*Purpose: BK virus-associated nephropathy (BKVAN) is a clinically important entity that results in an allograft loss in kidney transplant recipients (KTRs). Mammalian target of rapamycin inhibitors (mTOR-i) have been proposed as possible immunosuppressive therapy in BK virus infection because of their antiviral capacity. However, the effect on biopsy proven BKVAN is still unclear.

*Methods: This a retrospective single center review of 27 (KTRs) on triple immunosuppression regimen (CNI/MMF/prednisone), who developed BK viremia and had biopsy proven BKVAN (n=13, 48%). Patients were converted to Everolimus, reduced CNI and prednisone. We present the renal allograft function, BK viremia status and histological data after a mean follow up period of 28.4±17.9 months post-transplant.

*Results: We reviewed 27 KTRs (17 males, 11 AA) transplanted between 2012 and 2019, who developed BK viremia, 23/27 patients (85%) underwent surveillance & for cause biopsies. All patients were switched to Everolimus, reduced CNI (one patient was on Cyclosporin) and prednisone regimen. Median time from transplant to BK viremia was 2.5 months (min 0.7-max 76.7). After a mean follow up period of 17.9±12 months post conversion, the mean serum creatinine remained relatively stable (1.54 mg/dl ±0.47; 1.79 mg/dl±0.82; P=0.17). The mean BK viral load was statistically significantly reduced (P=0.045), pre/post conversion median BK levels were (35900 (655-2.5 million copies) and 752 (0-92150) respectively), 13/27 (48%) patients had undetectable BK viral load. 13/27 (48%) had biopsy proven BKVAN, with 9/13 (69%) had at least one follow up allograft biopsy and 4/9 (44.4%) had a subsequent biopsy proven resolved BKVAN. Post conversion 3/27 (11%) patients were treated for borderline acute cellular rejection with pulse steroids and had negative DSA.

*Conclusions: Conversion to mTOR-i-based therapy could provide an added benefit in BK viremia as well as BKVAN and could be an effective strategy for the decrease of the viremia and increase of graft survival in selected patients. In the medium-term follow up, the BK viral load was statistically significantly lower and almost half of the biopsy proven BKVAN have resolved.

« Back to 2022 American Transplant Congress