How can the safety of biotherapy products be ensured for patients?

The topic of the round table being very broad, it was agreed with the participants that the discussion should be focused on autologous cell therapy (CT) used in tissue repair, immunomodulation or gene transduction. Autologous CT is actually comprised of both very innovative procedures as well as of products used in routine clinical practice. In France, the regulatory framework for CT has now been finalised, underlining the fact that a CT product (CTP) is intrinsically linked to the process used in its preparation.

Chemical synthesis and biological activity of bromohydrin pyrophosphate, a potent stimulator of human gamma delta T cells.

Small phosphorylated metabolites from mycobacteria stimulate human gammadelta T lymphocytes. Although such phosphoantigens could prove useful in the composition of vaccines involving gammadelta T cell-mediated immunity, their very low abundance in natural sources limits such applications. Here, we describe the chemical production, purification, and bioactivity of a phosphorylated bromohydrin (BrHPP) analogue that mimics the biological properties of natural phosphoantigens.

Modification of P-selectin glycoprotein ligand-1 with a natural killer cell-restricted sulfated lactosamine creates an alternate ligand for L-selectin.

Natural killer (NK) cells are components of the innate immune system that can recognize and kill virally infected cells, tumor cells, and allogeneic cells without prior sensitization. NK cells also elaborate cytokines (e.g.

Identification of the soluble granulocyte-macrophage colony stimulating factor receptor protein in vivo.

On the basis of the finding of alternatively spliced mRNAs, the alpha-subunit of the receptor for GM-CSF is thought to exist in both a membrane spanning (tmGMRalpha) and a soluble form (solGMRalpha). However, only limited data has been available to support that the solGMRalpha protein product exists in vivo. We hypothesized that hematopoietic cells bearing tmGMRalpha would have the potential to also produce solGMRalpha.

Characterization of two monoclonal antibodies against the RON tyrosine kinase receptor.

RON is a receptor protein tyrosine kinase belonging to the hepatocyte growth factor (HGF) receptor family. Using Récepteur d'Origine Nantais (RON) transfected cell lines, Macrophage Stimulating Protein (MSP) was identified as the ligand of RON. RON is synthesized as a single chain precursor, which subsequently is cleaved to yield a disulfide-linked heterodimer, with a 40-kDa alpha chain and a 150-kDa beta chain.

Analysis of the mechanism of action of anti-human interleukin-6 and anti-human interleukin-6 receptor-neutralising monoclonal antibodies.

Anti-human interleukin-6 (human IL-6) and anti-human IL-6 receptor (IL-6R)-neutralising monoclonal antibodies (mAbs) are among the most promising human IL-6-specific inhibitors and have been shown to exert short-term beneficial effects in clinical trials. Simultaneous treatment with different anti-human IL-6 or anti-human IL-6R mAbs was recently suggested to be a potent way to inhibit the action of the cytokine in vivo. Although some of these mAbs are already used, their mechanisms of action and the location of their epitopes on the surface of human IL-6 and human IL-6R are still unknown.

Characterization of soluble gp130 released by melanoma cell lines: A polyvalent antagonist of cytokines from the interleukin 6 family.

gp130 acts as a common transducing signal chain for all receptors belonging to the interleukin (IL)-6 receptor family. The IL-6-related cytokines [IL-6, IL-11, oncostatin M (OSM), leukemia inhibitory factor, ciliary neurotrophic factor, and cardiotrophin] often modulate tumor phenotype and control the proliferation of many tumor cell lines. We demonstrate that melanoma cell lines release, in vitro and in vivo (when transplanted in nude mice), soluble gp130 (sgp130), a potential antagonist of cytokines from the IL-6 family.

Reconstitution of two isoforms of the human interleukin-11 receptor and comparison of their functional properties.

Long-term stable Ba/F3 transfectants (B13R alpha1 and B13R alpha2) expressing two isoforms of the human IL-IIR alpha receptor (alpha1 full length or alpha2 lacking the cytoplasmic domain) in combination with human gp130 were established. IL-11R alpha1 and IL-11R alpha2 were each expressed and detected as three bands upon Western blot analysis, with apparent molecular masses in agreement with those of the polypeptide backbone (47 and 44 kDa, respectively) with no, one or two N-linked sugars. B13R alpha1 and B13R alpha2 bound IL-11-thioredoxin with similar efficiencies and proliferated with superimposable dose-response curves to IL-11, demonstrating that the intracellular domain of IL-11R alpha has no significant contribution on ligand binding and signaling.

Analysis of the human interleukin-6/human interleukin-6 receptor binding interface at the amino acid level: proposed mechanism of interaction.

The interaction between interleukin-6 (IL-6) and IL-6 receptor (IL-6R) is the initial and most specific step in the IL-6 signaling pathway. Understanding its mechanism at the amino acid level is the basis for developing small IL-6-inhibiting molecules. We studied the human IL-6 (hIL-6)/hIL-6R binding interface by a combination of molecular modelling and site-directed mutagenesis.

Participation of two Ser-Ser-Phe-Tyr repeats in interleukin-6 (IL-6)-binding sites of the human IL-6 receptor.

The alpha-subunit of interleukin-6 (IL-6) receptor is a member of the hematopoietin receptor family. The alignment of its amino acid sequence with those of other members of this family (human somatotropin receptor/murine IL-3 receptor beta and human IL-2 receptor beta) has suggested that amino acids included in two SSFY repeats found in each of its hematopoietin receptor domains, contribute to the binding of the ligand. The involvement of these amino acids in IL-6 binding and signal transduction was studied by site-directed mutagenesis and molecular modelling.

IL2 triggers a tumor progression process in a melanoma cell line MELP derived from a patient whose metastasis increased in size during IL2/INFalpha biotherapy.

Human melanomas may express both in vivo and in vitro functional IL-Rs and may be expected to directly respond to injected IL2. This may generate biological situations which may be favourable for the patient, but also for tumor progression. Here, we analyse the latter hypothesis.

Measurement of whole body interleukin-6 (IL-6) production: prediction of the efficacy of anti-IL-6 treatments.

A major limitation on the therapeutic use of cytokine antagonists is that the amount of cytokine to be neutralized in vivo is not presently known. We previously reported that anti-interleukin-6 (IL-6) monoclonal antibody (MoAb) administered to a patient with multiple myeloma (MM) induced high amounts of IL-6 to circulate in the form of monomeric immune complexes. Based on this observation, the present study developed a new methodology to estimate daily IL-6 production in 13 patients with MM or renal cancer who received anti-IL-6 MoAb.

Immunological characterization of antigenic domains on human IL-2 receptor beta subunit: epitope-function relationships.

Five mAb directed at the IL-2R beta chain were analyzed for their binding and functional properties. They define three epitopes on a recombinant soluble beta chain or on the beta chain expressed at the surface of YT-2C2 cells. Epitope 1 (A41 and 6E8 mAb) is part of the IL-2 binding domain, whereas epitope 2 (CF1 and 6E10 mAb) is not involved in IL-2 binding.

Cytokine-binding proteins: stimulating antagonists.

Cytokine-binding proteins (CBPs) block the ability of cytokines to interact with their receptors. These agents can potentially provide a means of treating pathological conditions that have a significant cytokine involvement. However, a major drawback of such approaches relates to the fact that CBPs stabilize the cytokine in the form of a cytokine-CBP complex in vivo.

Pharmacokinetic study of anti-interleukin-6 (IL-6) therapy with monoclonal antibodies: enhancement of IL-6 clearance by cocktails of anti-IL-6 antibodies.

The use of inhibiting cytokine-binding-proteins (CBPs) such as soluble cytokine receptors and anticytokine antibodies is considered for the treatment of cytokine-dependent diseases. The pleiotropic cytokine interleukin-6 (IL-6) is a target for immunointervention in numerous pathologic situations, including multiple myeloma, B-cell lymphoma, and rheumatoid arthritis. An antitumor response was obtained in the treatment of a patient with multiple myeloma.

Serum interleukin 6 and C-reactive protein levels correlate with resistance to IL-2 therapy and poor survival in melanoma patients.

Interleukin 6 and C-reactive protein (CRP) were determined prior to IL-2 therapy in sera from metastatic melanoma patients. Patients with elevated serum IL-6 (> 20 pg ml-1) and/or CRP (> 10 mg l-1) levels were associated with resistance to IL-2 therapy. A correlation between high serum IL-6 levels and a shorter median survival was also observed.

Epitope analysis of human IL-6 receptor gp80 molecule with monoclonal antibodies.

Gp80 human IL-6R was studied using 7 murine mAb (M37, M91, M113, M139, M164, M182 and M195) obtained after fusion of splenocytes of Balb/c mice immunised with a mixture of recombinant IL-6 receptor (rIL-6R) and cells from 2 cell lines expressing IL-6R. These were U266, which is IL-6 independent and XG-1 which is IL-6-dependent. In ELISA the 7 mAb reacted against the rIL-6R and against the natural soluble form found in plasma (nIL-6R), which both lack transmembrane and cytoplasmic domains.

Immunoassay for functional human soluble interleukin-6 receptor in plasma based on ligand/receptor interactions.

Soluble forms of most cytokine receptors, able to bind effectively to their respective ligands, have now been described. A soluble interleukin-6-binding molecule derived from the gp80 component of the multichain IL-6 receptor can be detected in biological fluids, and can act as an agonist of IL-6 activity. The clinical significance of the soluble receptor levels still remains to be explored.

Total interleukin-6 in plasma measured by immunoassay.

Determinations of total cytokine concentration in biological fluids by immunoassays face two major problems: the biochemical heterogeneity of the analyte and the interference of cytokine-binding proteins. We developed an ultrasensitive enzyme immunoassay for interleukin-6 (IL-6), using monoclonal antibodies and acetylcholinesterase as the tracer enzyme. The antibodies recognized recombinant and glycosylated forms of IL-6 equally.

Overall interleukin-6 production exceeds 7 mg/day in multiple myeloma complicated by sepsis.

We previously reported that injection of anti-IL-6 monoclonal antibody (mAb) in a patient with multiple myeloma (MM) induced the circulation of high amounts of IL-6 in the form of IL-6/anti-IL-6 monomeric complexes. This made it possible to estimate overall daily IL-6 production in patients in vivo, which had not been achieved in animals or humans before. In this study, estimations are given for a patient with MM who developed Escherichia coli sepsis during anti-IL-6 mAb.

Interleukin-7 is a potent co-stimulus of the adhesion pathway involving CD2 and CD28 molecules.

Co-stimulation of highly purified peripheral T lymphocytes from healthy blood donors with the adhesion molecules CD2 and CD28 in association with recombinant interleukin-7 (rIL-7) induced T-cell proliferation, multiple cytokine secretion and IL-2 receptivity. We demonstrated that rIL-7 is as potent as rIL-2 in inducing the proliferation of unseparated, CD4+ and CD8+ T cells. In contrast to low or undetectable levels of IL-1 alpha, IL-6 and IL-2, high levels of tumour necrosis factor-alpha (TNF-alpha), IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF) were secreted.

TNF alpha acts in synergy with GM-CSF to induce proliferation of acute myeloid leukemia cells by up-regulating the GM-CSF receptor and GM-CSF gene expression.

Acute myeloid leukemia (AML) cells are dependent for their survival and proliferation on hematopoietic growth factors. As tumor necrosis factor alpha (TNF alpha) can increase the proliferation of primary cultures of AML cells, we have investigated the effect of TNF alpha on the autocrine and/or paracrine growth control by one of the major AML growth factor, granulocyte-macrophage colony-stimulating factor (GM-CSF). First, a panel of AML cells were analysed with respect to their proliferative response to TNF alpha.