ASP7266, a Novel Antibody against Human Thymic Stromal Lymphopoietin Receptor for the Treatment of Allergic Diseases.

Thymic stromal lymphopoietin (TSLP), positioned at the top of the inflammatory cascade, is a key regulator that enhances allergic inflammatory responses by activating T helper type 2 cells, Group 2 innate lymphoid cells (ILC2), and myeloid dendritic cells (mDCs) via the TSLP receptor (TSLPR). We evaluated the inhibitory effects of ASP7266, a novel recombinant fully human IgG1 monoclonal antibody against TSLPR, on TSLP signaling and inflammation. The inhibitory effects of ASP7266 and the control antibody tezepelumab on TSLP and TSLPR interactions were investigated using a proliferation assay with TSLP stimulation and a chemokine production assay. The pharmacological effects of ASP7266 were investigated by examining differentiation of naive CD4+ T cells, ILC2 cytokine production, and ascaris extract-induced skin allergic reaction in cynomolgus monkeys. ASP7266 potently inhibited TSLP-induced cell proliferation and C-C motif chemokine ligand 17 production. Furthermore, ASP7266 inhibited TSLP-stimulated mDC-mediated naive CD4+ T-cell differentiation and interleukin 5 production by lineage-negative peripheral blood mononuclear cells, which can be considered ILC2 in vitro. In sensitized monkeys, ASP7266 completely suppressed ascaris extract-induced allergic skin reactions. Based on these results, ASP7266, a novel human therapeutic antibody against TSLPR, is a potential therapy for patients with allergic diseases. SIGNIFICANCE STATEMENT: TSLP, positioned at the top of the inflammatory cascade, plays a key role in various allergic diseases, including asthma, chronic rhinosinusitis with nasal polyposis, and atopic dermatitis. Here we show that the anti-TSLPR antibody ASP7266 exhibited excellent pharmacological activity in preclinical studies. Therefore, ASP7266 has the potential to be a promising treatment option for patients with allergic disorders.

YM-341619 suppresses the differentiation of spleen T cells into Th2 cells in vitro, eosinophilia, and airway hyperresponsiveness in rat allergic models.

T helper (Th) 2 cells play a central role in the pathogenesis of allergic diseases such as allergic asthma, atopic dermatitis, and allergic rhinitis. We have found that YM-341619 hydrochloride, which suppressed IL-4-induced STAT6-dependent reporter gene expression, inhibited the differentiation of mouse spleen T cells into Th2 cells in vitro. YM-341619 suppressed the production of IL-4 and the expression of GATA-3 mRNA, a Th2 transcription factor, in T cells cultured with anti-CD3 antibody and anti-CD28 antibody in the presence of IL-4. In contrast, the production of IFN-gamma and the expression of T-bet mRNA, a Th1 transcription factor, in T cells cultured with anti-CD3 antibody in the presence of IL-12, were not effected by YM-341619. Orally administered YM-341619 (0.003-0.03 mg/kg) reduced the plasma IgE level of DNP-Ascaris-sensitized rats, but not the IgG(2a) level. YM-341619 suppressed IL-4 and IL-13 production in the splenocytes of these DNP-Ascaris-sensitized rats without augmenting IFN-gamma production. YM-341619 also dose-dependently suppressed eosinophil accumulation in the lung (0.003-3 mg/kg, p.o.) and airway hyperresponsiveness (0.3-3 mg/kg, p.o.) induced by repeated exposure to ovalbumin in ovalbumin-sensitized rats. These results suggest that YM-341619 has the ability to suppress allergen-induced Th2 responses by selectively inhibiting the differentiation of CD4(+) T cells into the Th2 subset.

Inhibition of antigen-induced airway inflammation and hyperresponsiveness in guinea pigs by a selective antagonist of "chemoattractant receptor homologous molecule expressed on Th2 cells" (CRTH2).

Chemoattractant receptor homologous molecule expressed on T helper type 2 cells (CRTH2) is a PGD2 receptor found on eosinophils, basophils, and Th2 type T cells which exhibits chemotaxis and functions in activation cascades. However, while a number of CRTH2 antagonists, including ramatroban, are known to exert activity in certain animal models, activity in a guinea pig model of EA-induced airway hyperresponsiveness has not been demonstrated. The newly developed CRTH2 antagonist ASP5642 has shown antagonistic activity against human and guinea pig CRTH2 in previous studies and has also been found effective in treating guinea pig models of airway inflammation and airway hyperresponsiveness. While previous studies have used animals such as rats and mice to evaluate CRTH2 antagonist effects, ours is the first attempt to evaluate CRTH2 function in a guinea pig asthma model, which may prove useful in evaluating the compound's effects in humans, given the comparable airway function between the two species taken together, these data from the present study strongly suggest the utility of ASP5642 in investigating the role of CRTH2 in inflammatory responses and as a drug treatment for human asthma.