Solitary pancreas transplants: a new era

Islet transplantation in type 1 diabetics using an immunosuppressive protocol based on the anti-LFA-1 antibody efalizumab

The applicability of islet transplantation as treatment for type 1 diabetes is limited by renal and islet toxicities of currently available immunosuppressants. We describe a novel immunosuppressive regimen using the antileukocyte functional antigen-1 antibody efalizumab which permits long-term islet allograft survival while reducing the need for corticosteroids and calcineurin inhibitors (CNI). Eight patients with type 1 diabetes and hypoglycemic unawareness received intraportal allogeneic islet transplants. Immunosuppression consisted of antithymocyte globulin induction followed by maintenance with efalizumab and sirolimus or mycophenolate. When efalizumab was withdrawn from the market in mid 2009, all patients were transitioned to regimens consisting of mycophenolate and sirolimus or mycophenolate and tacrolimus. All patients achieved insulin independence and four out of eight patients became independent after single-islet transplants. Insulin independent patients had no further hypoglycemic events, hemoglobin A1c levels decreased and renal function remained stable. Efalizumab was well tolerated and no serious adverse events were encountered. Although long-term follow-up is limited by discontinuation of efalizumab and transition to conventional imunnosuppression (including CNI in four cases), these results demonstrate that insulin independence after islet transplantation can be achieved with a CNI and steroid-free regimen. Such an approach may minimize renal and islet toxicity and thus further improve long-term islet allograft survival.

Beta-cell replacement for type I diabetes

The ability to achieve insulin independence with either solid-organ pancreas or islet transplantation has increased the number of patients seeking beta-cell replacement as an alternative to insulin therapy. Despite dramatic improvements in the ability to achieve insulin independence following solid-organ pancreas transplantation, the secondary complications of long-standing diabetes are frequently irreversible by the time surgical intervention is justified based on the risk of this procedure. Pancreatic islet transplantation provides a safer and less invasive alternative for beta-cell replacement that could be justified earlier in the course of diabetes to prevent the development of secondary complications. Recent advances in the technology of islet isolation, as well as the ability to prevent the alloimmune and recurrent autoimmune response following islet transplantation with immunosuppressive regimens that are not toxic to beta cells, have rekindled an interest in this field. Widespread application of islet transplantation will depend on further improvements in selective immunosuppression, development of immunologic tolerance, and finding new sources of beta cells.

Chronic rejection: the next major challenge for pancreas transplant recipients

OBJECTIVE

With newer immunosuppressive agents, acute rejection and graft loss resulting from acute rejection have become less common for pancreas transplant recipients. As long-term graft survival rates have improved, an increasing number of grafts are being lost to chronic rejection (CR). We studied the incidence of CR and identified risk factors.

METHODS

We retrospectively analyzed all cadaver pancreas transplants performed at the University of Minnesota between June 19, 1994, and December 31, 2002. We determined the causes of graft loss, the incidence of graft loss to CR and, using multivariate techniques, the major risk factors for CR.

RESULTS

A total of 914 cadaver pancreas transplants were performed in the following three categories: simultaneous pancreas-kidney (SPK) (n=321), pancreas after kidney (PAK) (n=389), and pancreas transplant alone (PTA) (n=204). The mean recipient age was 41.3 years and the mean donor age was 30.1 years. Of the 914 pancreas grafts, 643 (70.3%) continue to function (mean length of follow-up, 39 months). The most common cause of graft loss was technical failure, accounting for 118 (12.9%) of the failed grafts. The second most common cause was CR, accounting for 80 (8.8%) of the failed grafts. The incidence of graft loss to CR was highest for PTA (n=23 [11.3%]) and PAK (n=45 [11.6%]) recipients and lowest for SPK recipients (n=12 [3.7%]) (P=0.002). By multivariate analysis, the most significant risk factors for graft loss to CR were a previous episode of acute rejection (relative risk [RR]=4.41, P<0.0001), an isolated (vs. simultaneous) transplant (PAK or PTA [vs. SPK], RR=3.02, P=0.002), cytomegalovirus infection posttransplant (RR=2.41, P=0.001), a retransplant (versus primary transplant) (RR=2.27, P=0.004), and one or two (vs. zero) antigen mismatches at the B loci (RR=1.68, P=0.04).

CONCLUSIONS

As short-term pancreas transplant results improve and as isolated (PAK or PTA) pancreas transplants gain in popularity, CR will become increasingly common as a cause of pancreas graft loss.

Improving results in solitary pancreas transplantation with portal-enteric drainage, thymoglobin induction, and tacrolimus/mycophenolate mofetil-based immunosuppression

Advances in surgical techniques and clinical immunosuppression have led to steadily improving results in pancreas transplantation (PTX). The purpose of this study was to analyze retrospectively the outcomes in patients undergoing solitary PTX with portal-enteric (P-E) drainage and contemporary immunosuppression. From June 1998 through December 2000, we performed 28 solitary PTXs with antibody induction and tacrolimus/mycophenolate mofetil maintenance therapy. The first 13 patients received daclizumab (DAC) induction, while the next 15 received thymoglobulin (rabbit anti-human thymocyte gamma globulin; Thymo) induction. The study group included 13 pancreas alone (PA) and 15 sequential pancreas-after-kidney-transplantations (PAKT). Solitary PTX was performed with P-E drainage in 18 patients and systemic-enteric (S-E) drainage in ten. Patient and pancreas graft survival rates were 96% and 79%, respectively, with a mean follow-up of 22 (range 1-39) months. The 1-year actual death-censored pancreas graft survival rate was 89%. One PAKT patient died with a functioning graft at 1 month; three patients (11%) experienced early graft loss due to thrombosis and were excluded from the immunological analysis, leaving 24 evaluable patients. The incidence of acute rejection was 54%, including 50% in PA and 58% in PAKT recipients ( P=NS). In patients receiving Thymo induction, the rate of acute rejection was slightly lower (43% Thymo vs 70% DAC). Moreover, P-E drainage was associated with a slightly lower rate of acute rejection (44% P-E vs 75% S-E; P=NS). In patients with both Thymo induction and P-E drainage ( n=11), there was a tendency toward less rejection (the incidence of acute rejection was 36%). Two immunological graft losses occurred (one due to non-compliance), both in patients with P-E drainage. Only one patient had a cytomegalovirus (CMV) infection. Event-free survival (no rejection, graft loss, or death) was slightly higher in patients receiving Thymo (47%) than in those on DAC (23%) induction ( P=NS). We can conclude that solitary PTX with P-E drainage and Thymo induction may be associated with improved intermediate-term outcomes and a possible immunological advantage.

Reduced dose Thymoglobulin, tacrolimus, and mofetil mycophenolate results in excellent solitary pancreas transplantation outcomes

BACKGROUND

Graft survival following solitary pancreas transplantation has traditionally lagged behind that of simultaneous pancreas-kidney transplants. Thymoglobulin (TMG), a polyclonal rabbit-derived antilymphocyte antibody was originally introduced as treatment for acute rejection of renal allografts. However, data regarding the efficacy of TMG induction in solitary pancreas transplants is lacking. We present the 1-yr graft survival and acute rejection rate of 22 solitary pancreas transplants performed at the McGill University Health Centre using reduced dose TMG induction with lower dose tacrolimus and mophetil mycophenolate.

PATIENTS AND METHODS

Eighteen pancreas after kidney and four pancreas transplants alone were performed between January 1998 and October 2000 at McGill University. Induction therapy with TMG at a starting dose of 1.5 mg/kg/d was started 12 h post-operatively. The daily dose of TMG was held if the total leukocyte count was <2,500/mm3 or if the lymphocyte count was <100/mm3. Maintenance therapy was initiated with steroids (tapered to 20 mg prednisone orally once a day) tacrolimus (2 mg twice a day), and mofetil mycophenolate (1 g daily).

RESULTS

Patients received three to seven doses of TMG over the first seven post-operative days at a dose of 0.85 +/- 0.27 mg/kg/d (mean +/- SD). The mean follow-up was 1.28 +/- 0.14 yr. The 1-yr patient and graft survival was 100% (22 of 22) and 96% (21 of 22), respectively. The 1 yr acute rejection rate was 27.3% (six of 22). Five of the six rejections responded to steroid boluses. One was refractory to steroids and TMG resulting in graft loss. Presumed rejections were diagnosed on the basis of decreasing urine amylase and/or hyperglycemia.

DISCUSSION

Monitoring the total leukocyte and lymphocyte count resulted in a 43% reduction in the amount of TMG used compared with the recommended dosing. Despite the reduced amounts, patient and graft survival were excellent with acute rejection rates comparing favorably to other published series.

Lessons learned from more than 1,000 pancreas transplants at a single institution

OBJECTIVE

To determine outcome in diabetic pancreas transplant recipients according to risk factors and the surgical techniques and immunosuppressive protocols that evolved during a 33-year period at a single institution.

SUMMARY BACKGROUND DATA

Insulin-dependent diabetes mellitus is associated with a high incidence of management problems and secondary complications. Clinical pancreas transplantation began at the University of Minnesota in 1966, initially with a high failure rate, but outcome improved in parallel with other organ transplants. The authors retrospectively analyzed the factors associated with the increased success rate of pancreas transplants.

METHODS

From December 16, 1966, to March 31, 2000, the authors performed 1,194 pancreas transplants (111 from living donors; 191 retransplants): 498 simultaneous pancreas-kidney (SPK) and 1 simultaneous pancreas-liver transplant; 404 pancreas after kidney (PAK) transplants; and 291 pancreas transplants alone (PTA). The analyses were divided into five eras: era 0, 1966 to 1973 (n = 14), historical; era 1, 1978 to 1986 (n = 148), transition to cyclosporine for immunosuppression, multiple duct management techniques, and only solitary (PAK and PTA) transplants; era 2, 1986 to 1994 (n = 461), all categories (SPK, PAK, and PTA), predominantly bladder drainage for graft duct management, and primarily triple therapy (cyclosporine, azathioprine, and prednisone) for maintenance immunosuppression; era 3, 1994 to 1998 (n = 286), tacrolimus and mycophenolate mofetil used; and era 4, 1998 to 2000 (n = 275), use of daclizumab for induction immunosuppression, primarily enteric drainage for SPK transplants, pretransplant immunosuppression in candidates awaiting PTA.

RESULTS

Patient and primary cadaver pancreas graft functional (insulin-independence) survival rates at 1 year by category and era were as follows: SPK, era 2 (n = 214) versus eras 3 and 4 combined (n = 212), 85% and 64% versus 92% and 79%, respectively; PAK, era 1 (n = 36) versus 2 (n = 61) versus 3 (n = 84) versus 4 (n = 92), 86% and 17%, 98% and 59%, 98% and 76%, and 98% and 81%, respectively; in PTA, era 1 (n = 36) versus 2 (n = 72) versus 3 (n = 30) versus 4 (n = 40), 77% and 31%, 99% and 50%, 90% and 67%, and 100% and 88%, respectively. In eras 3 and 4 combined for primary cadaver SPK transplants, pancreas graft survival rates were significantly higher with bladder drainage (n = 136) than enteric drainage (n = 70), 82% versus 74% at 1 year (P =.03). Increasing recipient age had an adverse effect on outcome only in SPK recipients. Vascular disease was common (in eras 3 and 4, 27% of SPK recipients had a pretransplant myocardial infarction and 40% had a coronary artery bypass); those with no vascular disease had significantly higher patient and graft survival rates in the SPK and PAK categories. Living donor segmental pancreas transplants were associated with higher technically successful graft survival rates in each era, predominately solitary (PAK and PTA) in eras 1 and 2 and SPK in eras 3 and 4. Diabetic secondary complications were ameliorated in some recipients, and quality of life studies showed significant gains after the transplant in all recipient categories.

CONCLUSIONS

Patient and graft survival rates have significantly improved over time as surgical techniques and immunosuppressive protocols have evolved. Eventually, islet transplants will replace pancreas transplants for suitable candidates, but currently pancreas transplants can be applied and should be an option at all stages of diabetes. Early transplants are preferable for labile diabetes, but even patients with advanced complications can benefit.

Simultaneous cadaver pancreas living-donor kidney transplantation: a new approach for the type 1 diabetic uremic patient

OBJECTIVE

To review the authors' experience with a new approach for type I diabetic uremic patients: simultaneous cadaver-donor pancreas and living-donor kidney transplant (SPLK).

SUMMARY BACKGROUND DATA

Simultaneous cadaver kidney and pancreas transplantation (SPK) and living-donor kidney transplantation alone followed by a solitary cadaver-donor pancreas transplant (PAK) have been the transplant options for type I diabetic uremic patients. SPK pancreas graft survival has historically exceeded that of solitary pancreas transplantation. Recent improvement in solitary pancreas transplant survival rates has narrowed the advantage seen with SPK. PAK, however, requires sequential transplant operations. In contrast to PAK and SPK, SPLK is a single operation that offers the potential benefits of living kidney donation: shorter waiting time, expansion of the organ donor pool, and improved short-term and long-term renal graft function.

METHODS

Between May 1998 and September 1999, the authors performed 30 SPLK procedures, coordinating the cadaver pancreas transplant with simultaneous transplantation of a laparoscopically removed living-donor kidney. Of the 30 SPLKs, 28 (93%) were portally and enterically drained. During the same period, the authors also performed 19 primary SPK and 17 primary PAK transplants.

RESULTS

One-year pancreas, kidney, and patient survival rates were 88%, 95%, and 95% for SPLK recipients. One-year pancreas graft survival rates in SPK and PAK recipients were 84% and 71%. Of 30 SPLK transplants, 29 (97%) had immediate renal graft function, whereas 79% of SPK kidneys had immediate function. Reoperative rates, early readmission to the hospital, and initial length of stay were similar between SPLK and SPK recipients. SPLK recipients had a shorter wait time for transplantation.

CONCLUSIONS

Early pancreas, kidney, and patient survival rates after SPLK are similar to those for SPK. Waiting time was significantly shortened. SPLK recipients had lower rates of delayed renal graft function than SPK recipients. Combining cadaver pancreas transplantation with living-donor kidney transplantation does not harm renal graft outcome. Given the advantages of living-donor kidney transplant, SPLK should be considered for all uremic type I diabetic patients with living donors.

Initial results of solitary pancreas transplants performed without regard to donor/recipient HLA mismatching

BACKGROUND

We hypothesized that solitary pancreas transplants could be performed successfully even in the presence of poor HLA matching if an aggressive approach were taken with regard to immunosuppressive protocol and the performance of allograft biopsy.

METHODS

Seven pancreas-after-kidney transplants and seven pancreas transplants alone were performed without consideration given to the degree of HLA mismatching (MM) using tacrolimus (FK506)/mycophenolate mofetil (MMF)/prednisone maintenance therapy. Mean (+/-SD) total HLA MM was 4.8+/-1.2. All patients were followed for at least 6 months. The first four cases were induced with ATGAM for 7 to 10 days. In the remaining 10 cases, an ultrasound-guided percutaneous needle biopsy was attempted on a protocol basis 10 days after completing induction with OKT3 for 7 (n=2) or 14 (n=8) days.

RESULTS

Overall patient survival, graft survival, and incidence of acute rejection requiring treatment were 86, 79, and 50%, respectively. Two patients receiving ATGAM developed grade III-IV rejection at 3 weeks. Both patients receiving OKT3 for 7 days developed early grade III rejection. However, only three of eight patients receiving OKT3 for 14 days developed rejection requiring treatment. Protocol biopsy was successfully performed in six of seven patients and uncovered three cases of otherwise undetectable grade III-IV rejection.

CONCLUSIONS

Although based on a small number of cases, our results suggest that solitary pancreas transplants with a poor HLA match can be performed with an acceptable rejection incidence and graft survival rate using an OKT3/FK506/MMF/prednisone regimen with protocol biopsy.

Vascularized pancreas allotransplantation--clinical indications and outcome

AIMS

This review examines the status of vascularized pancreas transplantation as a treatment for Type 1 diabetes mellitus (DM).

METHODS

The world literature, with a particular emphasis on data from the International Pancreas Transplant Registry (IPTR), is reviewed and interpreted particularly for clinical indications and outcome.

RESULTS

Over 9000 cases of vascularized pancreas transplant (VPT) have been registered, with insulin dependence approaching 82% at 1 year with 94% patient survival. The majority of transplants are simultaneous pancreas and kidney (SPK) transplants, with far fewer pancreas after kidney (PAK) or pancreas transplants alone (PTA). The success rates differ between the procedures but are generally improving as technical advances, improvements in immunosupression and greater experience are gained. The most obvious advantage is an improved quality of life (QoL) but there are risks associated with the procedure and with the immunosuppression. There is some evidence coming to light of a very slow beneficial effect on microvascular complications.

CONCLUSIONS

VPT is an attractive option to offer Type 1 DM patients who need or already have a renal allograft. Patients have to decide between the increased surgical risk and the risks of long-term immunosuppression and the benefits of improved QoL. In the absense of end-stage renal failure (ESRF) there is no justification for PTA, except where the diabetes itself poses a greater risk to life than the transplantation procedure.