Ezio Bonvini

Teplizumab for treatment of type 1 diabetes (Protégé study): 1-year results from a randomised, placebo-controlled trial

BACKGROUND Findings of small studies have suggested that short treatments with anti-CD3 monoclonal antibodies that are mutated to reduce Fc receptor binding preserve β-cell function and decrease insulin needs in patients with recent-onset type 1 diabetes. In this phase 3 trial, we assessed the safety and efficacy of one such antibody, teplizumab. METHODS In this 2-year trial, patients aged 8-35 years who had been diagnosed with type 1 diabetes for 12 weeks or fewer were enrolled and treated at 83 clinical centres in North America, Europe, Israel, and India. Participants were allocated (2:1:1:1 ratio) by an interactive telephone system, according to computer-generated block randomisation, to receive one of three regimens of teplizumab infusions (14-day full dose, 14-day low dose, or 6-day full dose) or placebo at baseline and at 26 weeks. The Protégé study is still underway, and patients and study staff remain masked through to study closure. The primary composite outcome was the percentage of patients with insulin use of less than 0·5 U/kg per day and glycated haemoglobin A(1c) (HbA(1C)) of less than 6·5% at 1 year. Analyses included all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, number NCT00385697. FINDINGS 763 patients were screened, of whom 516 were randomised to receive 14-day full-dose teplizumab (n=209), 14-day low-dose teplizumab (n=102), 6-day full-dose teplizumab (n=106), or placebo (n=99). Two patients in the 14-day full-dose group and one patient in the placebo group did not start treatment, so 513 patients were eligible for efficacy analyses. The primary outcome did not differ between groups at 1 year: 19·8% (41/207) in the 14-day full-dose group; 13·7% (14/102) in the 14-day low-dose group; 20·8% (22/106) in the 6-day full-dose group; and 20·4% (20/98) in the placebo group. 5% (19/415) of patients in the teplizumab groups were not taking insulin at 1 year, compared with no patients in the placebo group at 1 year (p=0·03). Across the four study groups, similar proportions of patients had adverse events (414/417 [99%] in the teplizumab groups vs 98/99 [99%] in the placebo group) and serious adverse events (42/417 [10%] vs 9/99 [9%]). The most common clinical adverse event in the teplizumab groups was rash (220/417 [53%] vs 20/99 [20%] in the placebo group). INTERPRETATION Findings of exploratory analyses suggest that future studies of immunotherapeutic intervention with teplizumab might have increased success in prevention of a decline in β-cell function (measured by C-peptide) and provision of glycaemic control at reduced doses of insulin if they target patients early after diagnosis of diabetes and children. FUNDING MacroGenics, the Juvenile Diabetes Research Foundation, and Eli Lilly.

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, HbA1c <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.

IgG antibodies produced during subcutaneous allergen immunotherapy mediate inhibition of basophil activation via a mechanism involving both FcγRIIA and FcγRIIB

The majority of human subjects who receive subcutaneous allergen immunotherapy (IT) develop decreased sensitivity to their allergens. Multiple factors may explain the efficacy of IT, some evidence support a role for allergen specific IgG antibodies. There is controversy whether such antibodies act by blocking allergen binding to IgE or initiation of active inhibitory signaling through low affinity IgG receptors (FcgammaRIIB) on mast cells and basophils. In this study, we addressed this question using peripheral blood from cat non-allergic, cat allergic, and immunotherapy-treated cat allergic subjects. Blood from subjects who received IT contain IgG antibodies that mediate inhibition of basophil activation by a mechanism that is blocked by antibodies specific for the inhibitory IgG receptor FcgammaRIIB. Surprisingly, inhibition was also blocked by aglycosylated, putatively non-FcR binding, antibodies that are specific for the FcgammaRIIA, suggesting a contribution of this receptor to the observed effect. Consistent with a cooperative effect, ex vivo basophils were found to express both IgG receptors. In other studies we found that basophils from subjects who were both chronically exposed to allergen and were producing both cat allergen specific IgE and IgG, are hyporesponsive to allergen. These studies confirm that IgG antibodies produced during IT act primarily by stimulation of inhibitory signaling, and suggest that FcgammaRIIA and FcgammaRIIB function cooperatively in activation of inhibitory signaling circuit. We suggest that under normal physiologic conditions in which only a small proportion of FcepsilonRI are occupied by IgE of a single allergen specificity, FcgammaRIIA co-aggregation may, by providing activated Lyn, be required to fuel activation of inhibitory FcgammaRIIB function.

Targeting CD123 in acute myeloid leukemia using a T-cell-directed dual-affinity retargeting platform.

T-cell-directed killing of tumor cells using bispecific antibodies is a promising approach for the treatment of hematologic malignancies. Here we describe our preclinical work with a dual-affinity retargeting (DART) molecule generated from antibodies to CD3 and CD123, designed to redirect T cells against acute myeloid leukemia blasts. The CD3×CD123 DART (also referred to as MGD006/S80880) consists of 2 independent polypeptides, each composed of the VH of 1 antibody in tandem with the VL of the other antibody. The target antigen CD123 (interleukin 3RA) is highly and differentially expressed in acute myeloid leukemia (AML) blasts compared with normal hematopoietic stem and progenitor cells. In this study we demonstrate that the CD3×CD123 DART binds to both human CD3 and CD123 to mediate target-effector cell association, T-cell activation, proliferation, and receptor diversification. The CD3×CD123 DART also induces a dose-dependent killing of AML cell lines and primary AML blasts in vitro and in vivo. These results provide the basis for testing the CD3×CD123 DART in the treatment of patients with CD123(+) AML.

CD32B is highly expressed on clonal plasma cells from patients with systemic light-chain amyloidosis and provides a target for monoclonal antibody–based therapy

Despite advances in therapy, many patients with systemic light-chain amyloidosis (AL) die within 3 years from diagnosis. The humanized 2B6 monoclonal antibody (MoAb) is specific for the low-affinity IgG Fc receptor CD32B and effective in a human CD32B+ B-cell lymphoma murine xenograft model. Because MoAb therapy could improve outcomes in AL, we studied CD32B expression by clonal plasma cells obtained from 48 patients with AL. Transcript profiling showed that expression of CD32B was significantly higher than expression of all other Fc receptor family members. Reverse-transcriptase polymerase chain reaction (RT-PCR) using double-enriched CD138+ plasma cells showed uniform expression of the stable cell surface CD32B1 isoform at diagnosis and relapse, and flow cytometry showed intense CD32B cell surface staining on 99% of CD138+ plasma cells at diagnosis and relapse. These data provide a rationale for the novel therapeutic targeting of CD32B using the humanized 2B6 MoAb in patients with systemic AL-amyloidosis.

C-Reactive Protein Causes Insulin Resistance in Mice Through Fcγ Receptor IIB–Mediated Inhibition of Skeletal Muscle Glucose Delivery

Elevations in C-reactive protein (CRP) are associated with an increased risk of insulin resistance. Whether CRP plays a causal role is unknown. Here we show that CRP transgenic mice and wild-type mice administered recombinant CRP are insulin resistant. Mice lacking the inhibitory Fcγ receptor IIB (FcγRIIB) are protected from CRP-induced insulin resistance, and immunohistochemistry reveals that FcγRIIB is expressed in skeletal muscle microvascular endothelium and is absent in skeletal muscle myocytes, adipocytes, and hepatocytes. The primary mechanism in glucose homeostasis disrupted by CRP is skeletal muscle glucose delivery, and CRP attenuates insulin-induced skeletal muscle blood flow. CRP does not impair skeletal muscle glucose delivery in FcγRIIB−/− mice or in endothelial nitric oxide synthase knock-in mice with phosphomimetic modification of Ser1176, which is normally phosphorylated by insulin signaling to stimulate nitric oxide–mediated skeletal muscle blood flow and glucose delivery and is dephosphorylated by CRP/FcγRIIB. Thus, CRP causes insulin resistance in mice through FcγRIIB-mediated inhibition of skeletal muscle glucose delivery.

Tailoring CD19xCD3-DART exposure enhances T-cells to eradication of B-cell neoplasms

ABSTRACT Many patients with B-cell malignancies can be successfully treated, although tumor eradication is rarely achieved. T-cell-directed killing of tumor cells using engineered T-cells or bispecific antibodies is a promising approach for the treatment of hematologic malignancies. We investigated the efficacy of CD19xCD3 DART bispecific antibody in a broad panel of human primary B-cell malignancies. The CD19xCD3 DART identified 2 distinct subsets of patients, in which the neoplastic lymphocytes were eliminated with rapid or slow kinetics. Delayed responses were always overcome by a prolonged or repeated DART exposure. Both CD4 and CD8 effector cytotoxic cells were generated, and DART-mediated killing of CD4+ cells into cytotoxic effectors required the presence of CD8+ cells. Serial exposures to DART led to the exponential expansion of CD4+ and CD8+ cells and to the sequential ablation of neoplastic cells in absence of a PD-L1-mediated exhaustion. Lastly, patient-derived neoplastic B-cells (B-Acute Lymphoblast Leukemia and Diffuse Large B Cell Lymphoma) could be proficiently eradicated in a xenograft mouse model by DART-armed cytokine induced killer (CIK) cells. Collectively, patient tailored DART exposures can result in the effective elimination of CD19 positive leukemia and B-cell lymphoma and the association of bispecific antibodies with unmatched CIK cells represents an effective modality for the treatment of CD19 positive leukemia/lymphoma.