Teplizumab Preserves C-Peptide in Recent-Onset Type 1 Diabetes: Two-Year Results From the Randomized,Placebo-Controlled Protégé Trial

Protégé was a phase 3, randomized, double-blind, parallel, placebo-controlled 2-year study of three intravenous teplizumab dosing regimens, administered daily for 14 days at baseline and again after 26 weeks, in new-onset type 1 diabetes. We sought to determine efficacy and safety of teplizumab immunotherapy at 2 years and to identify characteristics associated with therapeutic response. Of 516 randomized patients, 513 were treated, and 462 completed 2 years of follow-up. Teplizumab (14-day full-dose) reduced the loss of C-peptide mean area under the curve (AUC), a prespecified secondary end point, at 2 years versus placebo. In analyses of prespecified and post hoc subsets at entry, U.S. residents, patients with C-peptide mean AUC >0.2 nmol/L, those randomized ≤6 weeks after diagnosis, HbA_1c <7.5% (58 mmol/mol), insulin use <0.4 units/kg/day, and 8–17 years of age each had greater teplizumab-associated C-peptide preservation than their counterparts. Exogenous insulin needs tended to be reduced versus placebo. Antidrug antibodies developed in some patients, without apparent change in drug efficacy. No new safety or tolerability issues were observed during year 2. In summary, anti-CD3 therapy reduced C-peptide loss 2 years after diagnosis using a tolerable dose.Immunotherapy that directly inhibits β-cell destruction is an unfulfilled need for treatment of autoimmune type 1 diabetes. Although it may eventually be useful in prediabetes, treatment at clinical onset is an excellent opportunity when patients are easily identified and functional β-cell mass remains (1). Preservation of residual β-cell function, represented by higher levels of C-peptide, facilitates better glycemic control to lessen retinopathy, nephropathy, hypoglycemia, and ketoacidosis (2–4). Immunotherapy given at diagnosis aims to prolong and augment this effect by preventing further β-cell death and possibly also by enabling living β-cells to recover function after resolution of inflammation (5). Clinical trials of different agents have had modest success in this regard, but treatment responses have often waned within 2 years (6–8).Teplizumab is a nonactivating, Fc-modified, anti-CD3 monoclonal antibody thought to attenuate activated autoreactive T cells mediating β-cell death. These T cells disappear from the peripheral circulation during immunotherapy but return within weeks after stopping treatment (9). Preclinical and clinical studies suggest that the drug may induce regulatory T-cell activity, suggesting augmented immune tolerance (10).Protégé was a large, randomized, placebo-controlled, double-blinded trial of immunotherapy in type 1 diabetes (11). Recently diagnosed patients (8–35 years of age) were randomized to receive daily infusions of placebo or one of three teplizumab regimens at baseline and at 6 months. The primary outcome, a composite of insulin <0.5 units/kg/day and HbA_1c <6.5% (48 mmol/mol) at year 1, had not been validated previously and did not achieve statistical significance. In exploratory analyses, a significant improvement in area under the curve (AUC) mean C-peptide during a 4-h mixed-meal tolerance test (MMTT) was observed in the group treated with a full-dose 14-day course. In certain prespecified subgroups, the AUC mean C-peptide differences versus placebo appeared to be most pronounced in recently diagnosed patients, patients in the U.S., and in younger patients. The drug was generally well tolerated.A recent study reported that teplizumab treatment reduced β-cell death at 1 year, but the differences versus placebo were not significant earlier, at 6 months (12). The acute (i.e., within 1 year) effects of immunotherapy on β-cell function may not occur through the same mechanisms as longer-term effects that have greater clinical importance. Improvement in C-peptide responses may be seen in type 1 diabetes trials, even with therapies that do not affect immune responses, through mechanisms that may involve recovery of dysfunctional β-cells when inflammation is acutely resolved (5,13). To be of value, a lasting effect on β-cell function and survival is needed.The objective of this report is to characterize the efficacy and safety of teplizumab over 2 years and identify characteristics associated with response to therapy. Regarding efficacy, we focus on the 14-day full-dose regimen that was administered versus placebo, because at 1 year, efficacy was seen in the 14-day full-dose arm but not in the reduced-dose or curtailed-dose arms (11). Emphasis is given to AUC mean C-peptide because this has become the preferred measure of efficacy in type 1 diabetes immunotherapy (14). To explore the potential implications for dosing in future studies, we also describe the pharmacokinetics and pharmacodynamics of teplizumab, the effect of antidrug antibodies, and the safety profiles of all three dosing regimens.     

Left ventricular ejection fraction and volumes from gated blood-pool SPECT: comparison with planar gated blood-pool imaging and assessment of repeatability in patients with heart failure.

Gated blood-pool SPECT (GBPS) has several potential advantages over planar radionuclide ventriculography (PRNV), including the possibility of greater repeatability of left ventricular ejection fraction (LVEF) and the noninvasive calculation of left ventricular end-systolic volume and left ventricular end-diastolic volume (LVEDV). The aim of this study was to assess the repeatability of LVEF and LVEDV from GBPS and to compare LVEF with those from PRNV. METHODS: Fifty patients underwent PRNV and GBPS, 23 of whom also had repeated studies in the same session. GPBS studies were processed using the Cedars Sinai Quantitative Blood-Pool SPECT (QBS) software that automatically calculates LVEF and LVEDV. Automatic processing with QBS was successful in 70% of the GBPS studies, with the remaining studies processed using the manual option in QBS. All PRNV studies were processed using a manual processing technique. RESULTS: Comparison of LVEF from PRNV and GBPS yielded a correlation coefficient of 0.80. Bland-Altman analysis demonstrated a mean difference of 0.74% +/- 7.62% (mean +/- SD) between LVEF from the 2 techniques. The 95% limits of agreement are therefore -14.50% to +15.98%. The correlation between repeated measurements was 0.87 for GBPS and 0.95 for PRNV. Bland-Altman analysis revealed poorer repeatability for GBPS (95% limits of agreement, -9.63% to +14.97% vs. -4.66% to +5.92%; P = 0.003). The mean LVEDV was 198 +/- 94 mL, with a mean difference of 9 +/- 47 mL between repeated measurements. The 95% limits of agreement are therefore -85 to +103 mL. CONCLUSION: GBPS provides a less repeatable measurement of LVEF than PRNV. Repeatability of LVEDV measurements from GBPS is poor.     

Defining limits of treatment with humanized neutralizing monoclonal antibody for West Nile virus neurological infection in a hamster model

A potent anti-West Nile virus (anti-WNV)-neutralizing humanized monoclonal antibody, hE16, was previously shown to improve the survival of WNV-infected hamsters when it was administered intraperitoneally (i.p.), even after the virus had infected neurons in the brain. In this study, we evaluated the therapeutic limit of hE16 for the treatment of WNV infection in hamsters by comparing single-dose peripheral (i.p.) therapy with direct administration into the pons through a convection-enhanced delivery (CED) system. At day 5 after infection, treatments with hE16 by the peripheral and the CED routes were equally effective at reducing morbidity and mortality. In contrast, at day 6 only the treatment by the CED route protected the hamsters from lethal infection. These experiments suggest that hE16 can directly control WNV infection in the central nervous system. In support of this, hE16 administered i.p. was detected in a time-dependent manner in the serum, cerebrospinal fluid (CSF), cerebral cortex, brain stem, and spinal cord in CSF. A linear relationship between the hE16 dose and the concentration in serum was observed, and maximal therapeutic activity occurred at doses of 0.32 mg/kg of body weight or higher, which produced serum hE16 concentrations of 1.3 microg/ml or higher. Overall, these data suggest that in hamsters hE16 can ameliorate neurological disease after significant viral replication has occurred, although there is a time window that limits therapeutic efficacy.     

Surveillance of clinical isolates of respiratory syncytial virus for palivizumab (Synagis)-resistant mutants

Premature infants and those with chronic lung disease or congenital heart disease are at high risk of severe respiratory syncytial virus (RSV) disease. Palivizumab (Synagis), a humanized anti-RSV monoclonal antibody, has been used extensively since 1998 to prevent severe RSV disease in high-risk infants. To monitor for possible palivizumab-resistant mutants, an immunofluorescence binding assay that predicts palivizumab neutralization of RSV was developed. RSV isolates were collected at 8 US sites from 458 infants hospitalized for RSV disease (1998-2002). Palivizumab bound to all 371 RSV isolates able to be evaluated, including 25 from active-palivizumab recipients. The palivizumab epitope appears to be highly conserved, even in infants receiving prophylaxis with palivizumab.     

Monoclonal antibodies capable of discriminating the human inhibitory Fcgamma-receptor IIB (CD32B) from the activating Fcgamma-receptor IIA (CD32A): biochemical, biological and functional characterization

Human CD32B (FcgammaRIIB), the low-affinity inhibitory Fcgamma receptor (FcgammaR), is highly homologous in its extracellular domain to CD32A (FcgammaRIIA), an activating FcgammaR. Available monoclonal antibodies (mAb) against the extracellular region of CD32B recognize both receptors. Through immunization of mice transgenic for human CD32A, we generated a set of antibodies specific for the extracellular region of CD32B with no cross-reactivity with CD32A, as determined by enzyme-linked immunosorbent assay and surface plasmon resonance with recombinant CD32A and CD32B, and by fluorescence-activated cell sorting analysis of CD32 transfectants. A high-affinity mAb, 2B6, was used to explore the expression of CD32B by human peripheral blood leucocytes. While all B lymphocytes expressed CD32B, only a fraction of monocytes and almost no polymorphonuclear cells stained with 2B6. Likewise, natural killer cells, which express CD32C, a third CD32 variant, did not react with 2B6. Immune complexes co-engage the inhibitory receptor with activating Fcgamma receptors, a mechanism that limits cell responses. 2B6 competed for immune complex binding to CD32B as a monomeric Fab, suggesting that it directly recognizes the Fc-binding region of the receptor. Furthermore, when co-ligated with an activating receptor, 2B6 triggered CD32B-mediated inhibitory signalling, resulting in diminished release of inflammatory mediators by FcepsilonRI in an in vitro allergy model or decreased proliferation of human B cells induced by B-cell receptor stimulation. These antibodies form the basis for the development of investigational tools and therapeutics with multiple potential applications, ranging from adjuvants in FcgammaR-mediated responses to the treatment of allergy and autoimmunity.     

Anti-tumor activity and toxicokinetics analysis of MGAH22, an anti-HER2 monoclonal antibody with enhanced Fcγ receptor binding properties

Introduction

Response to trastuzumab in metastatic breast cancer correlates with expression of the high binding variant (158V) of the activating Fcγ receptor IIIA (CD16A). We engineered MGAH22, a chimeric anti-HER2 monoclonal antibody with specificity and affinity similar to trastuzumab, with an Fc domain engineered for increased binding to both alleles of human CD16A.

Methods

MGAH22 was compared to an identical anti-HER2 mAb except for a wild type Fc domain. Antibody-dependent cell cytotoxicity (ADCC) assays were performed with HER2-expressing cancer cells as targets and human PBMC or purified NK cells as effectors. Xenograft studies were conducted in mice with wild type murine FcγRs; in mice lacking murine CD16; or in mice lacking murine CD16 but transgenic for human CD16A-158F, the low-binding variant. The latter model reproduces the differential binding between wild type and the Fc-optimized mAb for human CD16A. The JIMT-1 human breast tumor line, derived from a patient that progressed on trastuzumab therapy, was used in these studies. Single and repeat dose toxicology studies with MGAH22 administered intravenously at high dose were conducted in cynomolgus monkeys.

Results

The optimized Fc domain confers enhanced ADCC against all HER2-positive tumor cells tested, including cells resistant to trastuzumab's anti-proliferative activity or expressing low HER2 levels. The greatest improvement occurs with effector cells isolated from donors homozygous or heterozygous for CD16A-158F, the low-binding allele. MGAH22 demonstrates increased activity against HER2-expressing tumors in mice transgenic for human CD16A-158F. In single and repeat-dose toxicology studies in cynomolgus monkeys, a species with a HER2 expression pattern comparable to that in humans and Fcγ receptors that exhibit enhanced binding to the optimized Fc domain, MGAH22 was well tolerated at all doses tested (15-150 mg/kg) and exhibited pharmacokinetic parameters similar to that of other anti-HER2 antibodies. Induction of cytokine release by MGAH22 in vivo or in vitro was similar to that induced by the corresponding wild type mAb or trastuzumab.

Conclusions

The data support the clinical development of MGAH22, which may have utility in patients with low HER2 expressing tumors or carrying the CD16A low-binding allele.     

Formal intergenerational mentoring at Australian Men's Sheds: a targeted survey about mentees,mentors, programmes and quality

Intergenerational mentoring enables a purposeful exchange of skills and knowledge to enhance individual and social outcomes for sub‐groups at risk of health and social disparities. Male intergenerational mentoring may be an approach to help address these disparities in young men. Over 1000 Men's Sheds operate in Australia with 39% providing some form of mentoring mainly to youth. Yet, little is known about the variables intrinsic to creating and running quality programmes. This study aimed to identify the characteristics of formal intergenerational mentoring programmes, review their quality against the Australian Youth Mentoring Network (AYMN) quality benchmarks, and identify the factors that predict quality in these programmes. All known Australian Men's Sheds were invited to participate in an online cross‐sectional survey. Forty sheds with formal mentor programmes completed the survey for a total of 387 mentees (mean = 9.7 mentees/programme), the majority being male. The majority of mentor programme facilitators were unpaid male volunteers aged 61 years and older, and programmes were unfunded. Promoting social and emotional well‐being of the mentees was the primary focus in more than half of the programmes, and working on a shared construction project was the most common activity. Respondents rated the three most important factors that influenced programme effectiveness as being: (i) meaningful activities; (ii) mentors’ approach; and (iii) a safe environment. Univariate analyses revealed that mentoring programmes that had a system in place for screening mentors, trained mentors and evaluated the programme were most likely to rate highly against the AYMN quality benchmarks.