Immunosuppression withdrawal in living-donor renal transplant recipients following induction with antithymocyte globulin and rituximab: Results of a prospective clinical trial.

Durable tolerance in kidney transplant recipients remains an important but elusive goal. We hypothesized that adding B cell depletion to T cell depletion would generate an immune milieu postreconstitution dominated by immature transitional B cells, favoring tolerance. The Immune Tolerance Network ITN039ST Research Study of ATG and Rituximab in Renal Transplantation was a prospective multicenter pilot study of live donor kidney transplant recipients who received induction with rabbit antithymocyte globulin and rituximab and initiated immunosuppression (IS) withdrawal (ISW) at 26 weeks. The primary endpoint was freedom from rejection at 52 weeks post-ISW. Six of the 10 subjects successfully completed ISW. Of these 6 subjects, 4 restarted immunosuppressive medications due to acute rejection or recurrent disease, 1 remains IS-free for over 9 years, and 1 was lost to follow-up after being IS-free for 42 weeks. There were no cases of patient or graft loss. CD19+ B cell frequencies returned to predepletion levels by 26 weeks posttransplant; immunoglobulin D+CD27--naïve B cells predominated. In contrast, memory cells dominated the repopulation of the T cell compartment. A regimen of combined B and T cell depletion did not generate the tolerogenic B cell profile observed in preclinical studies and did not lead to durable tolerance in the majority of kidney transplant recipients.

Persistent SARS-CoV-2-specific immune defects in kidney transplant recipients following third mRNA vaccine dose.

Kidney transplant recipients (KTRs) show poorer response to SARS-CoV-2 mRNA vaccination, yet response patterns and mechanistic drivers following third doses are ill-defined. We administered third monovalent mRNA vaccines to n = 81 KTRs with negative or low-titer anti-receptor binding domain (RBD) antibody (n = 39 anti-RBDNEG; n = 42 anti-RBDLO), compared with healthy controls (HCs, n = 19), measuring anti-RBD, Omicron neutralization, spike-specific CD8+%, and SARS-CoV-2-reactive T cell receptor (TCR) repertoires. By day 30, 44% anti-RBDNEG remained seronegative; 5% KTRs developed BA.5 neutralization (vs 68% HCs, P < .001). Day 30 spike-specific CD8+% was negative in 91% KTRs (vs 20% HCs; P = .07), without correlation to anti-RBD (rs = 0.17). Day 30 SARS-CoV-2-reactive TCR repertoires were detected in 52% KTRs vs 74% HCs (P = .11). Spike-specific CD4+ TCR expansion was similar between KTRs and HCs, yet KTR CD8+ TCR depth was 7.6-fold lower (P = .001). Global negative response was seen in 7% KTRs, associated with high-dose MMF (P = .037); 44% showed global positive response. Of the KTRs, 16% experienced breakthrough infections, with 2 hospitalizations; prebreakthrough variant neutralization was poor. Absent neutralizing and CD8+ responses in KTRs indicate vulnerability to COVID-19 despite 3-dose mRNA vaccination. Lack of neutralization despite CD4+ expansion suggests B cell dysfunction and/or ineffective T cell help. Development of more effective KTR vaccine strategies is critical. (NCT04969263).

Efficacy and Safety of Immunosuppression Withdrawal in Pediatric Liver Transplant Recipients: Moving Toward Personalized Management.

BACKGROUND AND AIMS: Tolerance is transplantation's holy grail, as it denotes allograft health without immunosuppression and its toxicities. Our aim was to determine, among stable long-term pediatric liver transplant recipients, the efficacy and safety of immunosuppression withdrawal to identify operational tolerance. APPROACH AND RESULTS: We conducted a multicenter, single-arm trial of immunosuppression withdrawal over 36-48 weeks. Liver tests were monitored biweekly (year 1), monthly (year 2), and bimonthly (years 3-4). For-cause biopsies were done at investigators' discretion but mandated when alanine aminotransferase or gamma glutamyltransferase exceeded 100 U/L. All subjects underwent final liver biopsy at trial end. The primary efficacy endpoint was operational tolerance, defined by strict biochemical and histological criteria 1 year after stopping immunosuppression. Among 88 subjects (median age 11 years; 39 boys; 57 deceased donor grafts), 33 (37.5%; 95% confidence interval [CI] 27.4%, 48.5%) were operationally tolerant, 16 were nontolerant by histology (met biochemical but failed histological criteria), and 39 were nontolerant by rejection. Rejection, predicted by subtle liver inflammation in trial entry biopsies, typically (n = 32) occurred at ≤32% of the trial-entry immunosuppression dose and was treated with corticosteroids (n = 32) and/or tacrolimus (n = 38) with resolution (liver tests within 1.5 times the baseline) for all but 1 subject. No death, graft loss, or chronic, severe, or refractory rejection occurred. Neither fibrosis stage nor the expression level of a rejection gene set increased over 4 years for either tolerant or nontolerant subjects. CONCLUSIONS: Immunosuppression withdrawal showed that 37.5% of selected pediatric liver-transplant recipients were operationally tolerant. Allograft histology did not deteriorate for either tolerant or nontolerant subjects. The timing and reversibility of failed withdrawal justifies future trials exploring the efficacy, safety, and potential benefits of immunosuppression minimization.

A noninferiority design for a delayed calcineurin inhibitor substitution trial in kidney transplantation.

Improving long-term kidney transplant outcomes requires novel treatment strategies, including delayed calcineurin inhibitor (CNI) substitution, tested using informative trial designs. An alternative approach to the usual superiority-based trial is a noninferiority trial design that tests whether an investigational agent is not unacceptably worse than standard of care. An informative noninferiority design, with biopsy-proven acute rejection (BPAR) as the endpoint, requires determination of a prespecified, evidence-based noninferiority margin for BPAR. No such information is available for delayed CNI substitution in kidney transplantation. Herein we analyzed data from recent kidney transplant trials of CNI withdrawal and "real world" CNI- based standard of care, containing subjects with well-documented evidence of immune quiescence at 6 months posttransplant-ideal candidates for delayed CNI substitution. Our analysis indicates an evidence-based noninferiority margin of 13.8% for the United States Food and Drug Administration's composite definition of BPAR between 6 and 24 months posttransplant. Sample size estimation determined that ~225 randomized subjects would be required to evaluate noninferiority for this primary clinical efficacy endpoint, and superiority for a renal function safety endpoint. Our findings provide the basis for future delayed CNI substitution noninferiority trials, thereby increasing the likelihood they will provide clinically implementable results and achieve regulatory approval.

The Fourth International Workshop on Clinical Transplant Tolerance.

The International Workshop on Clinical Transplant Tolerance is a biennial meeting that aims to provide an update on the progress of studies of immunosuppression minimization or withdrawal in solid organ transplantation. The Fourth International Workshop on Clinical Tolerance was held in Pittsburgh, Pennsylvania, September 5-6, 2019. This report is a summary of presentations on the status of clinical trials designed to minimize or withdraw immunosuppressive drugs in kidney, liver, and lung transplantation without subsequent evidence of rejection. All protocols had in common the use of donor or recipient cell therapy combined with organ transplantation. The workshop also included presentations of mechanistic studies designed to improve understanding of the cellular and molecular basis of tolerance and to identify potential predictors/biomarkers of tolerance. Strategies to enhance the safety of hematopoietic cell transplantation and to improve patient selection/risk stratification for clinical trials were also discussed.

Phase 3 trial of human islet-after-kidney transplantation in type 1 diabetes.

Allogeneic islet transplant offers a minimally invasive option for ß cell replacement in the treatment of type 1 diabetes (T1D). The CIT consortium trial of purified human pancreatic islets (PHPI) in patients with T1D after kidney transplant (CIT06), a National Institutes of Health-sponsored phase 3, prospective, open-label, single-arm pivotal trial of PHPI, was conducted in 24 patients with impaired awareness of hypoglycemia while receiving intensive insulin therapy. PHPI were manufactured using standardized processes. PHPI transplantation was effective with 62.5% of patients achieving the primary endpoint of freedom from severe hypoglycemic events and HbA1c  ≤ 6.5% or reduced by ≥ 1 percentage point at 1 year posttransplant. Median HbA1c declined from 8.1% before to 6.0% at 1 year and 6.3% at 2 and 3 years following transplant (P < .001 for all vs baseline), with related improvements in hypoglycemia awareness and glucose variability. The improved metabolic control was associated with better health-related and diabetes-related quality of life. The procedure was safe and kidney allograft function remained stable after 3 years. These results add to evidence establishing allogeneic islet transplant as a safe and effective treatment for patients with T1D and unstable glucose control despite intensive insulin treatment, supporting the indication for PHPI in the post-renal transplant setting.

Discovery and validation of a novel blood-based molecular biomarker of rejection following liver transplantation.

Noninvasive biomarker profiles of acute rejection (AR) could affect the management of liver transplant (LT) recipients. Peripheral blood was collected following LT for discovery (Northwestern University [NU]) and validation (National Institute of Allergy and Infectious Diseases Clinical Trials in Organ Transplantation [CTOT]-14 study). Blood gene profiling was paired with biopsies showing AR or ADNR (acute dysfunction no rejection) as well as stable graft function samples (Transplant eXcellent-TX). CTOT-14 subjects had serial collections prior to AR, ADNR, TX, and after AR treatment. NU cohort gene expression (46 AR, 45 TX) was analyzed using random forest models to generate a classifier training set (36 gene probe) distinguishing AR vs TX (area under the curve 0.92). The algorithm and threshold were locked and tested on the CTOT-14 validation cohort (14 AR, 50 TX), yielding an accuracy of 0.77, sensitivity 0.57, specificity 0.82, positive predictive value (PPV) 0.47, and negative predictive value (NPV) 0.87 for AR vs TX. The probability score line slopes were positive preceding AR, and negative preceding TX and non-AR (TX + ADNR) (P ≤ .001) and following AR treatment. In conclusion, we have developed a blood biomarker diagnostic for AR that can be detected prior to AR-associated graft injury as well a normal graft function (non-AR). Further studies are needed to evaluate its utility in precision-guided immunosuppression optimization following LT.

Avoidance of CNI and steroids using belatacept-Results of the Clinical Trials in Organ Transplantation 16 trial.

Immunosuppression devoid of corticosteroids has been investigated to avoid long-term comorbidities. Likewise, alternatives to calcineurin inhibitors have been investigated as a strategy to improve long-term kidney function following transplanion. Costimulatory blockade strategies that include corticosteroids have recently shown promise, despite their higher rates of early acute rejection. We designed a randomized clinical trial utilizing depletional induction therapy to mitigate early rejection risk while limiting calcineurin inhibitors and corticosteroids. This trial, Clinical Trials in Organ Transplantation 16 (CTOT-16), sought to evaluate novel belatacept-based strategies employing tacrolimus and corticosteroid avoidance. Sixty-nine kidney transplant recipients were randomized from 4 US transplant centers comparing a control group of with rabbit antithymocyte globulin (rATG) induction, rapid steroid taper, and maintenance mycophenolate and tacrolimus, to 2 arms using maintenance belatacept. There were no graft losses but there were 2 deaths in the control group. However, the trial was halted early because of rejection in the belatacept treatment groups. Serious adverse events were similar across groups. Although rejection was not uniform in the belatacept maintenance therapy groups, the frequency of rejection limits the practical implementation of this strategy to avoid both calcineurin inhibitors and corticosteroids at this time.

Early immune biomarkers and intermediate-term outcomes after heart transplantation: Results of Clinical Trials in Organ Transplantation-18.

Clinical Trials in Organ Transplantation-18 (CTOT-18) is a follow-up analysis of the 200-subject multicenter heart transplant CTOT-05 cohort. CTOT-18 aimed to identify clinical, epidemiologic, and biologic markers associated with adverse clinical events past 1 year posttransplantation. We examined various candidate biomarkers including serum antibodies, angiogenic proteins, blood gene expression profiles, and T cell alloreactivity. The composite endpoint (CE) included death, retransplantation, coronary stent, myocardial infarction, and cardiac allograft vasculopathy. The mean follow-up was 4.5 ± SD 1.1 years. Subjects with serum anti-cardiac myosin (CM) antibody detected at transplantation and at 12 months had a higher risk of meeting the CE compared to those without anti-CM antibody (hazard ratio [HR] = 2.9, P = .046). Plasma VEGF-A and VEGF-C levels pretransplant were associated with CE (odds ratio [OR] = 13.24, P = .029; and OR = 0.13, P = .037, respectively). Early intravascular ultrasound findings or other candidate biomarkers were not associated with the study outcomes. In conclusion, anti-CM antibody and plasma levels of VEGF-A and VEGF-C were associated with an increased risk of adverse events. Although this multicenter report supports further evaluation of the mechanisms through which anti-CM antibody and plasma angiogenesis proteins lead to allograft injury, we could not identify additional markers of adverse events or potential novel therapeutic targets.

Outcomes of immunosuppression minimization and withdrawal early after liver transplantation.

The Immune Tolerance Network ITN030ST A-WISH assessed immunosuppression withdrawal in liver transplant recipients with hepatitis C or nonimmune nonviral liver disease. Of 275 recipients enrolled before transplantation, 95 were randomly assigned 4:1 to withdrawal (n = 77) or maintenance (n = 18) 1- to 2-years posttransplant. Randomization eligibility criteria included stable immunosuppression monotherapy; adequate liver and kidney function; ≤Stage 2 Ishak fibrosis; and absence of rejection on biopsy. Immunosuppression withdrawal followed an 8-step reduction algorithm with ≥8 weeks per level. Fifty-two of 77 subjects (67.5%) reduced to ≤50% of baseline dose, and 10 of 77 (13.0%) discontinued all immunosuppression for ≥1 year. Acute rejection and/or abnormal liver tests were treated with increased immunosuppression; 5 of 32 rejection episodes required a methylprednisolone bolus. The composite end point (death or graft loss; grade 4 secondary malignancy or opportunistic infection; Ishak stage ≥3; or >25% decrease in glomerular filtration rate within 24 months of randomization) occurred in 12 of 66 (18%) and 4 of 13 (31%) subjects in the withdrawal and maintenance groups. Early immunosuppression minimization is feasible in selected liver recipients, while complete withdrawal is successful in only a small proportion. The composite end point comparison was inconclusive for noninferiority of the withdrawal to the maintenance group.

Evidence of Chronic Allograft Injury in Liver Biopsies From Long-term Pediatric Recipients of Liver Transplants.

BACKGROUND & AIMS: A substantial proportion of pediatric liver transplant recipients develop subclinical chronic allograft injury. We studied whether there are distinct patterns of injury based on histopathologic features and identified associated immunologic profiles. METHODS: We conducted a cross-sectional study of 157 stable, long-term pediatric recipients of transplanted livers (70 boys; > 6 years old at time of transplantation; mean, 8.9 ± 3.46 years after liver transplantation) who underwent liver biopsy analysis from August 13, 2012, through May 1, 2014. Participants had received livers from a living or deceased donor and had consistently normal results from liver tests. Liver biopsy specimens were scored by a central pathologist; an unsupervised hierarchical cluster analysis of histologic features was used to sort biopsy samples into 3 clusters. We conducted transcriptional and cytometric analyses of liver tissue samples and performed a systems biology analysis that incorporated clinical, serologic, histologic, and transcriptional data. RESULTS: The mean level of alanine aminotransferase in participants was 27.6 ± 14.57 U/L, and the mean level of γ-glutamyl transferase was 17.4 ± 7.93 U/L. Cluster 1 was characterized by interface activity (n = 34), cluster 2 was characterized by periportal or perivenular fibrosis without interface activity (n = 45), and cluster 3 had neither feature (n = 78). We identified a module of genes whose expression correlated with levels of alanine aminotransferase, class II donor-specific antibody, portal inflammation, interface activity, perivenular inflammation, portal and perivenular fibrosis, and cluster assignment. The module was enriched in genes that regulate T-cell-mediated rejection (TCMR) of liver and other transplanted organs. Functional pathway analysis showed overrepresentation of TCMR gene sets for cluster 1 but not clusters 2 or 3. CONCLUSION: In an analysis of biopsies from an apparently homogeneous group of stable, long-term pediatric liver transplant recipients with consistently normal liver test results, we found evidence of chronic graft injury (inflammation and/or fibrosis). Biopsy samples with interface activity had a gene expression pattern associated with TCMR.

Urine Metabolite Profiles Predictive of Human Kidney Allograft Status.

Noninvasive diagnosis and prognostication of acute cellular rejection in the kidney allograft may help realize the full benefits of kidney transplantation. To investigate whether urine metabolites predict kidney allograft status, we determined levels of 749 metabolites in 1516 urine samples from 241 kidney graft recipients enrolled in the prospective multicenter Clinical Trials in Organ Transplantation-04 study. A metabolite signature of the ratio of 3-sialyllactose to xanthosine in biopsy specimen-matched urine supernatants best discriminated acute cellular rejection biopsy specimens from specimens without rejection. For clinical application, we developed a high-throughput mass spectrometry-based assay that enabled absolute and rapid quantification of the 3-sialyllactose-to-xanthosine ratio in urine samples. A composite signature of ratios of 3-sialyllactose to xanthosine and quinolinate to X-16397 and our previously reported urinary cell mRNA signature of 18S ribosomal RNA, CD3ε mRNA, and interferon-inducible protein-10 mRNA outperformed the metabolite signatures and the mRNA signature. The area under the receiver operating characteristics curve for the composite metabolite-mRNA signature was 0.93, and the signature was diagnostic of acute cellular rejection with a specificity of 84% and a sensitivity of 90%. The composite signature, developed using solely biopsy specimen-matched urine samples, predicted future acute cellular rejection when applied to pristine samples taken days to weeks before biopsy. We conclude that metabolite profiling of urine offers a noninvasive means of diagnosing and prognosticating acute cellular rejection in the human kidney allograft, and that the combined metabolite and mRNA signature is diagnostic and prognostic of acute cellular rejection with very high accuracy.

Urinary-cell mRNA profile and acute cellular rejection in kidney allografts.

BACKGROUND: The standard test for the diagnosis of acute rejection in kidney transplants is the renal biopsy. Noninvasive tests would be preferable. METHODS: We prospectively collected 4300 urine specimens from 485 kidney-graft recipients from day 3 through month 12 after transplantation. Messenger RNA (mRNA) levels were measured in urinary cells and correlated with allograft-rejection status with the use of logistic regression. RESULTS: A three-gene signature of 18S ribosomal (rRNA)-normalized measures of CD3ε mRNA and interferon-inducible protein 10 (IP-10) mRNA, and 18S rRNA discriminated between biopsy specimens showing acute cellular rejection and those not showing rejection (area under the curve [AUC], 0.85; 95% confidence interval [CI], 0.78 to 0.91; P<0.001 by receiver-operating-characteristic curve analysis). The cross-validation estimate of the AUC was 0.83 by bootstrap resampling, and the Hosmer-Lemeshow test indicated good fit (P=0.77). In an external-validation data set, the AUC was 0.74 (95% CI, 0.61 to 0.86; P<0.001) and did not differ significantly from the AUC in our primary data set (P=0.13). The signature distinguished acute cellular rejection from acute antibody-mediated rejection and borderline rejection (AUC, 0.78; 95% CI, 0.68 to 0.89; P<0.001). It also distinguished patients who received anti-interleukin-2 receptor antibodies from those who received T-cell-depleting antibodies (P<0.001) and was diagnostic of acute cellular rejection in both groups. Urinary tract infection did not affect the signature (P=0.69). The average trajectory of the signature in repeated urine samples remained below the diagnostic threshold for acute cellular rejection in the group of patients with no rejection, but in the group with rejection, there was a sharp rise during the weeks before the biopsy showing rejection (P<0.001). CONCLUSIONS: A molecular signature of CD3ε mRNA, IP-10 mRNA, and 18S rRNA levels in urinary cells appears to be diagnostic and prognostic of acute cellular rejection in kidney allografts. (Funded by the National Institutes of Health and others.).

Adverse Outcomes of Tacrolimus Withdrawal in Immune-Quiescent Kidney Transplant Recipients.

Concerns about adverse effects of calcineurin inhibitors (CNIs) have prompted development of protocols that minimize their use. Whereas previous CNI withdrawal trials in heterogeneous cohorts showed unacceptable rates of acute rejection (AR), we hypothesized that we could identify individuals capable of tolerating CNI withdrawal by targeting immunologically quiescent kidney transplant recipients. The Clinical Trials in Organ Transplantation-09 Trial was a randomized, prospective study of nonsensitized primary recipients of living donor kidney transplants. Subjects received rabbit antithymocyte globulin, tacrolimus, mycophenolate mofetil, and prednisone. Six months post-transplantation, subjects without de novo donor-specific antibodies (DSAs), AR, or inflammation at protocol biopsy were randomized to wean off or remain on tacrolimus. The intended primary end point was the change in interstitial fibrosis/tubular atrophy score between implantation and 24-month protocol biopsies. Serially collected urine CXCL9 ELISA results were correlated with outcomes. The study was terminated prematurely because of unacceptable rates of AR (4 of 14) and/or de novo DSAs (5 of 14) in the tacrolimus withdrawal arm. Positive urinary CXCL9 predated clinical detection of AR by a median of 15 days. Analyses showed that >16 HLA-DQ epitope mismatches and pretransplant, peripheral blood, donor-reactive IFN-γ ELISPOT assay results correlated with development of DSAs and/or AR on tacrolimus withdrawal. Although data indicate that urinary CXCL9 monitoring, epitope mismatches, and ELISPOT assays are potentially informative, complete CNI withdrawal must be strongly discouraged in kidney transplant recipients who are receiving standard-of-care immunosuppression, including those who are deemed to be immunologically quiescent on the basis of current clinical and laboratory criteria.

Complete immunosuppression withdrawal and subsequent allograft function among pediatric recipients of parental living donor liver transplants.

CONTEXT: Although life-saving, liver transplantation burdens children with lifelong immunosuppression and substantial potential for morbidity and mortality. OBJECTIVE: To establish the feasibility of immunosuppression withdrawal in pediatric living donor liver transplant recipients. DESIGN, SETTING, AND PATIENTS: Prospective, multicenter, open-label, single-group pilot trial conducted in 20 stable pediatric recipients (11 male; 55%) of parental living donor liver transplants for diseases other than viral hepatitis or an autoimmune disease who underwent immunosuppression withdrawal. Their median age was 6.9 months (interquartile range [IQR], 5.5-9.1 months) at transplant and 8 years 6 months (IQR, 6 years 5 months to 10 years 9 months) at study enrollment. Additional entry requirements included stable allograft function while taking a single immunosuppressive drug and no evidence of acute or chronic rejection or significant fibrosis on liver biopsy. Gradual immunosuppression withdrawal over a minimum of 36 weeks was instituted at 1 of 3 transplant centers between June 5, 2006, and November 18, 2009. Recipients were followed up for a median of 32.9 months (IQR, 1.0-49.9 months). MAIN OUTCOME MEASURES: The primary end point was the proportion of operationally tolerant patients, defined as patients who remained off immunosuppression therapy for at least 1 year with normal graft function. Secondary clinical end points included the durability of operational tolerance, and the incidence, timing, severity, and reversibility of rejection. RESULTS: Of 20 pediatric patients, 12 (60%; 95% CI, 36.1%-80.9%) met the primary end point, maintaining normal allograft function for a median of 35.7 months (IQR, 28.1-39.7 months) after discontinuing immunosuppression therapy. Follow-up biopsies obtained more than 2 years after completing withdrawal showed no significant change compared with baseline biopsies. Eight patients did not meet the primary end point secondary to an exclusion criteria violation (n = 1), acute rejection (n = 2), or indeterminate rejection (n = 5). Seven patients were treated with increased or reinitiation of immunosuppression therapy; all returned to baseline allograft function. Patients with operational tolerance compared with patients without operational tolerance initiated immunosuppression withdrawal later after transplantation (median of 100.6 months [IQR, 71.8-123.5] vs 73.0 months [IQR, 57.6-74.9], respectively; P = .03), had less portal inflammation (91.7% [95% CI, 61.5%-99.8%] vs 42.9% [95% CI, 9.9%-81.6%] with no inflammation; P = .04), and had lower total C4d scores on the screening liver biopsy (median of 6.1 [IQR, 5.1-9.3] vs 12.5 [IQR, 9.3-16.8]; P = .03). CONCLUSION: In this pilot study, 60% of pediatric recipients of parental living donor liver transplants remained off immunosuppression therapy for at least 1 year with normal graft function and stable allograft histology.

Long-term Outcomes With Islet-Alone and Islet-After-Kidney Transplantation for Type 1 Diabetes in the Clinical Islet Transplantation Consortium: The CIT-08 Study.

OBJECTIVE: To determine long-term outcomes for islet-alone and islet-after-kidney transplantation in adults with type 1 diabetes complicated by impaired awareness of hypoglycemia. RESEARCH DESIGN AND METHODS: This was a prospective interventional and observational cohort study of islet-alone (n = 48) and islet-after-kidney (n = 24) transplant recipients followed for up to 8 years after intraportal infusion of one or more purified human pancreatic islet products under standardized immunosuppression. Outcomes included duration of islet graft survival (stimulated C-peptide ≥0.3 ng/mL), on-target glycemic control (HbA1c <7.0%), freedom from severe hypoglycemia, and insulin independence. RESULTS: Of the 48 islet-alone and 24 islet-after-kidney transplantation recipients, 26 and 8 completed long-term follow-up with islet graft function, 15 and 7 withdrew from follow-up with islet graft function, and 7 and 9 experienced islet graft failure, respectively. Actuarial islet graft survival at median and final follow-up was 84% and 56% for islet-alone and 69% and 49% for islet-after-kidney (P = 0.007) with 77% and 49% of islet-alone and 57% and 35% of islet-after-kidney transplantation recipients maintaining posttransplant HbA1c <7.0% (P = 0.0017); freedom from severe hypoglycemia was maintained at >90% in both cohorts. Insulin independence was achieved by 74% of islet-alone and islet-after-kidney transplantation recipients, with more than one-half maintaining insulin independence during long-term follow-up. Kidney function remained stable during long-term follow-up in both cohorts, and rates of sensitization against HLA were low. Severe adverse events occurred at 0.31 per patient-year for islet-alone and 0.43 per patient-year for islet-after-kidney transplantation. CONCLUSIONS: Islet transplantation results in durable islet graft survival permitting achievement of glycemic targets in the absence of severe hypoglycemia for most appropriately indicated recipients having impaired awareness of hypoglycemia, with acceptable safety of added immunosuppression for both islet-alone and islet-after-kidney transplantation.

Selective decrease of donor-reactive Tregs after liver transplantation limits Treg therapy for promoting allograft tolerance in humans.

Promoting immune tolerance to transplanted organs can minimize the amount of immunosuppressive drugs that patients need to take, reducing lifetime risks of mortality and morbidity. Regulatory T cells (Tregs) are essential for immune tolerance, and preclinical studies have shown their therapeutic efficacy in inducing transplantation tolerance. Here, we report the results of a phase 1/2 trial (ARTEMIS, NCT02474199) of autologous donor alloantigen-reactive Treg (darTreg) therapy in individuals 2 to 6 years after receiving a living donor liver transplant. The primary efficacy endpoint was calcineurin inhibitor dose reduction by 75% with stable liver function tests for at least 12 weeks. Among 10 individuals who initiated immunosuppression withdrawal, 1 experienced rejection before planned darTreg infusion, 5 received darTregs, and 4 were not infused because of failure to manufacture the minimal infusible dose of 100 × 106 cells. darTreg infusion was not associated with adverse events. Two darTreg-infused participants reached the primary endpoint, but an insufficient number of recipients were treated for assessing the efficacy of darTregs. Mechanistic studies revealed generalized Treg activation, senescence, and selective reduction of donor reactivity after liver transplantation. Overall, the ARTEMIS trial features a design concept for evaluating the efficacy of Treg therapy in transplantation. The mechanistic insight gained from the study may help guide the design of future trials.

Open Randomized Multicenter Study to Evaluate Safety and Efficacy of Low Molecular Weight Sulfated Dextran in Islet Transplantation.

BACKGROUND: When transplanted human pancreatic islets are exposed to blood during intraportal infusion, an innate immune response is triggered. This instant blood-mediated inflammatory reaction (IBMIR) activates the coagulation and complement cascades and leads to the destruction of 25% of all transplanted islets within minutes, contributing to the need, in most patients, for islets from more than 1 donor. Low molecular dextran sulfate (LMW-DS) has been shown in experimental settings to inhibit IBMIR. METHODS: The Clinical Islet Transplantation consortium 01 study was a phase II, multicenter, open label, active control, randomized study. Twenty-four subjects were randomized to peritransplant intraportal and systemic treatment with either LMW-DS or heparin, targeting an activated partial thromboplastin time of 150 ± 10 seconds and 50 ± 5 seconds, respectively. C-peptide response was measured with a mixed meal tolerance test at 75 and 365 days after transplant. RESULTS: Low molecular dextran sulfate was safe and well tolerated with similar observed adverse events (mostly attributed to immunosuppression) as in the heparin arm. There was no difference in the primary endpoint (stimulated C-peptide 75 ± 5 days after the first transplant) between the 2 arms (1.33 ± 1.10 versus 1.56 ± 1.36 ng/mL, P = 0.66). Insulin requirement, metabolic parameters, Clarke and HYPO score, quality of life, and safety were similar between the 2 treatments groups. CONCLUSIONS: Even with low dosing, LMW-DS showed similar efficacy in preventing IBMIR to promote islet engraftment when compared to "state-of-the art" treatment with heparin. Furthermore, no substantial differences in the efficacy and safety endpoints were detected, providing important information for future studies with more optimal dosing of LMW-DS for the prevention of IBMIR in islet transplantation.

Accelerated Allograft Vasculopathy With Rituximab After Cardiac Transplantation.

BACKGROUND: The CTOT-11 (Prevention of Cardiac Allograft Vasculopathy Using Rituximab Therapy in Cardiac Transplantation [Clinical Trials in Organ Transplantation-11]) study was a randomized, placebo-controlled, multicenter, double-blinded clinical trial in nonsensitized primary heart transplant (HTX) recipients. OBJECTIVES: The study sought to determine whether B cell depletion therapy would attenuate the development of cardiac allograft vasculopathy. METHODS: A total of 163 HTX recipients were randomized to rituximab 1,000 mg intravenous or placebo on days 0 and 12 post-transplant. Primary outcome was change in percent atheroma volume (PAV) from baseline to 1 year measured by intravascular ultrasound. Secondary outcomes included treated episodes of acute rejection, de novo anti-HLA antibodies (including donor-specific antibodies), and phenotypic differentiation of B cells. RESULTS: There were no significant differences at study entry between the rituximab and placebo groups. Paired intravascular ultrasound measures were available at baseline and 1 year in 86 subjects (49 rituximab, 37 placebo). The mean ± SD change in PAV at 12 months was +6.8 ± 8.2% rituximab versus +1.9 ± 4.4% placebo (p = 0.0019). Mortality at 12 months was 3.4% rituximab versus 6.8% placebo (p = 0.47); there were no retransplants or post-transplant lymphoproliferative disorder. The rate of treated rejection was 24.7% rituximab versus 32.4% placebo (p = 0.28). Rituximab therapy effectively eliminated CD20+/CD19+ B cells followed by a gradual expansion of a CD19- cell population in the rituximab-treated group. CONCLUSIONS: A marked, unexpected increase in coronary artery PAV with rituximab was observed during the first year in HTX recipients. One-year mortality was not impacted; however, longer-term follow-up and mechanistic explanations are required. (Prevention of Cardiac Allograft Vasculopathy Using Rituximab [Rituxan] Therapy in Cardiac Transplantation; NCT01278745).

Improved Health-Related Quality of Life in a Phase 3 Islet Transplantation Trial in Type 1 Diabetes Complicated by Severe Hypoglycemia.

OBJECTIVE: Attaining glycemic targets without severe hypoglycemic events (SHEs) is a challenging treatment goal for patients with type 1 diabetes complicated by impaired awareness of hypoglycemia (IAH). The CIT Consortium Protocol 07 (CIT-07) trial showed islet transplantation to be an effective treatment for subjects with IAH and intractable SHEs. We evaluated health-related quality of life (HRQOL), functional health status, and health utility before and after pancreatic islet transplantation in CIT-07 trial participants. RESEARCH DESIGN AND METHODS: Four surveys, the Diabetes Distress Scale (DDS), the Hypoglycemic Fear Survey (HFS), the Short Form 36 Health Survey (SF-36), and the EuroQoL 5 Dimensions (EQ-5D), were administered repeatedly before and after islet transplantation. Summary statistics and longitudinal modeling were used to describe changes in survey scores from baseline and to characterize change in relation to a minimally important difference (MID) threshold of half an SD. RESULTS: Improvements in condition-specific HRQOL met the MID threshold. Reductions from baseline in the DDS total score and its four DDS subscales (all P ≤ 0.0013) and in the HFS total score and its two subscales (all P < 0.0001) were observed across all time points. Improvements were observed after both 1 and 2 years for the EQ-5D visual analog scale (both P < 0.0001). CONCLUSIONS: In CIT-07, 87.5% of the subjects achieved the primary end point of freedom from SHE along with glycemic control (HbA1c <7% [<53 mmol/mol]) at 1 year post-initial islet transplantation. The same subjects reported consistent, statistically significant, and clinically meaningful improvements in condition-specific HRQOL as well as self-assessments of overall health.