Immunologic risks of combined kidney-pancreas transplantation

Successful long-term kidney-pancreas transplants regardless of C-peptide status or race

BACKGROUND

We have previously shown that our patient population of 60% minority races has end-stage renal disease primarily as a result of diabetes mellitus and hypertension. It therefore was logical to explore the restoration of normal insulin production and renal function by simultaneous pancreas-kidney (SPK) transplantation, without regard to race. This study represents new analyses integrating race with C-peptide status and reports the outcome of 136 SPK transplantations performed over the last 10 years.

RESULTS

Of the 49 African-Americans with diabetes mellitus and end-stage renal disease, 60% were type I and 40% were type II, based on C-peptide levels. In comparison, only 16% of Caucasians were type II. The average age at onset of diabetes mellitus was 15.7 years for type I compared with 20.7 years for type II (P>0.05). The actuarial 10-year survival rates for the 136 SPKs were 91.79% (patient), 85.07% (pancreas), and 83.58% (kidney). The type I and type II survival rates were similar in the two diabetic groups.

CONCLUSIONS

The data strongly suggest that pretransplant C-peptide status does not influence the outcome of SPK transplantation in patients with renal failure from diabetes mellitus. SPK transplants should be offered to all suitable diabetic patients with renal failure regardless of C-peptide status or race.

A study comparing mycophenolate mofetil to azathioprine in simultaneous pancreas-kidney transplantation

BACKGROUND

Mycophenolate mofetil (MMF; Cell-Cept) is a potent and selective inhibitor of B and T lymphocyte proliferation that has proven effective in reducing the incidence of acute rejection in cadaveric kidney transplant recipients in several randomized, blinded clinical studies. Because the frequency and characteristics of rejection episodes may be different and more severe after combined pancreas-kidney transplantation, we hypothesized that MMF would have a significant impact on pancreas-kidney rejection and graft outcome. Therefore, we compared the efficacy of MMF versus azathioprine (AZA) in cyclosporine-treated simultaneous pancreas-kidney transplantations.

METHODS

A retrospective comparison of 358 consecutive primary SPK transplantations performed from 1990 to 1997 was conducted. Patients received either MMF (n=109, 3 g/day) or AZA (n=249, 2 mg/kg q.d.) in combination with cyclosporine-based immunosuppression. All patients received a quadruple-drug sequential induction protocol with either OKT3 or Atgam. Several outcome parameters, including patient and graft survival rates and frequency of rejection, were analyzed.

RESULTS

MMF-treated patients demonstrated a markedly reduced rate of biopsy-proven kidney rejection (31 vs. 75% AZA, P=0.0001), clinically significant pancreas rejection (7 vs. 24% AZA; P=0.003), and steroid-refractory rejection (15 vs. 52% AZA; P=0.01). As a result, kidney and pancreas allograft survival was significantly better in MMF patients compared with AZA patients (2-year survival rates: kidney, 95 vs. 86%; and pancreas, 95 vs. 83%). Although surgical infections after transplantation were more frequent in MMF patients, MMF patients were more likely to have undergone enteric drainage. Importantly, we did not observe an increased incidence of any of the bacterial, fungal, or viral infections that typically plague immunosuppressed transplant recipients.

CONCLUSIONS

This retrospective study demonstrates that MMF is a highly effective immunosuppressant in SPK transplantation. It is not associated with an increased risk of opportunistic infections when a balanced immunosuppressive management approach is used. MMF strikingly reduces the frequency of acute cellular and steroid-resistant rejection. As a result of this combined experience, it is not unexpected then that we observe significantly improved graft survival rates in MMF-treated SPK patients compared with patients receiving a more traditional immunosuppressive regimen.