How Should Pancreas Transplant Rejection Be Treated?

Indications, Techniques, and Barriers for Pancreas Transplant Biopsy: A Consensus Perspective From a Survey of US Centers

BACKGROUND

Pancreas transplant biopsy practices for the diagnosis of rejection or other pathologies are not well described.

METHODS

We conducted a survey of staff at US pancreas transplant programs (March 22, 2022, to August 22, 2022) to assess current program practices and perceptions about the utility and challenges in the performance and interpretation of pancreas allograft biopsies.

RESULTS

Respondents represented 65% (76/117) of active adult pancreas transplant programs, capturing 66% of recent pancreas transplant volume in the United States. Participants were most often nephrologists (52%), followed by surgeons (46%), and other staff (4%). Pancreas allograft biopsies were performed mostly by interventional radiologists (74%), followed by surgeons (11%), nephrologists (8%), and gastroenterologists (1%). Limitations in the radiologist's or biopsy performer's comfort level or expertise to safely perform a biopsy, or to obtain sufficient/adequate samples were the two most common challenges with pancreas transplant biopsies. Pancreas transplant biopsies were read by local pathologists at a majority (86%) of centers. Challenges reported with pancreas biopsy interpretation included poor reliability, lack of reporting of C4d staining, lack of reporting of rejection grading, and inconclusive interpretation of the biopsy. Staff at a third of responding programs (34%) stated that they rarely or never perform pancreas allograft biopsies and treat presumed rejection empirically.

CONCLUSIONS

This national survey identified significant variation in clinical practices related to pancreas allograft biopsies and potential barriers to pancreas transplant utilization across the United States. Consideration of strategies to improve program experience with percutaneous pancreas biopsy and to support optimal management of pancreas allograft rejection informed by histology is warranted.

Banff 2022 pancreas transplantation multidisciplinary report: Refinement of guidelines for T cell-mediated rejection, antibody-mediated rejection and islet pathology. Assessment of duodenal cuff biopsies and noninvasive diagnostic methods

The Banff pancreas working schema for diagnosis and grading of rejection is widely used for treatment guidance and risk stratification in centers that perform pancreas allograft biopsies. Since the last update, various studies have provided additional insight regarding the application of the schema and enhanced our understanding of additional clinicopathologic entities. This update aims to clarify terminology and lesion description for T cell-mediated and antibody-mediated allograft rejections, in both active and chronic forms. In addition, morphologic and immunohistochemical tools are described to help distinguish rejection from nonrejection pathologies. For the first time, a clinicopathologic approach to islet pathology in the early and late posttransplant periods is discussed. This update also includes a discussion and recommendations on the utilization of endoscopic duodenal donor cuff biopsies as surrogates for pancreas biopsies in various clinical settings. Finally, an analysis and recommendations on the use of donor-derived cell-free DNA for monitoring pancreas graft recipients are provided. This multidisciplinary effort assesses the current role of pancreas allograft biopsies and offers practical guidelines that can be helpful to pancreas transplant practitioners as well as experienced pathologists and pathologists in training.

Technology and Transplants: Troubleshooting Insulin Pumps and Pancreas Transplants in the Emergency Department

Diabetes management has continued to evolve with new treatments and technology. This article discusses the approach to evaluation and management of two distinctive subsets of patients: (1) patients who manage their diabetes with an insulin pump (artificial pancreas) and (2) patients who have received a pancreas transplant. The most current literature is reviewed and pearls and pitfalls distinctive to these two patient populations are discussed. Relevant diagnostics are reviewed with emphasis on recognition of complications faced in the emergency department management of these unique patient populations.

Analysis of Individual Components of Frailty in Simultaneous Pancreas and Kidney, and Solitary Pancreas Transplant Recipients

Backgrounds

It is not known which of the 5 components of the Fried frailty score have the most predictive value for outcomes in simultaneous pancreas-kidney transplant (SPK) and solitary pancreas transplant (SPT) recipients.

Methods

In this study, we sought to investigate the association between pretransplant overall frailty and individual frailty components, with posttransplant outcomes among SPK and SPT recipients. Outcomes of interest were length of stay, kidney delayed graft function (K-DGF), readmission within 30 d after discharge, cardiovascular events, acute rejection, pancreas death-censored graft failure (DCGF), kidney DCGF, and death.

Results

Of the individual frailty components among SPK (n = 113), only slow walk time was associated with an increased risk of mortality (adjusted odds ratio [aOR]: 4.99; P = 0.03). Among SPT (n = 49), higher sum frailty scores (coefficient correlation 0.29; P = 0.04) and weight loss (coefficient correlation  = 0.30; P = 0.03) were associated with prolonged length of stay. Similarly, weight loss among SPT was associated with an increased risk of DCGF (aOR: 4.34; P = 0.049). Low grip strength was strongly associated with an increased risk of early readmission (aOR: 13.08; P = 0.008).

Conclusions

We found that not all components of frailty contribute equally to predicting outcomes. Objective measurements of slow walk time, unintentional weight loss, and low grip strength were found to be associated with less optimal outcomes in pancreas transplant recipients. Targeted interventions may improve posttransplant outcomes.

Chronic Pancreas Allograft Rejection Followed by Successful HLA-Incompatible Islet Alloautotransplantation: A Novel Strategy?

The purpose of pancreas or islet transplantation is to restore glycemic control in order to mitigate diabetes-related complications and prevent severe hypoglycemia. Complications from chronic pancreas allograft rejection may lead to transplantectomy, even when the endocrine function remains preserved. We present first evidence of a successful HLA incompatible islet re-transplantation with islets isolated from a rejecting pancreas allograft after simultaneous kidney pancreas transplantation. The pancreas allograft was removed because of progressively painful pancreatic panniculitis from clinically uncontrolled chronic rejection. The endocrine function was preserved. Induction treatment for this "islet alloautotransplantation" consisted of plasmapheresis, IVIg and alemtuzumab. At 1 year, the patient retained islet graft function with good glycemic control and absence of severe hypoglycemia, despite persistent low-grade HLA donor-specific antibodies. His panniculitis had resolved completely. In our point of view, islet alloautotransplantation derived from a chronically rejecting pancreas allograft is a potential option to salvage (partial) islet function, despite preformed donor-specific antibodies, in order to maintain stable glycemic control. Thereby it protects against severe hypoglycemia, and it potentially mitigates kidney graft dysfunction and other diabetes-related complications in patients with continued need for immunosuppression and who are otherwise difficult to retransplant.

An Initial Analysis of the Baseline Levels of Dd-cfDNA After Pancreas Transplantation: A Prospective Study From High-volume Centers in the United States

Pancreas transplantation offers patients with diabetes an opportunity for glucose homeostasis. Current blood tests to surveil for rejection have poor sensitivity and specificity for identifying rejection, and pancreas biopsies are challenging and associated with morbidity and graft loss. Donor-derived cell-free DNA (dd-cfDNA) is shed from transplanted organs and detectable in peripheral blood. Thus, a potential dd-cfDNA blood test assessing rejection would be clinically advantageous.

Methods

One hundred eighty-one dd-cfDNA samples (n) were collected from 77 patients (N) up to 132 mo posttransplant.

Results

The median dd-cfDNA level among all subjects was 0.28% (0.13%, 0.71%). In simultaneous pancreas-kidney (SPK) transplant recipients, the median dd-cfDNA level was 0.29% (0.13%, 0.71%), and it was 0.23% (0.08%, 0.71%) in pancreas transplant alone (PTA) recipients. When isolating for when without infection or rejection, the median dd-cfDNA level was 0.28% (0.13%, 0.64%) for SPK and 0.20% (0.00%, 0.32%) for PTA. Both transplant types approached 1.0% ≤1 mo posttransplant followed by a decrease in median dd-cfDNA. During episodes of rejection or infection, median dd-cfDNA levels were greater among all transplant types.

Conclusions

The mean dd-cfDNA level for all pancreas transplant recipients is <1.0%, consistent with the published kidney transplant rejection threshold (>1.0%), regardless of SPK or PTA. Early posttransplant dd-cfDNA levels are transiently higher than later measurements. Dd-cfDNA elevation also correlates with rejection and infection and thus is a promising biomarker for surveilling pancreas transplant dysfunction.

Early Increases in Posttransplant Pancreatic Enzymes Are Associated With Surgical Complications But Not Graft Failure Among Pancreas Transplant Recipients

OBJECTIVES

This study aimed to find the association between immediate postoperative increases in pancreatic enzymes and posttransplant complications among pancreas transplant recipients (PTRs).

METHODS

We analyzed all PTRs transplanted at the University of Wisconsin between June 2009 and September 2018. Enzyme levels were presented as a ratio of absolute numbers to the upper limit of normal value, with value >1 considered as abnormal. We specifically evaluated bleeding, fluid collections, and thrombosis complications based on the amylase or lipase ratios on day 1 (Amylase1, Lipase1) and maximum ratios within 5 days of transplant (Amylasemax, Lipasemax). For early complications, we focused on technical complications that occurred within 90 days of transplant. For long-term outcomes, we assessed patient and graft survival, and rejections.

RESULTS

There were a total of 443 PTRs, 287 were simultaneous pancreas and kidney recipients, and 156 were solitary pancreas recipients. Higher Amylase1, Liplase1, Amylasemax, and Lipasemax were associated with an increase in early complications, mainly need for pancreatectomy, fluid collections, bleeding complications, or graft thrombosis, particularly in the solitary pancreas group.

CONCLUSIONS

Our finding suggests that cases of early perioperative enzyme increase merit consideration for early imaging investigation to mitigate detrimental outcomes.

International Survey of Clinical Monitoring Practices in Pancreas and Islet Transplantation

BACKGROUND

The long-term outcomes of both pancreas and islet allotransplantation have been compromised by difficulties in the detection of early graft dysfunction at a time when a clinical intervention can prevent further deterioration and preserve allograft function. The lack of standardized strategies for monitoring pancreas and islet allograft function prompted an international survey established by an International Pancreas and Islet Transplant Association/European Pancreas and Islet Transplant Association working group.

METHODS

A global survey was administered to 24 pancreas and 18 islet programs using Redcap. The survey addressed protocolized and for-cause immunologic and metabolic monitoring strategies following pancreas and islet allotransplantation. All invited programs completed the survey.

RESULTS

The survey identified that in both pancreas and islet allograft programs, protocolized clinical monitoring practices included assessing body weight, fasting glucose/C-peptide, hemoglobin A1c, and donor-specific antibody. Protocolized monitoring in islet transplant programs relied on the addition of mixed meal tolerance test, continuous glucose monitoring, and autoantibody titers. In the setting of either suspicion for rejection or serially increasing hemoglobin A1c/fasting glucose levels postpancreas transplant, Doppler ultrasound, computed tomography, autoantibody titers, and pancreas graft biopsy were identified as adjunctive strategies to protocolized monitoring studies. No additional assays were identified in the setting of serially increasing hemoglobin A1c levels postislet transplantation.

CONCLUSIONS

This international survey identifies common immunologic and metabolic monitoring strategies utilized for protocol and for cause following pancreas and islet transplantation. In the absence of any formal studies to assess the efficacy of immunologic and metabolic testing to detect early allograft dysfunction, it can serve as a guidance document for developing monitoring algorithms following beta-cell replacement.

The Presence of Donor-specific Antibodies Around the Time of Pancreas Graft Biopsy With Rejection Is Associated With an Increased Risk of Graft Failure

BACKGROUND

Donor-specific antibodies (DSA) against HLA are an important biomarker predicting graft injury, rejection (Rej), and failure in various solid-organ transplant recipients. However, the impact of DSA with or without histopathological evidence of rejection among pancreas transplant recipients (PTRs) is unknown.

METHODS

In this study, we included all PTRs at our center between 2005 and 2020, with pancreas allograft biopsy before March 31, 2021, and with DSA checked within 15 d of the biopsy. PTRs were divided into 4 groups based on the biopsy findings on the index biopsy and DSA status as Rej-/DSA-, Rej+/DSA-, Rej-/DSA+, and Rej+/DSA+.

RESULTS

Two hundred two PTRs had a pancreas allograft biopsy during the study period. Thirty-nine were in Rej-/DSA-, 84 Rej+/DSA-, 24 Rej-/DSA+, and 55 Rej+/DSA+. The mean interval from transplant to index biopsy was not statistically different between the 4 groups. The most common type of rejection was T cell-mediated rejection; however, antibody-mediated rejection was more prevalent in the Rej+/DSA+ group. At 5 y postbiopsy, the rate of death-censored graft failure (DCGF) for Rej-/DSA- was 18%, 24% in Rej+/DSA-; 17% in Rej-/DSA+ and 36% in Rej+/DSA+ (P = 0.14). In univariate analysis, mixed rejection (hazard ratio [HR], 3.0; 95% confidence intervals [CI], 1.22-7.39; P = 0.02) along with solitary pancreas transplantation and Rej+/DSA+ were associated with DCGF. In multivariate analysis, compared with Rej-/DSA-, Rej+/DSA+ was significantly associated with DCGF (HR, 2.32; 95% CI, 1.03-5.20; P = 0.04); however, Rej+/DSA- was not (HR, 1.06; 95% CI, 0.32-3.56; P = 0.92).

CONCLUSIONS

PTRs with pancreas allograft rejection and concomitant DSA have an increased risk of DCGF.

Association of human leukocyte antigen mismatches between donor-recipient and donor-donor in pancreas after kidney transplant recipients

The effects of HLA mismatching on pancreas outcomes among pancreas after kidney (PAK) recipients are undefined. Outcomes might potentially differ depending on whether there is a mismatch between pancreas donor and recipient (PD-R) or pancreas donor and kidney donor(PD-KD). All primary PAK at our centre were included in this study. Patients were divided into two groups based on the degree of HLA mismatching: low (L-MM) as 0-4 and high (H-MM) as 5-6. We analysed all (N = 73) PAK for PD-R mismatch and the subset of PAK for PD-KD mismatch (N = 71). Comparing PD-R L-MM (n = 39) and H-MM (n = 34) PAKs, we observed no difference in the rate of pancreas graft failure. There was also no difference in the rate of rejection (L-MM 33% vs. H-MM 41%) or the severity of rejection. However, we observed a significantly (P < 0.01) shorter time to acute pancreas rejection in the H-MM group (6.8 ± 8.7 mo) versus the L-MM cohort (29.0 ± 36.2 mo) (P < 0.001). Similar to the PD-R mismatched cohort, we did not observe a detrimental effect of HLA mismatching on graft outcomes in the PD-KD cohort; time to rejection was again shorter in the H-MM subset. In this study, we found no impact of HLA mismatch on either pancreas graft survival or rejection rates, though rejection occurred earlier in high mismatched PAK transplants.

First World Consensus Conference on pancreas transplantation: Part II - recommendations

The First World Consensus Conference on Pancreas Transplantation provided 49 jury deliberations regarding the impact of pancreas transplantation on the treatment of diabetic patients, and 110 experts' recommendations for the practice of pancreas transplantation. The main message from this consensus conference is that both simultaneous pancreas-kidney transplantation (SPK) and pancreas transplantation alone can improve long-term patient survival, and all types of pancreas transplantation dramatically improve the quality of life of recipients. Pancreas transplantation may also improve the course of chronic complications of diabetes, depending on their severity. Therefore, the advantages of pancreas transplantation appear to clearly surpass potential disadvantages. Pancreas after kidney transplantation increases the risk of mortality only in the early period after transplantation, but is associated with improved life expectancy thereafter. Additionally, preemptive SPK, when compared to SPK performed in patients undergoing dialysis, appears to be associated with improved outcomes. Time on dialysis has negative prognostic implications in SPK recipients. Increased long-term survival, improvement in the course of diabetic complications, and amelioration of quality of life justify preferential allocation of kidney grafts to SPK recipients. Audience discussions and live voting are available online at the following URL address: http://mediaeventi.unipi.it/category/1st-world-consensus-conference-of-pancreas-transplantation/246.

Alloimmunity in pancreas transplantation

PURPOSE OF REVIEW

Despite significant improvement in pancreas allograft survival, rejection continues to be a major clinical problem. This review will focus on emerging literature related to the impact of pretransplant and de-novo DSA (dnDSA) in pancreas transplant recipients, and the diagnosis and treatment of T-cell-medicated rejection (TCMR) and antibody-mediated rejection (ABMR) in this complex group of patients.

RECENT FINDINGS

Recent data suggest that pretransplant DSA and the emergence of dnDSA in pancreas transplant recipients are both associated with increased risk of ABMR. The pancreas allograft biopsy is essential for the specific diagnosis of TCMR and/or ABMR, distinguish rejection from other causes of graft dysfunction, and to guide-targeted therapy. This distinction is important especially in the setting of solitary pancreas transplants but also in simultaneous pancreas-kidney transplants where solid evidence has now emerged demonstrating discordant biopsy findings. Treatment of rejection in a functioning pancreas can prolong allograft survival.

SUMMARY

The accurate and timely diagnosis of active alloimmune destruction in pancreas transplant recipients is paramount to preserving graft function in the long term. This review will discuss new, rapidly evolving information that is valuable for the physician caring for these patients to achieve optimal immunological outcomes.

Enteric Conversion of Bladder-drained Pancreas as a Predictor of Outcomes in Almost 600 Recipients at a Single Center

Complications associated with bladder-drained pancreata necessitating enteric conversion are common. Data on the outcomes after enteric conversion are conflicting. We studied the association between enteric conversion and the pancreas graft rejection, loss, and mortality.

Methods

At our center, 1117 pancreas transplants were performed between 2000 and 2016. We analyzed 593 recipients with bladder-drained pancreata, of which 523 received solitary transplants and 70 received simultaneous pancreas-kidney transplants. Kaplan-Meier function was used to estimate time to conversion by transplant type. Cox proportional hazards models were utilized to evaluate patient survival, death-censored graft survival, and acute rejection-free survival while treating conversion as a time-dependent covariate. Subsequently, we examined the association between timing of conversion and the same outcomes in the conversion cohort.

Results

At 10 y posttransplant, 48.8% of the solitary pancreas recipients and 44.3% of simultaneous pancreas-kidney transplant recipients had undergone enteric conversion. The enteric conversion was associated with 85% increased risk of acute rejection (hazard ratio [HR] = 1.85; 95% confidence interval [CI] = 1.37-2.49; P < 0.001). However, the conversion was not associated with graft loss or mortality. In the conversion cohort, a longer interval from engraftment to conversion was associated with an 18% lower rejection rate (HR = 0.82; 95% CI = 0.708-0.960; P = 0.013) and a 22% better graft survival (HR = 0.78; 95% CI = 0.646-0.946; P = 0.01).

Conclusions

Enteric conversion was associated with increased risk of rejection, but not increased risks of graft loss or mortality. The decision to convert should consider the increased rejection risk. A longer interval from engraftment to conversion appears favorable.

Incidence and Outcomes of Significant Weight Changes After Pancreas Transplant Alone

Background.

Weight change, primarily weight gain, is a common problem among solid organ transplant recipients. The incidence of weight gain or loss after successful pancreas transplant alone (PTA) and the effect on graft survival is unknown.

Methods.

This was a single-center observational study among PTA recipients, transplanted at our center between January 1, 2005, and July 31, 2017, who had a functional pancreas graft for at least 1 year and documented weight change at the 1-year clinic visit.

Results.

In this cohort study of 105 PTA recipients, 28 had significant weight gain, 27 had significant weight loss, and the remaining 50 did not have significant weight change at 1-year posttransplant. When comparing the weight gain and no weight change groups, the weight gain cohort started to gain weight at 3 months posttransplant to 5 years or last follow up. Similarly, the weight loss group lost weight at 3 months posttransplant up to last follow up. Clinically significant weight gain or weight loss were not associated with uncensored or death censored graft failure in univariate regression and Kaplan-Meier survival analysis. Also, there were no significant differences between the groups in the glycated hemoglobin at last follow up.

Conclusions.

Approximately 50% of PTA recipients had a significant weight change at 1-year posttransplant, of which 25% gained significant weight and 25% loss. There was no significant difference in graft survival due to the significant weight changes. Further research is needed in this field.