Inhibition of tyrosine kinases blocks adhesion-induced T-cell coactivation without interfering with T-cell adhesion to endothelial cell-surface ligands.

Integrin and cell adhesion molecule-regulated cellular adhesion plays an integral part in the recruitment and activation of lymphocytes. T-cell activation is a dynamic process subject to integrin-dependent and -independent regulation. Stimulation of human peripheral blood T cells by the anti-CD3 monoclonal antibody results in a rapid upregulation of integrin affinity. In conjunction with adhesion to endothelial cell-derived ligands and extracellular matrix proteins, anti-CD3 antibodies have been shown to result in significant increases in IL-2 production and T-cell proliferation. Therefore, at least two signal cascades are activated by ligation of the TCR: One results in a change in affinity of integrins for their ligands, whereas the other activates a signaling cascade that leads to gene induction. We investigated the effects of several tyrosine kinase inhibitors on human peripheral blood T-cell adhesion and adhesion-induced costimulation of IL-2 expression and secretion. These compounds did not inhibit anti-CD3-induced short-term (30 min) or long-term (18 hr) T-cell adhesion to VCAM-1, MAdCAM, or ICAM-1. When T cells were stimulated with anti-CD3 and allowed to adhere to VCAM-1, MAdCAM, or ICAM-1 in the presence of these inhibitors; IL-2 production was significantly reduced. The MEK specific inhibitor, PD98059, did not block T-cell adhesion to the various substrates, but it did block IL-2 synthesis. In addition, the tyrosine kinase inhibitors and PD98059 blocked anti-CD3-mediated stimulation of IL-2 synthesis. These data suggest that the signaling mechanism for anti-CD3-mediated integrin activation is distinct from the signaling pathway that results in adhesion-induced IL-2 synthesis via specific integrins and anti-CD3.

Synthesis and SAR of N-benzoyl-L-biphenylalanine derivatives: discovery of TR-14035, a dual alpha(4)beta(7)/alpha(4)beta(1) integrin antagonist.

alpha(4)beta(1) and alpha(4)beta(7) integrins are key regulators of physiologic and pathologic responses in inflammation and autoimmune disease. The effectiveness of anti-integrin antibodies to attenuate a number of inflammatory/immune conditions provides a strong rationale to target integrins for drug development. Important advances have been made in identifying potent and selective candidates, peptides and peptidomimetics, for further development. Herein, we report the discovery of a series of novel N-benzoyl-L-biphenylalanine derivatives that are potent inhibitors of alpha4 integrins. The potency of the initial lead compound (1: IC(50) alpha(4)beta(7)/alpha(4)beta(1)=5/33 microM) was optimized via sequential manipulation of substituents to generate low nM, orally bioavailable dual alpha(4)beta(1)/alpha(4)beta(7) antagonists. The SAR also led to the identification of several subnanomolar antagonists (134, 142, and 143). Compound 81 (TR-14035; IC(50) alpha(4)beta(7)/alpha(4)beta(1)=7/87 nM) has completed Phase I studies in Europe. The synthesis, SAR and biological evaluation of these compounds are described.