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Body weight changes in tumor-xenografted mice treated with U3-1402.

Supplementary Table from HER3 Augmentation via Blockade of EGFR/AKT Signaling Enhances Anticancer Activity of HER3-Targeting Patritumab Deruxtecan in EGFR-Mutated Non–Small Cell Lung Cancer

Supplementary Figure from HER3 Augmentation via Blockade of EGFR/AKT Signaling Enhances Anticancer Activity of HER3-Targeting Patritumab Deruxtecan in EGFR-Mutated Non–Small Cell Lung Cancer

Growth inhibition activity in 8 cell lines with different HER3 expression levels

Cell surface expression of HER3 and HER2 on human cancer cell lines

Purpose:HER3 is a compelling target for cancer treatment; however, no HER3-targeted therapy is currently clinically available. Here, we produced U3-1402, an anti-HER3 antibody–drug conjugate with a topoisomerase I inhibitor exatecan derivative (DXd), and systematically investigated its targeted drug delivery potential and antitumor activity in preclinical models.Experimental Design:In vitro pharmacologic activities and the mechanisms of action of U3-1402 were assessed in several human cancer cell lines. Antitumor activity of U3-1402 was evaluated in xenograft mouse models, including patient-derived xenograft (PDX) models. Safety assessments were also conducted in rats and monkeys.Results:U3-1402 showed HER3-specific binding followed by highly efficient cancer cell internalization. Subsequently, U3-1402 was translocated to the lysosome and released its payload DXd. While U3-1402 was able to inhibit HER3-activated signaling similar to its naked antibody patritumab, the cytotoxic activity of U3-1402 in HER3-expressing cells was predominantly mediated by released DXd through DNA damage and apoptosis induction. In xenograft mouse models, U3-1402 exhibited dose-dependent and HER3-dependent antitumor activity. Furthermore, U3-1402 exerted potent antitumor activity against PDX tumors with HER3 expression. Acceptable toxicity was noted in both rats and monkeys.Conclusions:U3-1402 demonstrated promising antitumor activity against HER3-expressing tumors with tolerable safety profiles. The activity of U3-1402 was driven by HER3-mediated payload delivery via high internalization into tumor cells.

Summary of repeated dose toxicity studies in rats and monkeys

Supplementary materials and methods for xenograft studies and IHC

Purpose:EGFR-tyrosine kinase inhibitor (TKI) is a standard first-line therapy for activated EGFR-mutated non–small cell lung cancer (NSCLC). Treatment options for patients with acquired EGFR-TKI resistance are limited. HER3 mediates EGFR-TKI resistance. Clinical trials of the HER3-targeting antibody–drug conjugate patritumab deruxtecan (HER3-DXd) demonstrated its anticancer activity in EGFR-mutated NSCLC; however, the mechanisms that regulate HER3 expression are unknown. This study was conducted with the aim to clarify the mechanisms underlying HER3 regulation in EGFR-mutated NSCLC tumors and explored the strategy for enhancing the anticancer activity of HER3-DXd in EGFR-mutated NSCLC.Experimental Design:Paired tumor samples were obtained from 48 patients with EGFR-mutated NSCLC treated with EGFR-TKI(s). HER3 expression was immunohistochemically quantified with H-score, and genomic alteration and transcriptomic signature were tested in tumors from pretreatment to post-EGFR-TKI resistance acquisition. The anticancer efficacy of HER3-DXd and osimertinib was evaluated in EGFR-mutated NSCLC cells.Results:We showed augmented HER3 expression in EGFR-mutated tumors with acquired EGFR-TKI resistance compared with paired pretreatment samples. RNA sequencing revealed that repressed PI3K/AKT/mTOR signaling was associated with HER3 augmentation, especially in tumors from patients who received continuous EGFR-TKI therapy. An in vitro study also showed that EGFR-TKI increased HER3 expression, repressed AKT phosphorylation in multiple EGFR-mutated cancers, and enhanced the anticancer activity of HER3-DXd.Conclusions:Our findings help clarify the mechanisms of HER3 regulation in EGFR-mutated NSCLC tumors and highlight a rationale for combination therapy with HER3-DXd and EGFR-TKI in EGFR-mutated NSCLC.

Antitumor activity of U3-1402 in HER3-positive HCC1569 and MDA-MB-453 xenograft models

Purpose: EGFR-tyrosine kinase inhibitor (TKI) is a standard first-line therapy for activated EGFR-mutated non–small cell lung cancer (NSCLC). Treatment options for patients with acquired EGFR-TKI resistance are limited. HER3 mediates EGFR-TKI resistance. Clinical trials of the HER3-targeting antibody–drug conjugate patritumab deruxtecan (HER3-DXd) demonstrated its anticancer activity in EGFR-mutated NSCLC; however, the mechanisms that regulate HER3 expression are unknown. This study was conducted with the aim to clarify the mechanisms underlying HER3 regulation in EGFR-mutated NSCLC tumors and explored the strategy for enhancing the anticancer activity of HER3-DXd in EGFR-mutated NSCLC. Experimental Design: Paired tumor samples were obtained from 48 patients with EGFR-mutated NSCLC treated with EGFR-TKI(s). HER3 expression was immunohistochemically quantified with H-score, and genomic alteration and transcriptomic signature were tested in tumors from pretreatment to post-EGFR-TKI resistance acquisition. The anticancer efficacy of HER3-DXd and osimertinib was evaluated in EGFR-mutated NSCLC cells. Results: We showed augmented HER3 expression in EGFR-mutated tumors with acquired EGFR-TKI resistance compared with paired pretreatment samples. RNA sequencing revealed that repressed PI3K/AKT/mTOR signaling was associated with HER3 augmentation, especially in tumors from patients who received continuous EGFR-TKI therapy. An in vitro study also showed that EGFR-TKI increased HER3 expression, repressed AKT phosphorylation in multiple EGFR-mutated cancers, and enhanced the anticancer activity of HER3-DXd. Conclusions: Our findings help clarify the mechanisms of HER3 regulation in EGFR-mutated NSCLC tumors and highlight a rationale for combination therapy with HER3-DXd and EGFR-TKI in EGFR-mutated NSCLC.

Purpose: HER3 is a compelling target for cancer treatment; however, no HER3-targeted therapy is currently clinically available. Here, we produced U3-1402, an anti-HER3 antibody–drug conjugate with a topoisomerase I inhibitor exatecan derivative (DXd), and systematically investigated its targeted drug delivery potential and antitumor activity in preclinical models. Experimental Design: In vitro pharmacologic activities and the mechanisms of action of U3-1402 were assessed in several human cancer cell lines. Antitumor activity of U3-1402 was evaluated in xenograft mouse models, including patient-derived xenograft (PDX) models. Safety assessments were also conducted in rats and monkeys. Results: U3-1402 showed HER3-specific binding followed by highly efficient cancer cell internalization. Subsequently, U3-1402 was translocated to the lysosome and released its payload DXd. While U3-1402 was able to inhibit HER3-activated signaling similar to its naked antibody patritumab, the cytotoxic activity of U3-1402 in HER3-expressing cells was predominantly mediated by released DXd through DNA damage and apoptosis induction. In xenograft mouse models, U3-1402 exhibited dose-dependent and HER3-dependent antitumor activity. Furthermore, U3-1402 exerted potent antitumor activity against PDX tumors with HER3 expression. Acceptable toxicity was noted in both rats and monkeys. Conclusions: U3-1402 demonstrated promising antitumor activity against HER3-expressing tumors with tolerable safety profiles. The activity of U3-1402 was driven by HER3-mediated payload delivery via high internalization into tumor cells.

HER3 is overexpressed in several cancers, including colorectal cancer. Although therapies with anti-HER3 antibodies have been investigated, significant clinical benefits have not been reported. U3-1402 is a novel HER3-antibody–drug conjugate (ADC) composed of the HER3 antibody patritumab and a novel topoisomerase I inhibitor, DX-8951 derivative (DXd). The sensitivity of DXd was evaluated by a growth inhibition assay. The antitumor activity of U3-1402 was evaluated in a murine xenograft model in which its effects on cells, with a range of HER3 expression levels, were compared with those of patritumab alone, irinotecan, control-ADC, and saline. In the growth inhibition assay, all colorectal cancer cell lines were sensitive to DXd. In the tumor xenograft model, significant tumor regression with U3-1402 was observed both in the DiFi cell line (high HER3 expression; KRAS wild type) and in SW620 (high HER3 expression; KRAS mutation), but no treatment effect was observed in Colo320DM (low HER3 expression). Notably, SW620 tumor growth was significantly suppressed with U3-1402 compared with the saline-treated group (P < 0.001) and showed greater activity compared with the irinotecan group. By contrast, patritumab alone, control-ADC, and saline did not significantly differ in tumor growth inhibition. The antitumor activity of U3-1402 was dependent on HER3 expression level, but not on KRAS mutation status. These results support further investigation of development strategies for U3-1402 in patients with HER3-expressing colorectal cancer.

e21175 Background: Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) is a standard first-line therapy for activated EGFR-mutated non-small-cell lung cancer (NSCLC). Treatment options for patients with acquired EGFR-TKI resistance are limited. HER3 mediates EGFR-TKI resistance and is hence a promising target for anticancer treatment. Patritumab deruxtecan (HER3-DXd) is an antibody drug conjugate comprised of a fully human anti-HER3 IgG1 monoclonal antibody, covalently linked to a topoisomerase 1 inhibitor payload, an exatecan derivative, via a tetrapeptide-based cleavable linker. Clinical trials of theHER3-DXd demonstrated its anticancer activity in EGFR-mutated NSCLC. However, the genomic background that regulates HER3 expression is unknown. This study was conducted with the aim to clarify the genomic background for HER3 regulation in EGFR-mutated NSCLC tumors and to explore the strategy for enhancing the anticancer activity of HER3-DXd. Methods: 48 paired samples were obtained before EGFR-TKI treatment and after the acquisition of EGFR-TKI resistance from patients with EGFR-mutated NSCLC. HER3 expression was immunohistochemically quantified with H-score, and genomic alteration and transcriptomic signature were tested in tumors from pre-treatment to post-EGFR-TKI resistance acquisition. For statistical tests, linear regression analysis was performed to investigate whether a factor, including EGFR-TKI administration, affected HER3 expression. Pearson correlation coefficients were calculated to explore the relationships between HER3 expression level and other genomic expression in the tumors. Results: We showed augmented HER3 expression in EGFR-mutated tumors with acquired EGFR-TKI resistance compared to paired pretreatment samples (mean H-score 100.8 vs. 155.9, paired t-test p = 0.0007). Although genomic alterations including EGFR secondary T790M mutation did not correlate with HER3 augmentation, RNA sequencing revealed that repressed PI3K/AKT/mTOR signaling was associated with HER3 augmentation (GSEA; normalized enrichment score -1.78, p = 0.004). Multivariable regression analysis of HER3 augmentation revealed that re-biopsy under continuing EGFR-TKI treatment independently effected HER3 augmentation. Indeed, an in-vitro study also showed that EGFR-TKI increased HER3 expression via repressed AKT phosphorylation in multiple EGFR-mutated cancers, and it finally enhanced the anticancer activity of HER3-DXd. Conclusions: Our findings highlight a rationale for combination therapy with HER3-DXd and EGFR-TKI in EGFR-mutated NSCLC that is currently being evaluated in a clinical trial for patients with EGFR-mutated NSCLC tumors, not only with regard to an acquired resistance to EGFR-TKI but also in EGFR-TKI-naïve tumors (NCT04676477).

Immunotherapy targeting programmed cell death-1 (PD-1) induces durable antitumor efficacy in many types of cancer. However, such clinical benefit is limited because of the insufficient reinvigoration of antitumor immunity with the drug alone; therefore, rational therapeutic combinations are required to improve its efficacy. In our preclinical study, we evaluated the antitumor effect of U3-1402, a human epidermal growth factor receptor 3-targeting (HER3-targeting) antibody-drug conjugate, and its potential synergism with PD-1 inhibition. Using a syngeneic mouse tumor model that is refractory to anti-PD-1 therapy, we found that treatment with U3-1402 exhibited an obvious antitumor effect via direct lysis of tumor cells. Disruption of tumor cells by U3-1402 enhanced the infiltration of innate and adaptive immune cells. Chemotherapy with exatecan derivative (Dxd, the drug payload of U3-1402) revealed that the enhanced antitumor immunity produced by U3-1402 was associated with the induction of alarmins, including high-mobility group box-1 (HMGB-1), via tumor-specific cytotoxicity. Notably, U3-1402 significantly sensitized the tumor to PD-1 blockade, as a combination of U3-1402 and the PD-1 inhibitor significantly enhanced antitumor immunity. Further, clinical analyses indicated that tumor-specific HER3 expression was frequently observed in patients with PD-1 inhibitor-resistant solid tumors. Overall, U3-1402 is a promising candidate as a partner of immunotherapy for such patients.

The pharmacokinetic (PK) and pharmacodynamic (PD) modeling was conducted for the reduction of peripheral lymphocytes after oral administration of CS-0777 to healthy rats, monkeys and experimental autoimmune encephalomyelitis (EAE) induced rats. M1, the phosphorylated active metabolite of CS-0777, is a selective sphingosine 1-phosphate receptor-1 modulator. A linear one-and two-compartment model with reversible metabolism process characterized the time courses of CS-0777 and M1 concentrations in rats and monkeys, respectively. The relationship between lymphocyte counts and M1 concentrations in blood was well described via an indirect response model in all animals examined. An Imax of 0.815 and an IC50 of 6.58 ng/ml in healthy rats, an Imax of 0.807 and an IC50 of 5.09 ng/ml in the EAE rats, an Imax of 0.789 and an IC50 of 0.484 ng/ml in monkeys were estimated by indirect PD model. Since the IC50 values calculated in terms of an unbound plasma concentration-basis in rats and monkeys were within the similar range by correcting the IC50 in blood described above with blood to plasma concentration ratio and plasma free fraction of M1 in each animal, it is considered that the intrinsic activity of M1 against lymphocyte reduction exhibits no species difference. The sensitivity of the lymphocytes against M1 was not affected by the status of EAE. The comparison of the simulated lymphocyte reduction in EAE rats by multiple dosing of CS-0777 and actual EAE clinical scores implies that to show significant suppressive effect on EAE does not require absolute elimination of all lymphocytes from the blood.

EGFR tyrosine kinase inhibitors (TKIs) are standard therapy for EGFR-mutant non-small cell lung cancer (NSCLC); however, these tumours eventually acquire chemoresistance. U3-1402 is an anti-HER3 antibody-drug conjugate with a novel topoisomerase I inhibitor, DXd. In the current study, we evaluated the anticancer efficacy of U3-1402 in EGFR-mutant NSCLC cells with acquired resistance to EGFR-TKIs. HCC827GR5 and PC9AZDR7 are EGFR-TKI-resistant clones for gefitinib and osimertinib, respectively. U3-1402 alone or in combination with the EGFR-TKI erlotinib demonstrated potent anticancer efficacy in HCC827GR5 cells using an in vitro growth inhibition assay and in vivo xenograft mouse model. U3-1402 induced apoptosis in HCC827GR5 cells accompanying phosphorylation of histone H2A.X, a marker of DNA damage, but did not block HER3/PI3K/AKT signalling. Further, we found using flow cytometry that the cell surface HER3 expression level in HCC827GR5 cells was twice that found in HCC827 cells, indicating internalization of U3-1402 was increased in resistant cells. In addition, administration of U3-1402 notably repressed growth of EGFR-TKI osimertinib-resistant PC9AZDR7 xenograft tumours, and that PC9AZDR7 cells expressed five times greater cell surface HER3 than PC9 cells. Furthermore, using immunofluorescent microscopy, HER3 was observed predominantly in the nucleus of PC9 cells, but was localized in the cytoplasm of PC9AZDR7 cells. This finding indicates that altered trafficking of the HER3-U3-1402 complex may accelerate linker payload cleavage by cytoplasmic lysosomal enzymes, resulting in DNA damage. Our results indicate that administration of U3-1402 alone or in combination with an EGFR-TKI may have potential as a novel therapy for EGFR-TKI-resistant EGFR-mutant NSCLC.

Psoriasis is a common inflammatory skin disease that affects approximately 1% of the population worldwide. Tumor necrosis factor-alpha-induced protein 3 (TNFAIP3) gene polymorphisms have been strongly associated with psoriasis susceptibility. In this study, we investigate how TNFAIP3, also known as A20, may regulate psoriasis susceptibility. We found that haplo-insufficient A20+/- mice develop severe toll-like receptor (TLR)-induced skin inflammation compared to wild type mice owing to amplified production of interleukin (IL)-17 and IL-23. Examination of TNFAIP3 mRNA expression in skin biopsies from patients with psoriasis revealed reduced expression in both involved and uninvolved skin. Our results demonstrate the clinical importance of reduced dermal expression of A20 in psoriasis and suggest that A20 restriction of the IL-23/17 axis protects against psoriasis.

We report herein the synthesis and structure-activity relationships (SAR) of a series of benzyl ether compounds as an S1P₁ receptor modulator. From our SAR studies, the installation of substituents onto the central benzene ring of 2a was revealed to potently influence the S1P₁ and S1P₃ agonistic activities, in particular, an ethyl group on the 2-position afforded satisfactory S1P₁/S1P₃ selectivity. These changes of the S1P₁ and S1P₃ agonistic activities caused by the alteration of substituents on the 2-position were reasonably explained by a docking study using an S1P₁ X-ray crystal structure and S1P₃ homology modeling. We found that compounds 2b and 2e had a potent in vivo immunosuppressive efficacy along with acceptable S1P₁/S1P₃ selectivity, and confirmed that these compounds had less in vivo bradycardia risk through the evaluation of heart rate change after oral administration of the compounds (30 mg/kg, p.o.) in rats.

Background: HER3 (human epidermal growth factor receptor 3) is a member of the HER family and overexpressed in a broad range of cancer types including colorectal cancer. HER3 targeted therapies such as anti-HER3 antibodies have been investigated in clinical trials; however, no HER3-targeting therapy has been approved to date. U3-1402 is a novel antibody drug conjugate (ADC) composed of a fully human anti-HER3 antibody (patritumab) and a novel topoisomerase I inhibitor (DXd) which is conjugated via an enzymatically cleavable peptide-linker with high drug antibody ratio (DAR: 7-8 to 1). Purpose: To investigate the antitumor efficacy of U3-1402 in HER3-expressing colorectal cancer xenograft models. Material and methods: The following cell lines were used in this study; WiDr, Colo320DM, and DiFi with KRAS wild type, DLD-1, HCT15, HCT116, LoVo, SW480, and SW620 harboring KRAS mutation. The sensitivities of 9 colorectal cancer cell lines to DXd were evaluated by in vitro cell killing assay. Cells were treated with DXd at different concentrations (0.5pM to 500nM) over 144 hours, and the 50% inhibitory concentration (IC50) values were determined. Cell surface HER3 antigen was quantified by flow cytometry. In vivo screening assay and tumor growth inhibition assay were performed in tumor xenograft models exhibiting a range of HER3 expression levels. In addition, the efficacy of U3-1402 was compared to that of parental antibody patritumab, CPT-11, control-ADC, and saline in SW620 tumor xenograft model harboring KARS mutation. All results were expressed as mean ± standard deviation (SD) and statistical significance was analyzed using ANOVA with Dunnet multiple comparison. Results: In in vitro study, the range of IC50 value of DXd for each cell line was 2.16 ± 0.11 nM to 16.04 ± 0.10 nM. Most of the cell lines were sensitive to DXd. In in vivo screening assay, the maximum regression from U3-1402 was observed in the tumor xenograft model of both DiFi (high HER3 expression; KRAS wild type) and SW620 (high HER3 expression; KRAS mutation). In in vivo tumor growth inhibition assay, the antitumor efficacy was dependent on the HER3 expression level. Notably, SW620 tumor growth was significantly suppressed with U3-1402 compared with that of saline group (p < 0.001) and had improved potency compared with CPT-11. Of note, no significant difference in tumor growth inhibition was observed amongst the treatments with the same dose of patritumab or control-ADC and saline. Tumor regression was only observed in U3-1402 treated group, and some of which achieved complete regression. Conclusions: The antitumor efficacy of U3-1402 in xenograft models was dependent on HER3 expression and did not show a clear relationship to KRAS mutation status. These results support further investigation of development strategies for U3-1402 in patients with HER3-expressing colorectal cancer. Citation Format: Shigehiro Koganemaru, Yasutoshi Kuboki, Yoshikatsu Koga, Takashi Kojima, Mayumi Yamauchi, Naoyuki Maeda, Takashi Kagari, Kenji Hirotani, Masahiro Yasunaga, Yasuhiro Matsumura, Toshihiko Doi. U3-1402, a novel HER3-targeting ADC, inhibits the tumor growth of colorectal cancer xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 220.

Background: Human epidermal growth factor receptor 3 (HER3), a member of the ErbB receptor tyrosine kinase family, is overexpressed in a variety of human cancers and plays an important role in cell proliferation and survival. U3-1402 is a novel HER3-targeting antibody-drug conjugate (ADC) consisting of a fully human anti-HER3 antibody (patritumab), a tetrapeptide-based linker, and a topoisomerase I inhibitor payload. It is currently being investigated in clinical trials for HER3-positive breast cancer (phase 1/2) and NSCLC (phase 1). In principle, effective action of ADCs depends on multiple dynamic factors including antigen-specific binding, internalization, trafficking to lysosomes, and payload release, as well as other inherent characteristics such as payload potency and linker stability. Methods: To assess the targeted delivery potential of U3-1402, the HER3-mediated molecular dynamics of U3-1402 (cell surface binding, internalization, trafficking, and payload release) were investigated in 8 cancer cell lines with various HER3 expression levels, along with cell growth inhibition activity. In vitro molecular dynamics were compared between U3-1402 and trastuzumab (anti-HER2 antibody) using the MDA-MB-453 cell line, which expresses both HER2 and HER3. The activity of patritumab (naked antibody of U3-1402) was tested. In vivo efficacy of U3-1402 was also evaluated and immunostaining of HER3 and γH2AX (marker of DNA double-stranded breaks) as well as drug concentration assessment were performed. Results: U3-1402 bound to the cell surface of HER3-positive cell lines in HER3 expression level-dependent manner, and was then internalized into cells. Interestingly, the internalization rate of U3-1402 in MDA-MB-453 cells at 1 h was 64%, which was higher than that observed with trastuzumab (2%). Subsequently, U3-1402 was translocated to the lysosome, followed by payload release, leading to an improved cell growth inhibition compared to that noted with patritumab. In vivo antitumor efficacy was also demonstrated in a HER3-dependent manner in MDA-MB-453 xenograft model. In the study, internalization of HER3 from cell membrane into the intracellular compartment by U3-1402 treatment was observed, followed by increased free payload and γH2AX levels in tumor tissue. Conclusion: U3-1402 has a high internalization property for effective payload delivery to HER3-expressing cancer cells, resulting in a favorable ADC-driven efficacy. Citation Format: Kumiko Koyama, Yuuri Hashimoto, Yasuki Kamai, Yoshinobu Shiose, Manabu Abe, Yuki Kaneda, Naoyuki Maeda, Kenji Hirotani, Yusuke Ogitani, Tsuyoshi Karibe, Takashi Kagari, Kenichi Wakita, Suguru Ueno, Toshinori Agatsuma, Masato Murakami. U3-1402, a novel HER3-targeting antibody-drug conjugate, exhibits its antitumor activity through increased payload intracellular delivery via highly efficient drug internalization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-275.

Pharmacokinetic (PK) and pharmacodynamic (PD) modeling was conducted for the reduction of peripheral lymphocytes after oral administration of CS-0777 to healthy rats, monkeys and experimental autoimmune encephalomyelitis (EAE) induced rats. The phosphorylated active metabolite of CS-0777, M1, is a selective sphingosine 1-phosphate receptor-1 modulator. A linear one- and two-compartment model with a reversible metabolism process characterized the time courses of CS-0777 and M1 concentrations in rats and monkeys, respectively. The relationship between lymphocyte counts and M1 concentrations in blood was well described by an indirect response model in all animals examined. An I

We have previously disclosed 1,2,4-oxadiazole derivative 3 as a potent S1P3-sparing S1P1 agonist. Although compound 3 exhibits potent and manageable immunosuppressive efficacy in various in vivo models, recent studies have revealed that its 1,2,4-oxadiazole ring is subjected to enterobacterial decomposition. As provisions for unpredictable issues, a series of alternative compounds were synthesized on the basis of compound 3. Extensive SAR studies led to the finding of 1,3-thiazole 24c with the EC50 value of 3.4 nM for human S1P1, and over 5800-fold selectivity against S1P3. In rat on host versus graft reaction (HvGR), the ID50 value of 24c was determined at 0.07 mg/kg. The pharmacokinetics in rat and monkey is also reported. Compared to compound 3, 24c showed excellent stability against enterobacteria.

S1P(3)-sparing S1P(1) agonists have attracted attention as a suppressant of autoimmunity with reduced side effects. Our synthetic efforts and extensive SAR studies led to the discovery of 10b named CS-2100 with the EC(50) value of 4.0 nM for human S1P(1) and over 5000-fold selectivity against S1P(3). The in vivo immunosuppressive efficacy was evaluated in rats on host versus graft reaction and the ID(50) value was determined at 0.407mg/kg. The docking studies of CS-2100 with the homology model of S1P(1) and S1P(3) showed that the ethyl group on the thiophene ring of CS-2100 was sterically hindered by Phe263 in S1P(3), not in the case of Leu276 in S1P(1). This observation gives an explanation for the excellent S1P(3)-sparing characteristic of CS-2100.

CS-0777 (3) is phosphorylated in vivo, and the phosphate of CS-0777 (CS-0777-P) (4) acts as a selective S1P receptor-1 (S1P1) modulator. We report herein the synthesis of CS-0777 and CS-0777-P, pharmacological effects such as S1P1 and S1P3 agonist activity in vitro, peripheral blood lymphocyte lowering effects and the suppressive effect on experimental autoimmune encephalomyelitis (EAE), and also the pharmacokinetics in rats. CS-0777-P had ∼320-fold greater agonist activity for human S1P1 (EC50; 1.1 nM) relative to S1P3 (EC50; 350 nM). Following administration of single oral doses of 0.1 and 1 mg/kg of CS-0777 in rats, lymphocyte counts decreased significantly, with a nadir at 12 h postdose and recovery to vehicle control levels by 5 days postdose. In the EAE model compared to the vehicle-treated group, significant decreases in the cumulative EAE scores were observed for the 0.1 and 1 mg/kg CS-0777 groups in rats. CS-0777 is currently in clinical trials for the treatment of multiple sclerosis (MS).

Arthritis can be induced in mice by the injection of anti-type II collagen (anti-CII) Ab and LPS. To elucidate the role of IL-1 receptor antagonist (IL-1ra) in Ab-induced arthritis, WT and IL-1ra(-/-) mice were administered anti-CII Ab and LPS. These IL-1ra(-/-) mice developed severe arthritis even at low doses of anti-CII Ab and LPS, while WT mice did not. The cells that invaded the arthritic joints were mainly Gr-1(+) neutrophils, and the number of the cells in the joints remained high over 4 weeks in the IL-1ra(-/-) mice. KC, a ligand for CXCR2, is found in higher levels in the arthritic paws of IL-1ra(-/-) mice compared with the WT, and most of the cells that infiltrated into the joints of the IL-1ra(-/-) mice were CXCR2-expressing neutrophils. Administration of anti-CXCR2 Ab completely inhibited arthritis development. The anti-CXCR2 Ab decreased the number of neutrophils in the blood and also inhibited the migration of neutrophils to KC. These results suggested that the high susceptibility of IL-1ra(-/-) mice to anti-CII Ab-induced arthritis was due to the higher expression of chemotactic factors like KC and the sustained infiltration of CXCR2-expressing neutrophils into the joints.

In mice arthritis model induced by anti-type II collagen (CII) antibodies and lipopolysaccharide (LPS), most of cells that infiltrated into the joint space were neutrophils. To investigate the role of neutrophils in the pathogenesis of arthritis, we depleted the neutrophils in vivo by injection of the antibody against Gr-1 expressed mainly on neutrophils. The neutrophil depletion completely inhibited the arthritis development. Furthermore, neutrophil depletion in mice that had already developed arthritis ameliorated the disease. These results showed that neutrophils are indispensable not only for the development, but also for the maintenance of arthritis. Next, we tried to develop arthritis in C5-deficient mice to investigate the involvement of C5a, one of chemotactic factors for neutrophils. C5-deficient mice showed significant reduction in arthritis development in comparison with wild type mice. Injection of pertussis toxin (Ptx) into the mice, which inhibits the signals from the inhibitory G-protein coupled-receptors including the C5a receptor, suppressed the development of arthritis. Furthermore, Ptx also ameliorated the arthritis when injected into mice that had already developed the disease. These results suggest the important role of chemotactic factors involving C5a and inhibitory G-protein (Gi)-coupled receptors not only in the development, but also in the maintenance of arthritis.

Anti-type II collagen (anti-CII) Ab is a well-known autoantibody observed in patients with rheumatoid arthritis. Injection of anti-CII Ab and LPS induces arthritis in mice in which anti-CII Ab as well as inflammatory cytokines, IL-1beta and TNF-alpha, play critical roles. We investigated the involvement of IgG FcRs (FcgammaRs) in this arthritis model. BALB/c mice injected with the F(ab')(2) of anti-CII Ab showed no signs of arthritis. Arthritis development was not observed in FcRgamma(-/-) mice and was partially suppressed in FcgammaRIII(-/-) mice despite the binding of anti-CII Ab and C3 to cartilage surface. Surprisingly, BALB/c mice lacking FcgammaRIIB, which is known as an inhibitory FcgammaR, developed arthritis with no exacerbation in arthritis score compared with wild-type (WT) mice, and only slight exacerbation was observed in the histopathological analysis. In contrast, aged FcgammaRIIB(-/-) BALB/c mice developed arthritis without LPS injection, suggesting an augmented susceptibility to arthritis in aged FcgammaRIIB(-/-) mice. No significant difference was observed among BALB/c-WT, -FcRgamma(-/-), and -FcgammaRIIB(-/-) mice on cytokine production induced by anti-CII Ab and LPS injection. Severe arthritis developed in BALB/c-WT and -FcgammaRIIB(-/-) mice, but not in BALB/c-FcRgamma(-/-) mice, after the injection of anti-CII Ab and inflammatory cytokines. These results suggest that the reason behind the nondevelopment of arthritis in FcRgamma(-/-) BALB/c mice is not due to a disorder in transient cytokine production, but to an irregularity downstream of cytokine production.

We report herein the synthesis and structure-activity relationships (SAR) of a series of benzyl ether compounds as an S1P₁ receptor modulator. From our SAR studies, the installation of substituents onto the central benzene ring of 2a was revealed to potently influence the S1P₁ and S1P₃ agonistic activities, in particular, an ethyl group on the 2-position afforded satisfactory S1P₁/S1P₃ selectivity. These changes of the S1P₁ and S1P₃ agonistic activities caused by the alteration of substituents on the 2-position were reasonably explained by a docking study using an S1P₁ X-ray crystal structure and S1P₃ homology modeling. We found that compounds 2b and 2e had a potent in vivo immunosuppressive efficacy along with acceptable S1P₁/S1P₃ selectivity, and confirmed that these compounds had less in vivo bradycardia risk through the evaluation of heart rate change after oral administration of the compounds (30 mg/kg, p.o.) in rats.

Some pyridyl-pyrrole compounds were found to have inhibitory activities against p38 MAP kinase. Their activity was much more potent than that of SB203580 that has a similar overall structure but with a different core group, i.e., an imidazole ring. The complex structure modeling was therefore carried out in an attempt to obtain insights into the interactions of the kinase with the pyridyl-pyrrole compounds and SB203580. The resultant complex models revealed that the imidazole and the pyrrole compounds had similar binding modes and that the representative interactions between the enzyme and the ligand moiety (pyridyl or phenyl) were common. For the sulfoxy moiety including the aliphatic tethers attached to a terminal functional group, the amino acid residues interacting with the moiety were elucidated. Lastly, the affinities of the inhibitors were estimated by calculating the score values with the Ludi program and a good correlation between the p38 MAP kinase inhibitory activities and the score values was found.

Calsequestrin (CSQ)-binding 30-kDa protein in the sarcoplasmic reticulum (SR) of rabbit skeletal muscle was purified from the junctional face membrane (JFM) in the SR. Analysis of proteins which bound to the affinity column conjugated with the purified 30-kDa protein was performed. As a result, in the heavy fraction of the SR (HSR), four proteins including CSQ proved to be adsorbed on the column, and in the JFM, one protein, whose molecular weight was about 25-kDa. was mainly adsorbed. Furthermore, the same 25-kDa protein was found to be adsorbed on the CSQ affinity column. This 25-kDa protein is probably the CSQ-binding 26-kDa protein (junctin) recently reported [Jones, L. R., et al. (1995) J. Biol. Chem. 270, 30787] judging from the molecular weight and the CSQ-binding property. These results suggest that three proteins, CSQ, 30-kDa protein, and 25-kDa protein, form a protein complex in the terminal cisternae of the SR.

We have previously disclosed 1,2,4-oxadiazole derivative 3 as a potent S1P(3)-sparing S1P(1) agonist. Although compound 3 exhibits potent and manageable immunosuppressive efficacy in various in vivo models, recent studies have revealed that its 1,2,4-oxadiazole ring is subjected to enterobacterial decomposition. As provisions for unpredictable issues, a series of alternative compounds were synthesized on the basis of compound 3. Extensive SAR studies led to the finding of 1,3-thiazole 24c with the EC(50) value of 3.4 nM for human S1P(1), and over 5800-fold selectivity against S1P(3). In rat on host versus graft reaction (HvGR), the ID(50) value of 24c was determined at 0.07 mg/kg. The pharmacokinetics in rat and monkey is also reported. Compared to compound 3, 24c showed excellent stability against enterobacteria.

Modulators of sphingosine phosphate receptor-1 (S1P(1)) have recently been focused as a suppressant of autoimmunity. We have discovered a 4-ethylthiophene-based S1P(1) agonist 1-({4-Ethyl-5-[5-(4-phenoxyphenyl)-1,2,4-oxadiazol-3-yl]-2-thienyl}methyl)azetidine-3-carboxylic acid (CS-2100, 8) showing potent S1P(1) agonist activity against S1P(3) and an excellent in vivo potency. We report herein the synthesis of CS-2100 (8) and pharmacological effects such as S1P(1) and S1P(3) agonist activity in vitro, peripheral blood lymphocyte lowering effects and the suppressive effects on adjuvant-induced arthritis and experimental autoimmune encephalomyelitis (EAE) in animal models. The pharmacokinetic data were also reported. CS-2100 (8) had >5000-fold greater agonist activity for human S1P(1) (EC(50); 4.0 nM) relative to S1P(3) (EC(50); >20,000 nM). Following administration of single oral doses of 0.1 and 1 mg/kg of CS-2100 (8) in rats, lymphocyte counts decreased significantly, with a nadir at 8 and/or 12 h post-dose and recovery to vehicle control levels by 24-48 h post-dose. CS-2100 (8) is efficacious in the adjuvant-induced arthritis model in rats (ID(50); 0.44 mg/kg). In the EAE model compared to the vehicle-treated group, significant decreases in the cumulative EAE scores were observed for 0.3 and 1 mg/kg CS-2100 (8) groups in mice. While CS-2100 (8) showed potent efficacy in various animal disease models, it was also revealed that the central 1,2,4-oxadiazole ring of CS-2100 (8) was decomposed by enterobacteria in intestine of rats and monkeys, implicating the latent concern about an external susceptibility in its metabolic process in the upcoming clinical studies.

Generation of a robust immunological memory response is essential for protection on subsequent encounters with the same pathogen. The magnitude and quality of the memory CD8 T-cell population are shaped and influenced by the strength and duration of the initial antigenic stimulus as well as by inflammatory cytokines. Although chemokine receptors have been established to play a role in recruitment of effector CD8 T cells to sites of inflammation, their contribution to determination of T-cell fate and shaping of the long-lived memory T-cell population is not fully understood. Here, we investigated whether reduced access to antigen and inflammation through alterations in expression of inflammatory and homeostatic chemokine receptors has an impact on generation of effector and memory CD8 T cells. We found that in mice infected with lymphocytic choriomeningitis virus, colocalization of virus-specific CD8 T cells with antigen in spleen is dependent on expression of the inflammatory chemokine receptor, CXCR3. In addition, absence of CXCR3 expression on CD8 T cells leads to formation of fewer short-lived effector cells and more memory precursor cells. Furthermore, the memory CD8 T-cell population derived from CXCR3-deficient cells has fewer cells of the effector memory phenotype and exhibits a recall response of greater magnitude than that of WT cells. These data demonstrate that CD8 T-cell positioning relative to antigen and inflammatory cytokines in secondary lymphoid organs affects the balance of effector and memory T-cell formation and has both a quantitative and qualitative impact on the long-lived memory CD8 T-cell population.

In order to develop a new class of anti-rheumatic drugs which inhibit production of proinflammatory cytokines such as TNFα, IL-1β, IL-6, and IL-8, a series of 3-pyridylpyrrole derivatives possessing a bicyclic tetrahydropyridine moiety at the 4-position of the pyrrole ring are synthesized and their pharmacological activities are evaluated.

The synthesis and biological activity of N- and α-position substituted tetrahydropyridine derivatives is presented.

In order to develop a new class of anti-rheumatic drug which inhibits production of proinflammatory cytokines such as TNFalpha, IL-1beta, IL-6, and IL-8, a series of 3-pyridylpyrrole derivatives possessing a bicyclic tetrahydropyridine moiety at the 4-position of the pyrrole ring were synthesized and their pharmacological activities were evaluated. The derivatives were found to have potent inhibitory activities on the production of the cytokines both in vitro and in vivo. Among them, compound 4a, (S)-2-(4-fluorophenyl)-4-(1,2,3,5,6,8a-hexahydroindolizin-7-yl)-3-(pyridin-4-yl)-1H-pyrrole (R-132811), achieved the most promising results in various in vitro and in vivo tests including several rheumatoid arthritis models ((i) inhibition of p38alpha, p38beta, p38gamma, and p38delta MAP kinases: IC(50)=0.034, 0.572, >10, and >10 microM, respectively; (ii) inhibition of TNFalpha, IL-1beta, IL-6, and IL-8 production in human whole blood: IC(50)=0.026, 0.020, 0.88, and 0.016 microM, respectively; (iii) inhibition of LPS induced TNFalpha, IL-1beta and IL-6 production in mice: ID(50)=0.93, 8.63, and 0.11 mg/kg, p.o., respectively; (iv) inhibition of anti-collagen antibody-induced arthritis in mice: ID(50)=2.22 mg/kg, p.o.; (v) inhibition of collagen-induced arthritis in mice: ID(50)=2.38 mg/kg, p.o.; (vi) prophylactic effect on adjuvant-induced arthritis in rats: ID(50)=3.1 mg/kg, p.o.; (vii) therapeutic effect on adjuvant-induced arthritis in rats: ID(50)=4.9 mg/kg, p.o.; (viii) analgesic effect on adjuvant-induced arthritic pain in rats: ID(50)=2.9 mg/kg, p.o.). As a result, compound 4a was chosen as a candidate for further pre-clinical studies.

We previously reported a novel pyrrole derivative 1 which possesses a tetrahydropyridine group at the beta-position with a proinflammatory cytokine TNFalpha production inhibitor. Herein, we report the synthesis and biological activity of N- and alpha-position substituted tetrahydropyridine derivatives. In this series, we found that compound 3o showed good inhibitory activity in vitro (inhibition of lipopolysaccharide (LPS)-induced TNFalpha production in human whole blood, IC(50)=0.44 microM) and compound 3i demonstrated potent inhibitory activity in vivo (inhibition of LPS-induced TNFalpha production in mice, ID(50)=1.42 mg/kg).

We investigated proinflammatory cytokine TNFalpha production inhibitors in order to develop novel anti-inflammatory agents. According to the results, we found that 17, a pyrrole derivative possessing a tetrahydropyridine group at the beta-position, showed potent inhibitory activity in vitro (inhibition of lipopolysaccharide (LPS) induced TNFalpha production in human whole blood, IC(50)=1.86 microM) and in vivo (inhibition of LPS induced TNFalpha production in mice, ID(50)=5.98 mg/kg).

Injection of anti-type II collagen Ab and LPS induces arthritis in mice. The levels of IL-1β, IL-6, and chemokines (macrophage inflammatory protein (MIP)-1α, MIP-2, and monocyte chemoattractant protein-1) in the hind paws increased with the onset of arthritis and correlated highly with arthritis scores. The level of TNF-α was also elevated, but only transiently. Quantitative real-time PCR analysis revealed increases in cytokine and chemokine mRNA. To elucidate the contribution of inflammatory cytokines and chemokines in arthritis development more directly, recombinant proteins, neutralizing Abs, and knockout mice were used. The injection of rIL-1β or TNF-α, but not IL-6 or chemokines, induced arthritis when mice were i.v. preinjected with anti-type II collagen Ab. However, a single injection of recombinant cytokines or chemokines into the hind paws did not induce swelling. Arthritis development was inhibited by neutralizing Ab against IL-1β, TNF-α, or MIP-1α. In contrast, the inhibitory effect by anti-MIP-2 Ab was partial and, surprisingly, Abs to IL-6 and monocyte chemoattractant protein-1 showed no inhibitory effect. Furthermore, arthritis development in IL-1R−/− mice and TNFR−/− mice was not observed at all, but severe arthritis was developed in IL-6−/− mice. These results suggest that IL-1β and TNF-α play more crucial roles than IL-6 or chemokines in this model. Because arthritis was also developed in SCID mice, the development of arthritis in the Ab-induced mice model is due to a mechanism that does not involve T or B cells.

The effects of an inhibitor of ADP/ATP translocase (AAT) mainly expressed in the mitochondria inner membrane, atractyloside (ATR), on the gating property of the Ca2+ channels in the sarcoplasmic reticulum (SR) vesicles from the rabbit skeletal muscle were investigated using ion flux measurement and single channel recording. At 10 microM of cytoplasmic Ca2+, ATR decreased the rate constant of choline+ influx through the Ca2+ channels up to about 60% and perfectly inhibited about half the population of single Ca2+ channels incorporated into planar bilayers. Furthermore, the inhibition of the Ca2+ channels by ATR was effective at lower Ca2+. These results support the previous results that AAT exists in the skeletal muscle SR and plays a key role in the Ca2+ mobilization of the skeletal muscle cell [Yamaguchi, N., and Kasai, M. (1998) Biochem. J. 335, 541-547], and the number of Ca2+ channels regulated by AAT is thought to depend on the cytoplasmic Ca2+ concentration.

In response to infection, activated CD8 T cells differentiate in vivo into a heterogeneous population of cells consisting of short-lived, terminally differentiated effector cells and memory precursor cells that give rise to long-lived memory cells. The strength and duration of antigenic stimulation and inflammatory signals influence CD8 T cell differentiation and the balance between these two fates. However, cell extrinsic cues, such as chemokines, that affect the localization and hence the exposure of CD8 T cells to antigenic and inflammatory signals are not completely understood. Here, we find that the inflammatory chemokine receptor CXCR3 is upregulated on activated CD8 T cells and influences their differentiation. CXCR3 guides activated CD8 T cells towards marginal zone areas where they are exposed to antigenic and potentially inflammatory stimuli. In the absence of CXCR3 expression, activated CD8 T cells are localized to the T zones of the splenic white pulp where they are less likely to receive antigenic stimulation. The increased exposure to antigen is associated with an increase in the generation of short-lived effector cells while the decreased exposure to antigen is associated with a quantitative and qualitative enhancement of memory cells. Our findings demonstrate that chemokine receptors and T cell positioning in secondary lymphoid organs can influence the balance of effector and memory T cell generation.