Oral MucoRice-CTB vaccine for safety and microbiota-dependent immunogenicity in humans: a phase 1 randomised trial.

BACKGROUND: There are an estimated 1·3-4·0 million cases of cholera and 20 000-140 000 cholera-related deaths worldwide each year. The rice-based cholera toxin B subunit (CTB) vaccine, MucoRice-CTB, is an oral candidate vaccine that does not require a cold chain, has shown efficacy in animal models, and could be of benefit in places where there is a paucity of medical infrastructure. We aim to assess the safety, tolerability, and immunogenicity of MucoRice-CTB in humans. METHODS: We did a double-blind, randomised, placebo-controlled, dose-escalation, phase 1 study at one centre in Tokyo, Japan. Eligible participants were healthy adult men with measurable serum and faecal antibodies against CTB at screening. Participants were excluded if they had allergy to rice; history of cholera or travellers' diarrhoea; poorly controlled constipation; abnormal results on hepatic, renal, or haematological screening tests; use of any over-the-counter drugs within 7 days before first administration; inability to use a medically acceptable means of contraception; or other reasons by medical judgment of the investigator. Three dose cohorts of participants were randomly assigned by block to receive oral MucoRice-CTB (1 g, 3 g, or 6 g) or placebo (1 g, 3 g, or 6 g), once every 2 weeks for 8 weeks (for a total of 4 doses). The dose groups were performed sequentially, and each dose cohort was completed before the higher dose cohort began. All medical staff, participants, and most trial staff were masked to treatment allocation. The primary outcomes were safety and tolerability, measured by 12-lead electrocardiogram; vital signs; haematology, biochemistry, and urinalysis; rice protein-specific serum IgE antibody concentration; and monitoring of adverse events. Participants were assessed at baseline and at 1, 2, 4, 6, 8, and 16 weeks after the first administration of vaccine or placebo. The safety analysis set included all participants enrolled in the trial who received at least one dose of the study drug or placebo and were compliant with good clinical practice. The full analysis population included all participants enrolled in the trial who received at least one dose of the study drug and for whom any data were obtained after the start of study drug administration. Meta-genomic analysis of study participants was performed using bacterial DNA from faecal samples before vaccination. This trial is registered with UMIN.ac.jp, UMIN000018001. FINDINGS: Between June 23, 2015, and May 31, 2016, 226 participants were recruited and assessed for eligibility. 166 participants were excluded based on health condition or schedule. We then randomly selected 60 male volunteers aged 20-40 years who were enrolled and assigned to MucoRice-CTB (10 participants assigned to 1 g, 10 participants assigned to 3 g, and 10 participants assigned to 6 g), or placebo (10 participants assigned to 1 g, 10 participants assigned to 3 g, and 10 participants assigned to 6 g). All participants received at least one dose of study drug or placebo and were included in the safety analyses. Two participants given MucoRice-CTB 3 g and one participant given MucoRice-CTB 6 g were lost to follow-up and excluded from the efficacy analysis. Serum CTB-specific IgG and IgA antibody concentrations in participants who received 6 g MucoRice-CTB increased significantly in both a time-dependent and dose-dependent manner compared with those in the placebo groups (p for interaction=0·002 for IgG, p=0·004 for IgA). Genome analysis of subjects' faeces before vaccination revealed that compared to non-responders, responders had a gut microbiota of higher diversity with the presence of Escherichia coli and Shigella spp. 28 (93%) of 30 participants who received MucoRice-CTB at any dose had at least one adverse event during the study period, compared with 30 (100%) of 30 participants given placebo. Grade 3 or higher adverse events were reported in four participants in the MucoRice-CTB group (5 events) and four participants in the placebo group (10 events). The most common serious adverse event was haemoglobin decreased (2 events in 2 participants in the pooled MucoRice-CTB group, 2 events in 2 participants in the placebo group; all grade 3). INTERPRETATION: Participants given MucoRice-CTB showed increased CTB-specific serum IgG and IgA antibody concentrations without inducing serious adverse events, indicating that MucoRice-CTB could be a safe and potent vaccine to prevent diarrhoeal disease. MucoRice-CTB induced neutralising antibodies against diarrhoeal toxins in a gut microbiota-dependent manner. A similar phase 1 trial will be done with participants of other ethnicities to substantiate our findings. FUNDING: Translational Research Acceleration Network Program of Japan Agency for Medical Research and Development; Ministry of Education, Culture, Sports, Science and Technology, Japan; Science and Technology Research Partnership for Sustainable Development; Grant-in-Aid for Scientific Research (S) (18H05280) (to H K) from the Japan Society for the Promotion of Science (JSPS); Grant-in-Aid for Young Scientists (B) (16K16144) (to Y K) from JSPS; Grant-in-Aid for Young Scientists (18K18148) (to Y K) from JSPS; Grant from International Joint Usage/Research Center (K3002), the Institute of Medical Science, University of Tokyo.

Effects of AS2819899, a novel selective PI3Kδ inhibitor, in a NZB/W F1 mouse lupus-like nephritis model.

Phosphoinositide 3-kinases generate lipid-based second messengers that control an array of intracellular signaling pathways. In particular, phosphoinositide 3-kinases delta (PI3Kδ) is expressed primarily in hematopoietic cells and plays an important role in B-cell development and function. B cells play a critical role in autoimmune diseases by producing autoantibodies. Studies have therefore increasingly focused on PI3Kδ as a therapeutic target for the treatment of inflammatory and autoimmune diseases. One such autoimmune disease is systemic lupus erythematosus (SLE). SLE is a chronic systemic autoimmune disease with repeated recurrence and remission, and autoantibodies play an important role in its pathogenesis. Here, we examined the pharmacological profile of the novel PI3Kδ selective inhibitor AS2819899 and investigated its therapeutic potential against SLE in a NZB/W F1 mouse lupus-like nephritis model, a widely-used SLE mouse model. AS2819899 prevented B and T cell activation in vitro, and inhibited antibody production in a T-cell independent de novo antibody production mouse model. In the spontaneous NZB/W F1 mouse model, AS2819899 treatment significantly reduced anti-dsDNA antibody titers and improved kidney dysfunction. Further, AS2819899 inhibited the memory recall reaction in a T-cell dependent antibody production mouse model, suggesting that AS2819899 can potentially maintain remission of SLE. Moreover, we identified a pharmacodynamics marker for AS2819899 that may be useful in clinical studies. These results indicate that AS2819899 may be an attractive therapeutic candidate for SLE, including the maintenance of remission.

The PI3Kδ selective inhibitor AS2541019 suppresses donor-specific antibody production in rat cardiac and non-human primate renal allotransplant models.

Long-term graft survival after organ transplantation is difficult to achieve because of the development of chronic rejection. One cause of chronic rejection arises from antibody-mediated rejection (AMR), which is dependent on the production of donor-specific antibodies (DSA). Current immunosuppression in organ transplantation is effective in preventing acute T cell-mediated rejection, but the risk of DSA production and graft loss due to AMR remains unchanged. Phosphatidylinositol-3-kinase p110δ (PI3Kδ), a member of the family of PI3K lipid kinases, is a key mediator of B cell activation, proliferation and antibody production. AS2541019 is a novel PI3Kδ selective inhibitor that prevents antibody production by inhibiting B cell immunity. The purpose of this study was to evaluate the inhibitory effect of AS2541019 on DSA production in preclinical rodent and non-human primate allotransplant models. Concomitant administration of AS2541019 with tacrolimus and mycophenolate mofetil (MMF) inhibited de novo DSA production in an ACI-to-Lewis rat cardiac allotransplant model. To predict the efficacy of AS2541019 in clinical practice, we evaluated its effects in cynomolgus monkeys. AS2541019 inhibited B cell proliferation and major histocompatibility complex (MHC) class II expression on B cells in cynomolgus monkeys. Oral administration of AS2541019 inhibited MHC class II expression on peripheral B cells and anti-tetanus toxoid antibody production. In cynomolgus monkey renal allotransplant model, concomitant administration of AS2541019 with tacrolimus and MMF significantly inhibited de novo DSA production. Together, our findings indicate that the PI3Kδ selective inhibitor AS2541019 is a potential candidate for preventing AMR development by inhibiting DSA production.

Effects of AS2541019, a novel selective PI3Kδ inhibitor, on antibody production and hamster to rat xenotransplantation.

B cell-mediated antibodies play a critical role in protecting the body from infections; however, excessive antibody production is involved in the pathogenesis of autoimmune diseases and transplanted organ rejection. Regulation of antibody production is therefore crucial for overcoming these complications. Phosphatidylinositol-3-kinase p110δ (PI3Kδ), a member of the family of PI3K lipid kinases, is a key mediator of B cell activation and proliferation, with a small molecule PI3Kδ inhibitor having been approved for the treatment of B cell lymphoma. However, the effect of PI3Kδ inhibitors on B cell-mediated antibody production has not been clearly elucidated. In this study, we investigated the effect of the selective PI3Kδ inhibitor, AS2541019, on B cell immunity and antibody production. Our results show that AS2541019 effectively prevented B cell activation and proliferation in vitro, and that oral administration of AS2541019 resulted in significant inhibition of both T-dependent and T-independent de novo antibody production in peripheral blood. Further, in a hamster to rat concordant xenotransplant model, AS2541019 significantly prolonged graft survival time by inhibiting xenoreactive antibody production. Therefore, our study demonstrates that the selective PI3Kδ inhibitor AS2541019 inhibits antibody production through potent inhibitory effects on B cell activation, and can protect against organ dysfunction.

The Effect of ASP2409, a Novel CD86-Selective Variant of CTLA4-Ig, on Renal Allograft Rejection in Nonhuman Primates.

BACKGROUND: Blockade of CD28-mediated T cell costimulation by a modified cytotoxic T lymphocyte-associated antigen 4 (CTLA4-Ig), belatacept, is a clinically effective immunosuppressive therapy for the prevention of renal allograft rejection. Use of belatacept-based calcineurin inhibitor-free immunosuppression, however, has demonstrated an increased frequency of cellular rejection episodes and immunosuppression-related safety issues relative to conventional regimens. Furthermore, belatacept typically requires infusion for its administration chronically, which may present an inconvenience to patients. To address these issues, a novel CTLA4-Ig variant, ASP2409, with improved CD86 binding selectivity and affinity relative to belatacept was created using DNA shuffling directed evolution methods. METHODS: We evaluated the immunosuppressive effect of ASP2409 on in vitro alloimmune T cell responses, in vivo tetanus toxoid (TTx)-induced immunological responses and renal transplantation in cynomolgus monkeys. RESULTS: ASP2409 had 6.1-fold higher and 2.1-fold lower binding affinity to monkey CD86 and CD80 relative to belatacept, respectively. ASP2409 was 18-fold more potent in suppressing in vitro alloimmune T cell responses relative to belatacept. In a cynomolgus monkey TTx immunization model, ASP2409 inhibited anti-TTx immune responses at a 10-fold lower dose level than belatacept. In a cynomolgus monkey renal transplantation model, subcutaneous injection of 1 mg/kg ASP2409 prevented allograft rejection through complete CD86 and partial CD80 receptor occupancies and dramatically prolonged renal allograft survival in combination with tacrolimus or mycophenolate mofetil/methylprednisolone. CONCLUSIONS: These results support the potential of ASP2409 as an improved CTLA4-Ig for maintenance immunosuppression in organ transplantation.

In vitro and in vivo characterization of AS2643361, a novel and highly potent inosine 5'-monophosphate dehydrogenase inhibitor.

Inosine 5'-monophosphate (IMP) dehydrogenase is a critical target in solid organ transplantation. To this end, the development of mycophenolate mofetil (MMF) represents a major advance in transplant medicine. Here, we investigated the in vitro and in vivo pharmacological effects of a novel IMP dehydrogenase inhibitor, AS2643361, in several immunological and non-immunological models. The in vitro inhibitory activity of AS2643361 on immune cell and endothelial cell proliferation and on antibody production from lipopolysaccharide-stimulated B cells, was significantly more potent than that of mycophenolic acid, the active form of MMF, despite the similar potency of these compounds on IMP dehydrogenase. In a rat heterotopic cardiac transplant model, monotherapy using orally administered AS2643361 at 10 or 20mg/kg/day prolonged the median graft survival time from 6 to 16 and 19days, respectively. In dinitrophenol-lipopolysaccharide stimulated rats, oral administration of AS2643361 at 2.5, 5 or 10mg/kg/day resulted in suppression of antibody production. In vivo antibody production against alloantigen was also suppressed by AS2643361 treatment at 5 or 10mg/kg/day. Furthermore, treatment with AS2543361 effectively inhibited balloon injury induced-intimal thickening, which is a major cause of late allograft loss. Overall, the in vivo activity of AS2643361 was over two-fold more potent than that of MMF. In addition, gastrointestinal toxicity, considered a dose-limiting factor for MMF, was reduced with AS2643361 treatment. These results suggest AS2643361 has higher potency and less toxicity than MMF, making it a potential candidate for treatment of acute and chronic rejection in transplant medicine.