Biomedical subjects

Christophe Legendre

Publications and source records attributed to Christophe Legendre.

At least 19 recordsLinked to original sources

PubMed2024

Comprehensive molecular profiling of multiple myeloma identifies refined copy number and expression subtypes.

Multiple myeloma is a treatable, but currently incurable, hematological malignancy of plasma cells characterized by diverse and complex tumor genetics for which precision medicine approaches to treatment are lacking. The Multiple Myeloma Research Foundation's Relating Clinical Outcomes in Multiple Myeloma to Personal Assessment of Genetic Profile study ( NCT01454297 ) is a longitudinal, observational clinical study of newly diagnosed patients with multiple myeloma (n = 1,143) where tumor samples are characterized using whole-genome sequencing, whole-exome sequencing and RNA sequencing at diagnosis and progression, and clinical data are collected every 3 months. Analyses of the baseline cohort identified genes that are the target of recurrent gain-of-function and loss-of-function events. Consensus clustering identified 8 and 12 unique copy number and expression subtypes of myeloma, respectively, identifying high-risk genetic subtypes and elucidating many of the molecular underpinnings of these unique biological groups. Analysis of serial samples showed that 25.5% of patients transition to a high-risk expression subtype at progression. We observed robust expression of immunotherapy targets in this subtype, suggesting a potential therapeutic option.

Humans↗

PubMed2006

Differences in the frequency and function of HHV8-specific CD8 T cells between asymptomatic HHV8 infection and Kaposi sarcoma.

It is unclear how the immune response controls human herpesvirus 8 (HHV8; also known as Kaposi sarcoma-associated herpesvirus [KSHV]) replication and thereby prevents Kaposi sarcoma (KS). We compared CD8 T-cell responses to HHV8 latent (K12) and lytic (glycoprotein B, ORF6, ORF61, and ORF65) antigens in patients who spontaneously controlled the infection and in patients with posttransplantation, AIDS-related, or classical KS. We found that anti-HHV8 responses were frequent, diverse, and strongly differentiated toward an effector phenotype in patients who controlled the infection. Conversely, HHV8-specific CD8 cells were very rare in patients who progressed to KS, and were not recruited to the tumoral tissue, as visualized by in situ tetramer staining of KS biopsies. Last, HHV8-specific CD8 T cells were observed in a seronegative recipient of an HHV8infected graft who remained persistently aviremic and antibody negative, suggesting that specific cytotoxic T lymphocytes (CTLs) may provide protection from persistent HHV8 infection. These results support the crucial role of cellular immune responses in controlling HHV8 replication, in preventing malignancies in latently infected subjects, and in conferring genuine resistance to persistent infection. They may also have important implications for the design of prophylactic and therapeutic HHV8 vaccines, and for adoptive immunotherapy of KS.

Acquired Immunodeficiency Syndrome↗

PubMed2006

[New diagnostic tools in renal transplantation].

Renal transplantation is the best treatment available for end stage renal disease. The determination of human genome has profoundly modified the possible approaches of renal transplant recipient by allowing tailoring of immunosuppressive drugs and immunologic diagnosis. The aim of this review article is to determine the role of these various techniques during the different step before and after transplantation. Genotyping, transcriptome analysis, proteomic as well as the specific immune response are analyzed in this article.

Biopsy↗

PubMed2006

[Nephrotoxicity of sirolimus: experimental and clinical data].

Sirolimus (SRL, rapamycin) is a potent immunosuppressive drug that binds to and inhibits mammalian Target Of Rapamycine (mTOR) kinase activity, a central controller of cell growth. In response to amino acids, hormones and growth factors, mTOR activates the translational machinery. By inhibiting mTOR, SRL reduces the translational process and T-cell proliferation in the mid-to-late G1 phase of the cell cycle. The antiproliferative effects of SRL are not limited to activated T cells. SRL has also been shown to block the cell cycle in various cell types such as epithelial renal cells, and many types of tumor cell lines. Since the approval by the US Food and Drug Administration and by the European agency, SRL has provoked great interest, as evidenced by the exponential increase in clinical studies. However, whereas preclinical studies failed to show any nephrotoxic effect on animal models, many clinical trials raised the possibility that SRL might be associated with renal adverse events. The evidence for SRL-associated early graft nephrotoxicity emerged from these results, and subsequent experimental data gave some explanations about the involved mechanisms. The aim of this review is to summarize the various renal adverse events reported in clinical studies and to present the experimental evidence for putative mechanisms of action for this SRL-induced nephrotoxicity.

Cell Proliferation↗

PubMed2006

Comparison of sequential protocol using basiliximab versus antithymocyte globulin with high-dose mycophenolate mofetil in recipients of a kidney graft from an expanded-criteria donor.

This retrospective pilot study investigated use of high-dose mycophenolate mofetil with biological induction and sequential introduction of low-dose cyclosporine in recipients of expanded criteria donor (ECD) kidneys. Fifty-four patients received mycophenolate mofetil 3 g/day for 45 days, cyclosporine 4 mg/kg/day, prednisolone, and rabbit antithymocyte globulin (rATG, n=14) or basiliximab (n=40). Acute rejection incidence was 11.3% (7.1% with rATG, 12.6% with basiliximab). Delayed graft function was observed in 31 patients (54%). At one year, measured glomerular filtration rate was 54+/-4 ml/min, with no significant differences between induction therapies. Thirty patients (55%) required > or =1 MMF dose reduction within month 1 due to adverse events (gastrointestinal symptoms, 67%; leucopenia 33%). Leucopenia was more frequent with rATG, while gastrointestinal symptoms were more frequent with basiliximab. Cytomegalovirus replication occurred in three patients (23%) with rATG and 3 (8%) with basiliximab. In conclusion, high-dose MMF, corticosteroids, delayed low-dose cyclosporine and induction therapy offers an excellent risk-to-benefit ratio in patients receiving an ECD allograft.

Antibodies, Monoclonal↗

PubMed2006

Adverse neuropsychiatric effects of cytomegalovirus prophylaxis with valaciclovir in renal transplant recipients.

BACKGROUND: Valaciclovir (VACV) has been reported to induce adverse neuropsychiatric effects (ANE), especially in patients with renal failure, but few data are available for renal transplant recipients (RTR). METHODS: We conducted a retrospective study in RTR given VACV as cytomegalovirus prophylaxis, from January 1999 to December 2000, to define the incidence rate, type and outcome of VACV-induced ANE, and to identify risk factors for ANE. The VACV-induced ANE were defined as neuropsychiatric disorders justifying VACV dose reduction or withdrawal. Patients with and without VACV-induced ANE were compared by univariate and multivariate analysis. RESULTS: In all, 167 RTR were included, of whom 25 (15%) displayed VACV-induced ANE (mainly hallucinations and confusion), which occurred with a mean of 4 days after the start of VACV. ANE were reversible in all cases. Multivariate analysis showed that delayed graft function (DGF) was the main risk factor for VACV-induced ANE [Odds ratio (OR): 12.1; 95% CI = 3.4-43.4; P = 0.0001]. All VACV doses given to patients with ANE were in accordance with the current recommended adaptation to estimated glomerular filtration rate (GFR). CONCLUSION: In RTR, VACV-induced ANE are significantly frequent but reversible. DGF occurrence is the main risk factor for these ANE. In RTR with DGF, the recommended doses for GFR below 10 ml/min might be too high. Several strategies, in RTR with DGF, might lower the risk of ANE, including reduction of the currently recommended VACV dosage, delayed VACV introduction until improvement of renal function, or use of another anti-cytomegalovirus drug.

Acyclovir↗

PubMed2006

[mTOR inhibitors: pleiotropic antiproliferative drugs].

Studies of rapamycin properties in yeast led to the discovery of TOR (target of rapamycin) and its mammalian analogue, mTOR. mTOR is a central regulator of cell growth and proliferation in response to environmental stimuli such as growth factors and nutrients. mTOR regulates several pathways, particularly translation process by controlling the activity of two proteins in response to a broad range of mitogenic stimuli, S6K1 and 4E-BP1. Inhibition of cell growth by rapamycine and analogues have been demonstrated in numerous cell types, explaining the broad development of these drugs in clinical practice. Rapamycine is a potent immunosuppressive drug used in solid organ transplantation for the prevention of allograft rejection. In oncology, mTOR inhibitors are currently evaluated in several types of cancers. They are now widely used for coating stents to reduce post-stenting restenosis after coronary angioplasty. Finally, rapamycine is now evaluated in various diseases characterized by cell growth disorders such as phacomatosis and autosomal dominant polycystic kidney disease.

Animals↗

PubMed2005

Tacrolimus-induced alopecia in female kidney-pancreas transplant recipients.

BACKGROUND: Immunosuppressive drugs given to solid organ transplant recipients may be responsible for cosmetic side effects which can endanger patient compliance. Cyclosporine is associated with hirsutism whereas tacrolimus has been associated with rare cases of alopecia. Since 1998, we have included tacrolimus within the immunosuppressive regimen following kidney-pancreas transplantation. The aim of this study was to evaluate the incidence of alopecia in this population and possible risk factors. METHODS: Between January 1, 1995 and October 31, 2003, 59 consecutive simultaneous kidney-pancreas (SPK) transplants were performed in 58 recipients (27 females and 31 males). The immunosuppressive regimen comprised corticosteroids, calcineurin inhibitor (cyclosporine, n=11; or tacrolimus, n=40) and a purine inhibitor (azathioprine or mycophenolate mofetil). RESULTS: Clinically significant alopecia occurred in 13 patients (28.9%) receiving tacrolimus versus none receiving cyclosporine (P<0.001). Of those who experienced alopecia, 11 were female and two were male (P=0.02). The mean delay between transplantation and alopecia was 422 days (range 100-1,567). Other causes of alopecia were excluded. Treatment of alopecia with topic minoxidil was successful in all cases but one, which required conversion from tacrolimus to cyclosporine. CONCLUSIONS: Alopecia is a frequent complication in women receiving tacrolimus therapy following SPK transplantation. Its pathogenesis is unknown. This cosmetic complication must be discussed with patients before transplantation to minimize the risk of noncompliance.

Alopecia↗

PubMed2005

Superior outcomes in renal transplantation after early cyclosporine withdrawal and sirolimus maintenance therapy, regardless of baseline renal function.

BACKGROUND: It has become increasingly important to refine therapeutic strategies according to individual patient characteristics. We evaluated the long-term impact of renal function at the time of withdrawing cyclosporine (CsA) in renal allograft recipients receiving sirolimus (SRL), CsA, and steroids (ST). METHODS: At 3 months+/-2 weeks, 430 of 525 patients were eligible to be randomized to remain on triple-therapy (SRL-CsA-ST, n=215) or to have CsA withdrawn (SRL-ST, n=215). Patients were divided into quartiles according to their baseline (last value before randomization) calculated GFR: 45 to 56 ml/min (quartile 2, n=105), >56 to 67 ml/min (quartile 3, n=112), and >67 ml/min (quartile 4, n=107). All data were included (ITT analysis). RESULTS: At 4 years, calculated GFR for SRL-CsA-ST vs. SRL-ST was 22.1 vs. 37.7 ml/min (P=0.017), 38.6 vs. 56.6 ml/min (P<0.001), 50.7 vs. 66.8 ml/min (P=0.006), and 62.7 vs. 71.4 ml/min (P=0.436), for quartiles 1 to 4, respectively. Death-censored graft loss ranged from 21.2% vs. 7.7% (SRL-CsA-ST vs. SRL-ST, P=0.092) in quartile 1 to 5.5% vs. 1.9% (P=0.618) in quartile 4. The incidence of death and biopsy-confirmed acute rejection also decreased with increasing baseline GFR, but was not significantly different between treatments. Overall, more patients remained on therapy in the SRL-ST group (46.3% vs. 57.9%, P=0.020). CONCLUSIONS: Early and complete withdrawal of CsA from a combination of SRL, CsA, and steroids was preferable to continuing on this regimen, regardless of baseline renal function. The benefit was most marked in patients with a baseline calculated GFR<or=45 ml/min.

Acute Disease↗

PubMed2005

Proteinuria following a switch from calcineurin inhibitors to sirolimus.

BACKGROUND: Sirolimus is an alternative option for kidney transplant patients treated with calcineurin inhibitors (CNI) when renal function is deteriorating. However, the incidence of proteinuria following a switch from CNI to sirolimus has caused concern, and was therefore investigated here. METHODS: In a retrospective study, 68 renal transplant recipients were switched from CNI to sirolimus. Proteinuria was measured using 24-hour urine collection before the switch and collections 3, 6, 12, and 24 months thereafter. In addition, proteinuria was measured in patients who had to be switched back to CNI due to side effects. Survival analyses were performed. RESULTS: Baseline proteinuria was 0.39+/-0.69 g/day in all 68 patients. It increased to a mean 1.44+/-1.90 g/day at 3 months (P<0.001) and remained elevated at 6, 12 and 24 months. When sirolimus was withdrawn after the CNI-sirolimus switch for 19 patients, proteinuria decreased from 1.95+/-2.06 g/day to 0.9+/-1.4 g/day (P<0.05). Proteinuria above 0.3 g/day before the CNI-sirolimus switch correlated significantly with the decrease of renal function thereafter. CONCLUSION: CNI-treated kidney transplant recipients may develop reversible proteinuria when switched to sirolimus.

Adult↗

PubMed2005

Corticosteroid-free immunosuppression with tacrolimus, mycophenolate mofetil, and daclizumab induction in renal transplantation.

BACKGROUND: Corticosteroid-free maintenance immunosuppression after organ transplantation eliminates the well-known corticosteroid-related side effects and may help to improve long-term outcome. We investigated whether a corticosteroid-free tacrolimus (Tac)/mycophenolate mofetil (MMF) regimen, in combination with daclizumab (Dac) induction therapy, provides adequate immunosuppression after renal transplantation. METHODS: This 6-month, open-label, multicenter, parallel-group study involved 538 renal patients randomized (1:1) to a Dac/Tac/MMF regimen (n = 260) or a Tac/MMF/corticosteroids regimen (n = 278) as a control group. RESULTS: Of the patients who completed the study, 88.8% in the Dac/Tac/MMF group were free from corticosteroid therapy at month 6. The incidence of biopsy-proven acute rejection was 16.5% in both treatment groups; the incidence of biopsy-proven corticosteroid-resistant acute rejection was 4.3% and 5.0% with Tac/MMF/corticosteroids and Dac/Tac/MMF, respectively (P = NS for both comparisons). Renal function was also similar in both groups: median serum creatinine at month 6 was 125.0 micromol/L (Tac/MMF/corticosteroids) and 131.0 microml/L (Dac/Tac/MMF), P = 0.277. The overall safety profile was similar with both regimens. However, compared with the Tac/MMF/steroid regimen, a significantly reduced incidence of new-onset insulin-dependent diabetes mellitus (5.4% vs. 0.4%, P = 0.003) was found with steroid-free immunosuppression. Moreover, mean total cholesterol concentrations increased from baseline in the Tac/MMF/corticosteroids group by 0.19 mmol/L, whereas in the Dac/Tac/MMF group, levels decreased by 0.19 mmol/L, P = 0.005. CONCLUSIONS: Corticosteroid-free immunosuppression with a Dac/Tac/MMF regimen is as effective at preventing acute rejection after renal transplantation as a standard triple regimen of Tac/MMF/corticosteroids. Furthermore, the safety benefits reported with Dac/Tac/MMF treatment may help improve the long-term outcome for renal-transplant patients.

Adolescent↗

PubMed2005

Replacement kidney lipomatosis after renal transplantation.

Renal sinus lipomatosis consists of abnormal fatty proliferation of the renal sinus, hilus, and perirenal spaces. Its pathogenesis is unknown, although it is generally associated with aging, renal atrophy, and long-standing chronic inflammation or urinary tract infection. Although this condition is rare, it may be important to recognize it in renal transplant recipients. We describe three cases of replacement kidney lipomatosis that occurred after cadaveric renal transplantation and discuss the possible differential diagnosis of this condition.

Adult↗

PubMed2005

The cost-effectiveness of prophylaxis with valaciclovir in the management of cytomegalovirus after renal transplantation.

Prophylaxis-based antiviral treatment and intensive monitoring followed by pre-emptive antiviral treatment are both commonly used management strategies to reduce risk of cytomegalovirus (CMV) infection following renal transplantation. This study employed a decision-model approach using published efficacy data and information from a recent survey of French clinical practice to consider the relative costs and outcomes associated with CMV prevention strategies for high-risk patient groups. The cost per case of treating tissue invasive and symptomatic CMV disease was estimated at euro 15,431 and euro 10,852, respectively. In the highest infection-risk patient group (positive donor with no previous CMV history) prophylactic oral valaciclovir was shown to avoid the greatest number of CMV disease cases (35 cases per 100 transplanted patients) and reduced the overall CMV-related costs per transplanted patient by around 14% over a'wait-and-treat' baseline strategy. In contrast, intensive monitoring and preemptive treatment resulted in a much higher cost per transplanted patient. This analysis suggests that prophylactic treatment remains the most cost-effective approach to the management of CMV in renal-transplanted patients. Further comparative studies between prophylactic and pre-emptive treatment would be a valuable addition to the current evidence based on CMV prevention.

Acyclovir↗

PubMed2005

Unusual post-transplantation recurrence of focal segmental glomerulosclerosis which resolved with cyclosporine but not with sirolimus.

Recurrence of idiopathic focal segmental glomerulosclerosis (FSGS) is frequent after the first kidney transplantation (KT), but a recurrence that only occurred after the second KT has never been reported. Although cyclosporine reduces proteinuria and prolongs graft survival in patients with recurrent glomerulosclerosis, the effectiveness of sirolimus for this condition is still not known. We report, for the first time as far as we know, the case of a 35-year-old black male patient who experienced a recurrence of FSGS, 10 days after a second KT, although no recurrence had occurred after the first. Cyclosporine treatment led to a decrease in proteinuria, whereas mycophenolate mofetil and angiotensin-converting enzyme inhibitor had no effect. Cyclosporine was replaced by sirolimus as treatment for chronic allograft nephropathy 24 months after KT. Nephrotic syndrome, which reappeared 3 weeks after the switch, was cured by cyclosporine re-introduction. The absence of FSGS recurrence after the first graft does not totally preclude its recurrence after the second. This observation points to the effectiveness of cyclosporine for the recurrence of FSGS and indicates that sirolimus should be given with caution in such cases.

Adult↗

PubMed2005

Rapamycin inhibits human renal epithelial cell proliferation: effect on cyclin D3 mRNA expression and stability.

BACKGROUND: Recent data have suggested that rapamycin use during the initial period after transplantation is associated with prolonged delayed graft function (DGF). Because of the known effects of rapamycin in other cell types, we speculated that this action may be secondary to human renal epithelial cells (HRECs) inhibition of proliferation. METHODS: Primary cultures of HRECs were incubated with various concentrations of rapamycin. Cell proliferation was evaluated by cytotoxicity assays. The cell cycle was analyzed by flow cytometry. Protein expression levels were assessed by Western blot. Cyclin D3 mRNA levels were measured by quantitative real-time polymerase chain reaction (PCR). The transcriptional activity of the cyclin D3 gene was evaluated using transient transfection. RESULTS: Rapamycin exerted a significant concentration-dependent antiproliferative effect on growing HRECs by inhibiting the G(1) to S transition. The p70(S6) kinase pathway leading to cell cycle progression was found to be active, and low concentrations of rapamycin dramatically reduced p70(S6) kinase phosphorylation. Rapamycin completely inhibited the increase in cyclin D3 protein expression and mRNA accumulation induced by fetal calf serum, but did not affect cyclin E or cdk-inhibitor expression levels. This regulation of cyclin D3 protein expression is mainly due to a destabilization of its mRNA. Rapamycin reduced the mRNA half-life by 26% (4.8 +/- 1.3 hours vs. 6.5 +/- 1.0 hours, P < 0.001). CONCLUSION: Rapamycin inhibits the proliferative response of HRECs to mitogenic stimuli, and causes cell cycle arrest in the early G(1) phase, not only by a nonspecific process due to inhibition of the p70(S6k) pathway, but also by a direct effect on cyclin D3 mRNA stability.

Cell Proliferation↗

PubMed2005

Consequences of genetic polymorphisms for sirolimus requirements after renal transplant in patients on primary sirolimus therapy.

Sirolimus (SRL) is a substrate for cytochromes P-450 3A and P-glycoprotein, the product of the MDR1 gene. We postulated that single nucleotide polymorphisms (SNPs) of these genes could be associated with inter-individual variations in SRL requirements. We then evaluated in 149 renal transplant recipients the effect of polymorphisms CYP3A4*1/*1B, CYP3A5*1/*3 and MDR1 SNPs in exon 12, 21 and 26 on SRL concentration/dose (C/D) ratio 3 months after sirolimus introduction. SRL C/D ratio was significantly higher in patients treated with calcineurin inhibitors. The CYP3A4*1B and CYP3A5*1 alleles were present in 17% and 21% of patients, respectively. When treated with a SRL-based therapy and low-dose steroids, patients carrying the CYP3A4*1B or the CYP3A5*1 alleles required significantly more SRL to achieve adequate blood trough concentrations (p < 0.01 and p < 0.02, respectively). None of the MDR1 SNPs was associated with the SRL concentration/dose ratio. These findings suggest that the variations in SRL requirements are secondary to both genetic and non-genetic factors including pharmacokinetic interactions. In patients with SRL-based therapy, genotyping of the CYP3As genes may help to optimize the SRL management in transplant recipients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Kidney transplant in black recipients: are African Europeans different from African Americans?

Despite recent improvement, significant racial disparities in outcome still persist after renal transplantation among African American patients in the United States. This study evaluated the association of race and ethnicity with allograft outcomes in a French population of 952 Caucasian (Cauc) patients and 140 African European (AE) patients who underwent renal transplantation in our center between 1987 and 2003. Demographic characteristics were similar for the two cohorts other than cause of end-stage renal failure (more hypertension among AE and more polycystic kidney disease among Cauc) and cold ischemia time (significantly longer for AE). Immunosuppressive treatment was comparable between groups. There were no significant differences between AE and Cauc in the incidence of acute rejection (31% vs. 30%). At 5 years post-transplant, patient survival (93% vs. 92%), graft survival (83% in both groups) and graft function (creatinine clearance 48 mL/min vs. 45 mL/min) were also similar among the AE and Cauc patients. We demonstrate that ethnic origin does not affect outcome after renal transplantation in France. Therefore, differences observed in the United States cannot be only related to immunologic or pharmacologic factors. The results of renal transplantation in patients of African origin could be improved with universal immunosuppressive drug coverage.

Adult↗

PubMed2004

Sequential protocols using basiliximab versus antithymocyte globulins in renal-transplant patients receiving mycophenolate mofetil and steroids.

BACKGROUND: Sequential anti-thymocyte globulins (ATG)/cyclosporine immunosuppression has two main advantages: delayed introduction of the nephrotoxic drug cyclosporine and prevention of acute rejection. Basiliximab, a recently developed chimeric monoclonal antibody that selectively depletes the minor subpopulation of activated T lymphocytes, has been shown to reduce the incidence of acute rejection when used with cyclosporine introduced on day 1. METHODS: This open, randomized, multicenter study was undertaken to compare the safety and efficacy of ATG versus basiliximab induction therapy (IT) with delayed introduction of cyclosporine for microemulsion (Neoral) in 105 low immunologic risk renal-transplant patients receiving mycophenolate mofetil and steroids. RESULTS: One-year patient and graft survival rates were 98.1% and 94.2%, respectively, in the basiliximab group (n = 52), and 98.1% and 96.2% in the ATG group (n = 53). The incidence of biopsy-confirmed acute rejection was comparable (basiliximab 9.6%, ATG 9.4%), as were key parameters of renal function, notably serum creatinine levels, time-to-nadir serum creatinine, and the number of patients requiring posttransplantation dialysis (basiliximab 28.8%, ATG 30.2%). However, significantly fewer patients in the basiliximab group experienced cytomegalovirus (CMV) infection, leukopenia, and thrombocytopenia, and this without any significant difference in any other key safety parameters (including the incidences of serum sickness, fever, lymphoma, and infections in general). CONCLUSIONS: Both ATG and basiliximab, when used for IT in a sequential protocol, are equally effective in terms of graft and patient survival as well as at preventing acute rejection. However, basiliximab is associated with a lower incidence of certain key adverse events, namely CMV infection, leukopenia, and thrombocytopenia.

Adolescent↗