Pyridones as Highly Selective, Noncovalent Inhibitors of T790M Double Mutants of EGFR

The rapid advancement of a series of noncovalent inhibitors of T790M mutants of EGFR is discussed. The optimization of pyridone <b>1</b>, a nonselective high-throughput screening hit, to potent molecules with high levels of selectivity over wtEGFR and the broader kinome is described herein

Discovery of a Noncovalent, Mutant-Selective Epidermal Growth Factor Receptor Inhibitor

Inhibitors targeting the activating mutants of the epidermal growth factor receptor (EGFR) have found success in the treatment of EGFR mutant positive non-small-cell lung cancer. A secondary point mutation (T790M) in the inhibitor binding site has been linked to the acquired resistance against those first generation therapeutics. Herein, we describe the lead optimization of a series of reversible, pan-mutant (L858R, del_746–750, T790M/L858R, and T790M/del_746–750) EGFR inhibitors. By use of a noncovalent double mutant (T790M/L858R and T790M/del_746–750) selective EGFR inhibitor (<b>2</b>) as a starting point, activities against the single mutants (L858R and del_746–750) were introduced through a series of structure-guided modifications. The in vitro ADME-PK properties of the lead molecules were further optimized through a number of rational structural changes. The resulting inhibitor (<b>21</b>) exhibited excellent cellular activity against both the single and double mutants of EGFR, demonstrating target engagement in vivo and ADME-PK properties that are suitable for further evaluation. The reversible, noncovalent inhibitors described complement the covalent pan-mutant EGFR inhibitors that have shown encouraging results in recent clinical trials

Noncovalent Mutant Selective Epidermal Growth Factor Receptor Inhibitors: A Lead Optimization Case Study

Because of their increased activity against activating mutants, first-generation epidermal growth factor receptor (EGFR) kinase inhibitors have had remarkable success in treating non-small-cell lung cancer (NSCLC) patients, but acquired resistance, through a secondary mutation of the gatekeeper residue, means that clinical responses only last for 8–14 months. Addressing this unmet medical need requires agents that can target both of the most common double mutants: T790M/L858R (TMLR) and T790M/del­(746-750) (TMdel). Herein we describe how a noncovalent double mutant selective lead compound was optimized using a strategy focused on the structure-guided increase in potency without added lipophilicity or reduction of three-dimensional character. Following successive rounds of design and synthesis it was discovered that cis-fluoro substitution on 4-hydroxy- and 4-methoxypiperidinyl groups provided synergistic, substantial, and specific potency gain through direct interaction with the enzyme and/or effects on the proximal ligand oxygen atom. Further development of the fluorohydroxypiperidine series resulted in the identification of a pair of diastereomers that showed 50-fold enzyme and cell based selectivity for T790M mutants over wild-type EGFR (wtEGFR) in vitro and pathway knock-down in an in vivo xenograft model

Mitigation of Acetylcholine Esterase Activity in the 1,7-Diazacarbazole Series of Inhibitors of Checkpoint Kinase 1

Checkpoint kinase 1 (ChK1) plays a key role in the DNA damage response, facilitating cell-cycle arrest to provide sufficient time for lesion repair. This leads to the hypothesis that inhibition of ChK1 might enhance the effectiveness of DNA-damaging therapies in the treatment of cancer. Lead compound <b>1</b> (GNE-783), the prototype of the 1,7-diazacarbazole class of ChK1 inhibitors, was found to be a highly potent inhibitor of acetylcholine esterase (AChE) and unsuitable for development. A campaign of analogue synthesis established SAR delineating ChK1 and AChE activities and allowing identification of new leads with improved profiles. In silico docking using a model of AChE permitted rationalization of the observed SAR. Compounds <b>19</b> (GNE-900) and <b>30</b> (GNE-145) were identified as selective, orally bioavailable ChK1 inhibitors offering excellent in vitro potency with significantly reduced AChE activity. In combination with gemcitabine, these compounds demonstrate an in vivo pharmacodynamic effect and are efficacious in a mouse p53 mutant xenograft model

Cell Active Hydroxylactam Inhibitors of Human Lactate Dehydrogenase with Oral Bioavailability in Mice

A series of trisubstituted hydroxylactams was identified as potent enzymatic and cellular inhibitors of human lactate dehydrogenase A. Utilizing structure-based design and physical property optimization, multiple inhibitors were discovered with <10 μM lactate IC₅₀ in a MiaPaca2 cell line. Optimization of the series led to <b>29</b>, a potent cell active molecule (MiaPaca2 IC₅₀ = 0.67 μM) that also possessed good exposure when dosed orally to mice

Discovery of a Potent and Selective in Vivo Probe (GNE-272) for the Bromodomains of CBP/EP300

The single bromodomain of the closely related transcriptional regulators CBP/EP300 is a target of much recent interest in cancer and immune system regulation. A co-crystal structure of a ligand-efficient screening hit and the CBP bromodomain guided initial design targeting the LPF shelf, ZA loop, and acetylated lysine binding regions. Structure–activity relationship studies allowed us to identify a more potent analogue. Optimization of permeability and microsomal stability and subsequent improvement of mouse hepatocyte stability afforded <b>59</b> (GNE-272, TR-FRET IC₅₀ = 0.02 μM, BRET IC₅₀ = 0.41 μM, BRD4(1) IC₅₀ = 13 μM) that retained the best balance of cell potency, selectivity, and in vivo PK. Compound <b>59</b> showed a marked antiproliferative effect in hematologic cancer cell lines and modulates <i>MYC</i> expression in vivo that corresponds with antitumor activity in an AML tumor model