Comparative in vitro study of the immunomodulatory activity of humanized and chimeric anti-CD25 monoclonal antibodies

Humanized or chimeric monoclonal antibodies (MoAbs) directed against the interleukin-2 (IL-2) receptor alpha-chain, CD25, are promising immunosuppressive agents due to improved pharmacokinetic profiles and less toxicity. These MoAbs have been used effectively in preventing and/or treating rejection in solid organ transplantation and are currently under investigation for prevention/treatment of graft-versus-host disease (GvHD) in stem cell transplantation. We analysed the in vitro activities of the chimeric anti-CD25 MoAb basiliximab and the humanized anti-CD25 MoAb daclizumab in various test systems for alloimmune response and T cell activation in comparison to cyclosporin A (CsA) and prednisolone. Anti-CD3- and alloantigen-induced T cell proliferation were decreased significantly by the anti-CD25 MoAbs in a dose-dependent fashion. At a concentration of 10 ng/ml daclizumab and CsA synergistically decreased T cell proliferation of mixed lymphocyte cultures, whereas basiliximab showed only subadditive activity. Simultaneous addition of the anti-CD25 MoAbs and prednisolone did not result in combined activity. Addition of exogenous IL-2 completely overcame the inhibitory effect on T cell proliferation of both anti-CD25 MoAbs, but not that of CsA and prednisolone. Anti-CD25 MoAbs inhibited the generation of antigen-specific cytotoxic T lymphocytes in a limiting dilution assay, whereas they showed no effect on the cytolytic activity of established antigen-specific T cell clones. This in vitro study demonstrates strong immunosuppressive activity by both chimeric and humanized MoAbs against CD25. The combined activity with CsA justifies their early use for prevention rather than treatment of GvHD.     

IL1 receptor accessory protein like,a protein involved in X-linked mental retardation,interacts with Neuronal Calcium Sensor-1 and regulates exocytosis

Previously, human genetics-based approaches allowed us to show that mutations in the IL-1 receptor accessory protein-like gene (IL1RAPL) are responsible for a non-specific form of X-linked mental retardation. This gene encodes a predicted protein of 696 amino acids that belongs to a novel class of the IL-1/Toll receptor family. In addition to the extracellular portion consisting of three Ig-like domains and the intracellular TIR domain characteristic of the IL-1/Toll receptor family, IL1RAPL contains a specific 150 amino acid carboxy terminus that has no significant homology with any protein of known function. In order to begin to elucidate the function of this IL-1/Toll receptor-like protein, we have assessed the effect of recombinant IL1RAPL on the binding affinity of type I IL-1R for its ligands IL-1alpha and beta and searched for proteins interacting with the specific carboxy terminus domain of IL1RAPL. Our results show that IL1RAPL is not a protein receptor for IL-1. In addition we present here the identification of Neuronal Calcium Sensor-1 (NCS-1) as an IL1RAPL interactor. Remarkably, although NCS-1 and its non-mammalian homologue, frequenin, are members of a highly conserved EF-hand Ca(2+) binding protein family, our data show that IL1RAPL interacts only with NCS-1 through its specific C-terminal domain. The functional relevance of IL1RAPL activity was further supported by the inhibitory effect on exocytosis in PC12 cells overexpressing IL1RAPL. Taken together, our data suggest that IL1RAPL may regulate calcium-dependent exocytosis and provide insight into the understanding of physiopathological mechanisms underlying cognitive impairment resulting from IL1RAPL dysfunction.     

Maintaining asthma control in persistent asthma: comparison of three strategies in a 6-month double-blind randomised study

In patients controlled with SFC250 Diskus bd, this double-blind, randomised 6-month study compared continuing SFC250 to stepping down to either SFC100 bd or FP250 bd. Six hundred and three patients previously using 1,000 microg BDP (or equivalent) daily +LABA and controlled according to investigator's judgement were recruited. Patients received SFC250 bd during an 8-week open run-in period. Four hundred and seventy six patients (mean age=43 years, mean FEV(1)=2.9+/-1.0) who fulfilled the randomisation criterion ('Well-controlled' asthma according to the GOAL weekly definition for the last 2 weeks of the run-in period) entered a 24-week treatment period. The statistical hypothesis was based on a non-inferiority of SFC100 or FP250 compared to SFC250. The main criterion was the change from baseline in morning PEF over weeks 1-12 in the per-protocol population. The non-inferiority limit was -15 L/min. At inclusion, the three treatment groups were well balanced. Mean morning PEF was 476, 470 and 465 L/min in the SFC250, SFC100 and FP250 groups, respectively. The adjusted mean change in morning PEF over weeks 1-12 was +1.76+/-2.43 L/min for SFC250, -3.07+/-2.32 L/min for SFC100 and -16.51+/-2.46 L/min for FP250. SFC100 was at least as effective as SFC250 (treatment difference -4.83 [-12.39; 2.72], p=0.151) whereas FP250 was not (treatment difference -18.27 [-26.05; -10.49], p<0.001). Similar results were observed over weeks 13-24 in morning PEF (SFC100-SFC250=-4.54+/-3.84, p=0.238; FP250-SFC250=-20.11+/-3.92, p<0.0001). Secondary endpoints showed a similar pattern. Over weeks 1-12, SFC250 was significantly more effective than FP250 on evening PEF, daily symptoms and bronchodilator use. There was no difference between SFC100 and SFC250. The mean annual rate of moderate exacerbations was 0.16 in both SFC 250 and SFC 100 groups, and 0.21 in FP 250 group (ns, Poisson analysis). All treatments were well tolerated. CONCLUSION: In patients achieving asthma control with SFC250, stepping treatment down with SFC100 was at least as effective on lung function and symptoms as continuing SFC250, whereas FP250 was not.     

Severe neonatal hypercalcemia caused by subcutaneous fat necrosis without any apparent cutaneous lesion

Subcutaneous fat necrosis is a classic, albeit uncommon, cause of neonatal hypercalcemia. It occurs in newborn infants within the first month of life following a complicated delivery. The diagnosis is usually easy because of the presence of red-purple plaques in fatty areas along with firm subcutaneous nodules. A 1-month-old neonate, born strangled by her umbilical cord, presented with diarrhea and hypercalcemia (3.46 mM) with an initial physical examination considered normal. Her biological evaluations were as follows: P = 1.37 mM (1.6–2.2); PTH = 3 ng/L (12–65); 25-OH vitamin D = 87 nM (23–113); (1,25)-OH₂ vitamin D = 192 ng/L (20–46). The third day, a careful exam of the whole cutaneous surface revealed small firm subcutaneous nodules in the ischial region. Despite the absence of any visible skin modification, the association of perinatal stress and high (1,25)-OH₂ vitamin D level with subcutaneous nodules led to the diagnosis of subcutaneous fat necrosis. She was treated with oral prednisone for 45 days. Serum calcium levels normalized within a week, and the nodules disappeared without complications. Conclusion: Subcutaneous fat necrosis may induce severe hypercalcemia without any visible cutaneous lesion. No funding or grant was received for this study.     

Evaluation of B cell maturation antigen as a target for antibody drug conjugate mediated cytotoxicity in multiple myeloma

B‐cell maturation antigen (BCMA, also termed TNFRSF17) is an attractive therapeutic target due to its restricted expression on normal and malignant plasma cells (PC). GSK2857916 (or J6M0‐MMAF) is a BCMA‐specific antibody conjugated to the microtubule‐disrupting agent monomethyl auristatin F (MMAF) via a protease‐resistant linker. To evaluate the clinical potential of this agent, tumour cells from seventy multiple myeloma (MM) patients were assessed for BCMA expression by immunohistochemistry and flow cytometry. All patients tested expressed BCMA, at varying levels, and both surface and intracellular expression were observed. BCMA expression is maintained through relapse, extramedullary spread and in residual disease post therapy. BCMA levels may also be prognostically useful as higher levels of BCMA were associated with poorer outcomes, even taking into account genetic risk. We observed rapid internalization of surface BCMA and newly expressed protein by 1 h, suggesting a mechanism for J6M0‐MMAF activity even with low surface antigen. J6M0‐MMAF mediated cytotoxicity of MM cells varied with dose and antigen levels, with clonogenic progenitors killed at lower doses than mature cells. In comparison, J6M0‐MMAF killing of primary CD138⁺ myeloma cells occurred with slower kinetics. Our observations support BCMA to be a promising therapeutic target in MM for novel therapies such as J6M0‐MMAF.