Pharmacodynamic Monitoring of NFAT- Regulated Gene Expression and P70S6 Kinase Activity in Kidney Transplant Patients With BKV Infection.

Abstract

Purpose: Measuring drug levels has been unhelpful in guiding management of patients with BKV infection. We measured NFAT-regulated gene expression and p70S6k activity in kidney transplant recipients (KTR) with BKV and correlated the results with clinical outcome. Methods: KTR with BK viruria > 1 million copies/ml or any detectable viremia on tacrolimus (TAC), mycophenolic acid (MPA) and prednisone were randomized to MPA reduction or conversion to everolimus (EVR). The primary endpoint (PE) was clearance of viremia or halving of viruria at 3 months (M). As a sub-study, peripheral blood was collected pre- (T0) and 1.5 hours post- (T1.5) TAC dose at enrollment and 3 M after randomization. Cells were stimulated with PMA/ionomycin. RT- PCR quantified the expression of NFAT-regulated genes IL-2, IFN-γ, and GM-CSF. Residual expression of each gene was calculated as T1.5/T0 x 100 and the average value expressed as mean residual expression (MRE). P70S6K activity was detected by flow cytometry and expressed as mean fluorescence intensity (MFI). The Mann-Whitney U test for comparison of median values was used. Results: 14 KTR with BKV enrolled. At enrollment, KTR with BKV viremia had significantly (SS) lower MRE than those with viruria alone (17.1% CI 14.3-36.4 vs. 43.3% CI 27.7-74.3 P= 0.04) despite similar TAC troughs (8.4, CI 7.0-10.4 vs 9.4, CI 8.6-10, P= 0.35) and P70S6K activity (5264 MFI CI 3379-8659 vs. 8128 MFI CI 2830-11593, P= 0.5). 12/14 KTR have data at 3 M of which 3 reached the PE. Median MRE at enrollment was SS higher in KTR who reached the PE (70.9% CI 27.5-98.1 vs. 17.1% CI 14.4-35, P =0.01). There was no SS difference between those that did and did not reach the PE in TAC levels at enrollment (9.7 CI 6.7-12.7 vs. 8.4 CI 7.4-10.4, P=0.35); at 3 M (5.7 CI 3.7-8.8 vs. 7.6 CI 5.6-8.8, P= 0.35) or P70S6K at enrollment (6765 CI-2904-15434 vs. 4151 CI 2390-7008, P=0.48); at 3 M (2959 CI -5777-14215 vs. 6508 CI 3109-7626, P=1.0). MRE at 3 M did not correlate with outcome (64.01 CI -7.2-128 vs. 53.1 CI 32.3-65.8, P=0.37). Conclusion: MRE of NFAT regulated genes at the time of BKV diagnosis, but not TAC levels or P70S6K activity, correlated with severity of BKV infection and outcome. Pharmacodynamic monitoring of NFAT regulated gene expression may play an important role in prognosis of BKV infection and may aid providers in the management of BKV associated disease. DISCLOSURES:Webber, A.: Grant/Research Support, Novartis, Astellas. Wojciechowski, D.: Grant/Research Support, Novartis, Bristol-Myers Squibb. Vincenti, F.: Grant/Research Support, Pfizer, Alexion, Novartis, Astellas, Bristol-Myers Squibb, Genetech.