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Bispecific degraders (PROTACs) of ERα are expected to be advantageous over current inhibitors of ERα signaling (aromatase inhibitors/SERMs/SERDs) used to treat ER+ breast cancer. Information from DNA-encoded chemical library (DECL) screening provides a method to identify novel PROTAC binding features as the linker positioning, and binding elements are determined directly from the screen. After screening ∼120 billion DNA-encoded molecules with ERα WT and 3 gain-of-function (GOF) mutants, with and without estradiol to identify features that enrich ERα competitively, the off-DNA synthesized small molecule exemplar 7 exhibited nanomolar ERα binding, antagonism, and degradation. Click chemistry synthesis on an alkyne E3 ligase engagers panel and an azide variant of 7 rapidly generated bispecific nanomolar degraders of ERα, with PROTACs 18 and 21 inhibiting ER+ MCF7 tumor growth in a mouse xenograft model of breast cancer. This study validates this approach toward identifying novel bispecific degrader leads from DECL screening with minimal optimization.

Mer is a member of the TAM (Tyro3, Axl, Mer) kinase family that has been associated with cancer progression, metastasis, and drug resistance. Their essential function in immune homeostasis has prompted an interest in their role as modulators of antitumor immune response in the tumor microenvironment. Here we illustrate the outcomes of an extensive lead-generation campaign for identification of Mer inhibitors, focusing on the results from concurrent, orthogonal high-throughput screening approaches. Data mining, HT (high-throughput), and DECL (DNA-encoded chemical library) screens offered means to evaluate large numbers of compounds. We discuss campaign strategy and screening outcomes, and exemplify series resulting from prioritization of hits that were identified. Concurrent execution of HT and DECL screening successfully yielded a large number of potent, selective, and novel starting points, covering a range of selectivity profiles across the TAM family members and modes of kinase binding, and offered excellent start points for lead development.

The sirtuins SIRT1, SIRT2, and SIRT3 are NAD(+) dependent deacetylases that are considered potential targets for metabolic, inflammatory, oncologic, and neurodegenerative disorders. Encoded library technology (ELT) was used to affinity screen a 1.2 million heterocycle enriched library of DNA encoded small molecules, which identified pan-inhibitors of SIRT1/2/3 with nanomolar potency (e.g., 11c: IC50 = 3.6, 2.7, and 4.0 nM for SIRT1, SIRT2, and SIRT3, respectively). Subsequent SAR studies to improve physiochemical properties identified the potent drug like analogues 28 and 31. Crystallographic studies of 11c, 28, and 31 bound in the SIRT3 active site revealed that the common carboxamide binds in the nicotinamide C-pocket and the aliphatic portions of the inhibitors extend through the substrate channel, explaining the observable SAR. These pan SIRT1/2/3 inhibitors, representing a novel chemotype, are significantly more potent than currently available inhibitors, which makes them valuable tools for sirtuin research.

SIRT1 is an NAD+-dependent protein deacetylase that appears to produce beneficial effects on metabolic parameters such as glucose and insulin homeostasis. Activation of SIRT1 by resveratrol (1) has been shown to modulate insulin resistance, increase mitochondrial content and prolong survival in lower organisms and in mice on a high fat diet. Herein, we describe the identification and SAR of a series of oxazolo[4,5-b]pyridines as novel small molecule activators of SIRT1 which are structurally unrelated to and more potent than resveratrol.

A series of imidazo[1,2-b]thiazole derivatives is shown to activate the NAD(+)-dependent deacetylase SIRT1, a potential new therapeutic target to treat various metabolic disorders. This series of compounds was derived from a high throughput screening hit bearing an oxazolopyridine core. Water-solubilizing groups could be installed conveniently at either the C-2 or C-3 position of the imidazo[1,2-b]thiazole ring. The SIRT1 enzyme activity could be adjusted by modifying the amide portion of these imidazo[1,2-b]thiazole derivatives. The most potent analogue within this series, namely, compound 29, has demonstrated oral antidiabetic activity in the ob/ob mouse model, the diet-induced obesity (DIO) mouse model, and the Zucker fa/fa rat model.

Calorie restriction extends lifespan and produces a metabolic profile desirable for treating diseases of ageing such as type 2 diabetes1,2. SIRT1, an NAD+-dependent deacetylase, is a principal modulator of pathways downstream of calorie restriction that produce beneficial effects on glucose homeostasis and insulin sensitivity3–9. Resveratrol, a polyphenolic SIRT1 activator, mimics the anti-ageing effects of calorie restriction in lower organisms and in mice fed a high-fat diet ameliorates insulin resistance, increases mitochondrial content, and prolongs survival10–14. Here we describe the identification and characterization of small molecule activators of SIRT1 that are structurally unrelated to, and 1,000-fold more potent than, resveratrol. These compounds bind to the SIRT1 enzyme—peptide substrate complex at an allosteric site amino-terminal to the catalytic domain and lower the Michaelis constant for acetylated substrates. In diet-induced obese and genetically obese mice, these compounds improve insulin sensitivity, lower plasma glucose, and increase mitochondrial capacity. In Zucker fa/fa rats, hyperinsulinaemic-euglycaemic clamp studies demonstrate that SIRT1 activators improve whole-body glucose homeostasis and insulin sensitivity in adipose tissue, skeletal muscle and liver. Thus, SIRT1 activation is a promising new therapeutic approach for treating diseases of ageing such as type 2 diabetes.

Template condensation between 2,6-dicarbonylpyridines and a tripodal tetramine tris(3-aminopropyl)amine in the presence of copper(II) or nickel(II) yielded macrocyclic complexes that contained a coordinated primary amine as an appended functional group. The derivatives of 2,6-diformylpyridine contained labile azomethine bonds susceptible to water or alcohol addition, and were isolated in the form of crystallographically characterized hemiaminals or O-ethyl hemiaminals. The nickel(II) hemiaminal complex produced a macrocyclic product upon reduction with sodium borohydride, and the structures of the two complexes had very similar ligand conformations. The derivatives of 2,6-diacetylpyridine formed stable Schiff-base macrocycles with rigid, nearly planar structures in which azomethine bonds were conjugated with the pyridine ring. The steric strain was relieved upon heating of the complexes in water–alcohol media. The products were determined by the coordination requirements of the metal ions: the copper(II) underwent a CN double bond shift, forming a more flexible five-coordinate macrocyclic complex, whereas the nickel(II) compound underwent a partial ring-opening hydrolysis, giving rise to a pseudo-octahedral six-coordinate species. The unusual isomerization of the copper(II) complex was accompanied by H/D exchange at CH-bonds, and was facilitated by alcohol addition. The mechanism of isomerization is similar to B6-catalyzed transamination reactions (D.E. Metzler, M. Ikawa and E.S. Snell. J. Am. Chem. Soc., 1954, 76, 648). The corresponding four-coordinate copper(II) complex lacking a pendant arm was more thermally stable than its five-coordinate counterpart, and underwent partial double-bond migration under harsh conditions (prolonged heating at reflux in water–ethanol mixtures at pH > 8.5).

Two nickel(II) complexes with deacylated unsaturated tetraaza macrocyclic cyclidene ligands were isolated and structurally characterized. Under acidic conditions, both acyl groups attached to the γ carbons in the precursor complex are cleaved off, yielding a symmetric dicationic complex (IIIc) which retains the usual saddle shaped conformation of the 16-membered cyclidene complexes. Under basic conditions, one acyl group remains attached to the cyclidene, while the other (deacylated) chelate ring becomes singly deprotonated. This asymmetric deacylation is observed for the first time in the family of cis-dimethyl cyclidenes. The presence of a deprotonated conjugated chelate ring in the 15-membered macrocycle (VIb) results in the overall planar shape of the molecule.