Hypothesis: Early detection, and treatment, of BK virus infection after kidney
transplantation will prevent BK virus associated kidney transplant injury.
BK virus associated nephropathy (BKVN) is estimated to cause a progressive kidney transplant
injury in 1-10% of renal transplant recipients. Diagnostic and monitoring strategies for BKVN
is still being developed. Detectable virus in the blood by polymerase change reaction-test
(PCR) is predictive of BKVN. Additionally, PCR provides a objective estimate of the degree of
infection.
If early detection and treatment of BK virus infection is effective in preventing subsequent
kidney transplant injury has not been studied. However, renal injury and dysfunction develops
late in the natural course of BKVN and it seems likely that screening in combination with
early treatment would be beneficial for long-term transplant survival.
There is no established treatment for BK virus infection. Nevertheless, in kidney
transplanted patients diagnosed with BK virus infection, immunosuppression is reduced to
allow the patients own immune system to handle the virus. However, reduction of
immunosuppression has not been associated with rejection. This indicate that these patients
were over-immunosuppressed, predisposing them to BKVN. Therefore, to compare the degree of
immunosuppression in BKVN patients (over-immunosuppressed) to other patients (not
over-immunosuppressed) could yield interesting information. One possibility would be to
quantify these patients specific cellular immune response to BK virus but also to other
viruses (T cell reactivity).
Leflunomide (Arava) is an immunosuppressive drug, approved for the treatment of rheumatoid
arthritis, and has been used in more than 300,000 patients worldwide. Furthermore,
leflunomide has been used safely in humans after clinical kidney and liver transplantation
for more than 300 days. In addition to leflunomide's value in preventing rejection, it has
been shown to exert inhibitory effects on different viruses. Recently published pilot studies
suggest that leflunomide treatment of patients with BKVN significantly reduces the amount of
BK virus in blood and prevents recurrence of kidney transplant injury. At Karolinska
University Hospital, leflunomide has been used for treatment of BKVN and, in some of the
patients, renal function has stabilized and BK virus load has decreased significantly.