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Hervé Watier

Publications and source records attributed to Hervé Watier.

At least 19 recordsLinked to original sources
PubMed2007

Relevance, advantages and limitations of animal models used in the development of monoclonal antibodies for cancer treatment.

Antibody humanisation through recombinant DNA technology was a key step in allowing monoclonal antibodies (mAbs) to reach the clinic, particularly for the treatment of cancer. As a consequence, they are less adapted to animal studies, although these studies continue to be important tools to study antibody distribution and action at the level of a whole organism. Moreover, preclinical studies in animals are mandatory before the approval of biologics license applications for mAbs by the U.S. Food and Drug Administration (FDA) or European Agency for the Evaluation of Medicinal Products (EMEA). Different parameters should be taken in consideration before starting animal experiments with recombinant mAbs, including antibody cross-reactivity, immunogenicity, pharmacokinetics, and possible interactions with the host immune system. The various interspecies differences are reviewed and discussed in light of the pharmacological properties expected in patients. In doing so, this article aims to provide a critical review of the animal models used in preclinical studies of mAbs for cancer treatment. In particular, their relevance, advantages and limitations will be discussed.

Animals↗
PubMed2006

No association between C-reactive protein gene polymorphisms and decrease of C-reactive protein serum concentration after infliximab treatment in Crohn's disease.

We recently showed an association between the FCGR3A V/F polymorphism and the biological response [assessed on the basis of a C-reactive protein (CRP) concentration decrease] to infliximab in Crohn's disease. The CRP and FCGR3A genes are located on the same 1q23 locus. The present study aimed: (i) to exclude a linkage disequilibrium (LD) between the two genes and (ii) to study the association between CRP polymorphisms and the response to infliximab, particularly the decrease in CRP after treatment, in Crohn's disease patients. FCGR3A (V/F) polymorphism and three CRP polymorphisms (-717G/A, 1444C/T, CRP 4A/G) were determined in 206 healthy blood donors and 189 Crohn's disease patients who had received infliximab for either refractory luminal or fistulizing Crohn's disease. Clinical response was defined as complete, partial or absent according to the same definition as in controlled trials. The biological response was defined on the basis of CRP decrease. There was no LD between CRP and FCGR3A in healthy donors or Crohn's disease patients. CRP polymorphisms had no impact on CRP decrease after infliximab. The proportions of Crohn's disease having a positive clinical or biological response were not statistically different among the various genotypes of CRP polymorphisms. There was no LD between CRP and FCGR3A polymorphisms. CRP polymorphisms were not associated with the response to infliximab in Crohn's disease.

Adolescent↗
PubMed2006

An enzyme-linked immunosorbent assay for therapeutic drug monitoring of infliximab.

An enzyme-linked immunosorbent assay (ELISA) measuring serum infliximab concentrations in treated patients was developed. Microtiter plates were sensitized with tumor necrosis factor alpha (TNF-alpha) and saturated with phosphate-buffered saline (PBS) containing 1% bovine serum albumin (BSA). Samples diluted 1:100 in PBS-1% BSA were added and bound infliximab was detected using peroxidase-conjugated goat anti-human immunoglobulin G specific for Fc fragment (HRP-anti hIgG). Reading was performed using an ELISA plate reader. The limit of detection, calculated by assaying 10 replicates of a drug-free serum sample or blank sample and defined as the lowest concentration distinguishable from zero at 2 standard deviations, was 0.014 microg/mL. Each quality control sample was tested on 7 occasions on 1 day and on 5 separate days. The intraday precision indices of the method were (percent coefficients of variation, CV%) 11.7%, 6.2%, and 6.9% for 0.04 microg/mL, 2 microg/mL, and 4.5 microg/mL, respectively. The corresponding bias measures (percent deviation) were -5.5%, -1.9%, and -7.9%, respectively. The between-days precision was 9.8%, 5.3%, and 5.3% for 0.04 microg/mL, 2 microg/mL, and 4.5 microg/mL, respectively. The corresponding bias were +0.3%, -0.3%, and -7.8%, respectively. Lower limit of quantitation and upper limit of quantitation were 0.04 microg/mL and 4.5 microg/mL, respectively. Trough serum concentrations of infliximab were measured in 6 adult patients with various diseases and in 5 pediatric patients with Crohn's disease. For the latter group, samples drawn 1 hour after the end of the infusion and repeated measurements also were available. Data were described using a 1-compartment population pharmacokinetic model. Terminal elimination half-life was 10.9 days. This method is rapid, accurate, and reproducible, and may be useful in therapeutic drug monitoring of infliximab.

Adolescent↗
PubMed2005

Pathophysiology of disk-related sciatica. I.--Evidence supporting a chemical component.

Sciatica in patients with disk disease was long ascribed to pressure put on the sciatic nerve root by a herniated disk. However, a role for chemical factors acting in conjunction with this mechanical insult is suggested by a number of clinical observations: disk surgery does not consistently provide pain relief, large disk herniations are not always symptomatic, severe pain may be present in patients without imaging evidence of nerve root compression, the severity of symptoms and neurological signs is not well correlated with the size of the disk herniation, and conservative therapy is often effective. Experimental studies have provided further evidence for a chemical component: disk herniations can undergo spontaneous resorption, the intervertebral disk is immunogenic, and mediators for inflammation have been identified within intervertebral disk tissue. The current pathophysiological theory incriminates proinflammatory substances secreted by the nucleus pulposus (NP). When preexisting or concomitant mechanical injury to a nerve root occurs, these substances can cause nerve root pain. Animal experiments have established that the NP can induce functional and structural nerve root abnormalities in the absence of mechanical compression and that this effect is mediated by substances located at the surface of NP cells. Methylprednisolone, diclofenac, indomethacin, doxycycline, and cyclosporine induce variable inhibition of this effect. Available information points to tumor necrosis factor-alpha (TNF-alpha) as the main candidate among substances potentially responsible for nerve root pain. Therefore, trials of TNF-alpha antagonists in patients with disk-related sciatica are warranted.

Animals↗
PubMed2005

Pathophysiology of disk-related low back pain and sciatica. II. Evidence supporting treatment with TNF-alpha antagonists.

Strong evidence suggests that TNF-alpha may be among the chemical factors involved in disk-related sciatica. TNF-alpha is involved in the genesis of nerve pain in animal models and may promote pain-signal production from nerve roots previously subjected to mechanical deformation. In animal experiments, TNF-alpha has been identified in nucleus pulposus and Schwann cells. Local production of endogenous TNF-alpha may occur early in the pathogenic process. Exposure to exogenous TNF-alpha induces electrophysiological, histological, and behavioral changes similar to those seen after exposure to nucleus pulposus, and these changes are more severe when mechanical compression is applied concomitantly. TNF-alpha antagonists diminish or abolish abnormalities in animal models. Other cytokines may be involved also, as suggested by the potent inhibitory effects of compounds such as doxycycline. Two open-label studies in humans suggest dramatic efficacy of TNF-alpha antagonists in alleviating disk-related sciatica. In contrast, the results of the only controlled study available to date do not support a therapeutic effect of TNF-alpha antagonists. Thus, whether TNF-alpha antagonist therapy is warranted in patients with disk-related sciatica remains an open question, and further randomized controlled studies are needed.

Animals↗
PubMed2005

The active role played by xenogeneic endothelial cells in the indirect presentation pathway is not lymphocyte trans-co-stimulation.

The human CD4+ T lymphocyte response to major histocompatibility complex (MHC) class II-negative porcine endothelial cells is dependent on the presence of human monocytes through a human leukocyte antigen (HLA) class II-restricted indirect presentation pathway. Because the role of porcine endothelial cells had been previously shown to do more than simply supply xenopeptides, co-stimulatory signals were analysed. Endothelial cells were shown to express the CD54, CD58, CD59 and CD86 transcripts; however, no membrane B7 molecule could be detected. Blocking experiments in a direct pathway model confirmed that porcine endothelial cells could provide co-stimulatory signals to human T cells through the CD2 and LFA-1 pathways. Nevertheless, the proliferation achieved in the indirect presentation model required co-stimulation by LFA-1, CD2 and CD28, engaged by co-stimulation molecules expressed in the cis-form by the human monocytes. These results clearly show that the active role played by the endothelial cells in the indirect pathway is not lymphocyte trans-co-stimulation and suggest that cis-co-stimulation dominates trans-co-stimulation when both are present.

Abatacept↗
PubMed2005

Variability factors in the clinical response to recombinant antibodies and IgG Fc-containing fusion proteins.

Recombinant monoclonal antibodies and IgG Fc-containing fusion proteins represent major therapeutic advances in many diseases. However, despite their similarity with endogenous IgG, some patients respond to the treatment whilst others do not; thus raising the question of the origin of this variability. Some variability factors are now identified, of genetic origin or not, which influence either pharmacokinetics or pharmacodynamics of these drugs. Known variability factors are reviewed and classified according to their relationship with the paratope (antigen binding site) of the antibodies, with other parts of the IgGs (mostly Fc) or with IgG epitopes (antigenic motifs).

Animals↗
PubMed2004

Rituximab-dependent cytotoxicity by natural killer cells: influence of FCGR3A polymorphism on the concentration-effect relationship.

The FCGR3A gene dimorphism generates two allotypes: FcgammaRIIIa-158V and FcgammaRIIIa-158F. The genotype homozygous for FcgammaRIIIa-158V (VV) is associated with higher clinical response to rituximab, a chimeric anti-CD20 IgG1 used in the treatment of B lymphoproliferative malignancies. Our objective was to determine whether this genetic association relates to rituximab-dependent cytotoxicity mediated by FcgammaRIIIa/CD16a+ cells. The number of CD16+ circulating monocytes, T cells, and natural killer (NK) cells in 54 donors was first shown to be unrelated to FCGR3A polymorphism. We then demonstrated that FcgammaRIIIa-158V displays higher affinity for rituximab than FcgammaRIIIa-158F by comparing rituximab concentrations inhibiting the binding of 3G8 mAb (anti-CD16) with VV NK cells and NK cells homozygous for FcgammaRIIIa-158F (FF). VV and FF NK cells killed Daudi cells similarly after FcgammaRIIIa engagement by saturating concentrations of rituximab or 3G8. However, the rituximab concentration resulting in 50% lysis (EC(50)) observed with NK cells from VV donors was 4.2 times lower than that observed with NK cells from FF donors (on average 0.00096 and 0.00402 microg/ml, respectively, P = 0.0043). Finally, the functional difference between VV and FF NK cells was restricted to rituximab concentrations weakly sensitizing CD20. This study supports the conclusion that FCGR3A genotype is associated with response to rituximab because it affects the relationship between rituximab concentration and NK cell-mediated lysis of CD20+ cells. Rituximab administration could therefore be adjusted according to FCGR3A genotype.

Antibodies, Monoclonal↗
PubMed2004

From the bench to the bedside: ways to improve rituximab efficacy.

Rituximab (MabThera, Rituxan) is a chimeric IgG1 monoclonal antibody that specifically targets the CD20 surface antigen expressed on normal and neoplastic B-lymphoid cells. Rituximab is currently used in the treatment of both follicular and aggressive B-cell non-Hodgkin lymphomas. Despite its demonstrated clinical effectiveness, its in vivo mechanisms of action remain unknown and could differ by subtype of lymphoma. Rituximab has been shown to induce apoptosis, complement-mediated lysis, and antibody-dependent cellular cytotoxicity in vitro, and some evidence points toward an involvement of these mechanisms in vivo. Rituximab also has a delayed therapeutic effect as well as a potential "vaccinal" effect. Here, we review the current understanding of the mechanism of action of rituximab and discuss approaches that could increase its clinical activity. A better understanding of how rituximab acts in vivo should make it possible to develop new and more effective therapeutic strategies.

Antibodies, Monoclonal↗
PubMed2004

The homozygous FcgammaRIIIa-158V genotype is a risk factor for heparin-induced thrombocytopenia in patients with antibodies to heparin-platelet factor 4 complexes.

We hypothesized that Fcgamma receptor IIIa (FcgammaRIIIa), a polymorphic receptor for the Fc portion of immunoglobulin G (IgG) other than FcgammaRIIa, was involved in heparin-induced thrombocytopenia (HIT). FcgammaRIIa-131 and FcgammaRIIIa-158 genotypes were determined in 102 patients with definite HIT and in 2 control groups of patients treated by heparin (86 subjects without detectable antibodies [Abs] to heparin-platelet factor 4 [H/PF4], Ab(-) group; 84 patients with Abs to H/PF4 without HIT, Ab(+) group). There were no significant differences in genotype distribution or allele frequencies between the 3 groups for FcgammaRIIa-131H/R polymorphism. In contrast, FcgammaRIIIa-158V homozygotes were more frequent in the HIT group than in the Ab(+) group (P = .02), a difference that was more pronounced in patients with high levels of anti-H/PF4 Abs (P = .01). Since anti-H/PF4 Abs are mainly IgG1 and IgG3, clearance of sensitized platelets may be increased in patients homozygous for the FcgammaRIIIa-158V allotype, thus contributing to the development of thrombocytopenia.

Antigens, CD↗
PubMed2004

Association of donor TNFRSF6 (FAS) gene polymorphism with acute rejection in renal transplant patients: a case-control study.

BACKGROUND: Genetic factors other than HLA have been reported to be associated with the outcome of organ transplantations. Because binding of FasL to its receptor Fas could play an important role in tubulitis and in the death of graft tubular epithelial cells during kidney allograft rejection, a gene polymorphism recently identified in position -671 in the promoter of the TNFRSF6 gene coding for Fas was investigated in donors. METHODS: A case-control study was performed within a cohort of non-hyperimmunized adult patients who had received cadaveric kidney transplants based on the occurrence or absence of acute cellular rejection in the first 6 months after renal transplantation. Each recipient from the acute rejection group (n = 35) was matched for age (+/- 5 years) and number of HLA-DR mismatches with two recipients within the non-acute rejection group (n = 70). RESULTS: The TNFRSF6-GG genotype was more frequent in donors in the group without rejection episodes. In contrast, patients who received a kidney from a TNFRSF6-A carrier were more likely to experience acute rejection episodes (relative risk nearly 2.1). CONCLUSION: This study suggests that donor TNFRSF6 polymorphism directly or indirectly influences acute kidney rejection episodes.

Adult↗
PubMed2003

Porcine CD58: cDNA cloning and molecular dissection of the porcine CD58-human CD2 interface.

The porcine ligands of human CD2 remain unknown in xenotransplantation despite being an important pathway of T cell costimulation. Of the two main candidates, i.e., CD48 and CD58, the cDNA of the most likely ligand poCD58 was cloned from CD48-negative endothelial cells costimulating human CD4(+) T cells through the CD2 pathway. The deduced protein sequence is 244 residues long and is 43% homologous to the human sequence. Based on similarity between porcine and human CD58 external V-set Ig-type domains, a structural model of poCD58-huCD2 interaction was built. Most of the charged residues located at the interface with huCD2 are highly conserved. Six putative hydrogen bonds between poCD58 and huCD2 were identified; five involve the same residues as in the syngeneic combination while the sixth is formed between an additional tyrosine in poCD58 and Arg48 in huCD2, increasing the complementarity between the two molecules. These structural data will help us to develop poCD58 blocking agents for xenotransplantation.

Amino Acid Sequence↗
PubMed2003

Rapid single-step FCGR3A genotyping based on SYBR Green I fluorescence in real-time multiplex allele-specific PCR.

A polymorphism at position 559 in the cDNA of the FCGR3A gene encoding the FcgammaRIIIa generates two allotypes with either a valine (Val) or a phenylalanine (Phe) at amino acid position 158. This polymorphism is of major importance in immunopathology and in pharmacogenetics, especially monoclonal antibody treatments. In this study, we report a single-step and single-tube method for FCGR3A-158V/F genotyping by real-time multiplex allele-specific PCR and melting curve analysis in the presence of SYBR Green I fluorescent dye. Results obtained from 113 samples showed 100% accuracy compared to those obtained with a conventional PCR-based allele-specific restriction assay. Although this method requires expensive equipment, it is inexpensive in terms of consumables. It is also very rapid, reliable and suitable for large-scale analysis.

Alleles↗
PubMed2003

Human choriocarcinoma cell resistance to natural killer lysis due to defective triggering of natural killer cells.

The trophoblast, the outermost layer of the human placenta, lacks expression of the classical human leukocyte antigen (HLA) class I molecules. This prevents allorecognition by T cells but raises the question of what protects the trophoblast from natural killer (NK) cells. In a previous study, we have shown that choriocarcinoma cell (CC) resistance to NK lysis was mainly independent of HLA class I molecules. In the present study, we postulated that CC may prevent activation of NK cells by failing to stimulate their triggering receptors (TR). To test this hypothesis, we evaluated the lysis of JAR and JEG-3 CC after effective cross-linking and activation of NK cells by means of lectins or antibodies. Our results show that NK-resistant CC were sensitive to lysis by unstimulated peripheral blood lymphocytes in the presence of phytohemagglutin (PHA), to antibody-dependent cell cytotoxicity in presence of anti-Tja antibodies, and to monoclonal antibody redirected killing using anti-TR antibodies anti-CD16 and anti-CD244/2B4. Finally, CC fail to express CD48, the ligand for CD244/2B4. These results indicate that the resistance of CC to lysis results primarily from defective NK cell activation, at least partially due to the lack of expression of ligands, such as CD48, involved in the triggering of NK cells.

Antibodies, Monoclonal↗
PubMed2003

Analysis of human CD4 T lymphocyte proliferation induced by porcine lymphoblastoid B cell lines.

BACKGROUND: This study was undertaken to characterize the two porcine lymphoblastoid cell lines L23 and L35, derived from a pig inoculated by the retrovirus Tsukuba-1, and to determine how they induce a strong human lymphocyte proliferation. METHODS: Phenotypic characterization was performed by flow cytometry and reverse transcriptase-polymerase chain reaction analyses. Xenogeneic mixed lymphocyte reactions (XMLR) were performed using unfractionated human peripheral blood mononuclear cells (huPBMC) and purified CD4+ T lymphocytes as responding cells, in the presence of blocking antibodies and fusion proteins. RESULTS: The immunoglobulin genes were demonstrated to be rearranged in L23 and L35 cell lines, in agreement with the expression of a B cell phenotype. Both induced a similar proliferation of huPBMCs and purified human CD4+ lymphocytes from adult or cord blood (naïve cells). Proliferation of CD4+ T lymphocytes was completely blocked by anti-SLA-DR plus anti-SLA-DQ mAbs, excluding human lymphocyte transformation by porcine viruses. The frequency of proliferative precursors was inconsistent with that induced by a retroviral superantigen but similar to classical direct xenoantigen presentation as observed with other porcine antigen-presenting cells. Extensive analysis of costimulatory signals led to the identification of the CD28 pathway, in agreement with membrane expression of B7 molecules on L23 and L35 cells, and of the CD2 pathway in L35 cells. CONCLUSION: These two porcine lymphoblastoid cell lines have been further characterized and clearly identified as belonging to the B cell lineage. By expressing major histocompatibility complex class II antigens and costimulatory molecules, they induce a vigorous proliferative response of human CD4+ lymphocytes through a direct presentation pathway.

Animals↗
PubMed2002

Therapeutic activity of humanized anti-CD20 monoclonal antibody and polymorphism in IgG Fc receptor FcgammaRIIIa gene.

Given that the FcgammaRIIIa receptor 158V allotype displays a higher affinity for human immunoglobulin G1 and increased antibody-dependent cellular cytotoxicity, the aim of this study was to determine the influence of that FCGR3A polymorphism on the therapeutic response to rituximab, an anti-CD20 humanized immunoglobulin G1 increasingly used in the treatment of non-Hodgkin lymphomas. The FCGR3A-158V/F genotype was determined in 49 patients having received rituximab for a previously untreated follicular non-Hodgkin lymphoma. The clinical response and the disappearance of the BCL2-JH gene rearrangement in both peripheral blood and bone marrow were evaluated at 2 months (M2) and at 1 year (M12). The study population consisted of 20% FCGR3A-158V homozygous patients, 35% FCGR3A-158F homozygous patients, and 45% heterozygous patients (FCGR3A-158F carriers). The objective response rates at M2 and M12 were 100% and 90%, respectively, in FCGR3A-158V homozygous patients compared with 67% (P =.03) and 51% (P =.03), respectively, in FCGR3A-158F carriers. A disappearance of the BCL2-JH gene rearrangement in both peripheral blood and marrow was observed at M12 in 5 of 6 of homozygous FCGR3A-158V patients compared with 5 of 17 of FCGR3A-158F carriers (P =.03). The homozygous FCGR3A-158V genotype was confirmed to be the single parameter associated with clinical and molecular responses by multivariate analysis. This study showed an association between the FCGR3A genotype and clinical and molecular responses to rituximab. This finding will certainly give rise to new pharmacogenetic approaches to the management of patients with non-Hodgkin lymphomas.

Antibodies, Monoclonal↗