Virus‐specific T‐cell therapy in solid organ transplantation

This article reviews the current state of T‐cell therapy as therapeutic option for virus‐associated diseases against the background of the most common viral complications and their standard treatment regimens after SOT. The available data of clinical T‐cell trials in SOT are summarized. References to the hematopoietic stem cell transplantation are made if applicable data in SOT are not available and their content was considered likewise valid for cell therapy in SOT. Moreover, aspects of different manufacturing approaches including beneficial product characteristics and the importance of GMP compliance are addressed.     

Human CMV‐specific T‐cell responses in kidney transplantation; toward changing current risk‐stratification paradigm

Despite the great efficacy of current antiviral preventive strategies, hCMV infection is still a major complication after renal transplantation, significantly challenging patient and graft survival. This issue seems to be explained because of the rather poor immunologic monitoring of the antiviral immune response. An important body of evidence has shown that monitoring the hCMV‐specific T‐cell response, at different time points of the transplant setting, seems to add crucial information for predicting the risk of viral infection, thus potentially helping individualization of therapeutic decision‐making in clinical transplantation. While several immune‐cellular assays have shown its capability for accurately monitoring hCMV‐specific T‐cell responses, only few such as the IFN‐γ ELISPOT and the ELISA based technology assays might be reliable for its application in the clinic. Nonetheless, an important effort has to be made among the transplant community to standardize and validate such immune assays. Noteworthy, large‐scale prospective randomized trials are highly warranted to ultimately introduce them in current clinical practice as a part of the highly desired personalized medicine.     

Timing of CMV‐specific effector memory T cells predicts viral replication and survival after allogeneic hematopoietic stem cell transplantation

The aim of this study was to characterize timing, kinetic, and magnitude of CMV‐specific immune response after hematopoietic stem cell transplantation (HSCT) and its ability to predict CMV replication and clinical outcomes. Using cell surface and intracellular cytokine staining by flow cytometry, CMV‐specific T‐cell response was measured in blood, while CMV viral load and chimerism were determined by real‐time PCR. Patients that reconstituted CMV‐specific T‐cell response within 6 weeks after Allo‐SCT showed a more robust immune response (CD8⁺: 0.7 cells/μl vs. 0.3/μl; P‐value = 0.01), less incidence of CMV replication (33% vs. 89.5%; P‐value = 0.007), reduced viral loads (1.81 log copies/ml vs. 0 copies/ml; P‐value = 0.04), and better overall survival (72%; CI: 0.53–0.96 vs. 42% CI: 0.24–0.71; P‐value = 0.07) than patients with a delayed immune reconstitution. Viremic patients had significantly higher transplant‐related mortality than nonviremic patients after 1 year (33% CI: 0.15–0.52 vs. 0% CI: 0.05–0.34; P‐value = 0.01). Risk factors independently associated with viral replication were receptor pretransplant CMV‐positive serostatus (P‐value = 0.02) and acquiring CMV‐specific T‐cell response after 6 weeks post‐transplantation (P‐value = 0.009). In conclusion, timing of acquiring a positive CMV‐specific T‐cell immune response after transplantation may identify patients with different risk for viral replication and different clinical outcomes, including survival.     

CMV-hyperimmune globulin for preventing cytomegalovirus infection and disease in solid organ transplant recipients: a meta-analysis

Abstract. Objective: The goal of this meta-analysis was to investigate the impact of cytomegalovirus hyperimmune globulin (CMVIG) on cytomegalovirus (CMV) infection, CMV disease, and mid-term survival in solid organ transplant recipients. Methods: Medline, EMBASE, and the Cochrane databases were searched since their inceptions until 2006. Inclusion criteria comprised: prospective randomized trials, in solid organ transplantation which received CMV prophylaxis including CMVIG on one of the treatment arms. Random effects models were used to calculate pooled risk ratios (RR) and meta-regression was employed to explain study heterogeneity. Stratified analyses were conducted and Funnel plot was used to assess publication bias. Results: Literature searches identified 11 randomized trials (698 patients; median follow-up: 12 months, range: 3–22 months) including six randomized trials (302 patients) after kidney transplantation. The analysis demonstrated a beneficial effect of the prophylactic use of CMVIG on total survival [RR (95% confidence interval; CI): 0.67 (0.47–0.95)] and prevention of CMV-associated death [RR (95% CI): 0.45 (0.24–0.84)] in solid organ transplant recipients but not kidney transplant recipients [RR (95% CI): 0.35 (0.12–1.04)]. CMV disease was significantly reduced in all recipients receiving prophylactic CMVIG [RR (95% CI): 0.697 (0.57–0.85)]. CMVIG had no impact on CMV-infections and clinically relevant rejections. Conclusions: Prophylactic administration of CMVIG after solid organ transplantation is associated with improved total survival, reduced CMV disease, and CMV-associated deaths.     

CMV‐specific T‐cell immunity,viral load,and clinical outcome in seropositive renal transplant recipients: a pilot study

Sund F, Lidehäll A‐K, Claesson K, Foss A, Tötterman TH, Korsgren O, Eriksson B‐M. CMV‐specific T‐cell immunity, viral load, and clinical outcome in seropositive renal transplant recipients: a pilot study.
Clin Transplant 2010: 24: 401–409. © 2009 Wiley Periodicals, Inc. Abstract: Background: Cytomegalovirus (CMV) infection is still the leading opportunistic infection following solid organ transplantation. The aim of this prospective study of renal transplant recipients was to evaluate the dynamics of CMV‐specific T‐cells, viral load, and clinical symptoms of CMV infection. Methods: Levels of tetramer‐selected CD8⁺ T‐cells (TetraCD8), CMV‐specific interferon‐γ producing CD8⁺ T‐cells (IFNγCD8), and CD4⁺ T‐cells (IFNγCD4), measured using major histocompatibility complex‐tetramer and cytokine flow cytometry techniques, and CMV DNA were monitored monthly in 17 CMV‐seropositive patients up to one yr (median 12 months, range 3–12) after transplantation and correlated to clinical outcome. Results: CMV DNAemia was detected in 94% of the patients, but only one patient developed CMV disease. CMV DNAemia >1 million copies/mL was seen in asymptomatic patients. CMV‐specific T‐cells decreased rapidly after transplantation. TetraCD8 and IFNγCD8 regenerated within three months, whereas IFNγCD4 recovery was impaired up to one yr after transplantation. The proportion of IFNγCD4 at two months post‐transplantation as compared with baseline, correlated strongly with the magnitude of the CMV DNAemia. Conclusions: Monitoring the reduction of IFNγCD4 compared with baseline during the first months after transplantation could be considered in predicting risk for high‐grade CMV DNAemia and in deciding strategic approaches for pre‐emptive and prophylactic therapy.     

Assessment and prevention of cytomegalovirus infection in allogeneic hematopoietic stem cell transplant and in solid organ transplant: A multidisciplinary consensus conference by the Italian GITMO,SITO, and AMCLI societies

Cytomegalovirus (CMV) remains a major cause of morbidity and mortality in allogeneic hematopoietic stem cell transplantation (allo‐HSCT) and solid organ transplantation (SOT) recipients. In view of the uncertainties on the assessment and prevention of CMV infection in both transplant procedures, three Italian scientific societies for HSCT and SOT and for Clinical Microbiology appointed a panel of experts to compose a framework of recommendations. Recommendations were derived from a comprehensive analysis of the scientific literature and from a multidisciplinary consensus conference process. The lack of adequate clinical trials focused on certain diagnostic procedures, and antiviral intervention forced the panel to use the methods of consensus for shaping some recommendations. Recommendations concerning the two types of transplant were given for the following issues: assessment of pretransplant CMV serostatus, immunological monitoring after transplant, CMV prophylaxis with antivirals, CMV preemptive strategy, and CMV prophylaxis with immunoglobulin infusion and with adoptive immunotherapy. The questions raised by and the recommendations resulting from this consensus conference project may contribute to the improvement of certain crucial aspects of the management of CMV infections in allo‐HSCT and in SOT populations.     

CMV specific T cell immune response in hepatitis C negative kidney transplant recipients receiving transplant from hepatitis C viremic donors and hepatitis C aviremic donors

Kidney transplants (KT) from hepatitis C (HCV) viremic donors to HCV negative recipients has shown promising renal outcomes, however, high incidence of cytomegalovirus (CMV) viremia were reported. We performed a prospective cohort study of 52 HCV negative KT recipients from Methodist University Hospital including 41 receiving transplants from HCV aviremic donors and 11 from HCV viremic donors. CMV specific CD4+ and CD8 + T cell immunity was measured by intracellular flow cytometry assay. Primary outcome was the development of positive CMV specific CD4+ and CD8 + T cell immune response in the entire cohort and each subgroup. The association between donor HCV status and CMV specific CD4+ and CD8 + T cell immune response was analyzed by Cox proportional hazard models. Mean recipient age was 48 ± 13 years, with 73% male and 82% African American. Positive CMV specific CD4+ and CD8 + T cell immune response was found in 53% and 47% of the cohort at 1 month, 65% and 70% at 2 months, 80% and 75% at 4 months, 89% and 87% at 6 months, and 94% and 94% at 9 months post-transplant, respectively. There was no significant difference in the incidence of positive CMV specific T cell immune response between recipients of transplants from HCV aviremic donors compared to HCV viremic donors in unadjusted (for CD8+: HR = 1.169, 95%CI: 0.521–2.623; for CD4+: HR = 1.208, 95%CI: 0.543–2.689) and adjusted (for CD8+: HR = 1.072, 95%CI: 0.458–2.507; for CD4+: HR = 1.210, 95%CI: 0.526–2.784) Cox regression analyses. HCV viremia in donors was not associated with impaired development of CMV specific T cell immunity in this cohort.     

Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients

Costa C, Touscoz GA, Bergallo M, Terlizzi ME, Astegiano S, Sidoti F, Sinesi F, Segoloni GP, Cavallo R. Non‐organ‐specific and anti‐endothelial antibodies in relation to CMV infection and acute rejection in renal transplant recipients.
Clin Transplant 2010: 24: 488–492.
© 2009 John Wiley & Sons A/S. Abstract: The presence of non‐organ‐specific (NOSA) and anti‐endothelial antibodies (AECAs) and the onset of rejection in relation to cytomegalovirus (CMV) infection was investigated in 96 renal transplant recipients: 48 CMV pp65‐antigenemia‐negative (group 1) and 48 positive (group 2). The presence of autoantibodies (autoAbs) was evaluated before and following renal transplantation (first three months) by indirect immunofluoresce. Before transplantation, none of the patients was positive to AECAs, while eight (8.3%) were positive to NOSAs. Post‐transplantation, AECA were found in none of patients from group 1 vs. 15/48 (31.2%) from group 2 (p < 0.05); NOSAs were detected in 9/48 (18.8%) and 9/48 patients from group 1 and 2, respectively. An acute rejection was diagnosed in ten cases: six of interstitial type (antigenemia‐, and AECA‐negative; two NOSA‐positive); four of vascular type (all of them NOSA‐negative, 3/4 antigenemia‐, and AECA‐positive). CMV infection did not seem to be significantly associated with the appearance of NOSAs, while there was a significant correlation with the occurrence of AECAs. No significant correlation was found between acute rejection and the occurrence of NOSAs, while 75% of the cases of vascular rejection was associated to CMV infection and AECA‐positivity, suggesting the pathogenic role of CMV‐mediated endothelial damage.     

Potential role of CC chemokine receptor 6 in prediction of late‐onset cytomegalovirus infection following solid organ transplant

CCR6 is a chemokine receptor involved in homing memory T cells, particularly Th17 cells, to sites of mucosal inflammation. Despite the critical role of memory T cells in long‐term protective immunity against cytomegalovirus (CMV), a virus that reactivates at multiple mucosal sites, the ability of CCR6 or other Th17 marker expression to predict CMV reactivation following transplantation is not clear. Using 11‐color flow cytometry, in this prospective single‐center pilot study, we measured the expression of CCR6 and other markers of T‐cell function in peripheral blood samples obtained from 21 SOT recipients at the time of discontinuation of anti‐CMV prophylaxis. CMV viremia was monitored on a monthly basis after discontinuation of prophylaxis. Eleven patients (52%) developed CMV viremia during the six‐month follow‐up period. Late‐onset CMV infection was preceded by an immune phenotype characterized by increased CCR6 expression on bulk CD4⁺ T cells and a reduced number of circulating CMV IE‐1‐specific Th1 (CD4⁺ IFN‐γ⁺) cells. Among the markers evaluated, CCR6 was the best single predictor of late‐onset CMV infection. Our results suggest that CCR6 expression at the time of discontinuation of antiviral prophylaxis might be a useful predictor of late‐onset CMV reactivation and provide the basis for future larger prospective studies.     

COVID‐19 in solid organ transplant recipients: Initial report from the US epicenter

Solid organ transplant recipients may be at a high risk for SARS‐CoV‐2 infection and poor associated outcomes. We herein report our initial experience with solid organ transplant recipients with SARS‐CoV‐2 infection at two centers during the first 3 weeks of the outbreak in New York City. Baseline characteristics, clinical presentation, antiviral and immunosuppressive management were compared between patients with mild/moderate and severe disease (defined as ICU admission, intubation or death). Ninety patients were analyzed with a median age of 57 years. Forty‐six were kidney recipients, 17 lung, 13 liver, 9 heart, and 5 dual‐organ transplants. The most common presenting symptoms were fever (70%), cough (59%), and dyspnea (43%). Twenty‐two (24%) had mild, 41 (46%) moderate, and 27 (30%) severe disease. Among the 68 hospitalized patients, 12% required non‐rebreather and 35% required intubation. 91% received hydroxychloroquine, 66% azithromycin, 3% remdesivir, 21% tocilizumab, and 24% bolus steroids. Sixteen patients died (18% overall, 24% of hospitalized, 52% of ICU) and 37 (54%) were discharged. In this initial cohort, transplant recipients with COVID‐19 appear to have more severe outcomes, although testing limitations likely led to undercounting of mild/asymptomatic cases. As this outbreak unfolds, COVID‐19 has the potential to severely impact solid organ transplant recipients.     

A prospective multicenter observational study of cell‐mediated immunity as a predictor for cytomegalovirus infection in kidney transplant recipients

T cell immunity is essential for the control of cytomegalovirus (CMV) infection after transplantation. We evaluated a CMV‐specific peptide‐based enzyme‐linked immunosorbent spot (ELISPOT) assay to determine whether assay results could predict subsequent CMV events. Adult kidney transplant recipients at 43 centers underwent ELISPOT testing to enumerate interferon gamma (IFN‐γ) binding spot‐forming units (sfu) after stimulation of cells with an overlapping peptide pool of CMV phosphoprotein 65 (pp65) and immediate early‐1 (IE‐1) protein at the end of antiviral prophylaxis (EOP) and various time points thereafter. The primary outcome was a CMV event in the first posttransplant year. In 583 kidney transplant recipients (260 seropositive donor [D+]/seronegative recipient [R?] and 277 R+), CMV events occurred in 44 of 368 eligible patients (11.8%) at a median of 227 days (range 92‐360) posttransplant. A cutoff value of >40 sfu/2.5 × 10⁵ cells for either IE‐1 or pp65 was derived as a threshold for positivity, with a negative predictive value of >97% for CMV events. CMV events were significantly lower in assay positive vs assay negative patients (3.0% vs 19.5%, P < .0001 for pp65). Time to CMV event post‐EOP was significantly greater in those with sfu >40 at EOP (P < .0001). In this large, multicenter trial of kidney transplant recipients, we show that an assessment of CMV‐specific immunity using a novel ELISPOT assay is able to predict protection from CMV infection.     

Cytomegalovirus infection and graft rejection as risk factors for pneumocystis pneumonia in solid organ transplant recipients: A systematic review and meta‐analysis

A growing number of publications have reported the outbreaks of post‐transplant pneumocystis pneumonia (PJP). In most studies, the onset of PJP was beyond 6‐12 months of prophylaxis. Cytomegalovirus (CMV) infection and allograft rejection have been repeatedly reported as probable risk factors for post‐transplant PJP. In this systematic review and meta‐analysis, we determined the pooled effect estimates of these 2 variables as risk factors. Data sources included PUBMED, MEDLINE‐OVID, EMBASE‐OVID, Cochrane Library, Networked Digital Library of Theses and Dissertations, World Health Organization, and Web of Science. We excluded publications related to hematopoietic stem cell transplantation (HSCT) or Human Immunodeficiency Virus (HIV) patients. Eventually, 15 studies remained for the final stage of screening. Cytomegalovirus infection (OR: 3.30, CI 95%: 2.07‐5.26, I²: 57%, P = 0.006) and allograft rejection (OR:2.36, CI95%: 1.54‐3.62, I2: 45.5%, P = 0.05) significantly increased the risk of post‐transplant PJP. Extended prophylaxis targeting recipients with allograft rejection or CMV infection may reduce the risk of PJP.     

A quantitative assessment model of T‐cell immune function for predicting risks of infection and rejection during the early stage after liver transplantation

Although more and more clinical studies indicated that ImmuKnow assay could efficiently assess the immune status of recipients, it still has the challenge to predict the occurrence of clinical adverse events. This study aimed to establish a quantitative assessment model, which could more efficiently predict immune function of T lymphocytes after liver transplantation based on three indexes: CD4+ T lymphocyte count (C), CD4+/CD8+ ratio (R), and ImmuKnow adenosine triphosphate (ATP) value (A). We selected 194 recipients and measured the A, C, and R index every week, then obtained the Fisher linear discriminant functions by SPSS 16.0. Next, we divided the recipients into three groups: infection, stable, and rejection groups according to clinical status. After calculating, the discriminant function, 0.012A + 0.019C + 1.322R (simplified into T = 2A + 3C + 200R), was selected to represent the T‐cell‐mediated immune function. Based on the model, the optimal cutoff T values for infection and rejection were 1415 (sensitivity = 80%, specificity = 79.9%,AUC = 92.3%) and 1939.5 (sensitivity = 93.9%, specificity = 77.6%, AUC = 88.6%), relatively (p < 0.001). In conclusion, this model may be a more feasible way to evaluate the cellular immune function status in liver transplantation recipients.     

Impact of MBL2 gene polymorphisms on the risk of infection in solid organ transplant recipients: A systematic review and meta‐analysis

Mannose‐binding lectin (MBL) is a soluble pattern recognition molecule involved in complement activation. Single nucleotide polymorphisms (SNPs) in the MBL2 gene have been associated with susceptibility to infection, although data in solid organ transplant recipients remains inconclusive. This meta‐analysis was primarily aimed at investigating the association between posttransplant bacterial and fungal infection and variant alleles of MBL2 gene SNPs in the promoter/5’ untranslated region and exon 1. Cytomegalovirus (CMV) infection and/or disease were considered secondary outcomes. PubMed, EMBASE, and Web of Knowledge were searched for relevant articles up to August 2018. Eleven studies (comprising 1858 patients) were included, with liver transplant (LT) recipients accounting for 80.4% of the pooled population. As compared to high‐MBL expression haplotypes (YA/YA, YA/XA), any MBL‐deficient haplotype was associated with an increased risk of posttransplant bacterial and fungal infections (risk ratio [RR]: 1.30; P = .04). Low/null‐MBL expression haplotypes (XA/O, O/O) also increased the risk of primary outcome (RR: 1.51; P = .008) and CMV events (RR: 1.50; P = .006). No effect was observed for individual promoter SNPs. In conclusion, MBL‐deficient haplotypes are associated with a significant, albeit moderate, increase in the risk of posttransplant infection, with this association being mainly restricted to LT recipients.     

Clinical validation of a novel enzyme‐linked immunosorbent spot assay‐based in vitro diagnostic assay to monitor cytomegalovirus‐specific cell‐mediated immunity in kidney transplant recipients: a multicenter,longitudinal, prospective,observational study

Impaired cytomegalovirus (CMV)‐specific cell‐mediated immunity (CMV‐CMI) is a major cause of CMV reactivation and associated complications in solid‐organ transplantation. Reliably assessing CMV‐CMI is desirable to individually adjust antiviral and immunosuppressive therapy. This study aimed to evaluate the suitability of T‐Track^® CMV, a novel IFN‐γ ELISpot assay based on the stimulation of peripheral blood mononuclear cells with pp65 and IE‐I CMV proteins, to monitor CMV‐CMI following kidney transplantation. A prospective longitudinal multicenter study was conducted in 86 intermediate‐risk renal transplant recipients. CMV‐CMI, CMV viral load, and clinical complications were monitored over 6 months post‐transplantation. Ninety‐five percent and 88–92% ELISpot assays were positive pre‐ and post‐transplantation, respectively. CMV‐specific response was reduced following immunosuppressive treatment and increased in patients with graft rejection, indicating the ability of the ELISpot assay to monitor patients' immunosuppressive state. Interestingly, median pp65‐specific response was ninefold higher in patients with self‐clearing viral load compared to antivirally treated patients prior to first viral load detection (P < 0.001), suggesting that reactivity to pp65 represents a potential immunocompetence marker. Altogether, T‐Track^® CMV is a highly sensitive IFN‐γ ELISpot assay, suitable for the immunomonitoring of CMV‐seropositive renal transplant recipients, and with a potential use for the risk assessment of CMV‐related clinical complications (ClinicalTrials.gov Identifier: NCT02083042).     

Idiopathic pulmonary fibrosis lung transplant recipients are at increased risk for EBV‐associated posttransplant lymphoproliferative disorder and worse survival

Epstein‐Barr virus (EBV)–associated posttransplant lymphoproliferative disorder (EBV‐PTLD) is a serious complication in lung transplant recipients (LTRs) associated with significant mortality. We performed a single‐center retrospective study to evaluate the risks for PTLD in LTRs over a 7‐year period. Of 611 evaluable LTRs, we identified 28 cases of PTLD, with an incidence of 4.6%. Kaplan‐Meier analysis showed a decreased freedom from PTLD in idiopathic pulmonary fibrosis (IPF)‐LTRs (P < .02). Using a multivariable Cox proportional hazards model, we found IPF (hazard ratio [HR] 3.51, 95% confidence interval [CI] 1.33‐8.21, P = .01) and alemtuzumab induction therapy (HR 2.73, 95% CI 1.10‐6.74, P = .03) as risk factors for PTLD, compared to EBV mismatch (HR: 34.43, 95% CI 15.57‐76.09, P < .0001). Early PTLD (first year) was associated with alemtuzumab use (P = .04), whereas IPF was a predictor for late PTLD (after first year) (P = .002), after controlling for age and sex. Kaplan‐Meier analysis revealed a shorter time to death from PTLD in IPF LTRs compared to other patients (P = .04). The use of alemtuzumab in EBV mismatch was found to particularly increase PTLD risk. Together, our findings identify IPF LTRs as a susceptible population for PTLD. Further studies are required to understand the mechanisms driving PTLD in IPF LTRs and develop strategies to mitigate risk.     

Cytomegalovirus (CMV) infection and risk of mortality in allogeneic hematopoietic stem cell transplantation (Allo‐HSCT): A systematic review,meta‐analysis,and meta‐regression analysis

Controversy surrounds the potential association between cytomegalovirus (CMV) infection and increased risk of mortality after allogeneic hematopoietic stem cell transplantation (Allo‐HSCT). A systematic literature search was conducted using the PubMed, EMBASE, and Web of Science databases, assessing the association between CMV infection, as documented by the pp65 antigenemia assay or by polymerase chain reaction (PCR) using blood specimens, and overall mortality (OM) and nonrelapse mortality (NRM) in the allo‐HSCT setting. Pooled effects were estimated using the generic inverse variance random effects model. Heterogeneity was evaluated by Cochrane's Q test and I² statistics. The source of heterogeneity was investigated by meta‐regression and subgroup analyses. Twenty‐six of 1367 studies fulfilled eligibility criteria. CMV infection identified by PCR monitoring was significantly associated with an increased risk of OM and NRM (hazard ratio 1.47, 95% confidence interval [1.20‐1.81], P ≤ .001; hazard ratio 1.68, 95% confidence interval [1.14‐2.49], P = .05, respectively). In this setting, the use of preemptive antiviral therapy (PET) resulted in a twofold increased risk of OM and NRM. The estimated effect sizes were associated with allo‐HSCT modalities. Although our analyses point to an association between CMV infection and an increased risk of OM and NRM in allo‐HSCT recipients, the high heterogeneity across studies prevented drawing of robust conclusions on this matter.