors have been shown to lower liver triglyceride content and are being explored clinically as a treatment for non-alcoholic steatohepatitis (NASH). ...This work details efforts to find an extended-half-life DGAT2 inhibitor. A basic moiety was added to a known inhibitor template, and the basicity and lipophilicity were fine-tuned by the addition of electrophilic fluorines. A weakly basic profile was required to find an appropriate balance of potency, clearance, and permeability. This work culminated in the discovery of PF-07202954 (12), a weakly basic DGAT2 inhibitor that has advanced to clinical studies. This molecule displays a higher volume of distribution and longer half-life in preclinical species, in keeping with its physicochemical profile, and lowers liver triglyceride content in a Western-diet-fed rat model.
Glucokinase is a key regulator of glucose homeostasis, and small molecule allosteric activators of this enzyme represent a promising opportunity for the treatment of type 2 diabetes. Systemically ...acting glucokinase activators (liver and pancreas) have been reported to be efficacious but in many cases present hypoglycaemia risk due to activation of the enzyme at low glucose levels in the pancreas, leading to inappropriately excessive insulin secretion. It was therefore postulated that a liver selective activator may offer effective glycemic control with reduced hypoglycemia risk. Herein, we report structure–activity studies on a carboxylic acid containing series of glucokinase activators with preferential activity in hepatocytes versus pancreatic β-cells. These activators were designed to have low passive permeability thereby minimizing distribution into extrahepatic tissues; concurrently, they were also optimized as substrates for active liver uptake via members of the organic anion transporting polypeptide (OATP) family. These studies lead to the identification of 19 as a potent glucokinase activator with a greater than 50-fold liver-to-pancreas ratio of tissue distribution in rodent and non-rodent species. In preclinical diabetic animals, 19 was found to robustly lower fasting and postprandial glucose with no hypoglycemia, leading to its selection as a clinical development candidate for treating type 2 diabetes.
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