Discovery of mobocertinib, a potent, oral inhibitor of EGFR exon 20 insertion mutations in non-small cell lung cancer.

In the treatment of non-small cell lung cancer (NSCLC), patients harboring exon 20 insertion mutations in the epidermal growth factor receptor (EGFR) gene (EGFR) have few effective therapies because this subset of mutants is generally resistant to most currently approved EGFR inhibitors. This report describes the structure-guided design of a novel series of potent, irreversible inhibitors of EGFR exon 20 insertion mutations, including the V769_D770insASV and D770_N771insSVD mutants. Extensive structure-activity relationship (SAR) studies led to the discovery of mobocertinib (compound 21c), which inhibited growth of Ba/F3 cells expressing the ASV insertion with a half-maximal inhibitory concentration of 11 nM and with selectivity over wild-type EGFR.

Mobocertinib (TAK-788): A Targeted Inhibitor of Exon 20 Insertion Mutants in Non-Small Cell Lung Cancer.

Most exon 20 insertion (ex20ins) driver mutations in non-small cell lung cancer (NSCLC) are insensitive to approved EGFR tyrosine kinase inhibitors (TKI). To address the limitations of existing therapies targeting -mutated NSCLC, mobocertinib (TAK-788), a novel irreversible EGFR TKI, was specifically designed to potently inhibit oncogenic variants containing activating ex20ins mutations with selectivity over wild-type EGFR. The and activity of mobocertinib was evaluated in engineered and patient-derived models harboring diverse ex20ins mutations.

The Potent ALK Inhibitor Brigatinib (AP26113) Overcomes Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in Preclinical Models.

Purpose: Non-small cell lung cancers (NSCLCs) harboring ALK gene rearrangements (ALK) typically become resistant to the first-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI) crizotinib through development of secondary resistance mutations in ALK or disease progression in the brain. Mutations that confer resistance to second-generation ALK TKIs ceritinib and alectinib have also been identified. Here, we report the structure and first comprehensive preclinical evaluation of the next-generation ALK TKI brigatinib.

Discovery of Brigatinib (AP26113), a Phosphine Oxide-Containing, Potent, Orally Active Inhibitor of Anaplastic Lymphoma Kinase.

In the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC), secondary mutations within the ALK kinase domain have emerged as a major resistance mechanism to both first- and second-generation ALK inhibitors. This report describes the design and synthesis of a series of 2,4-diarylaminopyrimidine-based potent and selective ALK inhibitors culminating in identification of the investigational clinical candidate brigatinib. A unique structural feature of brigatinib is a phosphine oxide, an overlooked but novel hydrogen-bond acceptor that drives potency and selectivity in addition to favorable ADME properties.

Ponatinib inhibits polyclonal drug-resistant KIT oncoproteins and shows therapeutic potential in heavily pretreated gastrointestinal stromal tumor (GIST) patients.

Purpose: KIT is the major oncogenic driver of gastrointestinal stromal tumors (GIST). Imatinib, sunitinib, and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistance mutations in KIT, with those located in the activation (A) loop (exons 17/18) being particularly problematic. Here, we explore the KIT-inhibitory activity of ponatinib in preclinical models and describe initial characterization of its activity in patients with GIST.

Crizotinib-resistant mutants of EML4-ALK identified through an accelerated mutagenesis screen.

Activating gene rearrangements of anaplastic lymphoma kinase (ALK) have been identified as driver mutations in non-small-cell lung cancer, inflammatory myofibroblastic tumors, and other cancers. Crizotinib, a dual MET/ALK inhibitor, has demonstrated promising clinical activity in patients with non-small-cell lung cancer and inflammatory myofibroblastic tumors harboring ALK translocations. Inhibitors of driver kinases often elicit kinase domain mutations that confer resistance, and such mutations have been successfully predicted using in vitro mutagenesis screens.

Discovery of 5-(arenethynyl) hetero-monocyclic derivatives as potent inhibitors of BCR-ABL including the T315I gatekeeper mutant.

Ponatinib (AP24534) was previously identified as a pan-BCR-ABL inhibitor that potently inhibits the T315I gatekeeper mutant, and has advanced into clinical development for the treatment of refractory or resistant CML. In this study, we explored a novel series of five and six membered monocycles as alternate hinge-binding templates to replace the 6,5-fused imidazopyridazine core of ponatinib. Like ponatinib, these monocycles are tethered to pendant toluanilides via an ethynyl linker.

Ridaforolimus (AP23573; MK-8669), a potent mTOR inhibitor, has broad antitumor activity and can be optimally administered using intermittent dosing regimens.

The mTOR pathway is hyperactivated through oncogenic transformation in many human malignancies. Ridaforolimus (AP23573; MK-8669) is a novel rapamycin analogue that selectively targets mTOR and is currently under clinical evaluation. In this study, we investigated the mechanistic basis for the antitumor activity of ridaforolimus in a range of human tumor types, exploring potential markers of response, and determining optimal dosing regimens to guide clinical studies.

Discovery of 3-[2-(imidazo[1,2-b]pyridazin-3-yl)ethynyl]-4-methyl-N-{4-[(4-methylpiperazin-1-yl)methyl]-3-(trifluoromethyl)phenyl}benzamide (AP24534), a potent, orally active pan-inhibitor of breakpoint cluster region-abelson (BCR-ABL) kinase including the T315I gatekeeper mutant.

In the treatment of chronic myeloid leukemia (CML) with BCR-ABL kinase inhibitors, the T315I gatekeeper mutant has emerged as resistant to all currently approved agents. This report describes the structure-guided design of a novel series of potent pan-inhibitors of BCR-ABL, including the T315I mutation. A key structural feature is the carbon-carbon triple bond linker which skirts the increased bulk of Ile315 side chain.

AP24534, a pan-BCR-ABL inhibitor for chronic myeloid leukemia, potently inhibits the T315I mutant and overcomes mutation-based resistance.

Inhibition of BCR-ABL by imatinib induces durable responses in many patients with chronic myeloid leukemia (CML), but resistance attributable to kinase domain mutations can lead to relapse and a switch to second-line therapy with nilotinib or dasatinib. Despite three approved therapeutic options, the cross-resistant BCR-ABL(T315I) mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges. We report design and preclinical evaluation of AP24534, a potent, orally available multitargeted kinase inhibitor active against T315I and other BCR-ABL mutants.

9-(Arenethenyl)purines as dual Src/Abl kinase inhibitors targeting the inactive conformation: design, synthesis, and biological evaluation.

A novel series of potent dual Src/Abl kinase inhibitors based on a 9-(arenethenyl)purine core has been identified. Unlike traditional dual Src/Abl inhibitors targeting the active enzyme conformation, these inhibitors bind to the inactive, DFG-out conformation of both kinases. Extensive SAR studies led to the discovery of potent and orally bioavailable inhibitors, some of which demonstrated in vivo efficacy.

Novel N9-arenethenyl purines as potent dual Src/Abl tyrosine kinase inhibitors.

Novel N(9)-arenethenyl purines, optimized potent dual Src/Abl tyrosine kinase inhibitors, are described. The key structural feature is a trans vinyl linkage at N(9) on the purine core which projects hydrophobic substituents into the selectivity pocket at the rear of the ATP site. Their synthesis was achieved through a Horner-Wadsworth-Emmons reaction of N(9)-phosphorylmethylpurines and substituted benzaldehydes or Heck reactions between 9-vinyl purines and aryl halides.

Alveolar macrophage cytokine response to air pollution particles: oxidant mechanisms.

Alveolar macrophages (AMs) primed with LPS and treated with concentrated ambient air particles (CAPs) showed enhanced release of tumor necrosis factor (TNF) and provide an in vitro model for the amplified effects of air pollution particles seen in people with preexisting lung disease. To investigate the mechanism(s) by which CAPs mediate TNF release in primed rat AMs, we first tested the effect of a panel of antioxidants. N-Acetyl-l-cysteine (20 mM), dimethyl thiourea (20 mM) and catalase (5 microM) significantly inhibited TNF release by primed AMs incubated with CAPs.

The macrophage scavenger receptor SR-AI/II and lung defense against pneumococci and particles.

The class A macrophage scavenger receptor SR-AI/II is implicated as a pattern recognition receptor for innate immunity, but its functional role in lung defense has not been studied. We used mice genetically deficient in SR-AI/II and their wild-type C57BL/6 counterparts to investigate the contribution of this receptor to defense against pneumococcal infection and inhaled particles. SR-AI/II deficiency caused impaired phagocytosis of fluorescent bacteria in vivo, diminished clearance of live bacteria from the lungs, and substantially increased pneumonic inflammation.

The scavenger receptor MARCO is required for lung defense against pneumococcal pneumonia and inhaled particles.

Alveolar macrophages (AMs) express the class A scavenger receptor macrophage receptor with collagenous structure (MARCO), but its role in vivo in lung defense against bacteria and environmental particles has not been studied. We used MARCO-deficient mice to directly test the in vivo role of AM MARCO in innate defense against pneumococcal infection and environmental particles. In a murine model of pneumococcal pneumonia, MARCO(-/-) mice displayed an impaired ability to clear bacteria from the lungs, increased pulmonary inflammation and cytokine release, and diminished survival.

Particle-epithelial interaction: effect of priming and bystander neutrophils on interleukin-8 release.

Exposure to ambient air pollution particles causes greater health effects in individuals with preexisting inflammatory lung diseases. To model inflammatory priming in vitro, HTB54 lung epithelial cells were pretreated with tumor necrosis factor-alpha (TNF-alpha) and then exposed to a panel of environmental particles, including concentrated ambient particles (CAPs). TNF-alpha priming significantly enhanced interleukin (IL)-8 secretion in response to CAPs and other urban air particles in HTB54 cells.

Combined air pollution particle and ozone exposure increases airway responsiveness in mice.

We investigated whether coexposure to inhaled ambient particles and ozone affects airway responsiveness (AR, measured as enhanced pause, Penh) and allergic inflammation (AI) in a murine model of asthma. Ovalbumin-sensitized mice were challenged with either ovalbumin ("asthmatic") or phosphate-buffered saline (PBS) aerosols for 3 successive days. Immediately after daily challenge, mice were exposed for 5 h to concentrated ambient particles (CAPs), or 0.