CellCept CellCept contains Mycophenolate Mofetil, an immunosuppressive prodrug that is converted in the body into its active metabolite, mycophenolic acid. It works by inhibiting inosine monophosphate dehydrogenase (IMPDH), an enzyme essential for purine synthesis in active lymphocytes. By blocking the proliferation of T and B immune cells, it selectively dampens the body's immune response to prevent the rejection of transplanted organs such as the kidney, heart, or liver.