*Purpose: BK virus-associated nephropathy (BKVAN) is a clinically important entity that contributes to allograft loss in kidney transplant recipients (KTRs). Mammalian target of rapamycin inhibitors (mTOR-i) have been proposed as possible immunosuppressive therapies in BK virus infection because of their antiviral capacity. However, the effect on biopsy (bx) 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, including patients with bx proven BKVAN (n=13, 48%). Patients were converted to Everolimus, reduced/or no 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 bxs (n=55). All patients were switched to Everolimus, reduced or no CNI 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). The viral load became undetectable in 13/27 (48%). BKVAN was present on bx in 13/27 (48%). A follow up bx was obtained in 9 of these patients, with 4 showing resolution of BKVAN and 5 showing persistent BKVAN. The trend in viral load in all BKVAN patients is shown in the Figure. 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 even in bx proven persistent BKVAN, and almost half (4/9) of the bx proven BKVAN have resolved.

« Back to 2020 American Transplant Congress