Simultaneous pancreas-kidney transplantation: analysis of rejection

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.

Impact of Early Pancreatic Graft Loss on Outcome after Simultaneous Pancreas-Kidney Transplantation (SPKT)-A Landmark Analysis

(1) Background: Simultaneous pancreas-kidney transplantation (SPKT) is a standard therapeutic option for patients with diabetes mellitus type I and kidney failure. Early pancreas allograft failure is a complication potentially associated with worse outcomes. (2) Methods: We performed a landmark analysis to assess the impact of early pancreas graft loss within 3 months on mortality and kidney graft survival over 10 years. This retrospective single-center study included 114 adult patients who underwent an SPKT between 2005 and 2018. (3) Results: Pancreas graft survival rate was 85.1% at 3 months. The main causes of early pancreas graft loss were thrombosis (6.1%), necrosis (2.6%), and pancreatitis (2.6%). Early pancreas graft loss was not associated with reduced patient survival (p = 0.168) or major adverse cerebral or cardiovascular events over 10 years (p = 0.741) compared to patients with functioning pancreas, after 3 months. Moreover, kidney graft function (p = 0.494) and survival (p = 0.461) were not significantly influenced by early pancreas graft loss. (4) Conclusion: In this study, using the landmark analysis technique, early pancreas graft loss within 3 months did not significantly impact patient or kidney graft survival over 10 years.

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.

How Should Pancreas Transplant Rejection Be Treated?

BACKGROUND

Limited published data exist to guide the treatment of pancreas transplant rejection.

METHODS

We reviewed the treatment and outcomes of 158 first episodes of biopsy-proven pancreas rejection between 1 January 1997 and 31 December 2016. Within each Banff grade of rejection, we compared response rates and long-term outcomes with steroids alone versus steroids plus antithymocyte globulin (ATG).

RESULTS

Of 158 pancreas recipients with rejection, 65 were treated with steroids alone. Eighty-three percent of patients with grade I, 60% with grade II, and 33.33% with grade III rejection responded to treatment with steroids alone. Ninety-three patients were treated with steroids plus ATG. The response rates were 69% in grade I, 76% in grade II, and 73% in grade III. Response rates and graft survival were not different with grade I rejection treated with steroids alone versus steroids plus ATG. However, response rates and graft survival were significantly better with grade III rejection treated with the addition of ATG, and graft survival rates were significantly better with grade II rejection treated with the addition of ATG.

CONCLUSIONS

Grade I pancreas rejection can usually be successfully treated with steroids alone, whereas grade II and III rejection should usually be treated with steroids plus ATG, as the addition of ATG improves both response rates and graft survival.

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.

Steroid avoidance or withdrawal for pancreas and pancreas with kidney transplant recipients

BACKGROUND

Pancreas or kidney-pancreas transplantation improves survival and quality of life for people with type 1 diabetes mellitus and kidney failure. Immunosuppression after transplantation is associated with complications. Steroids have adverse effects on cardiovascular risk factors such as hypertension, hyperglycaemia or hyperlipidaemia, increase risk of infection, obesity, cataracts, myopathy, bone metabolism alterations, dermatologic problems and cushingoid appearance. Whether avoiding steroids changes outcomes is unclear.

OBJECTIVES

We aimed to assess the safety and efficacy of steroid early withdrawal (treatment for less than 14 days after transplantation), late withdrawal (after 14 days after transplantation) or steroid avoidance in patients receiving a pancreas (including a vascularized organ) alone (PTA), simultaneous with a kidney (SPK) or after kidney transplantation (PAK).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (to 18 June 2014) through contact with the Trials' Search Co-ordinator. We handsearched: reference lists of nephrology textbooks, relevant studies, recent publications and clinical practice guidelines; abstracts from international transplantation society scientific meetings; and sent emails and letters seeking information about unpublished or incomplete studies to known investigators.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or cohort studies of steroid avoidance (including early withdrawal) versus steroid maintenance or versus late withdrawal in pancreas or pancreas with kidney transplant recipients. We defined steroid avoidance as complete avoidance of steroid immunosuppression, early steroid withdrawal as steroid treatment for less than 14 days after transplantation and late withdrawal as steroid withdrawal after 14 days after transplantation.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the retrieved titles and abstracts, and where necessary the full text reports to determine which studies satisfied the inclusion criteria. Authors of included studies were contacted to obtain missing information. Statistical analyses were performed using random effects models and results expressed as risk ratio (RR) or mean difference (MD) with 95% confidence interval (CI). Cohort studies were not meta-analysed, but their findings summarised descriptively.

MAIN RESULTS

Three RCTs enrolling 144 participants met our inclusion criteria. Two compared steroid avoidance versus late steroid withdrawal and one compared late steroid withdrawal versus steroid maintenance. All studies included SPK and only one also included PTA. All studies had an overall moderate risk of bias and presented only short-term results (six to 12 months). Two studies (89 participants) compared steroid avoidance or early steroid withdrawal versus late steroid withdrawal. There was no clear evidence of an impact on mortality (2 studies, 89 participants: RR 1.64, 95% CI 0.21 to 12.75), risk of kidney loss censored for death (2 studies, 89 participants: RR 0.35, 95% CI 0.04 to 3.09), risk of pancreas loss censored for death (2 studies, 89 participants: RR 1.05, 95% CI 0.36 to 3.04), or acute kidney rejection (1 study, 49 participants: RR 2.08, 95% CI 0.20 to 21.50), however results were uncertain and consistent with no difference or important benefit or harm of steroid avoidance/early steroid withdrawal. The study that compared late steroid withdrawal versus steroid maintenance observed no deaths, no graft loss or acute kidney rejection at six months in either group and reported uncertain effects on acute pancreas rejection (RR 0.88, 95% CI 0.06 to 13.35). Of the possible adverse effects only infection was reported by one study. There were significantly more UTIs reported in the late withdrawal group compared to the steroid avoidance group (1 study, 25 patients: RR 0.41, 95% CI 0.26 to 0.66).We also identified 13 cohort studies and one RCT which randomised tacrolimus versus cyclosporin. These studies in general showed that steroid-sparing and withdrawal strategies had benefits in lowering HbAc1 and risk of infections (BK virus and CMV disease) and improved blood pressure control without increasing the risk of rejection. However, two studies found an increased incidence of acute pancreas rejection (HR 2.8, 95% CI 0.89 to 8.81, P = 0.066 in one study and 43.3% in the steroid withdrawal group versus 9.3% in the steroid maintenance, P < 0.05 at three years in the other) and one study found an increased incidence of acute kidney rejection (18.7% in the steroid withdrawal group versus 2.8% in the steroid maintenance, P < 0.05) at three years.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence for the benefits and harms of steroid withdrawal in pancreas transplantation in the three RCTs (144 patients) identified. The results showed uncertain results for short-term risk of rejection, mortality, or graft survival in steroid-sparing strategies in a very small number of patients over a short period of follow-up. Overall the data was sparse, so no firm conclusions are possible. Moreover, the 13 observational studies findings generally concur with the evidence found in the RCTs.

Microvascular damage in type 1 diabetic patients is reversed in the first year after simultaneous pancreas-kidney transplantation

Simultaneous pancreas-kidney transplantation (SPK) is an advanced treatment option for type 1 diabetes mellitus (DM) patients with microvascular disease including nephropathy. Sidestreamdarkfield (SDF) imaging has emerged as a noninvasive tool to visualize the human microcirculation. This study assessed the effect of SPK in diabetic nephropathy (DN) patients on microvascular alterations using SDF and correlated this with markers for endothelial dysfunction. Microvascular morphology was visualized using SDF of the oral mucosa in DN (n = 26) and SPK patients (n = 38), healthy controls (n = 20), DM1 patients (n = 15, DM ≥ 40 mL/min) and DN patients with a kidney transplant (KTx, n = 15). Furthermore, 21 DN patients were studied longitudinally up to 12 months after SPK. Circulating levels of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2) and soluble thrombomodulin (sTM) were measured using ELISA. Capillary tortuosity in the DN (1.83 ± 0.42) and DM ≥ 40 mL/min (1.55 ± 0.1) group was increased and showed reversal after SPK (1.31 ± 0.3, p < 0.001), but not after KTx (1.64 ± 0.1). sTM levels were increased in DN patients and reduced in SPK and KTx recipients (p < 0.05), while the Ang-2/Ang-1 ratio was normalized after SPK and not after KTx alone (from 0.16 ± 0.04 to 0.08 ± 0.02, p < 0.05). Interestingly, in the longitudinal study, reversal of capillary tortuosity and decrease in Ang-2/Ang-1 ratio and sTM was observed within 12 months after SPK. SPK is effective in reversing the systemic microvascular structural abnormalities in DN patients in the first year after transplantation.

Acute pancreas allograft rejection is associated with increased risk of graft failure in pancreas transplantation

The effect of acute allograft rejection (AR) on long-term pancreas allograft function is unclear. We retrospectively studied 227 consecutive pancreas transplants performed at our institution between January 1, 998 and December 31, 2009 including: 56 simultaneous pancreas and kidney (SPK), 69 pancreas transplantation alone (PTA); and 102 pancreas after kidney (PAK) transplants. With a median follow-up of 6.1 (IQR 3-9) years, 57 patients developed 79 episodes of AR, and 19 experienced more than one episode. The cumulative incidence for AR was 14.7%, 19.7%, 26.6% and 29.1% at 1, 2, 5 and 10 years. PTA transplant (hazards ratio [HR]=2.28, p=0.001) and donor age (per 10 years) (HR=1.34, p=0.006) were associated with higher risk for AR. The first AR episode after 3 months post PT was associated with increased risk for complete loss (CL) (HR 3.79, p<0.001), and the first AR episode occurring during 3- to 12-month and 12- to 24-month periods after PT were associated with significantly increased risk for at least partial loss (PL) (HR 2.84, p=0.014; and HR 6.25, p<0.001, respectively). We conclude that AR is associated with increased risk for CL and at least PL. The time that the first AR is observed may influence subsequent graft failure.

Minimization and withdrawal of steroids in pancreas and islet transplantation

For reducing the corticosteroid (CS)-related side-effects, especially cardiovascular events, CS-sparing protocols have become increasingly common in pancreas transplantation (PT). Lympho-depleting induction antibodies, such as rabbit anti-thymocyte globulin (rATG) or alemtuzumab, have been widely used in successful trials. The results of various CS-sparing protocols combining calcineurin inhibitors (CNI) and mycophenolate or sirolimus, have been mixed for rejection and survival rates. Most of the studies were uncontrolled trials of low-risk patients, therefore the grade of evidence is limited. Large-scale prospective studies with long-term follow up are necessary to assess risks and benefits of CS-sparing regimens in PT before recommending such strategies as standard practice. Islet allo-transplantation for patients with brittle type 1 diabetes mellitus, less invasive and safer procedure than PT, has been attempted since late 1980s, but diabetogenic immunosuppressants at maintenance, mainly CS and high-dose CNI, prevented satisfactory results (10% insulin-independence at 1-year post-transplant). Since 2000, CS-free and CNI-reducing protocols, including more potent induction [daclizumab, OKT3gamma1(ala-ala) anti-CD3 antibody, rATG] and maintenance (sirolimus, mycophenolate) agents, have significantly improved short-term outcomes whereas long-term are still inadequate (from 80% to 20% insulin-independence from 1- to 5-year post-transplant). Main limitations are allo- and autoimmunity, immunosuppression-related islet and systemic toxicity and transplant site unsuitability, which tolerogenic protocols and biotechnological solutions may solve.

What happens to the kidney in an SPK transplant when the pancreas fails due to a technical complication?

We examined a group of SPK recipients that had early (<90 d post-transplant) pancreas graft failure caused by a technical complication, and looked at outcomes of the kidney graft in these recipients. Of 289 SPK transplants, 36 (12.5%) had early pancreas graft failure because of a technical complication: thrombosis (n = 16), leak (n = 5), infection (n = 14), and pancreatitis (n = 1). Once the pancreas was lost, there was a high incidence of subsequent kidney graft failure. Kidney graft survival in these 36 recipients was 71.4% at one yr and 59.5% at three yr, significantly inferior compared to recipients that did not have early failure of the pancreas (86% at one yr and 82% at three yr, p < 0.001). Of the 36 recipients with early pancreas loss, 18 have gone on to failure of the kidney graft. Causes included thrombosis (n = 3), infection (n = 1), death with function (n = 6), chronic rejection (n = 4), ischemia (n = 1), and other (n = 3). Of the 18 kidney graft failures, nine occurred within three months after loss of the pancreas graft, usually either because of graft thrombosis, or patient death (usually from systemic sepsis). Multivariate analysis showed technical failure of the pancreas to be the most significant risk factor for kidney graft loss (HR = 2.08, p = 0.006).