Discovery of BLU-945, a Reversible, Potent, and Wild-Type-Sparing Next-Generation EGFR Mutant Inhibitor for Treatment-Resistant Non-Small-Cell Lung Cancer.

While epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have changed the treatment landscape for EGFR mutant (L858R and ex19del)-driven non-small-cell lung cancer (NSCLC), most patients will eventually develop resistance to TKIs. In the case of first- and second-generation TKIs, up to 60% of patients will develop an EGFR T790M mutation, while third-generation irreversible TKIs, like osimertinib, lead to C797S as the primary on-target resistance mutation. The development of reversible inhibitors of these resistance mutants is often hampered by poor selectivity against wild-type EGFR, resulting in potentially dose-limiting toxicities and a sub-optimal profile for use in combinations. BLU-945 (compound 30) is a potent, reversible, wild-type-sparing inhibitor of EGFR+/T790M and EGFR+/T790M/C797S resistance mutants that maintains activity against the sensitizing mutations, especially L858R. Pre-clinical efficacy and safety studies supported progression of BLU-945 into clinical studies, and it is currently in phase 1/2 clinical trials for treatment-resistant EGFR-driven NSCLC.

The discovery of benzoxazine sulfonamide inhibitors of NaV1.7: Tools that bridge efficacy and target engagement.

The voltage-gated sodium channel NaV1.7 has received much attention from the scientific community due to compelling human genetic data linking gain- and loss-of-function mutations to pain phenotypes. Despite this genetic validation of NaV1.7 as a target for pain, high quality pharmacological tools facilitate further understanding of target biology, establishment of target coverage requirements and subsequent progression into the clinic. Within the sulfonamide class of inhibitors, reduced potency on rat NaV1.7 versus human NaV1.7 was observed, rendering in vivo rat pharmacology studies challenging. Herein, we report the discovery and optimization of novel benzoxazine sulfonamide inhibitors of human, rat and mouse NaV1.7 which enabled pharmacological assessment in traditional behavioral rodent models of pain and in turn, established a connection between formalin-induced pain and histamine-induced pruritus in mice. The latter represents a simple and efficient means of measuring target engagement.

Correction to "Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement".

[This corrects the article DOI: 10.1021/acsmedchemlett.6b00243.].

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency, Pharmacokinetics, and Metabolic Properties to Obtain Atropisomeric Quinolinone (AM-0466) that Affords Robust in Vivo Activity.

Because of its strong genetic validation, NaV1.7 has attracted significant interest as a target for the treatment of pain. We have previously reported on a number of structurally distinct bicyclic heteroarylsulfonamides as NaV1.7 inhibitors that demonstrate high levels of selectivity over other NaV isoforms. Herein, we report the discovery and optimization of a series of atropisomeric quinolinone sulfonamide inhibitors [ Bicyclic sulfonamide compounds as sodium channel inhibitors and their preparation . WO 2014201206, 2014 ] of NaV1.7, which demonstrate nanomolar inhibition of NaV1.7 and exhibit high levels of selectivity over other sodium channel isoforms. After optimization of metabolic and pharmacokinetic properties, including PXR activation, CYP2C9 inhibition, and CYP3A4 TDI, several compounds were advanced into in vivo target engagement and efficacy models. When tested in mice, compound 39 (AM-0466) demonstrated robust pharmacodynamic activity in a NaV1.7-dependent model of histamine-induced pruritus (itch) and additionally in a capsaicin-induced nociception model of pain without any confounding effect in open-field activity.

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics While Mitigating Metabolic Liabilities.

Several reports have recently emerged regarding the identification of heteroarylsulfonamides as NaV1.7 inhibitors that demonstrate high levels of selectivity over other NaV isoforms. The optimization of a series of internal NaV1.7 leads that address a number of metabolic liabilities including bioactivation, PXR activation, as well as CYP3A4 induction and inhibition led to the identification of potent and selective inhibitors that demonstrated favorable pharmacokinetic profiles and were devoid of the aforementioned liabilities. The key to achieving this within a series prone to transporter-mediated clearance was the identification of a small range of optimal cLogD values and the discovery of subtle PXR SAR that was not lipophilicity dependent. This enabled the identification of compound 20, which was advanced into a target engagement pharmacodynamic model where it exhibited robust reversal of histamine-induced scratching bouts in mice.

Sulfonamides as Selective NaV1.7 Inhibitors: Optimizing Potency and Pharmacokinetics to Enable in Vivo Target Engagement.

Human genetic evidence has identified the voltage-gated sodium channel NaV1.7 as an attractive target for the treatment of pain. We initially identified naphthalene sulfonamide 3 as a potent and selective inhibitor of NaV1.7. Optimization to reduce biliary clearance by balancing hydrophilicity and hydrophobicity (Log D) while maintaining NaV1.7 potency led to the identification of quinazoline 16 (AM-2099). Compound 16 demonstrated a favorable pharmacokinetic profile in rat and dog and demonstrated dose-dependent reduction of histamine-induced scratching bouts in a mouse behavioral model following oral dosing.

Development of 2-aminooxazoline 3-azaxanthenes as orally efficacious ß-secretase inhibitors for the potential treatment of Alzheimer's disease.

The ß-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) is one of the most hotly pursued targets for the treatment of Alzheimer's disease. We used a structure- and property-based drug design approach to identify 2-aminooxazoline 3-azaxanthenes as potent BACE1 inhibitors which significantly reduced CSF and brain Aß levels in a rat pharmacodynamic model. Compared to the initial lead 2, compound 28 exhibited reduced potential for QTc prolongation in a non-human primate cardiovascular safety model.

Lead optimization and modulation of hERG activity in a series of aminooxazoline xanthene ß-site amyloid precursor protein cleaving enzyme (BACE1) inhibitors.

The optimization of a series of aminooxazoline xanthene inhibitors of ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) is described. An early lead compound showed robust Aß lowering activity in a rat pharmacodynamic model, but advancement was precluded by a low therapeutic window to QTc prolongation in cardiovascular models consistent with in vitro activity on the hERG ion channel. While the introduction of polar groups was effective in reducing hERG binding affinity, this came at the expense of higher than desired Pgp-mediated efflux. A balance of low Pgp efflux and hERG activity was achieved by lowering the polar surface area of the P3 substituent while retaining polarity in the P2' side chain. The introduction of a fluorine in position 4 of the xanthene ring improved BACE1 potency (5-10-fold). The combination of these optimized fragments resulted in identification of compound 40, which showed robust Aß reduction in a rat pharmacodynamic model (78% Aß reduction in CSF at 10 mg/kg po) and also showed acceptable cardiovascular safety in vivo.

Inhibitors of ß-site amyloid precursor protein cleaving enzyme (BACE1): identification of (S)-7-(2-fluoropyridin-3-yl)-3-((3-methyloxetan-3-yl)ethynyl)-5'H-spiro[chromeno[2,3-b]pyridine-5,4'-oxazol]-2'-amine (AMG-8718).

We have previously shown that the aminooxazoline xanthene scaffold can generate potent and orally efficacious BACE1 inhibitors although certain of these compounds exhibited potential hERG liabilities. In this article, we describe 4-aza substitution on the xanthene core as a means to increase BACE1 potency while reducing hERG binding affinity. Further optimization of the P3 and P2' side chains resulted in the identification of 42 (AMG-8718), a compound with a balanced profile of BACE1 potency, hERG binding affinity, and Pgp recognition. This compound produced robust and sustained reductions of CSF and brain Aß levels in a rat pharmacodynamic model and exhibited significantly reduced potential for QTc elongation in a cardiovascular safety model.

Structure- and property-based design of aminooxazoline xanthenes as selective, orally efficacious, and CNS penetrable BACE inhibitors for the treatment of Alzheimer's disease.

A structure- and property-based drug design approach was employed to identify aminooxazoline xanthenes as potent and selective human ß-secretase inhibitors. These compounds exhibited good isolated enzyme, cell potency, and selectivity against the structurally related aspartyl protease cathepsin D. Our efforts resulted in the identification of a potent, orally bioavailable CNS penetrant compound that exhibited in vivo efficacy. A single oral dose of compound 11a resulted in a significant reduction of CNS Aß40 in naive rats.

Establishing the relationship between in vitro potency, pharmacokinetic, and pharmacodynamic parameters in a series of orally available, hydroxyethylamine-derived ß-secretase inhibitors.

Sequential proteolytic cleavage of the amyloid precursor protein (APP) by ß-site APP-cleaving enzyme 1 (BACE1) and the γ-secretase complex produces the amyloid-ß peptide (Aß), which is believed to play a critical role in the pathology of Alzheimer's disease (AD). The aspartyl protease BACE1 catalyzes the rate-limiting step in the production of Aß, and as such it is considered to be an important target for drug development in AD. The development of a BACE1 inhibitor therapeutic has proven to be difficult. The active site of BACE1 is relatively large. Consequently, to achieve sufficient potency, many BACE1 inhibitors have required unfavorable physicochemical properties such as high molecular weight and polar surface area that are detrimental to efficient passage across the blood-brain barrier. Using a rational drug design approach we have designed and developed a new series of hydroxyethylamine-based inhibitors of BACE1 capable of lowering Aß levels in the brains of rats after oral administration. Herein we describe the in vitro and in vivo characterization of two of these molecules and the overall relationship of compound properties [e.g., in vitro permeability, P-glycoprotein (P-gp) efflux, metabolic stability, and pharmacological potency] to the in vivo pharmacodynamic effect with more than 100 compounds across the chemical series. We demonstrate that high in vitro potency for BACE1 was not sufficient to provide central efficacy. A combination of potency, high permeability, low P-gp-mediated efflux, and low clearance was required for compounds to produce robust central Aß reduction after oral dosing.

Design and preparation of a potent series of hydroxyethylamine containing ß-secretase inhibitors that demonstrate robust reduction of central ß-amyloid.

A series of potent hydroxyethyl amine (HEA) derived inhibitors of ß-site APP cleaving enzyme (BACE1) was optimized to address suboptimal pharmacokinetics and poor CNS partitioning. This work identified a series of benzodioxolane analogues that possessed improved metabolic stability and increased oral bioavailability. Subsequent efforts focused on improving CNS exposure by limiting susceptibility to Pgp-mediated efflux and identified an inhibitor which demonstrated robust and sustained reduction of CNS ß-amyloid (Aß) in Sprague-Dawley rats following oral administration.

Design and synthesis of potent, orally efficacious hydroxyethylamine derived ß-site amyloid precursor protein cleaving enzyme (BACE1) inhibitors.

We have previously shown that hydroxyethylamines can be potent inhibitors of the BACE1 enzyme and that the generation of BACE1 inhibitors with CYP 3A4 inhibitory activities in this scaffold affords compounds (e.g., 1) with sufficient bioavailability and pharmacokinetic profiles to reduce central amyloid-ß peptide (Aß) levels in wild-type rats following oral dosing. In this article, we describe further modifications of the P1-phenyl ring of the hydroxyethylamine series to afford potent, dual BACE1/CYP 3A4 inhibitors which demonstrate improved penetration into the CNS. Several of these compounds caused robust reduction of Aß levels in rat CSF and brain following oral dosing, and compound 37 exhibited an improved cardiovascular safety profile relative to 1.

Efficient transamidation of primary carboxamides by in situ activation with N,N-dialkylformamide dimethyl acetals.

Two protocols for the transamidation of primary amides with primary and secondary amines, forming secondary and tertiary amides, respectively, are described. Both processes employ N,N-dialkylformamide dimethyl acetals for primary amide activation, producing N'-acyl-N,N-dialkylformamidines as intermediates, as widely documented in the literature. Although the latter intermediates react irreversibly with amines by amidinyl transfer, we show that in the presence of certain Lewis acid additives efficient acyl transfer occurs, providing new and useful methods for amide exchange. In one protocol for transamidation, the N'-acyl-N,N-dialkylformamidine intermediates are purified by flash-column chromatography and the purified intermediates are then treated with an amine (typically, 2.5 equiv) in the presence of scandium triflate (10 mol %) in ether to form in high yields the products of transamidation. In a second procedure, N'-acyl-N,N-dialkylformamidines are generated in situ and, without isolation, are subjected to transamidation in the presence of zirconium chloride (0.5 equiv) and an amine (typically 2 equiv). A variety of different primary amides and amines are found to undergo efficient transamidation using the methods described.

Stereoselective synthesis of the octahydronaphthalene unit of integramycin via an intramolecular Diels-Alder reaction.

[reaction: see text] The racemic cis-decalin core fragment 30 of integramycin was synthesized by a sequence involving a highly diastereoselective intramolecular Diels-Alder reaction of triene 24. A remarkable switch in stereoselectivity occurred upon changing the dienophile unit of 24 from (Z)- to (E)-geometry.

Total synthesis of cochleamycin A.

[reaction: see text] Cochleamycin A (1) was synthesized in 2.4% overall yield via a 23-step linear sequence starting from 3-butene-1-ol. Key features of the synthesis include the synthesis of (Z)-1,3-diene 21 via a Stille coupling of 4 and 5 and a transannular Diels-Alder reaction of macrocycle 26 to provide the complete carbon skeleton of 1.

Probing the Lewis acid-catalyzed intramolecular Diels-Alder cyclizations of allylic alkoxy-substituted (Z)-1,3-dienes.

[reaction: see text] The Lewis acid-promoted Diels-Alder reaction of (E,Z,E)-trienal 1 provides not only the expected cis-fused cycloadduct 16 but also the trans-fused products 17 and 18. Trans-fused cycloadducts 17 and 18 are also products of the Lewis acid-promoted cyclization of (E,Z,E)-trienyl acetal 2. These products presumably derive from a stepwise cyclization pathway.

Structure activity studies of a novel cytotoxic benzodiazepine.

Analogues of Bz-423, a pro-apoptotic 1,4-benzodiazepine with potent activity in animal models of systemic lupus erythematosus and rheumatoid arthritis, have been designed, synthesized, and evaluated in cell-culture assays. The results of these experiments have defined the structural elements of this new cytotoxic agent required for activity.