Effects of immune suppression for transplantation on inflammatory colorectal cancer progression

BACKGROUND: Ulcerative colitis patients and transplant recipients are at risk for colorectal cancer. Here, we show that immunosuppressive regimens for kidney transplants are associated with the progression of ulcerative colitis-related carcinogenesis. METHODS: We describe the case of a patient diagnosed with colorectal cancer in ulcerative colitis while on immunosuppressive therapy for a kidney transplant. The immunological microenvironment of the cancer and its mutational status were analyzed, and a mouse colon cancer model was created to replicate the unique clinical conditions. AOM/DSS mice were randomized into seven experimental groups that received different immunosuppressants and an untreated control group to assess the frequencies of adenocarcinoma and high-grade dysplasia. Histopathology, immunohistochemistry, and flow cytometry were also performed on the harvested mouse colons. RESULTS: All mice treated with an immunosuppressive regimen developed at least an adenoma, and several of those receiving anti-CD3, anti-CD8, and mycophenolate mofetil also developed adenocarcinomas. In contrast, mice receiving rapamycin did not develop adenocarcinomas, and the extent of high-grade dysplasia in those mice was similar to that in control mice. CONCLUSIONS: Patients with pre-neoplastic conditions, such as ulcerative colitis, who are undergoing a solid organ transplant might benefit from the use of mTOR inhibitors given their intrinsic anti-tumor properties.