Conversion to Rapamycin Immunosuppression for Malignancy After Kidney Transplantation

Introduction. Malignancies are a well-known complication of immunosuppressive therapy among renal transplant recipients, representing an important cause of long-term morbidity and mortality. Rapamycin has been shown to limit the proliferation of a number of malignant cell lines in vivo and in vitro. Methods. Fifteen patients developed the following malignancies at a mean of 90.3 months (range = 10-252) after kidney transplantation: metastatic gastric cancer (n = 1), metastatic colon cancer (n = 1), bilateral nephrourothelioma (n = 1), skin cancer (n = 2), Kaposi's sarcoma (n = 2), posttransplant lymphoproliferative disorder (PTLD; n = 4), renal cell carcinoma T1 (n = 1), MALT lymphoma (n = 1), intramucous colon carcinoma (n = 1), liposarcoma of the spermatic cord (n = 1). After the diagnosis of malignancy, the patients were switched from calcineurin inhibitor-based immunosuppression to rapamycin (monotherapy, n = 3), or associated with steroids (n = 6) or with mycophenolate mofetil (n = 6). Results. Both patients with metastatic cancer underwent chemotherapy but succumbed after 6 and 13 months. Two patients with PTLD who underwent chemotherapy died after 12 and 36 months. At a mean follow-up of 32.7 months (range = 7-56), the remaining 11 patients are cancer-free. Two patients lost their grafts after 24 and 36 months after the switch due to chronic rejection. Renal graft function remained stable in all other patients from diagnosis throughout follow-up. Conclusion. Our observations suggested that rapamycin-based immunosuppression offers the possibility for regression of nonmetastatic tumors. Nevertheless, it is difficult to assess whether tumor regression was due to rapamycin treatment or to the reduced immunosuppression.