Safety and Immune Effects of Blocking CD40 Ligand in Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Costimulation by CD40 and its ligand CD40L (CD154) is important for the functional differentiation of T cells. Preclinical studies have recognized the importance of this costimulatory interaction in the pathogenesis of experimental models of multiple sclerosis (MS). To determine safety, pharmacokinetics, and immune effect of a humanized monoclonal antibody (mAb) against CD40 ligand (toralizumab/IDEC-131) in patients with relapsing-remitting MS (RRMS). METHODS: This single-institution open-label dose-escalation study (phase I) enrolled 12 patients with RRMS to receive 4 doses of 1, 5, 10, or 15 mg/kg of humanized αCD40L (toralizumab) IV infusion every other week. Patients were followed up to 18 weeks, annually, and finally at 5 years. In addition to safety and pharmacokinetics, other secondary and exploratory measurements are immune effects, clinical, MRI, laboratory, and neuropsychological evaluations. RESULTS: Fifteen adverse events, all of mild to moderate severity, were considered to be of possible or of unknown relationship to treatment. No serious adverse events, including thromboembolic events, occurred during the 18-week defined study period. Annual and long-term follow-up at 5 years revealed no delayed toxicity. Pharmacokinetics were nonlinear between the 5 and 10 mg/kg dose groups. The serum half-life of toralizumab was consistent between the dose groups with a mean of 15.3 days (SD = 1.9). Flow cytometry revealed no depletion of lymphocyte subsets. An increase in the CD25+/CD3+ and CD25+/CD4+ ratio and a shift toward an anti-inflammatory cytokine response were seen after treatment. DISCUSSION: Our study suggests that blocking CD40L is safe and well tolerated in patients with RRMS while increasing CD25 + T cells and anti-inflammatory cytokine profile. These findings support further studies to assess the efficacy of blocking CD40L as a potential treatment of RRMS. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence on the safety, pharmacokinetics, and immune effects of an mAb to CD40L in patients with RRMS.

Blocking antibodies induced by peanut oral and sublingual immunotherapy suppress basophil activation and are associated with sustained unresponsiveness.

BACKGROUND: Oral and sublingual immunotherapies for peanut allergy have demonstrated efficacy in small clinical trials; however, mechanisms and biomarkers correlating with clinical outcomes remain elusive. Previous studies have demonstrated a role for IgG in post-OIT plasma in the suppression of IgE-mediated mast cell reactions. OBJECTIVE: The aim of this study was to characterize the role that peanut oral and sublingual immunotherapy-induced plasma factors play in the inhibition of ex vivo basophil activation and whether inhibitory activity is associated with clinical outcomes. METHODS: Plasma samples from subjects on placebo, peanut oral immunotherapy (OIT) or peanut sublingual immunotherapy (SLIT), and IgG-depleted plasma or the IgG fraction were incubated with sensitized basophils, and the inhibition of basophil activation following stimulation with peanut extract was measured. Basophil inhibition results were compared between the two routes of immunotherapy, time on treatment and clinical outcomes. RESULTS: Plasma from subjects after 12 months of active peanut OIT, but not placebo, inhibits basophil activation ex vivo. Depletion of IgG abrogated the blocking effect of OIT plasma, while the IgG fraction substantially blocked basophil activation. Basophils are inhibited to a similar extent by undiluted OIT and SLIT plasma; however, diluted OIT plasma from the time of desensitization challenge inhibited basophils more than diluted SLIT plasma from time of desensitization challenge. Plasma from subjects who experienced sustained unresponsiveness following OIT inhibited basophils to a greater extent than plasma from subjects who were desensitized, but this was not true for SLIT. CONCLUSIONS AND CLINICAL RELEVANCE: Peanut immunotherapy induces IgG-dependent functional changes in plasma that are associated with OIT but not SLIT clinical outcomes. Understanding the mechanisms of peanut OIT and SLIT may help derive informative biomarkers.

Immune checkpoint inhibitors in sarcomas: in quest of predictive biomarkers.

Sarcomas are a rare group of tumors of mesenchymal origin. Metastatic sarcomas are often difficult to treat and unresponsive to standard radio- and chemotherapy, resulting in a poor survival rate for patients. Novel treatments with immune checkpoint inhibitors have been proven to prolong survival of patients with a variety of cancers, including metastatic melanoma, lung, and renal cell carcinoma. Since immune checkpoint inhibitors could provide a novel treatment option for patients with sarcomas, clinical trials investigating their efficacy in these group of tumors are ongoing. However, the discrimination of patients that are the most likely to respond to these treatments is still an obstacle in the design of clinical trials. In this review, we provide a brief overview of the mechanisms of action of immune checkpoint inhibitors and discuss the proposed biomarkers of therapy response, such as lymphocytic infiltration, intratumoral PD-L1 expression, and mutational load in sarcomas.

Effect of a glucagon receptor antibody (REMD-477) in type 1 diabetes: A randomized controlled trial.

The aim of the current study (Clinical trial reg. no. NCT02715193, clinicaltrials.gov) was to study the efficacy and safety of REMD-477, a glucagon receptor antagonist, in type 1 diabetes. This was a randomized controlled trial in which 21 patients with type 1 diabetes were enrolled. Glycaemic control and insulin use were evaluated in outpatient and inpatient settings, before and after a single 70-mg dose of REMD-477 (half-life 7-10 days) or placebo. Inpatient insulin use was 26% (95% CI, 47%, 4%) lower 1 day after dosing with REMD-477 than with placebo (P = .02). Continuous glucose monitoring during post-treatment days 6 to 12 showed that average daily glucose was 27 mg/dL lower (P < .001), percent time-in-target-range (70-180 mg/dL) was ~25% greater (~3.5 h/d) (P = .001), and percent time-in-hyperglycaemic-range (> 180 mg/dL) was ~40% lower (~4 h/d) (P = .001) in the REMD-477 group than in the placebo group, without a difference in percent time-in-hypoglycaemic-range (<70 mg/dL). No serious adverse events were reported. Glucagon receptor antagonism decreases insulin requirements and improves glycaemic control in patients with type 1 diabetes.

Bimagrumab improves body composition and insulin sensitivity in insulin-resistant individuals.

AIM: To test the hypothesis that an improving body composition in insulin-resistant individuals could enhance insulin sensitivity. METHODS: A total of 16 people with a mean body mass index of 29.3 kg/m2 and insulin resistance, received a single dose of bimagrumab or placebo and were assessed at week 10 for insulin sensitivity, using a hyperinsulinaemic-euglycaemic clamp and an intravenous glucose tolerance test (IVGTT), and for body composition using dual energy X-ray absorptiometry and positron-emission tomography. RESULTS: Bimagrumab increased lean mass by 2.7% (P < .05) and reduced fat mass by 7.9% (P = .011) at week 10 compared with placebo, and had a neutral effect on body weight. Bimagrumab reduced glycated haemoglobin by 0.21% at week 18 (P < .001) and improved insulin sensitivity by ~20% (according to the clamp) to ~40% (according to the IVGTT). CONCLUSION: Taking the observed changes together, and given that these occurred without accompanying dietary intervention and without any prescribed regular physical exercise, bimagrumab may offer a novel approach for the treatment of the metabolic complications of obesity.

A first-in-human pharmacodynamic and pharmacokinetic study of a fully human anti-glucagon receptor monoclonal antibody in normal healthy volunteers.

AIMS: Glucagon receptor (GCGR) blockers are being investigated as potential therapeutics for type 1 and type 2 diabetes. Here we report the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of REGN1193, a fully human glucagon receptor blocking monoclonal antibody from a first-in-human healthy volunteer randomized double-blinded trial. METHODS: Healthy men and women received single ascending doses of REGN1193 ranging from 0.05 to 0.6 mg/kg (n = 42) or placebo (n = 14) intravenously. Safety, tolerability and PK were assessed over 106 days. The glucose-lowering effect of REGN1193 was assessed after induction of hyperglycaemia by serial glucagon challenges. RESULTS: REGN1193 was generally well tolerated. There were small (<3× the upper limit of normal) and transient dose-dependent increases in hepatic aminotransferases. No increase in LDL-C was observed. Hypoglycaemia, assessed as laboratory blood glucose ≤70 mg/dL, occurred in 6/14 (43%) subjects on placebo and 27/42 (57%) on REGN1193 across all dose groups. All episodes of hypoglycaemia were asymptomatic, >50 mg/dL, and did not require treatment or medical assistance. Concentration-time profiles suggest a 2-compartment disposition and marked nonlinearity, consistent with target-mediated clearance. REGN1193 inhibited the glucagon-stimulated glucose increase in a dose-dependent manner. The 0.6 mg/kg dose inhibited the glucagon-induced glucose area under the curve for 0 to 90 minutes (AUC0-90 minutes ) by 80% to 90% on days 3 and 15, while blunting the increase in C-peptide. REGN1193 dose-dependently increased total GLP-1, GLP-2 and glucagon, with plasma levels returning to baseline by day 29 in all dose groups. CONCLUSION: REGN1193, a GCGR-blocking monoclonal antibody, produced a safety, tolerability and PK/PD profile suitable for further clinical development. The occurrence of transient elevations in serum hepatic aminotransferases observed here and reported with several small molecule glucagon receptor antagonists suggests an on-target effect of glucagon receptor blockade. The underlying mechanism is unknown.

Pharmacokinetic, Pharmacodynamic, and Safety Profile of a Novel Anti-CD28 Domain Antibody Antagonist in Healthy Subjects.

We report pharmacokinetics, pharmacodynamics, and safety of a novel anti-CD28 domain antibody antagonist (lulizumab pegol) in healthy subjects following single- or multiple-dose administration. A minimal anticipated biological effect level approach was used to select a 0.01 mg starting dose for a single-ascending-dose (SAD), double-blind, first-in-human study. Part 1 included 9 intravenous (IV; 0.01-100 mg) and 3 subcutaneous (SC; 9-50 mg) doses or placebo. In part 2, a keyhole limpet hemocyanin (KLH) immunization was performed in 16 subjects/panel, who received 1 of 3 IV doses (9-100 mg) or placebo. In a double-blind, multiple-ascending-dose (MAD) study, subjects received SC lulizumab 6.25 mg every 2 weeks, 12.5 mg weekly, 37.5 mg weekly, or placebo. Among 180 treated subjects, 169 completed the studies. Peak concentrations and areas under the curve from time 0 to infinity increased dose proportionally. Estimated SC bioavailability was 68.2%. Receptor occupancy of approximately ≥80% was maintained for ≥2 weeks at ≥9-mg doses (SAD) and throughout the dosing interval (MAD). IV doses ≥9 mg inhibited antibody production against KLH for 2 weeks. No significant cytokine or immune cell changes were observed. No immunogenicity responses persisted, and there was no correlation to adverse events. Headache occurred in 21 SAD and 4 MAD subjects receiving lulizumab; in the MAD study 5 lulizumab subjects experienced infections. Lulizumab IV or SC was safe at all doses studied, without evidence of cytokine release.

Hypophysitis Secondary to Cytotoxic T-Lymphocyte-Associated Protein 4 Blockade: Insights into Pathogenesis from an Autopsy Series.

Hypophysitis that develops in cancer patients treated with monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein 4 (CTLA-4; an inhibitory molecule classically expressed on T cells) is now reported at an incidence of approximately 10%. Its pathogenesis is unknown, in part because no pathologic examination of the pituitary gland has been reported to date. We analyzed at autopsy the pituitary glands of six cancer patients treated with CTLA-4 blockade, one with clinical and pathologic evidence of hypophysitis, one with mild lymphocytic infiltration in the pituitary gland but no clinical signs of hypophysitis, and four with normal pituitary structure and function. CTLA-4 antigen was expressed by pituitary endocrine cells in all patients but at different levels. The highest levels were found in the patient who had clinical and pathologic evidence of severe hypophysitis. This high pituitary CTLA-4 expression was associated with T-cell infiltration and IgG-dependent complement fixation and phagocytosis, immune reactions that induced an extensive destruction of the adenohypophyseal architecture. Pituitary CTLA-4 expression was confirmed in a validation group of 37 surgical pituitary adenomas and 11 normal pituitary glands. The study suggests that administration of CTLA-4 blocking antibodies to patients who express high levels of CTLA-4 antigen in the pituitary can cause an aggressive (necrotizing) form of hypophysitis through type IV (T-cell dependent) and type II (IgG dependent) immune mechanisms.

Fully human anti-BAFF inhibitory monoclonal antibody tabalumab does not adversely affect T-dependent antibody responses in cynomolgus monkey (Macaca fasicularis): A summary of three pre-clinical immunotoxicology evaluations.

The potential immunotoxicity of tabalumab was assessed as a component of standard pre-clinical toxicology studies in cynomolgus monkeys. To evaluate potential tabalumab-associated immunosuppression after antigen challenge, cynomolgus monkeys were administered placebo control or tabalumab in three immunotoxicological safety studies. Study 1, a 4-week pilot study, evaluated biweekly intravenous (IV) control, and 0.3, 1.0, 5.0, and 15.0 mg/kg tabalumab doses. Study 2 evaluated IV control, and 0.1, 1.0, and 30.0 mg/kg tabalumab doses biweekly for 6 weeks. Study 3 evaluated IV control and 0.1, 1.0, 30.0 mg/kg, and subcutaneous (SC) 30.0 mg/kg tabalumab biweekly for 6 months, with recovery (16 weeks) to monitor standard immunotoxicity endpoints. T-cell dependent primary and secondary antibody responses to tetanus toxoid antigen challenge (4-week and 6-week studies) or keyhole limpet hemocyanin (KLH; 6-week and 6-month studies) were evaluated as a measure of immunocompetence, together with quantitation of T- and B-cell subsets. In addition, anti-tabalumab antibody formation (6-week and 6-month studies) was assessed. The results indicated that, despite expected decreases in circulating B-cell populations, no changes in follicle histopathology or organ weights, except decreases in spleen weight (after 6-months of 30 mg/kg IV/SC treatment only), were attributed to tabalumab. Non-adverse microscopic decreases in size or number of germinal centers in spleen, mesenteric, and mandibular lymph nodes occurred, but without an effect on antibody responses to KLH or tetanus. At 16-weeks recovery, microscopic compound-related changes observed after 6 months of treatment were completely reversed (0.1 mg/kg group) and partially reversed (1.0 and 30.0 mg/kg groups), while peripheral blood B cells remained 66-72% reduced from baseline. Despite reduced germinal centres in lymphoid organs, and reductions in circulating B cells, T-cell-dependent humoral immunity was maintained following tabalumab administration in three safety studies in cynomolgus monkeys.

Risk of gastrointestinal complications in cancer patients treated with immune checkpoint inhibitors: a meta-analysis.

AIM: We performed a meta-analysis of the risk of selected gastrointestinal toxicities associated with immune checkpoint inhibitors. PATIENTS & METHODS: Eligible studies included randomized trials of patients with solid tumors on ipilimumab, nivolumab, pembrolizumab, tremelimumab, pidilizumab and atezolizumab, describing events of diarrhea, vomiting or colitis. RESULTS: After exclusion of ineligible studies, a total of ten clinical trials were considered eligible for the meta-analysis. The relative risk of all-grade diarrhea, vomiting and colitis was 1.64 (95% CI: 1.19-2.26; p = 0.002), 0.72 (95% CI: 0.49-1.07; p = 0.1), 10.35 (95% CI: 5.78-18.53; p < 0.00001), respectively. CONCLUSION: Our meta-analysis has demonstrated that immune checkpoint inhibitors are associated with a significantly increased risk of all grade and high-grade colitis.

Anti-CTLA-4 therapy may have mechanisms similar to those occurring in inherited human CTLA4 haploinsufficiency.

The inhibitory anti-CTLA-4 antibody, ipilimumab, dramatically improved survival in a subgroup of metastatic melanoma patients. The majority, however, suffered autoimmune-related adverse events (irAEs), sometimes pathognomonic of acute graft-versus-host-disease (GVHD). This implies that the CTLA-4 blockade is not tumor specific. We make a risky but testable prediction: anti-CTLA-4 therapy may have mechanism similar to that occurring in inherited human CTLA-4 haploinsufficiency. If so, a therapeutic paradigm shift is required. The task is not desperately trying to put the genie back in the bottle by immune-suppressive treatments, but harnessing the immense forces liberated by the anti-CTLA-4 antibody blockade by pretargeting or dose adjustment.

Fibroblast growth factor 21 (FGF21) ameliorates collagen-induced arthritis through modulating oxidative stress and suppressing nuclear factor-kappa B pathway.

It has been demonstrated that circulating FGF21 levels are elevated in the serum and synovial fluid of patients with rheumatoid arthritis (RA). The aim of this study is to investigate efficacy of FGF21 for treatment of RA and the molecular mechanisms of the therapeutic effect on collagen-induced arthritis (CIA). Mice with CIA were subcutaneously administered with FGF21 (5, 2 or 1mg·kg(-1)·d(-1)), IL-1ß antibody (5mg·kg(-1)·d(-1)), IL-17A antibody (5mg·kg(-1)·d(-1)) and dexamethasone (DEX) (1mg·kg(-1)·d(-1)), respectively. The effects of treatment were determined by arthritis severity score, histological damage and cytokine production. The activation of NF-κB was analyzed by Western blotting. We also detected the levels of oxidative stress parameters. Our results showed that FGF21 had beneficial effects on clinical symptom and histological lesion of CIA mice. Similar to antibody and DEX, FGF21 treatment alleviated the severity of arthritis by reducing humoral and cellular immune responses and down-regulating the expression of pro-inflammatory cytokines. FGF21 treatment also reduced the expression of TNF-α, IL-1ß, IL-6, IFN-γ and MMP-3 and increased level of IL-10 in the spleen tissue or the plasma of CIA mice in a dose-dependent manner. Furthermore, FGF21 inhibited IκBα degradation and NF-κB p65 nuclear translocation and induced significant changes of oxidative stress parameters (MDA, SOD, CAT, GSH-PX and GSH) in the plasma. FGF21 exerts therapeutic efficacy for RA through antioxidant reaction and inhibiting NF-κB inflammatory pathway. This study provides evidence that FGF21 may be a promising therapeutic agent for RA patients.

Inhibition of kidney ischemia-reperfusion injury through local infusion of a TLR2 blocker.

Kidney ischemia-reperfusion injury (IRI) occurs as a result of complex interactions of kidney parenchymal cells and immune cells that are initiated by hypoxic damage of parenchymal cells. In particular, tubular epithelial cells (TECs) not only are susceptible to ischemia but also have an auto-loop system to amplify renal inflammation caused by ischemia and reperfusion. Since endogenous TLR2 ligands released from TECs trigger renal inflammation leading to kidney IRI in an autocrine manner, we hypothesized that local infusion of TLR2 blockers would prevent kidney IRI. In this study, we demonstrated that injection of antagonist anti-TLR2 mAb through the renal vein after cross-clamping significantly reduced the recruitment of NK cells to the kidney after IRI, a phenomenon that is governed by TLR2 signaling in TECs. In addition, intrarenal blocking of TLR2 signaling was shown to inhibit NK cell-mediated neutrophil infiltration and subsequent renal damage. Overall, our simple experiment system will be of help in testing the efficacy of candidate blockers targeting kidney parenchymal cells in inhibition of kidney IRI.

Pituitary expression of CTLA-4 mediates hypophysitis secondary to administration of CTLA-4 blocking antibody.

Hypophysitis is a chronic inflammation of the pituitary gland of unknown (primary forms) or recognizable (secondary forms) etiology, such as the use of ipilimumab in cancer immunotherapy. Ipilimumab, which blocks the T cell inhibitory molecule CTLA-4 (cytotoxic T lymphocyte antigen-4), induces hypophysitis in about 4% of patients through unknown mechanisms. We first established a model of secondary hypophysitis by repeated injections of a CTLA-4 blocking antibody into SJL/J or C57BL/6J mice, and showed that they developed lymphocytic infiltration of the pituitary gland and circulating pituitary antibodies. We next assessed the prevalence of pituitary antibodies in a cohort of 20 patients with advanced melanoma or prostate cancer, 7 with a clinical diagnosis of hypophysitis, before and after ipilimumab administration. Pituitary antibodies, negative at baseline, developed in the 7 patients with hypophysitis but not in the 13 without it; these antibodies predominantly recognized thyrotropin-, follicle-stimulating hormone-, and corticotropin-secreting cells. We then hypothesized that the injected CTLA-4 antibody could cause pituitary toxicity if bound to CTLA-4 antigen expressed "ectopically" on pituitary endocrine cells. Pituitary glands indeed expressed CTLA-4 at both RNA and protein levels, particularly in a subset of prolactin- and thyrotropin-secreting cells. Notably, these cells became the site of complement activation, featuring deposition of C3d and C4d components and an inflammatory cascade akin to that seen in type II hypersensitivity. In summary, the study offers a mechanism to explain the pituitary toxicity observed in patients receiving ipilimumab, and highlights the utility of measuring pituitary antibodies in this form of secondary hypophysitis.

Rapid desensitization of mice with anti-FcγRIIb/FcγRIII mAb safely prevents IgG-mediated anaphylaxis.

BACKGROUND: Stimulatory IgG receptors (FcγRs) on bone marrow-derived cells contribute to the pathogenesis of several autoimmune and inflammatory disorders. Monoclonal antibodies that block FcγRs might suppress these diseases, but they can induce anaphylaxis. OBJECTIVE: We wanted to determine whether a rapid desensitization approach can safely suppress IgG/FcγR-mediated anaphylaxis. METHODS: Mice were injected with serially increasing doses of 2.4G2, a rat mAb that blocks the inhibitory FcγR, FcγRIIb, and the stimulatory receptor, FcγRIII. Rectal temperature was used to detect the development of anaphylaxis. Passive and active IgG-mediated anaphylaxis were evaluated in mice that had been rapidly desensitized with 2.4G2 or mock-desensitized in mice in which monocyte/macrophages, basophils, or neutrophils had been depleted or desensitized and in mice in which FcγRI, FcγRIII, and/or FcγRIV had been deleted or blocked. RESULTS: Rapid desensitization with 2.4G2 prevented 2.4G2-induced shock and completely suppressed IgG-mediated anaphylaxis. Rapid desensitization of ovalbumin-sensitized mice with 2.4G2 was safer and more effective than rapid desensitization with ovalbumin. 2.4G2 treatment completely blocked FcγRIII and removed most FcγRI and FcγRIV from nucleated peripheral blood cells. Because IgG(2a)-mediated anaphylaxis was partially FcγRI and FcγRIV dependent, the effects of 2.4G2 on FcγRI and FcγRIV were probably crucial for its complete inhibition of IgG(2a)-mediated anaphylaxis. IgG(2a)-mediated anaphylaxis was partially inhibited by depletion or desensitization of monocyte/macrophages, basophils, or neutrophils. CONCLUSION: IgG-mediated anaphylaxis can be induced by ligation of FcγRI, FcγRIII, or FcγRIV on monocycte/macrophages, basophils, or neutrophils and can be safely suppressed by rapid desensitization with anti-FcγRII/RIII mAb. A similar approach may safely suppress other FcγR-dependent immunopathology.

Murine bone marrow chimeras developing autoimmunity after CTLA-4-blockade show an expansion of T regulatory cells with an activated cytokine profile.

Autoimmune adverse events are a concern in patients treated with blocking anti-CTLA-4-mAb for solid and hematological tumors. Patient and mouse data on the contribution of a quantitative or qualitative defect of regulatory T cells (T(reg)) in this autoimmune phenomenon are conflicting. We have previously shown that a treatment course with blocking anti-CTLA-4-mAb in murine allogeneic bone marrow chimeras induces an antileukemic response in close association with systemic autoimmunity. Here, we used this model to investigate the effect of CTLA-4-blocking therapy on the kinetics of T(reg) frequency and function. As previously published, CTLA-4-blocking treatment, initiated on day 20 after bone marrow transplantation, led to overt autoimmunity by day 35. CD4(+)Foxp3(+) T(reg) frequency was determined (flowcytometry) on day 21, 23, 25 and 35: treated chimeras showed an expansion of CD4(+)Foxp3(+) T(reg) frequencies on day 25 and 35, without a prior frequency decrease. The T(reg) expansion occurred selectively in the recipient-derived CD4+ T-cell compartment. In vitro, purified CD4(+)CD25(+)FR4(high) T(reg) from 'day 35' autoimmune and control chimeras showed equal suppressive effects towards self-antigen-specific autoimmune T cells. Purified CD4(+)CD25(high)FR4(high) T(reg) from 'day 35' treated chimeras showed increased IL-10 and IFN-gamma mRNA-expression (RT-PCR) relative to control chimeras. In this model of CTLA-4-blockade-induced autoimmunity after allogeneic bone marrow transplantation, anti-CTLA-4-mAb gives rise to a progressive expansion - without a prior transient reduction - of T(reg) cells. T(reg) of autoimmune animals do not show a defect in in vitro suppressive function but show an in vivo activated cytokine profile, suggesting that the expansion occurs as a compensatory phenomenon to control autoimmunity.

Three siblings with self-resolving congenital hyperthyrotropinaemia secondary to thyrotropin receptor blocking antibodies.

Thyrotropin receptor blocking antibodies are a rare cause of hyperthyrotropinaemia and more rarely of congenital hypothyroidism. We report a case of hyperthyrotropinaemia but normal thyroid hormone in the newborn of a mother with hypothyroidism treated with thyroxine. Two older siblings had similar high thyrotropin and normal thyroid function in the newborn period which did not require hormone treatment and resolved spontaneously. Demonstration of thyrotropin receptor antibodies in the child confirmed our diagnosis. Our case was not treated with thyroid replacement hormone and has remained biochemically euthyroid, with thyrotropin levels returning to normal over a period of months.

Dendritic cell vaccination combined with CTLA4 blockade in patients with metastatic melanoma.

PURPOSE: Tumor antigen-loaded dendritic cells (DC) are believed to activate antitumor immunity by stimulating T cells, and CTL-associated antigen 4 (CTLA4)-blocking antibodies should release a key negative regulatory pathway on T cells. The combination was tested in a phase I clinical trial in patients with advanced melanoma. EXPERIMENTAL DESIGN: Autologous DC were pulsed with MART-1(26-35) peptide and administered with a dose escalation of the CTLA4-blocking antibody tremelimumab. Sixteen patients were accrued to five dose levels. Primary end points were safety and immune effects; clinical efficacy was a secondary end point. RESULTS: Dose-limiting toxicities of grade 3 diarrhea and grade 2 hypophysitis developed in two of three patients receiving tremelimumab at 10 mg/kg monthly. Four patients had an objective tumor response, two partial responses and two complete responses, all melanoma free between 2 and 4 years after study initiation. There was no difference in immune monitoring results between patients with an objective tumor response and those without a response. Exploratory gene expression analysis suggested that immune-related gene signatures, in particular for B-cell function, may be important in predicting response. CONCLUSION: The combination of MART-1 peptide-pulsed DC and tremelimumab results in objective and durable tumor responses at the higher range of the expected response rate with either agent alone.

BAFF blockade for systemic lupus erythematosus: will the promise be fulfilled?

SUMMARY: Systemic lupus erythematosus (SLE) is a complex immune disorder in which loss of tolerance to nucleic acid antigens and other cross-reactive antigens is associated with the development of pathogenic autoantibodies that damage target organs including the skin, joints, brain, and kidney. B cells are essential to lupus pathogenesis, not only because they produce pathogenic autoantibodies but also because they have multiple effector functions in the immune system. There has been much recent interest therefore in targeting of B cells for the treatment of SLE and other autoimmune diseases. BAFF (B-cell activation factor belonging to the tumor necrosis factor family) is a crucial homeostatic cytokine for B cells that is upregulated during inflammation and links adaptive with innate immunity. Excessive levels of BAFF may alter selection of autoreactive B cells and contribute to perpetuation of SLE by a variety of mechanisms. BAFF antagonists have been effective in the prevention and treatment of SLE in several different murine models. Three classes of BAFF antagonists have been developed for clinical use, and initial clinical trials have begun. However, immune modulation in SLE is complicated by differences in the immune defects between patients and at different disease stages. Further work will be needed both in animal models and humans to determine the most appropriate clinical applications for BAFF blockade.