Intravesicular Cidofovir in the Treatment of BK Virus-Associated Hemorrhagic Cystitis (BKV-HC) Following Allogeneic Hematopoietic Stem Cell Transplant (HSCT)

Background: BKV HC is a well-known complication following allo-SCT. Supportive care with bladder irrigation and blood transfusions were the only available treatment. Since our initial report (Bridges B et al. Am J Hematol 2006;81:535), several studies confirmed that intravesicular cidofovir is a potential effective treatment for BKV HC. In this study, we report a large series of consecutive patients who developed BKV HC following allo SCT and received intravesicular cidofovir.

Methods: We conducted a retrospective review of allo SCT patients who developed BKV HC and were prescribed intravesicular cidofovir from 2012 to 2017.

Results: 33 patients were diagnosed with BKV HC. The median age was 50 years (range=23-73), and 18 (55%) were male. Acute myeloid leukemia (n=12, 35%) was the most common diagnosis followed by non-Hodgkin lymphoma (n=7, 21%) and B cell acute lymphoblastic leukemia (n=4, 12%). Conditioning regimens were myeloablative (n=19, 58%) or reduced-intensity (n=14, 42%); 15 (45%) patients received cyclophosphamide, and 22 (67%) received total body irradiation. The median time to onset of HC symptoms following SCT was 37 days (range: 8-178); 17 (52%) patients had acute graft vs. host disease. HC symptom severity ranged from grade 0-4 (median=2). The median BK urine viral load pre-treatment was 100,000,000 IU/ml. Patients received a median of 2 intravesicular treatments (range=1-7) at a dose of 5 mg/kg. Four patients (12%) were also treated concurrently with intravenous cidofovir. 19 (59%) patients demonstrated complete clinical resolution of symptoms, 9 (28%) demonstrated partial response to treatment, and 4 (13%) had no change in symptoms following treatment. These improvements in clinical status were independent of viral load, though most had reductions in the viral load. The median time to symptom resolution was 17 days (range=7-53; n=28). 82% of patients had no recurrent symptoms of HC. The main side effect of intra-vesicular instillation was increased discomfort and bladder spasms; severe in 3 patients (9%). No patient had impaired renal function directly attributable to intra-vesicular cidofovir. At 12 months after BKV HC diagnosis, 26 (79%) patients were alive.

Conclusions: To our knowledge this is the largest study of intravesicular cidofovir for BKV HC reported to date; 77% of patients with BVK HC achieved clinical improvement of symptoms with minimal side effects. Clinical trials of intravesicular cidofovir could provide further evidence for adding intravesicular cidofovir as a standard tool for the treatment of BKV HC.