Effect of anti-claudin 18.2 monoclonal antibody zolbetuximab alone or combined with chemotherapy or programmed cell death-1 blockade in syngeneic and xenograft gastric cancer models.

The development of targeted cancer therapies based on monoclonal antibodies against tumor-associated antigens has progressed markedly over recent decades. This approach is dependent on the identification of tumor-specific, normal tissue-sparing antigenic targets. The transmembrane protein claudin-18 splice variant 2 (CLDN18.2) is frequently and preferentially displayed on the surface of primary gastric adenocarcinomas, making it a promising monoclonal antibody target. Phase 3 studies of zolbetuximab, a chimeric immunoglobulin G1 monoclonal antibody targeting CLDN18.2, combined with 5-fluorouracil/leucovorin plus oxaliplatin (modified FOLFOX6) or capecitabine plus oxaliplatin (CAPOX) in advanced or metastatic first-line gastric or gastroesophageal junction (G/GEJ) adenocarcinoma have demonstrated favorable clinical results with zolbetuximab. In studies using xenograft or syngeneic models with gastric cancer cell lines, zolbetuximab mediated death of CLDN18.2-positive human cancer cell lines via antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in vitro and demonstrated anti-tumor efficacy as monotherapy and combined with chemotherapy in vivo. Mice treated with zolbetuximab plus chemotherapy displayed a significantly higher frequency of tumor-infiltrating CD8+ T cells versus vehicle/isotype control-treated mice. Furthermore, zolbetuximab combined with an anti-mouse programmed cell death-1 antibody more potently inhibited tumor growth compared with either agent alone. These results support the potential of zolbetuximab as a novel treatment option for G/GEJ adenocarcinoma.

Development of a novel Poly (I:C)-induced murine model with accelerated lupus nephritis and examination of the therapeutic effects of mycophenolate mofetil and a cathepsin S inhibitor.

Systemic lupus erythematosus (SLE) is an autoimmune disease involving multi-organ systems with a widely heterogeneous clinical presentation. Renal involvement, observed mainly in lupus nephritis (LN), is the most common organ lesion associated with SLE and a determinant of prognosis. However, treatment of LN remains controversial and challenging, prompting the need for novel therapeutic approaches. In particular, development of a clinically relevant LN animal model would greatly facilitate the development of new treatments. Here, we report a novel murine model for LN established by administering polyinosinic-polycytidylic acid (Poly (I:C)) to NZB/W F1 mice. We investigated the effectiveness of administering Poly (I:C) to NZB/W F1 mice for accelerating nephritis onset and explored the optimal conditions under which to enroll mice with nephritis with similar pathology for studying treatment candidates. Gene-expression analysis revealed that activation of macrophages, which are reported to be involved in the progression of LN in patients, was a unique characteristic in this accelerated nephritis model. Evaluation of the therapeutic effect of mycophenolate mofetil (MMF), a recommended first-choice agent for LN, in this novel LN model showed that MMF significantly reduced proteinuria. The cathepsin S (CatS) inhibitor ASP1617, which has been reported to prevent development of lupus-like glomerulonephritis in the spontaneous NZB/W F1 mouse model, also showed marked therapeutic effect in this model. Our novel Poly (I:C) accelerated LN model would thus be very useful for screening clinical candidates for LN, and CatS may be an attractive therapeutic target for the treatment of LN.

Preclinical Characterization of ASP2713, a Novel Igß and FcγRIIB Cross-Linking Antibody, for Prediction of Human Pharmacokinetics and Clinically Effective Dose.

Previously, we reported the fundamental pharmacological characteristics of a novel Igß and Fc gamma receptor IIB cross-linking antibody, ASP2713, as a new treatment option for systemic lupus erythematosus. The aims of the present study were to investigate ASP2713's characteristics with regard to pharmacological effect, pharmacokinetics (PK), and receptor occupancy, and to predict its human PK and clinically effective dose. The relationship between the concentration and receptor occupancy of ASP2713 for Igß of B cell receptors was examined using whole blood B cells. Calculated EC50 values in cynomolgus monkeys and healthy volunteers were 0.35 and 0.058 µg/mL, respectively. Dose-dependent inhibition of anti-tetanus toxoid (TTx) antibody production, PK, and receptor occupancy of ASP2713 in TTx-sensitized cynomolgus monkeys suggested a minimally effective dose of 1 mg/kg by single intravenous (IV) administration. Scaling-up of monkey PK parameters to humans by allometric scaling predicted a clinically effective dose of 0.4 mg/kg IV administration at 4-week intervals to maintain a trough concentration in humans which achieved the same receptor occupancy expected at the effective dose in monkeys. This study aids in understanding the characteristics of ASP2713 and can be used as a basis for clinical dose setting.

Potential benefit of the cathepsin S inhibitor, ASP1617, as a treatment for systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the dysregulation of various cell types and immunological pathways. Autoantibodies play an important role in its pathogenesis. The presence of autoantibodies suggests that self-antigen presentation through major histocompatibility complex (MHC) class II on antigen presenting cells is involved in the pathogenesis of autoimmune diseases, including SLE. Cathepsin S (CatS) is a key protease for antigen peptide loading onto lysosomal/endosomal MHC class II molecules through invariant chain degradation to promote antigen presentation. Inhibition of CatS is therefore expected to suppress antigen presentation via MHC class II, T and B cell activation, and antibody production from B cells. Here, we report the pharmacological profile of ASP1617, a novel CatS inhibitor. ASP1617 induced invariant chain accumulation and decreased the expression level of MHC class ΙΙ on the cell surface in both mouse and human B cells. Further, ASP1617 prevented DO11.10 mice T cell proliferation to ovalbumin antigen. We investigated the effects of ASP1617 and mycophenolate mofetil (MMF) on the development of lupus-like nephritis in NZB/W F1 mice, a widely used SLE mouse model. Oral administration of ASP1617 suppressed anti-dsDNA IgG, prevented progression of lupus-like glomerulonephritis, and significantly prevented proteinuria excretion. In contrast, MMF did not suppress anti-dsDNA IgG. Further, we found that plasma and/or urine CatS levels were increased in specimens from NZB/W F1 mice and several SLE patients. These results indicate that CatS may be an attractive therapeutic target for the treatment of SLE.

Discovery of a novel Igß and FcγRIIB cross-linking antibody, ASP2713, and its potential application in the treatment of systemic lupus erythematosus.

B cell-targeted therapies have evolved as established therapies for systemic lupus erythematosus (SLE); however, existing approaches still do not thoroughly satisfy clinical requirements due to limited efficacy against memory B cells, autoantibody-producing plasmablasts and disease heterogeneity. To provide a new treatment option for SLE, we created a novel anti-Igß antibody with enhanced affinity for Fc gamma receptor (FcγR) IIB called ASP2713. ASP2713 cross-reacted with both human and cynomolgus monkey Igß and showed increased binding affinity for human and monkey FcγRIIB compared to native human IgG1. This binding property allows dominant B cell binding and induction of intrinsic negative feedback signals. In human B cells, ASP2713 significantly and concentration-dependently induced FcγRIIB ITIM phosphorylation, while suppressing proliferation under B cell receptor stimulation. This pharmacological effect was also confirmed in in vitro B cell proliferation and antibody production assays using peripheral B cells isolated from patients with SLE. In a cynomolgus monkey tetanus toxoid-induced antibody production model, ASP2713 almost completely inhibited the increase in antigen-specific antibodies with superior efficacy to rituximab. Additionally, ASP2713 significantly suppressed recall antibody production in response to secondary tetanus toxoid immunization, indicating the memory B cell- and plasmablast-targeting potential of ASP2713. Our results suggest that ASP2713 may have therapeutic potential as a treatment for SLE, where B cells play a pathogenic role.

Characterization of ASP8374, a fully-human, antagonistic anti-TIGIT monoclonal antibody.

The T-cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains (TIGIT) is a validated immune checkpoint protein expressed on memory CD4+T-cellls, Tregs, CD8+T-cell and natural killer (NK) cells. ASP8374 is a fully human monoclonal immunoglobulin (Ig) G4 antibody designed to block the interaction of TIGIT with its ligands and inhibit TIGIT signaling. ASP8374 exhibited high affinity binding to TIGIT and increased interferon (IFN)-γ production of cultured peripheral blood mononuclear cells (PBMCs) in a titratable manner. When used in combination with pembrolizumab, an anti-programmed death-1 (PD-1) antibody, ASP8374 induced higher T-cell activation in vitro than either treatment alone. An anti-mouse TIGIT antibody surrogate, mSEC1, displayed anti-tumor efficacy in an MC38 syngeneic mouse tumor model alone and in combination with an anti-programmed death-ligand 1 (PD-L1) antibody. In an additional syngeneic mouse tumor model (CT26), while mSEC1 alone did not demonstrate anti-tumor efficacy, mSEC1 combined with an anti-PD-1 antibody enhanced anti-tumor efficacy above that of the anti-PD-1 antibody alone. These data provide evidence that ASP8374 has therapeutic potential for advanced malignancies.

Effects of ASKP1240 combined with tacrolimus or mycophenolate mofetil on renal allograft survival in Cynomolgus monkeys.

BACKGROUND: Blocking the CD40-CD154 signal pathway has previously shown promise as a strategy to prevent allograft rejection. In this study, the efficacy of a novel fully human anti-CD40 monoclonal antibody-ASKP1240, administered as a monotherapy or combination therapy (subtherapeutic dose of tacrolimus or mycophenolate mofetil), on the prevention of renal allograft rejection was evaluated in Cynomolgus monkeys. METHODS: Heterotopic kidney transplants were performed in ABO-compatible, stimulation index 2.5 or higher in the two-way mixed lymphocyte reaction monkey pairs. Animals were divided into 12 groups and observed for a maximum of 180 days. Histopathologic, hematology, and biochemistry analyses were conducted in all groups. Cytokine release (interleukin [IL]-2, IL-4, IL-5, IL-6, tumor necrosis factor, and interferon-γ) was investigated in several groups. RESULTS: ASKP1240 prolonged renal allograft survival in a dose-dependent manner in monotherapy. Low-dose (2 mg/kg) or high-dose (5 mg/kg) ASKP1240, in combination with mycophenolate mofetil (15 mg/kg) or tacrolimus (1 mg/kg), showed a significantly longer allograft survival time compared with monotherapy groups. No obvious side effects including drug-related thromboembolic complications were found. Cytokine release was not induced by ASKP1240 administration. CONCLUSION: The present study indicates that ASKP1240, alone or in combination with other immunosuppressive drugs, could be a promising antirejection agent in organ transplantation.

Pharmacokinetics and pharmacodynamics of ASKP1240, a fully human anti-CD40 antibody, in normal and renal transplanted Cynomolgus monkeys.

BACKGROUND: The purpose of this study was to evaluate the serum concentration of ASKP1240 (pharmacokinetics [PK]) and the CD40 occupancy of ASKP1240 (pharmacodynamics [PD]) in normal and renal transplanted Cynomolgus monkeys to clarify the PK/PD relationship. METHODS: In a 70-day study, two ASKP1240 doses (2 and 5 mg/kg) were evaluated in normal and transplanted monkeys. Full doses were administered during the induction phase, and half doses were administered during the maintenance phase. The PK and PD were assessed using ELISA and FACS assays. RESULTS: The serum concentration and receptor occupancy of ASKP1240 reached their maximum levels rapidly after the first dose and remained at an almost saturated rate during the induction phase. They then decreased gradually during the maintenance phase in all of the groups. The serum concentration and duration of full receptor occupancy were dose dependent in the normal and transplanted monkeys. On day 70 after therapy with 5 mg/kg ASKP1240, the transplanted monkeys presented a significantly lower occupancy of the CD40 receptors compared with the normal animals (5.5%±14.1% vs. 72.8%±3.4%). The serum concentration of ASKP1240 was also strongly correlated with the occupancy of the ASKP1240 receptors. CONCLUSION: This study showed strong positive PK/PD relationships in renal transplanted and normal monkeys. The results may thus serve as a guide for optimal dosage and timing of ASKP1240 therapy in clinical trials and will propel the translation of ASKP1240 therapeutics from the bench to preclinical and clinical trials.

Effect of the inosine 5'-monophosphate dehydrogenase inhibitor BMS-566419 on renal fibrosis in unilateral ureteral obstruction in rats.

Chronic allograft nephropathy (CAN) is a major cause of late allograft loss. One morphological characteristic of CAN is renal interstitial fibrosis. Mycophenolate mofetil (MMF), the inosine 5'-monophosphate dehydrogenase (IMPDH) inhibitor, has been reported to attenuate the progression of renal interstitial fibrosis. However, the question of whether the newly synthesized IMPDH inhibitors with structures different from MMF have an antifibrotic effect remains unanswered. We evaluated the antifibrotic effects of BMS-566419, a chemically synthesized IMPDH inhibitor, using an experimental rat model, unilateral ureteral obstruction (UUO), in comparison with those of MMF. Expression levels of monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-beta1 (TGF-ß1), which play important roles in UUO-induced renal fibrosis, were also investigated to determine the mechanism by which BMS-566419 affects the progression of renal fibrosis. After 14 days of UUO, interstitial fibrosis was frequently observed in the renal cortex of rats administered vehicle control. BMS-566419 by oral administration showed a significant and dose-dependent suppressive effect on UUO-induced renal fibrosis in histopathological experiments. BMS-566419 treatment also decreased collagen content, as indicated by hydroxyproline concentration, and the expression of collagen type 1 mRNA. BMS-566419 also decreased the expression of mRNA for both MCP-1 and TGF-ß1. The antifibrotic effects of treatment with BMS-566419 at 60 mg/kg seemed comparable to those with MMF at 40 mg/kg. These results suggest that BMS-566419 and other chemically synthesized IMPDH inhibitors have beneficial pharmacological effects similar to those of MMF, and are potential pharmaceutical candidates in the treatment of fibrotic renal disease, including CAN.

Prevention of renal interstitial fibrosis via histone deacetylase inhibition in rats with unilateral ureteral obstruction.

Acute rejection following renal transplantation has become manageable with the introduction of calcineurin inhibitors, FK506 and cyclosporine A. However, chronic allograft dysfunction accompanied by renal interstitial fibrosis, which induces graft loss, remains unresolved. Here, we evaluated the effect of FR276457, a pan-histone deacetylase (HDAC) inhibitor, on interstitial fibrosis in the injured kidneys of a rat model of unilateral ureteral obstruction. The injured kidneys, harvested on Day 14 following the operation, showed progression of interstitial fibrosis, increases of hydroxyproline contents, and mRNA expression of collagen type Ialpha1 and monocyte chemotactic protein 1 (MCP-1). However, these changes were found to be prevented with daily oral administration of FR276457. In addition, given that MCP-1 is believed to contribute to progressive fibrosis, we investigated the direct effect of FR276457 on MCP-1 production by activated THP-1 cells in vitro. Results showed that FR276457 administration decreased MCP-1 production in these cells in a concentration-dependent manner. Findings from the present study suggested that a pan-HDAC inhibitor may exert a prophylactic effect against renal interstitial fibrosis by inhibiting MCP-1 production.

Surgical complications in kidney transplantation in nonhuman primates.

Surgical complications are important causes of graft loss in the nonhuman primate kidney transplantation model. We reviewed the incidence and intervention methods in 182 kidney transplantations performed in our lab recently 2 years in Cynomolgus monkeys. There were six renal artery thromboses (3.3%), eight urine leakages (4.4%), and five ureteral stenoses (2.7%). All renal artery thrombosis cases were found within 3 days after surgery. Urine leakage appeared from the 5th to 12th day after surgery and all cases were caused by ureter rupture. Reexploration was performed in five cases to reanastomose ureter with stent. Four cases reached long-term survival. The rest one died of graft rejection. Ureteral stenoses were found in long-term survival cases. Ureter reanastomoses with stent were performed in two cases. The postoperative renal functions of these two monkeys recovered to normal and they survived until study termination. From this large number of study, our experience indicated that kidney transplantation in the nonhuman primate is a safe procedure with low complications. Reexploration is recommended for salvage of the graft with urine leakage and ureteral stenosis.

Effect of the immunosuppressant histone deacetylase inhibitor FR276457 in a canine renal transplant model.

The histone deacetylase (HDAC) inhibitor FR276457, a hydroxamic derivative, was identified during chemical library screening and was found to exhibit potent inhibitory effects on the activity of mammalian HDACs. It has been shown that FR276457 exhibited marked immunosuppressive effects in a rat heterotopic cardiac transplant model. To predict clinical efficacy of FR276457, we investigated the inhibitory effect of the proliferation of Jurkat cells in vitro and immunosuppressive effect of orally administered FR276457 on allograft rejection as a monotherapy or in combination with tacrolimus (0.04 mg/kg) injected intramuscularly (i.m.) in a canine renal transplant model. Animal survival, the plasma creatinine level, and histopathology were evaluated. FR276457 inhibited the proliferation of Jurkat cells probably by targeting activity of NF-kappaB. FR276457 prolonged the median survival time (MST) of transplanted grafts from 11.5 days (untreated group) to 29.0 days (FR276457-treated group). FR276457 administered 1 mg/kg twice a day in combination with tacrolimus prevented allograft rejection. In addition, a dose of 1.5 mg/kg twice a day or 5.0 mg/kg once a day prolonged the MST from 18 days (control group) to >73 or >90 days, respectively. Histopathological analysis showed that FR276457 suppressed the score for mononuclear cell infiltration and vasculitis. In conclusion, the HDAC inhibitor FR276457 inhibited the proliferation of T cell line established from human in vitro. And more, FR276457 clinically prolonged allograft survival when administered as a monotherapy, and had additive or synergistic effects when combined with tacrolimus with the canine renal transplant model. These results showed HDAC inhibitor is a promising biological target for treatment in transplant field.

Efficacy of oral treatment with tacrolimus in the renal transplant model in cynomolgus monkeys.

Many studies have examined the efficacy of tacrolimus in rats and dogs, but few have reported its evaluation in cynomolgus monkeys. The aim of this study was to clarify the efficacy of tacrolimus in a cynomolgus monkey renal transplant model based on the efficacy of various doses. Monkeys that had undergone renal transplant were treated with a vehicle or 0.5, 1.0, or 2.0 mg/kg of tacrolimus by oral administration. Tacrolimus administration prolonged animal survival in a dose-dependent manner, and the median survival time (MST) was 11, 21, and >90 days for the 0.5, 1.0, and 2.0 mg/kg tacrolimus groups, respectively. The MST of the vehicle group was 6 days. Histopathological analyses of all transplanted kidneys were also performed. Typical pathological findings of acute rejection were observed in both the vehicle and tacrolimus (0.5 and 1.0 mg/kg)-treated groups. Only limited mononuclear cell infiltration and hemorrhage were present in the tacrolimus (2.0 mg/kg)-treated group. In conclusion, 2.0 mg/kg was considered to be a therapeutic dose in this model, and 0.5 or 1.0 mg/kg could be used for a study when efficacy of a new compound is evaluated in a combination therapy with tacrolimus.

Effect of a new immunosuppressant histon deacetylase (HDAC) inhibitor FR276457 in a rat cardiac transplant model.

Histone deacetylase (HDAC) is a known modulator of gene transcription, and the immunosuppressive activity of HDAC inhibitors has been demonstrated in recent several reports. In this study, the HDAC inhibitor FR276457, a hydroxamic derivative, was found to have a similar inhibitory effect on all mammalian HDACs tested, but no isozyme selectivity. Both FR276457 and tacrolimus exerted an immunosuppressive effect on in vitro rat splenocyte proliferation stimulated with Concanavalin A. Next, the effect of FR276457 on allograft rejection when administered either as a monotherapy or in combination with tacrolimus was investigated in a rat heterotopic cardiac transplant model. Orally administered FR276457 prolonged the median survival times (MST) of the transplanted grafts in the vehicle group from 6 d to 17 or 21 d at doses of 20 or 40 mg/kg, respectively. Histopathological analysis showed the structures of the myocardium were not affected, but interstitial cellular infiltration could not be suppressed completely. Tacrolimus (0.032 mg/kg) prolonged allograft MST to 16 d. FR276457, when combined with tacrolimus, prevented allograft rejection at a dose lower than that of the monotherapy. The combination dose prolonged the MST in the groups treated with 10 and 20 mg/kg to >28 d, and cellular infiltration was suppressed completely. In conclusion, this study demonstrated that the oral administration of HDAC inhibitor FR276457 can prevent allograft rejection as a monotherapy, and has additive or synergistic effects when combined with tacrolimus.

Antigen presentation by Peyer's patch cells can induce both Th1- and Th2-type responses depending on antigen dosage, but a different cytokine response pattern from that of spleen cells.

The Th1 and Th2 preference induced by cells from the Peyer's patch (PP) and spleen (SPL) with various doses of an antigen was examined. The same splenic T cell receptor-transgenic CD4+ T cells were first incubated with PP or SPL cells in the presence of various doses of an antigen, and the cytokine response was observed after secondary stimulation. A Th2-type pattern was only obtained for primary stimulation at 10 microM of the antigen with PP cells, whereas a Th1 pattern was induced at both higher and lower concentrations. SPL cells in the presence of 0.1 to 1 microM of the antigen induced the secretion of Th2-type cytokines. Ten and 100 microM of the antigen plus SPL cells did not induce the release of a large quantity of cytokines. PP cells induced a different cytokine pattern at the antigen concentration that induced a similar level of T cell proliferation with SPL cells. Our findings suggest that the antigen-dose dependent development of Th1/Th2 cells is differentially modulated by the antigen-presentation function of cells in PP and SPL.