Polyomavirus BK nephropathy Fabrizio Ginevri Kidney Transplantation Unit, Department of Nephrology, Istituto G. Gaslini

1. Polyomavirus BKnephropathy Fabrizio Ginevri Kidney Transplantation Unit, Department of Nephrology, Istituto G. Gaslini, Genova, Italy

2. BKV infection:the virus • DNA virus that belongs to the polyomaviridae family: • Polyomavirus BK • Polyomavirus JC • SV40 • New: Polyomavirus KI, Polyomavirus WU, Polyomavirus MC Structure: The BKV genome comprises three regions: 1. the NCCR 2. the structural region coding for early T proteins 3. the late structural region encoding the viral capsid proteins (VP1-3) and agnoprotein

3. BKV infection:the virus • Infects up to 90% of the general population • Transmitted via aerosol, urinary shedding, allograft • After primary infection, renal tubular epithelial cells and the urothelial cell layer represent the principal sites of viral latency or replication • BKV disease is rare, and almost invariably associated with an immunodeficiency status

4. BKV infection after kidney transplantation • Reactivation/primary infection in KTx recipients: • asymptomatic infection • ureteral stenosis • systemic vasculopathy • interstitial nephropathy (BKVN): • increased prevalence of BKVN in the last decade (from 1% in 1995 to 5-10% in 2001) • the majority of cases occur within the 1st year after Tx, but at least 25% of cases are diagnosed later • 10-80% graft loss: but, with increased awareness and improved diagnostic techniques, the rate of graft loss has lowered

5. BKV nephropathy after kidney Tx: risk factors

6. Renal injury + organ BK load BKV mutations  BKV replication BKV-mediated tissue damage PVAN BKV nephropathy after kidney Tx: pathogenesis Immunosuppression load: triple vs. double therapy Binet et al. Transplantation 1999 Hirsch et al. Transplantation 2005 + Lack of immune memory: BK seronegativity Ginevri et al. Transplantation 2003 Smith et al. Am J Transplant 2004 Failure of immune surveillance

7. Analysis of BKV-specific immunity after KTx:parameters correlated with protection from BK viruria IFN-g secreting cells cytotoxicity 50 300 VP1 VP1 37,5 225 % specific lysis 25 SFU/105 cells 150 12,5 75 0 0 N U+/U+P+ N U+/U+P+ 50 LT 300 p<0.005 ** p<0.05 * LT 37,5 225 % specific lysis 25 SFU/105 cells 150 12,5 75 0 0 N U+/U+P+ N U+/U+P+ Ginevri F, Comoli P, et al. manuscript in preparation

8. 500 LT p=0.07 333 SFU/105 cells 166 0 U+_pre U+_peak U+P+_pre U+P+_peakU Analysis of BKV-specific immunity after KTx:parameters correlated with protection from BK viremia IFN-g secreting cells Ginevri F, Comoli P, et al. manuscript in preparation

9. Approach to screening for BKVN diagnosis Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

10. BKV nephropathy after KTx:diagnosis • BKVN has a focal presentation • as a consequence, negative biopsy results cannot rule out BKVN with certainty Drachenberg et al. Hum Path 2005; 36:1245

11. Screening for BKVN and therapeutic intervention Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

12. Treatment of “definitive” BKVN • The therapeutic mainstay is reduction of maintenance immunosuppression • Antivirals and other pharmacologic approaches have been variably associated Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

13. Treatment of “definitive” BKVN:results Early diagnosis has allowed a significant amelioration of prognosis • graft outcome: • no screening: 35-50% of BKVN treated with any protocol  marked graft dysfunction, with possible progression to graft loss; • screening and early treatment: no graft loss, milder graft dysfunction. Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

14. Preemptive treatment of BKVN On the basis of plasma BKV-DNA analysis • DNA threshold for treatment: >104 ge/ml • graft outcome:viremiaclearance, no BKVN, no acute rejection Ginevri F, Hirsch HH. BK polyomavirus nephropathy. 2008

15. 1.0 0.8 Viruria: N = 62; E = 39 Viremia: N = 62; E = 13 0.6 Viruria: 64% (53-78) CUMULATIVE INCIDENCE (95% CI) 0.4 Viremia: 22% (13-35) 0.2 MONTHS AFTER TRANSPLANTATION 0.0 0 12 24 36 48 60 BKVN prospective monitoring and preemptive treatment after pediatric KTx • 62 pediatric KTx recipients referred between 01/02 and 08/05: • Group 1: BKV-sero+ patients, that did not reactivate after Tx • Group 2: patients with positive viruria after Tx • Group 3: patients with positive viruria and viremia after Tx • Prospective monitoring of BKV DNA, measured by Q-PCR, in urine and plasma. • +1, +3, +6, +9, +12, +18, +24, >24 months after KTX Number of patients at risk: 62 42 36 21 11 0 Ginevri et al. Am J Transplant 2007

16. Results:effect of IS reduction on viral load and outcome Ginevri et al. Am J Transplant 2007

17. * ** * * 800 VP1 LT 533 Spots/105 cells 266 0 Pre-BK viremia BK viremia increase BK viremia decrease Post-BK viremia clearance Sero+ controls Sero+ KTx-r no BKV Sero+ KTx-r no BKV Sero+ controls Pre-BK viremia BK viremia increase BK viremia decrease Post-BK viremia clearance Reconstitution dynamics of BKV-specific immunity after preemptive treatment IFNg-secreting cells Ginevri et al. Am J Transplant 2007

18. Reconstitution dynamics of BKV-specific T cells and serology in a patient with BKVN Comoli, Ginevri, Hirsch. Transplant Infect Dis 2006

19. 400 106 300 105 IFN-g SFU/105  VP1  LT Plasma BKV load 200 104 100 103 0 1 2 3 0.5 4 6 9 12 Months post-Tx Monitoring of specific immunity in patients with BK viremia Modulation of IS reduction according to cellular immunity analysis Comoli P, Hirsch HH, Ginevri F. Curr Opin Organ Transplant 2008

20. BKVN after KTx:conclusions and open issues • Outcome of BKVN • when BKVN is advanced (stages B2-3 and C), outcome is still suboptimal • early treatment (stages A and B1) yields better results in terms of graft outcome • preemptive treatment on the basis of BK viremia seems at present the best option, but screening protocol has to be defined • Long term outcome of allografts after BKV infection • data on long-term allograft outcome after successful treatment for BKVN are scarce. However, preliminary results suggest that BKVN is a risk factor for progressive chronic allograft dysfunction • direct virus damage ? • suboptimal IS ? • In case of prevalent direct damage, preemptive treatment may allow to reduce considerably the risk of progressive allograft failure • In the second instance, tailoring of preemptive treatment on the basis of viremia and specific immune reconstitution may avoid excess IS reduction, and thus suboptimal IS

21. Pediatric Hematology/Oncology Fondazione Policlinico S. Matteo, Pavia, Italy P Comoli S Basso A Gurrado • Pediatric Kidney Tx Program • Genova, Italy • Pediatric Nephrology • Istituto G. Gaslini • F Ginevri • A Parodi E Verrina • M Cioni G Barbano • Department of Transplantation Ospedale S Martino • I Fontana • U Valente Department of Public Health Università di Firenze, Italy A Azzi Department of Transplantation Virology University of Basel, Switzerland H H Hirsch Pediatric Kidney Disease Fund Genova, Italy R Gusmano

22. Retransplantation • Retransplantation is a feasible option after graft loss to PAN :PAN recurrence in 2/13 reported patients (15%) • In the absence of active BKV infection • Nephrectomy of the original graft may not be necessary • Baseline IS: does not need to be specifically adjusted In case of failure to reduce viral load or when IS reduction is contraindicated, the administration of antiviral drugs (e.g. cidofovir) and/or the surgical removal of the alloureter and kidney could be considered • Post-transplant follow-up management • Monitor: urine/plasma viral load general/specific immunity • Therapeutic intervention guided by plasma DNA levels