ITK inhibitor

Interleukin-2-inducible T cell kinase (ITK) is a non-receptor tyrosine kinase expressed in T cells, NKT cells and mast cells which plays a crucial role in regulating the T cell receptor (TCR), CD28, CD2, chemokine receptor CXCR4, and FcepsilonR-mediated signaling pathways. ITK inhibitors can be used for the treatment of inflammation and immune-mediated disorders. ITK inhibitor (N-[5-[[3-[(4-Acetylpiperazin-1-yl)carbonyl]-4-methyl-6-methoxy-phenyl]thio]thiazol-2-yl]-4-(N-1,2-dimethylpropylaminomethyl)benzamide) is the analogue of BMS-509744, which can potently and selectively inhibit Itk kinase activity.

In vitro: BMS-509744 could reduce TCR-induced functions including PLCγ1 tyrosine phosphorylation, calcium mobilization, IL-2 secretion, and T-cell proliferation in vitro in both human and mouse cells [1].

In vivo: BMS-509744 suppressed the production of IL-2 induced by anti-TCR antibody administered to mice. BMS-509744 also significantly diminishes lung inflammation in a mouse model of ovalbumin-induced allergy/asthma [1].

Clinical trial: Up to now, both BMS-509744 and ITK inhibitor is still in the preclinical development stage.

Reference:
[1] Lin TA, McIntyre KW, Das J, Liu C, O'Day KD, Penhallow B, Hung CY, Whitney GS, Shuster DJ, Yang X, Townsend R, Postelnek J, Spergel SH, Lin J, Moquin RV, Furch JA, Kamath AV, Zhang H, Marathe PH, Perez-Villar JJ, Doweyko A, Killar L, Dodd JH, Barrish JC, Wityak J, Kanner SB.  Selective Itk inhibitors block T-cell activation and murine lung inflammation. Biochemistry. 2004 Aug 31;43(34):11056-62.

Ibrutinib is an irreversible molecular inhibitor of ITK driving a Th1-selective pressure in T lymphocytes.[Pubmed:23886836]

Blood. 2013 Oct 10;122(15):2539-49.

Given its critical role in T-cell signaling, interleukin-2-inducible kinase (ITK) is an appealing therapeutic target that can contribute to the pathogenesis of certain infectious, autoimmune, and neoplastic diseases. Ablation of ITK subverts Th2 immunity, thereby potentiating Th1-based immune responses. While small-molecule ITK inhibitors have been identified, none have demonstrated clinical utility. Ibrutinib is a confirmed irreversible inhibitor of Bruton tyrosine kinase (BTK) with outstanding clinical activity and tolerability in B-cell malignancies. Significant homology between BTK and ITK alongside in silico docking studies support ibrutinib as an immunomodulatory inhibitor of both ITK and BTK. Our comprehensive molecular and phenotypic analysis confirms ITK as an irreversible T-cell target of ibrutinib. Using ibrutinib clinical trial samples along with well-characterized neoplastic (chronic lymphocytic leukemia), parasitic infection (Leishmania major), and infectious disease (Listeria monocytogenes) models, we establish ibrutinib as a clinically relevant and physiologically potent ITK inhibitor with broad therapeutic utility. This trial was registered at www.clinicaltrials.gov as #NCT01105247 and #NCT01217749.

A Small Molecule Inhibitor of ITK and RLK Impairs Th1 Differentiation and Prevents Colitis Disease Progression.[Pubmed:26466958]

J Immunol. 2015 Nov 15;195(10):4822-31.

In T cells, the Tec kinases IL-2-inducible T cell kinase (ITK) and resting lymphocyte kinase (RLK) are activated by TCR stimulation and are required for optimal downstream signaling. Studies of CD4(+) T cells from Itk(-/-) and Itk(-/-)Rlk(-/-) mice have indicated differential roles of ITK and RLK in Th1, Th2, and Th17 differentiation and cytokine production. However, these findings are confounded by the complex T cell developmental defects in these mice. In this study, we examine the consequences of ITK and RLK inhibition using a highly selective and potent small molecule covalent inhibitor PRN694. In vitro Th polarization experiments indicate that PRN694 is a potent inhibitor of Th1 and Th17 differentiation and cytokine production. Using a T cell adoptive transfer model of colitis, we find that in vivo administration of PRN694 markedly reduces disease progression, T cell infiltration into the intestinal lamina propria, and IFN-gamma production by colitogenic CD4(+) T cells. Consistent with these findings, Th1 and Th17 cells differentiated in the presence of PRN694 show reduced P-selectin binding and impaired migration to CXCL11 and CCL20, respectively. Taken together, these data indicate that ITK plus RLK inhibition may have therapeutic potential in Th1-mediated inflammatory diseases.

Targeting interleukin-2-inducible T-cell kinase (ITK) and resting lymphocyte kinase (RLK) using a novel covalent inhibitor PRN694.[Pubmed:25593320]

J Biol Chem. 2015 Mar 6;290(10):5960-78.

Interleukin-2-inducible T-cell kinase (ITK) and resting lymphocyte kinase (RLK or TXK) are essential mediators of intracellular signaling in both normal and neoplastic T-cells and natural killer (NK) cells. Thus, ITK and RLK inhibitors have therapeutic potential in a number of human autoimmune, inflammatory, and malignant diseases. Here we describe a novel ITK/RLK inhibitor, PRN694, which covalently binds to cysteine residues 442 of ITK and 350 of RLK and blocks kinase activity. Molecular modeling was utilized to design molecules that interact with cysteine while binding to the ATP binding site in the kinase domain. PRN694 exhibits extended target residence time on ITK and RLK and is highly selective for a subset of the TEC kinase family. In vitro cellular assays confirm that PRN694 prevents T-cell receptor- and Fc receptor-induced cellular and molecular activation, inhibits T-cell receptor-induced T-cell proliferation, and blocks proinflammatory cytokine release as well as activation of Th17 cells. Ex vivo assays demonstrate inhibitory activity against T-cell prolymphocytic leukemia cells, and in vivo assays demonstrate durable pharmacodynamic effects on ITK, which reduces an oxazolone-induced delayed type hypersensitivity reaction. These data indicate that PRN694 is a highly selective and potent covalent inhibitor of ITK and RLK, and its extended target residence time enables durable attenuation of effector cells in vitro and in vivo. The results from this study highlight potential applications of this dual inhibitor for the treatment of T-cell- or NK cell-mediated inflammatory, autoimmune, and malignant diseases.

Therapeutic antitumor immunity by checkpoint blockade is enhanced by ibrutinib, an inhibitor of both BTK and ITK.[Pubmed:25730880]

Proc Natl Acad Sci U S A. 2015 Mar 3;112(9):E966-72.

Monoclonal antibodies can block cellular interactions that negatively regulate T-cell immune responses, such as CD80/CTLA-4 and PD-1/PD1-L, amplifying preexisting immunity and thereby evoking antitumor immune responses. Ibrutinib, an approved therapy for B-cell malignancies, is a covalent inhibitor of BTK, a member of the B-cell receptor (BCR) signaling pathway, which is critical to the survival of malignant B cells. Interestingly this drug also inhibits ITK, an essential enzyme in Th2 T cells and by doing so it can shift the balance between Th1 and Th2 T cells and potentially enhance antitumor immune responses. Here we report that the combination of anti-PD-L1 antibody and ibrutinib suppresses tumor growth in mouse models of lymphoma that are intrinsically insensitive to ibrutinib. The combined effect of these two agents was also documented for models of solid tumors, such as triple negative breast cancer and colon cancer. The enhanced therapeutic activity of PD-L1 blockade by ibrutinib was accompanied by enhanced antitumor T-cell immune responses. These preclinical results suggest that the combination of PD1/PD1-L blockade and ibrutinib should be tested in the clinic for the therapy not only of lymphoma but also in other hematologic malignancies and solid tumors that do not even express BTK.