Project description:Kidney transplant recipients administered belatacept-based maintenance immunosuppression present with a more favorable metabolic profile, reduced incidence of de novo donor-specific antibodies (DSAs), and improved renal function and long-term patient/graft survival relative to individuals receiving calcineurin inhibitor (CNI)-based immunosuppression. However, the rates and severity of acute rejection (AR) are greater with the approved belatacept-based regimen than with CNI-based immunosuppression. Although these early co-stimulation blockade-resistant rejections are typically steroid sensitive, the higher rate of cellular AR has led many transplant centers to adopt immunosuppressive regimens that differ from the approved label. This article summarizes the available data on these alternative de novo belatacept-based maintenance regimens. Steroid-sparing, belatacept-based immunosuppression (following T cell-depleting induction therapy) has been shown to yield AR rates comparable to those seen with CNI-based regimens. Concomitant treatment with belatacept plus a mammalian target of rapamycin inhibitor (mTORi; sirolimus or everolimus) has yielded AR rates ranging from 0 to 4%. Because the optimal induction agent and number of induction doses; blood levels of mTORi; and dose, duration, and use of corticosteroids have yet to be determined, larger prospective clinical trials are needed to establish the optimal alternative belatacept-based regimen for minimizing early cellular AR occurrence.
Project description:In this study we focussed on malignant post-transplant lymphomas. Post-transplant lymphoma is strongly associated with Epstein-Barr Virus (EBV) infection in contrast to lymphoma arising in an immunocompetent population. Nevertheless, about 1 in 3 PTLD cases are negative for EBV. We used a microarray to define the gene expression profile of different PTLDs to elucidate the pathogenesis of EBV(+) and EBV(-) PTLD and to define whether EBV(-) PTLD is biologically different from EBV(-) lymphoma arising in an immunocompetent host. PTLD patient samples were randomly selected for RNA extraction and hybridization on an Affymetrix platform. The post-transplant tumors consisted of homogenous sheets of neoplastic cells ensuring reliability of the gene expression data.
Project description:PTLD is a rare but severe complication of hematopoietic or solid organ transplant recipients, with variable incidence and timing of occurrence depending on different patient-, therapy-, and transplant-related factors. The pathogenesis of PTLD is complex, with most cases of early PLTD having a strong association with Epstein-Barr virus (EBV) infection and the iatrogenic, immunosuppression-related decrease in T-cell immune surveillance. Without appropriate T-cell response, EBV-infected B cells persist and proliferate, resulting in malignant transformation. Classification is based on the histologic subtype and ranges from nondestructive hyperplasias to monoclonal aggressive lymphomas, with the most common subtype being diffuse large B-cell lymphoma-like PTLD. Management focuses on prevention of PTLD development, as well as therapy for active disease. Treatment is largely based on the histologic subtype. However, given lack of clinical trials providing evidence-based data on PLTD therapy-related outcomes, there are no specific management guidelines. In this review, we discuss the pathogenesis, histologic classification, and risk factors of PTLD. We further focus on common preventive and frontline treatment modalities, as well as describe the application of novel therapies for PLTD and elaborate on potential challenges in therapy.
Project description:BackgroundPost-transplant lymphoproliferative disorder (PTLD) is a devastating complication of immunosuppressive treatment in both solid organ transplantations (SOT) and hematopoietic stem cell transplantations (HSCT). Epstein-Barr virus (EBV) infection precedes PTLD in 90% of patients. Rituximab, a monoclonal anti-CD20 antibody, depletes B-lymphocytes, which are the ultimate reservoir for EBV. Although rituximab therapy is commonly used as a preventive measure for PTLD in high-risk HSCT, it is not established in SOT.MethodsPediatric kidney transplant recipients (PKTR) underwent routine EBV-PCR surveillance. Patients with increasing viral loads, despite immunosuppressive dose reduction, were managed with preventive rituximab therapy.ResultsBetween 2012 and 2023, we identified eight episodes of asymptomatic EBV-PCR-positive blood tests in seven out of 65 PKTR (11%) under our care. EBV DNAemia emerged 120-720 days post-transplantation. Five of seven patients with EBV DNAemia (71%) were EBV-seronegative prior to transplantation. All five patients did not respond to MMF dose reduction and were therefore treated with preventive rituximab therapy. Following this treatment, EBV PCR clearance was observed in all patients with only minimal complications.ConclusionsPKTR who are EBV-naïve prior to transplantation are expected to have a higher prevalence of EBV DNAemia. We found that PKTR who were EBV seronegative prior to transplantation were less likely to achieve EBV clearance in response to immunosuppression dose reduction. We suggest that rituximab therapy in PKTR may be safe and effective in EBV clearance and PTLD prevention.
Project description:In this study we focussed on malignant post-transplant lymphomas. Post-transplant lymphoma is strongly associated with Epstein-Barr Virus (EBV) infection in contrast to lymphoma arising in an immunocompetent population. Nevertheless, about 1 in 3 PTLD cases are negative for EBV. We used a microarray to define the gene expression profile of different PTLDs to elucidate the pathogenesis of EBV(+) and EBV(-) PTLD and to define whether EBV(-) PTLD is biologically different from EBV(-) lymphoma arising in an immunocompetent host.
Project description:Post-transplant lymphoproliferative disorder (PTLD) is a rare complication. It represents a spectrum of lymphoid proliferations which occur in the setting of immunosuppression and organ transplantation. There are no reported cases or recommendations for the treatment of residual masses post rituximab of PTLD.A patient with a long standing history of immunosuppression due to multiple kidney transplants starting in 1979, presented with a very large palpable hard abdominal mass (2004) after a fourth renal transplant. There was a past history of heavy immune suppression. CT scans revealed a conglomerate mass involving the right native kidney and two prior right sided renal allografts that crossed the midline. Biopsy of the large right retroperitoneal mass revealed large B cell lymphoma (CD 20 positive); consistent with post-transplant lymphoproliferative disorder (PTLD).Management of bulky PTLD, in a highly sensitized, heavily immune suppressed patient is not well described in the literature. The mainstay of therapy is IR and Ritixumab (R) monotherapy and combination R-CHOP. CHOP chemotherapy has an associated mortality rate of up to 38%. Radiotherapy is often considered over surgery and surgery has been most frequently used when associated with bowel complications. In this case report we describe upfront Ritiximab followed by consolidation resection and cytotoxic chemotherapy as a management strategy to reduce toxicity.The approach taken by our surgical team illustrates the benefits of disease debulking in certain cases of PTLD, by guiding further therapy and spacing and reducing chemotherapy in immune suppressed patients.
Project description:Human post-transplant lymphoproliferative disorder (PTLD) is an abnormal lymphoid proliferation that arises in 1-12% of transplant recipients as a consequence of prolonged immunosuppression and Epstein-Barr viral infection (EBV). Nonhuman primates, primarily rhesus macaques (Macaca mulatta), have been used extensively in research models of solid organ transplantation, as the nonhuman primate immune system closely resembles that of the human. Lymphocryptovirus of rhesus monkeys has been characterized and shown to be very similar to EBV in humans in regards to its cellular tropism, host immune response, and ability to stimulate B lymphocyte proliferation and lymphomagenesis. Thus, it appears that the NHP may be an appropriate animal model for EBV-associated lymphoma development in humans. The clinical management of post-transplant nonhuman primates that are receiving multiple immunosuppressive agents can be complicated by the risk of PTLD and other opportunistic infections. We report 3 cases of PTLD in rhesus macaques that illustrate this risk potential in the setting of potent immunosuppressive therapies for solid organ transplantation.
Project description:Compared with calcineurin inhibitor-based immunosuppression, belatacept (BELA)-based treatment has been associated with better renal function but higher acute rejection rates. This phase 2 study (NCT02137239) compared the antirejection efficacy of BELA plus everolimus (EVL) with tacrolimus (TAC) plus mycophenolate mofetil (MMF), each following lymphocyte-depleting induction and rapid corticosteroid withdrawal.MethodsPatients who were de novo renal transplant recipients seropositive for Epstein-Barr virus were randomized to receive BELA+EVL or TAC+MMF maintenance therapy after rabbit antithymocyte globulin induction and up to 7 d of corticosteroids. The primary endpoint was the rate of biopsy-proven acute rejection at month 6.ResultsBecause of an unanticipated BELA supply constraint, enrollment was prematurely terminated at 68 patients, of whom 58 were randomized and transplanted (intention-to-treat [ITT] population: n = 26, BELA+EVL; n = 32, TAC+MMF). However, 25 patients received BELA+EVL' and 33 received TAC+MMF (modified ITT population). In the ITT population, the 6-mo biopsy-proven acute rejection rates were 7.7% versus 9.4% in the BELA+EVL versus TAC+MMF group. The corresponding 24-mo biopsy-proven acute rejection rates were 19.2% versus 12.5% in the ITT population and 16.0% versus 15.2% in the mITT population; all events were Banff severity grade ≤IIA and similar between groups. One patient in each group experienced graft loss unrelated to acute rejection. The 24-mo mean unadjusted estimated glomerular filtration rates were 71.8 versus 68.7 mL/min/1.73 m2 in the BELA+EVL versus TAC+MMF groups. Posttransplant lymphoproliferative disorder was reported for 1 patient in each group. No deaths or unexpected adverse events were observed.ConclusionsA steroid-free maintenance regimen of BELA+EVL may be associated with biopsy-proven acute rejection rates comparable to TAC+MMF.
Project description:Preexisting donor-specific antibodies (DSA) to MHC antigens increase the risk of antibody-mediated rejection (AMR) in sensitized transplant recipients and reduces graft survival. Pretransplant desensitization with costimulation blockade and proteasome inhibition has facilitated transplantation in our preclinical nonhuman primate (NHP) model. However, long-term graft survival is limited by rebound of DSA after transplantation. In this study, we performed kidney transplants between highly sensitized, maximally MHC-mismatched NHPs (n=14). At kidney transplantation, primates received T cell depletion with rhesus-specific anti-thymocyte globulin (rhATG; n=10) or monoclonal anti-CD4 and anti-CD8 antibodies (n=4). Maintenance immunosuppression consisted of belatacept and tacrolimus (n=5) or belatacept and rapamycin (n=9) with steroids. Rebound of DSA post-kidney transplantation was significantly reduced compared with maintenance immunosuppression with tacrolimus, mycophenolate, and steroids. Protocol lymph node biopsy specimens showed a decrease in germinal center activity, with low frequencies of T follicular helper cells and class-switched B cells after kidney transplantation. Combined belatacept and rapamycin was superior in controlling viral reactivation, enabling weaning of ganciclovir prophylaxis. Tacrolimus was associated with increased morbidity that included cytomegalovirus and parvovirus viremia and post-transplant lymphoproliferative disorder. All primates in the tacrolimus/belatacept group failed discontinuation of antiviral therapy. Overall, belatacept-based immunosuppression increased AMR-free graft survival by controlling post-transplant humoral responses in highly sensitized NHP recipients and should be further investigated in a human clinical trial.