Inhibition of Arginase 1 Liberates Potent T Cell Immunostimulatory Activity of Human Neutrophil Granulocytes.

Myeloid cell arginase-mediated arginine depletion with consecutive inhibition of T cell functions is a key component of tumor immune escape. Both, granulocytic myeloid-derived suppressor cells (G-MDSC) and conventional mature human polymorphonuclear neutrophil granulocytes (PMN) express high levels of arginase 1 and can act as suppressor cells of adaptive anti-cancer immunity. Here we demonstrate that pharmacological inhibition of PMN-derived arginase 1 not only prevents the suppression of T cell functions but rather leads to a strong hyperactivation of T cells.

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.

Parsaclisib Is a Next-Generation Phosphoinositide 3-Kinase Inhibitor with Reduced Hepatotoxicity and Potent Antitumor and Immunomodulatory Activities in Models of B-Cell Malignancy.

The clinical use of first-generation phosphoinositide 3-kinase (PI3K) inhibitors in B-cell malignancies is hampered by hepatotoxicity, requiring dose reduction, treatment interruption, and/or discontinuation of therapy. In addition, potential molecular mechanisms by which resistance to this class of drugs occurs have not been investigated. Parsaclisib (INCB050465) is a potent and selective next-generation PI3K inhibitor that differs in structure from first-generation PI3K inhibitors and has shown encouraging anti-B-cell tumor activity and reduced hepatotoxicity in phase 1/2 clinical studies.

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 (, parsaclisib). The unique structure of contains a pyrazolopyrimidine hinge-binder in place of a purine motif that is present in other PI3Kδ inhibitors, such as idelalisib (), duvelisib (), and INCB040093 (, dezapelisib). Parsaclisib () 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.

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.

INCB38579, a novel and potent histamine H₄ receptor small molecule antagonist with anti-inflammatory pain and anti-pruritic functions.

The histamine H₄ receptor mediates several histamine-induced cellular functions of leukocytes, including cell migration and cytokine production. Recent studies suggest that histamine signaling through the histamine H₄ receptor can also have anti-pruritic and anti-nociceptive functions. 1-(7-(2-amino-6-(4-methylpiperazin-1-yl) pyrimidin-4-yl)-3, 4-dihdroisoquinolin-2(1H)-yl)-2-cyclopentylethanone (INCB38579) is a novel small molecule antagonist of the human and rodent histamine H₄ receptors with at least 80-fold selectivity over the human histamine H₁, H₂ and H₃ receptors, and has good pharmacokinetic properties in rats and mice.

Selective inhibition of IDO1 effectively regulates mediators of antitumor immunity.

Indoleamine 2,3-dioxygenase-1 (IDO1; IDO) mediates oxidative cleavage of tryptophan, an amino acid essential for cell proliferation and survival. IDO1 inhibition is proposed to have therapeutic potential in immunodeficiency-associated abnormalities, including cancer. Here, we describe INCB024360, a novel IDO1 inhibitor, and investigate its roles in regulating various immune cells and therapeutic potential as an anticancer agent.

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.

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.

Molecular modeling and site-specific mutagenesis of the histamine-binding site of the histamine H4 receptor.

The histamine H4 receptor is a novel G-protein-coupled receptor with a unique pharmacological profile. The distribution of H4 mRNA suggests that it may play a role in the regulation of immune function, particularly with respect to allergy and asthma. To define the histamine-binding site of this receptor, molecular modeling and site-directed mutagenesis were used to predict and alter amino acids residing in the histamine-binding pocket.