Preclinical characterization of itacitinib (INCB039110), a novel selective inhibitor of JAK1, for the treatment of inflammatory diseases.

Pharmacological modulation of the Janus kinase (JAK) family has achieved clinically meaningful therapeutic outcomes for the treatment of inflammatory and hematopoietic diseases. Several JAK1 selective compounds are being investigated clinically to determine their anti-inflammatory potential. We used recombinant enzymes and primary human lymphocytes to assess the JAK1 specificity of itacitinib (INCB039110) and study inhibition of signal transducers and activators of transcription (STAT) signaling. Rodent models of arthritis and inflammatory bowel disease were subsequently explored to elucidate the efficacy of orally administered itacitinib on inflammatory pathogenesis. Itacitinib is a potent and selective JAK1 inhibitor when profiled against the other JAK family members. Upon oral administration in rodents, itacitinib achieved dose-dependent pharmacokinetic exposures that highly correlated with STAT3 pharmacodynamic pathway inhibition. Itacitinib ameliorated symptoms and pathology of established experimentally-induced arthritis in a dose-dependent manner. Furthermore, itacitinib effectively delayed disease onset, reduced symptom severity, and accelerated recovery in three distinct mouse models of inflammatory bowel disease. Low dose itacitinib administered via cannula directly into the colon was highly efficacious in TNBS-induced colitis but with minimal systemic drug exposure, suggesting localized JAK1 inhibition is sufficient for disease amelioration. Itacitinib treatment in an acute graft-versus-host disease (GvHD) model rapidly reduced inflammatory markers within lymphocytes and target tissue, resulting in a marked improvement in disease symptoms. This is the first manuscript describing itacitinib as a potent and selective JAK1 inhibitor with anti-inflammatory activity across multiple preclinical disease models. These data support the scientific rationale for ongoing clinical trials studying itacitinib in select GvHD patient populations.

INCB050465 (Parsaclisib), a Novel Next-Generation Inhibitor of Phosphoinositide 3-Kinase Delta (PI3Kδ).

A medicinal chemistry effort focused on identifying a structurally diverse candidate for phosphoinositide 3-kinase delta (PI3Kδ) led to the discovery of clinical candidate INCB050465 (20, parsaclisib). The unique structure of 20 contains a pyrazolopyrimidine hinge-binder in place of a purine motif that is present in other PI3Kδ inhibitors, such as idelalisib (1), duvelisib (2), and INCB040093 (3, dezapelisib). Parsaclisib (20) is a potent and highly selective inhibitor of PI3Kδ with drug-like ADME properties that exhibited an excellent in vivo profile as demonstrated through pharmacokinetic studies in rats, dogs, and monkeys and through pharmacodynamic and efficacy studies in a mouse Pfeiffer xenograft model.

The Novel Bromodomain and Extraterminal Domain Inhibitor INCB054329 Induces Vulnerabilities in Myeloma Cells That Inform Rational Combination Strategies.

PURPOSE: Bromodomain and extraterminal domain (BET) proteins regulate the expression of many cancer-associated genes and pathways; BET inhibitors have demonstrated activity in diverse models of hematologic and solid tumors. We report the preclinical characterization of INCB054329, a structurally distinct BET inhibitor that has been investigated in phase I clinical trials. EXPERIMENTAL DESIGN: We used multiple myeloma models to investigate vulnerabilities created by INCB054329 treatment that could inform rational combinations. RESULTS: In addition to c-MYC, INCB054329 decreased expression of oncogenes FGFR3 and NSD2/MMSET/WHSC1, which are deregulated in t(4;14)-rearranged cell lines. The profound suppression of FGFR3 sensitized the t(4;14)-positive cell line OPM-2 to combined treatment with a fibroblast growth factor receptor inhibitor in vivo. In addition, we show that BET inhibition across multiple myeloma cell lines resulted in suppressed interleukin (IL)-6 Janus kinase-signal transducers and activators of transcription (JAK-STAT) signaling. INCB054329 displaced binding of BRD4 to the promoter of IL6 receptor (IL6R) leading to reduced levels of IL6R and diminished signaling through STAT3. Combination with JAK inhibitors (ruxolitinib or itacitinib) further reduced JAK-STAT signaling and synergized to inhibit myeloma cell growth in vitro and in vivo. This combination potentiated tumor growth inhibition in vivo, even in the MM1.S model of myeloma that is not intrinsically sensitive to JAK inhibition alone. CONCLUSIONS: Preclinical data reveal insights into vulnerabilities created in myeloma cells by BET protein inhibition and potential strategies that can be leveraged in clinical studies to enhance the activity of INCB054329.

Preclinical characterization of INCB053914, a novel pan-PIM kinase inhibitor, alone and in combination with anticancer agents, in models of hematologic malignancies.

The Proviral Integration site of Moloney murine leukemia virus (PIM) serine/threonine protein kinases are overexpressed in many hematologic and solid tumor malignancies and play central roles in intracellular signaling networks important in tumorigenesis, including the Janus kinase-signal transducer and activator of transcription (JAK/STAT) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways. The three PIM kinase isozymes (PIM1, PIM2, and PIM3) share similar downstream substrates with other key oncogenic kinases and have differing but mutually compensatory functions across tumors. This supports the therapeutic potential of pan-PIM kinase inhibitors, especially in combination with other anticancer agents chosen based on their role in overlapping signaling networks. Reported here is a preclinical characterization of INCB053914, a novel, potent, and selective adenosine triphosphate-competitive pan-PIM kinase inhibitor. In vitro, INCB053914 inhibited proliferation and the phosphorylation of downstream substrates in cell lines from multiple hematologic malignancies. Effects were confirmed in primary bone marrow blasts from patients with acute myeloid leukemia treated ex vivo and in blood samples from patients receiving INCB053914 in an ongoing phase 1 dose-escalation study. In vivo, single-agent INCB053914 inhibited Bcl-2-associated death promoter protein phosphorylation and dose-dependently inhibited tumor growth in acute myeloid leukemia and multiple myeloma xenografts. Additive or synergistic inhibition of tumor growth was observed when INCB053914 was combined with selective PI3Kδ inhibition, selective JAK1 or JAK1/2 inhibition, or cytarabine. Based on these data, pan-PIM kinase inhibitors, including INCB053914, may have therapeutic utility in hematologic malignancies when combined with other inhibitors of oncogenic kinases or standard chemotherapeutics.

Identification and characterization of INCB9471, an allosteric noncompetitive small-molecule antagonist of C-C chemokine receptor 5 with potent inhibitory activity against monocyte migration and HIV-1 infection.

C-C chemokine receptor 5 (CCR5) is a clinically proven target for inhibition of HIV-1 infection and a potential target for various inflammatory diseases. In this article, we describe 5-[(4-{(3S)-4-[(1R,2R)-2-ethoxy-5-(trifluoromethyl)-2,3-dihydro-1H-inden-1-yl]-3-methylpiperazin-1-yl}-4-methylpiperidin-1-yl)carbonyl]-4,6-dimethylpyrimidine dihydrochloride (INCB9471), a potent and specific inhibitor of human CCR5 that has been proven to be safe and efficacious in viral load reduction in phase I and II human clinical trails. INCB9471 was identified using a primary human monocyte-based radioligand competition binding assay. It potently inhibited macrophage inflammatory protein-1ß-induced monocyte migration and infection of peripheral blood mononuclear cells by a panel of R5-HIV-1 strains. The results from binding and signaling studies using incremental amounts of INCB9471 demonstrated INCB9471 as a noncompetitive CCR5 inhibitor. The CCR5 residues that are essential for interaction with INCB9471 were identified by site-specific mutagenesis studies. INCB9471 rapidly associates with but slowly dissociates from CCR5. When INCB9471 was compared with three CCR5 antagonists that had been tested in clinical trials, the potency of INCB9471 in blocking CCR5 ligand binding was similar to those of 4,6-dimethyl-5-{[4-methyl-4-((3S)-3-methyl-4-{(1R0-2-(methyloxy)-1-[4-(trifluoromethyl) phenyl]ethyl}-1-piperazingyl)-1-piperidinyl]carbonyl}pyrimidine (SCH-D; vicriviroc), 4-{[4-({(3R)-1-butyl-3-[(R)-cyclohexyl(hydroxyl)methyl]-2, 5-dioxo-1,4,9-triazaspiro[5.5]undec-9-yl}methyl)phenyl]oxy}benzoic acid hydrochloride (873140; aplaviroc), and 4,4-difluoro-N-((1S)-3-{(3-endo)-3-[3-methyl-5-(1-methylethyl)-4H-1,2,4-triazol-4-yl]-8-azabicyclo[3.2.1]oct-8-yl}-1-phenylpropyl)cyclohexanecarboxamide (UK427857; maraviroc). Its inhibitory activity against CCR5-mediated Ca(2+) mobilization was also similar to those of SCH-D and 873140. Further analysis suggested that INCB9471 and UK427857 may have different binding sites on CCR5. The significance of two CCR5 antagonists with different binding sites is discussed in the context of potentially overcoming drug-resistant HIV-1 strains.

Design and synthesis of novel CCR2 antagonists: investigation of non-aryl/heteroaryl binding motifs.

This report describes the design and synthesis of a series of CCR2 antagonists incorporating novel non-aryl/heteroaryl RHS (right hand side) motifs. Previous SAR in the area has suggested an aryl/heteroaryl substituent as a necessary structural feature for binding to the CCR2 receptor. Herein we describe the SAR with regards to potency (binding to hCCR2), dofetilide activity and metabolic stability (in vitro HLM) for this series. The resulting outcome was the identification of compounds with excellent properties for the investigation of the role of CCR2 in disease.

Discovery of INCB10820/PF-4178903, a potent, selective, and orally bioavailable dual CCR2 and CCR5 antagonist.

We report the discovery of a potent, selective, and orally bioavailable dual CCR2 and CCR5 antagonist (3S,4S)-N-[(1R,3S)-3-isopropyl-3-({4-[4-(trifluoromethyl)pyridin-2-yl]piperazin-1-yl}carbonyl)cyclopentyl]-3-methoxytetrahydro-2H-pyran-4-amine (19). After evaluation in 28-day toxicology studies, compound 19 (INCB10820/PF-4178903) was selected as a clinical candidate.

Discovery of ((1S,3R)-1-isopropyl-3-((3S,4S)-3-methoxy-tetrahydro-2H-pyran-4-ylamino)cyclopentyl)(4-(5-(trifluoromethyl)pyridazin-3-yl)piperazin-1-yl)methanone, PF-4254196, a CCR2 antagonist with an improved cardiovascular profile.

We describe the systematic optimization, focused on the improvement of CV-TI, of a series of CCR2 antagonists. This work resulted in the identification of 10 (((1S,3R)-1-isopropyl-3-((3S,4S)-3-methoxy-tetrahydro-2H-pyran-4-ylamino)cyclopentyl)(4-(5-(trifluoromethyl)pyridazin-3-yl)piperazin-1-yl)methanone) which possessed a low projected human dose 35-45mg BID and a CV-TI=3800-fold.

Discovery of INCB8761/PF-4136309, a Potent, Selective, and Orally Bioavailable CCR2 Antagonist.

We report the discovery of a new (S)-3-aminopyrrolidine series of CCR2 antagonists. Structure-activity relationship studies on this new series led to the identification of 17 (INCB8761/PF-4136309) that exhibited potent CCR2 antagonistic activity, high selectivity, weak hERG activity, and an excellent in vitro and in vivo ADMET profile. INCB8761/PF-4136309 has entered human clinical trials.

Discovery of INCB3284, a Potent, Selective, and Orally Bioavailable hCCR2 Antagonist.

We report the identification of 13 (INCB3284) as a potent human CCR2 (hCCR2) antagonist. INCB3284 exhibited an IC50 of 3.7 nM in antagonism of monocyte chemoattractant protein-1 binding to hCCR2, an IC50 of 4.7 nM in antagonism of chemotaxis activity, an IC50 of 84 µM in inhibition of the hERG potassium current, a free fraction of 58% in protein binding, high selectivity over other chemokine receptors and G-protein-coupled receptors, and acceptable oral bioavailability in rodents and primates. In human clinical trials, INCB3284 exhibited a pharmacokinetic profile suitable for once-a-day dosing (T 1/2 = 15 h).

Discovery of INCB3344, a potent, selective and orally bioavailable antagonist of human and murine CCR2.

Rational design based on a pharmacophore of CCR2 antagonists reported in the literature identified lead compound 9a with potent inhibitory activity against human CCR2 (hCCR2) but moderate activity against murine CCR2 (mCCR2). Modification on 9a led to the discovery of a potent CCR2 antagonist 21 (INCB3344) with IC(50) values of 5.1 nM (hCCR2) and 9.5 nM (mCCR2) in binding antagonism and 3.8 nM (hCCR2) and 7.8 nM (mCCR2) in antagonism of chemotaxis activity. INCB3344 exhibited >100-fold selectivity over other homologous chemokine receptors, a free fraction of 24% in human serum and 15% in mouse serum, and an oral bioavailability of 47% in mice, suitable as a tool compound for target validation in rodent models.

Discovery of INCB9471, a Potent, Selective, and Orally Bioavailable CCR5 Antagonist with Potent Anti-HIV-1 Activity.

To identify a CCR5 antagonist as an HIV-1 entry inhibitor, we designed a novel series of indane derivatives based on conformational considerations. Modification on the indane ring led to the discovery of compound 22a (INCB9471) that exhibited high affinity for CCR5, potent anti-HIV-1 activity, high receptor selectivity, excellent oral bioavailability, and a tolerated safety profile. INCB9471 has entered human clinical trials.

Pharmacological characterization of INCB3344, a small molecule antagonist of human CCR2.

The chemokine receptor 2 (CCR2) directs migration of monocytes and has been proposed to be a drug target for chronic inflammatory diseases. INCB3344 was first published as a small molecule nanomolar inhibitor of rodent CCR2. Here, we show that INCB3344 can also bind human CCR2 (hCCR2) with high affinity, having a dissociation constant (K(d)) of approximately 5nM. The binding of the compound to the receptor is rapid and reversible. INCB3344 potently inhibits hCCR2 binding of monocyte chemoattractant protein-1 (MCP-1) and MCP-1-induced signaling and function in hCCR2-expressing cells, including ERK phosphorylation and chemotaxis, and is competitive against MCP-1 in vitro. INCB3344 also blocks MCP-1 binding to monocytes in human whole blood, with potency consistent with in vitro studies. The whole blood binding assay described here can be used for monitoring pharmacodynamic activity of CCR2 antagonists in both preclinical models and in the clinic.

Discovery of beta-benzamido hydroxamic acids as potent, selective, and orally bioavailable TACE inhibitors.

Beta-benzamido hydroxamic acids were discovered as potent TACE inhibitors. A computer model was constructed to help understanding the binding activities and guiding SAR study. SAR optimization led to the discovery of compound 30 which met all in vitro and in vivo criteria for the program and was selected for further evaluation.

Hydantoins, triazolones, and imidazolones as selective non-hydroxamate inhibitors of tumor necrosis factor-alpha converting enzyme (TACE).

We have discovered selective and potent inhibitors of TACE that replace the common hydroxamate zinc binding group with a hydantoin, triazolone, and imidazolone heterocycle. These novel heterocyclic inhibitors of a zinc metalloprotease were designed using a pharmacophore model that we previously described while developing hydantoin and pyrimidinetrione (barbiturate) inhibitors of TACE. The potency and binding orientation of these inhibitors is discussed and they are modeled into the X-ray crystal structure of TACE and compared to hydroxamate and earlier hydantoin TACE inhibitors which share the same 4-[(2-methyl-4-quinolinyl)methoxy]benzoyl P1' group.

A new 4-(2-methylquinolin-4-ylmethyl)phenyl P1' group for the beta-amino hydroxamic acid derived TACE inhibitors.

A new P1' group for TACE inhibitors was identified by eliminating the oxygen atom in the linker of the original 4-(2-methylquinolin-4-ylmethoxy)phenyl P1' group. Incorporation of this 4-(2-methylquinolin-4-ylmethyl)phenyl group onto different beta-aminohydroxamic acid cores provided compound 18, which demonstrated potent porcine TACE (p-TACE) and human whole blood activity, excellent PK properties, and good selectivity against a variety of MMPs.

Discovery of novel hydantoins as selective non-hydroxamate inhibitors of tumor necrosis factor-alpha converting enzyme (TACE).

A series of novel hydantoins was designed and synthesized as structural alternatives to hydroxamate inhibitors of TACE. 5-Mono- and di-substituted hydantoins exhibited activity with IC50 values of 11-60 nM against porcine TACE in vitro and excellent selectivity against other MMPs.

Discovery and pharmacological characterization of a novel rodent-active CCR2 antagonist, INCB3344.

This report describes the characterization of INCB3344, a novel, potent and selective small molecule antagonist of the mouse CCR2 receptor. The lack of rodent cross-reactivity inherent in the small molecule CCR2 antagonists discovered to date has precluded pharmacological studies of antagonists of this receptor and its therapeutic relevance. In vitro, INCB3344 inhibits the binding of CCL2 to mouse monocytes with nanomolar potency (IC(50) = 10 nM) and displays dose-dependent inhibition of CCL2-mediated functional responses such as ERK phosphorylation and chemotaxis with similar potency. Against a panel of G protein-coupled receptors that includes other CC chemokine receptors, INCB3344 is at least 100-fold selective for CCR2. INCB3344 possesses good oral bioavailability and systemic exposure in rodents that allows in vivo pharmacological studies. INCB3344 treatment results in a dose-dependent inhibition of macrophage influx in a mouse model of delayed-type hypersensitivity. The histopathological analysis of tissues from the delayed-type hypersensitivity model demonstrates that inhibition of CCR2 leads to a substantial reduction in tissue inflammation, suggesting that macrophages play an orchestrating role in immune-based inflammatory reactions. These results led to the investigation of INCB3344 in inflammatory disease models. We demonstrate that therapeutic dosing of INCB3344 significantly reduces disease in mice subjected to experimental autoimmune encephalomyelitis, a model of multiple sclerosis, as well as a rat model of inflammatory arthritis. In summary, we present the first report on the pharmacological characterization of a selective, potent and rodent-active small molecule CCR2 antagonist. These data support targeting this receptor for the treatment of chronic inflammatory diseases.

Synthesis and structure-activity relationship of a novel sulfone series of TNF-alpha converting enzyme inhibitors.

Replacement of the amide functionality in IM491 (N-hydroxy-(5S,6S)-1-methyl-6-[[4-(2-methyl-4-quinolinylmethoxy)anilinyl]carbonyl]5-piperidinecarboxamide) with a sulfonyl group led to a new series of alpha,beta-cyclic and beta,beta-cyclic gamma-sulfonyl hydroxamic acids, which were potent TNF-alpha converting enzyme (TACE) inhibitors. Among them, inhibitor 4b (N-hydroxy-(4S,5S)-1-methyl-5-[[4-(2-methyl-4-quinolinylmethoxy)phenyl]sulfonylmethyl]-4-pyrrolidinecarboxamide) exhibited IC50 values of < 1 nM and 180 nM in porcine TACE (pTACE) and cell assays, respectively, with excellent selectivity over MMP-1, -2, -9 and -13 and was orally bioavailable with an F value of 46% in mice.

Rational design, synthesis and structure-activity relationships of a cyclic succinate series of TNF-alpha converting enzyme inhibitors. Part 2: lead optimization.

Modifications of the lead TACE inhibitor 1 (N-hydroxy-trans-2-[[4-(4-quinolinyloxymethyl)anilinyl]carbonyl]-1-cyclohexanecarboxamide) at the cyclohexyl ring and the quinoline moiety led to the identification of a series of piperidine containing TACE inhibitors with potent activity in the inhibition of TNF-alpha release in the whole blood assay (WBA). The most potent analogue IM491 [N-hydroxy-(5S,6S)-1-methyl-6-[[4-(2-methyl-4-quinolinylmethoxy)anilinyl]carbonyl]-5-piperidinecarboxamide] exhibited an IC(50) value of 20 nM in WBA with excellent selectivity over MMP-1, -2 and -9 and is orally bioavailable with an F value of 43% in beagle dogs.