BKV Disease during the First 100 Days after Allogeneic Hematopoietic Stem Cell Transplantation - Results of a Screening Program and Retrospective Analysis

BK virus (BKV) is a human polyomavirus often acquired in childhood which can reactivate after allogeneic hematopoietic stem cell transplantation (HSCT). BKV reactivation may present indifferent ways from asymptomatic viruria to hemorrhagic cystitis or nephritis.

Methods

We evaluated 377 patients (159 male, 218 female, median age 52 years) who were transplanted at the University of Cologne between 2008 and 2013 to assess incidence and risk factors for BKV disease after allogeneic HSCT. All 377 patients were screened routinely for BKV in urine and serum. We defined BKV disease as hemorrhagic cystitis (HC) with BK virus >100.000/ml in urine, hematuria (2+ until 4+ in dipstick test) and negative urine microbiology. To find risk factors for BKV disease, the impact of conditioning, CMV status, graft-versus-host disease (GvHD), underlying disease, donor mismatch and stem cell source was analyzed.

Results

According to our definition, BKV cystitis occurred in 37 of 377 patients (9,8%) in the first 100 days after HSCT. In 14 of these 37 patients (37,8%) BKV was also detected in serum. BKV was detected in the urine of 194 patients (51,4%) at any time during the screening program, but only 19,1% developed hemorrhagic cystitis. Sixty-two percent of patients suffering from BKV disease were female, 37,8% male. BKV disease was diagnosed in 13,3% of patients not in complete remission as opposed to 5,4 % of patients in complete remission prior to conditioning (p = 0,010). BKV disease was less common in matched related or unrelated (7,7%) as compared to mismatched or haplo-identical donors (16,7%; p=0,012). Acute GvHD grade II to IV was described in 122 of 377 patients (32,36%). Of them, 13,9% suffered from BKV cystitis in comparison to 7,84% with no or grade I acute GvHD, which did not reach statistical significance. We could not detect any correlation between BKV disease and administration of cyclophosphamide, total body irradiation or anti-thymocyte globuline. There was no association with the graft source. BKV disease was no predictor for non-relapse mortality, overall and relapse-free survival.

Conclusion

BKV disease is a common complication after allogeneic HSCT. The virus can be found in the urine of about half of our transplanted patients, but only a small proportion developed an HC. State of remission before conditioning and donor mismatch are associated with the development of BKV disease, which had no impact on survival in our cohort.