Conversion to rapamycin immunosuppression for malignancy after kidney transplantation: case reports

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.

Eight patients developed the following malignancies after kidney transplantation (mean 102.6 months; range 12 to 252): metastatic gastric cancer (n = 1), metastatic colon cancer (n = 1), bilateral nephrourothelioma (n = 1), skin cancer (n = 1), Kaposi's sarcoma (n = 2), posttransplant lymphoproliferative disorder (PTLD) (n = 2). After the diagnosis of malignancy, the patients were switched from calcineurin inhibitor-based immunosuppression to rapamycin (monotherapy, n = 2), associated with steroids (n = 4) or mycophenolate mofetil (n = 2).

Both patients with metastatic cancer underwent chemotherapy and then succummbed after 6 and 13 months. After a mean follow-up of 20.3 months (range 2 to 47), the remaining six patients are free from cancer disease. Renal graft function was unchanged from diagnosis throughout the follow-up.

Our observations suggested that rapamycin-based immunosuppression offered the possibility of regression of nonmetastatic tumors. Nevertheless, it is difficult to assess whether tumor regression was attributed to Rapamycin treatment or to the reduced immunosuppression.