Assessment of Efficacy and Safety of FK778 in Comparison With Standard Care in Renal Transplant Recipients With Untreated BK Nephropathy

Background. BK polyomavirus infection has been reported in 10% to 60% of renal transplant recipients with progression to BK nephropathy (BKN) occurring in 1% to 5% of patients. Graft loss occurs in up to 60% of renal transplant recipients with BKN. Because BK polyomavirus infection is believed, in part, to be a manifestation of overimmunosuppression, the current standard of care involves the reduction of immunosuppressants. This strategy has been associated with clearance of viral load, preservation of renal function, and improvement in graft survival; however, this may come at a risk of rejection. A safe and effective immunosuppressive agent that does not predispose to viral infection is needed in transplantation. Methods. In a phase 2, proof-of-concept, randomized, open-label, parallel-group, 6-month study in renal transplant patients, FK778 (an investigational immunosuppressant from the malononitrilamides class) was compared with the current standard of care (reduction of immunosuppression) for treatment of newly diagnosed or untreated BKN, which was confirmed by renal biopsy. Results. Demographic characteristics were similar between the two groups, except there were numerically more females in the FK778 group than in the standard care group. Although the treatment with FK778 decreased BK viral load in this study, it was associated with a less favorable rejection profile and renal function and a higher incidence of serious adverse events compared with reduction of immunosuppression. Conclusions. Data from this study are consistent with the findings of previous studies that found no benefit of drug therapy in the treatment of BKN in kidney transplant recipients.