High Incidence of BK-Virus-Related Hemorrhagic Cystitis after Busulfan/Fludarabine Myeloablative Conditioning in Allogeneic Stem Cell Transplantation Recipients

Busulfan (BU) and Fludarabine (F) has been reported by de Lima et al. to be a well-tolerated myeloablative conditioning regimen with 3% incidence of hemorrhagic cystitis (Blood2004;104:857). Between 5/2005 and 5/2006, we performed allogeneic stem cell transplantation (SCT) in 29 patients following BU+F (n=17) and other (n=12) myeloablative regimens. Nineteen (66%) patients were in remission and 10 (34%) had active disease at BMT. Twenty patients had AML, 4 ALL and 5 had other malignancies. Busulfan was given at 130mg/M2 over 3 hours on 4 successive days, along with Fludarabine 40mg/M2 on 4 successive days. Eighteen (72%) had matched-related 7 (24%) had matched-unrelated donor (MUD) transplant. GVHD prophylaxis consisted of Tacrolimus and low-dose Methotrexate. Thymoglobulin (n=4) and CAMPATH (n=3) were given along with conditioning in MUD/one-antigen mismatch transplant recipients (5 BU+F and 2 other). As of August 1st, 2006, 19 (65%) patients are alive. Of 26 evaluable patients, the incidence of bacterial (59% vs. 89%), fungal (29% vs. 11%) infections were similar between Bu+F and other group, respectively. CMV reactivation was observed in 78% in other group as compared to 35% in BU+F recipients (p=0.09). Hemorrhagic cystitis (HC) occurred in 6 patients (35%) in BU+F group and in 1 (11%) patient in other group (p=0.35). BK virus was detected by quantitative PCR in all patients with HC. Two BK(+) cases were in BU+F+CAMPATH group. Considering 18 AML patients who received transplant in remission and had at least 2 months of follow-up, 5 patients (38%) in BU+F group relapsed within 6 months of transplant. Two out of 5 patients relapsed in the other group. Our findings suggest that BU+F myeloablative conditioning appears to be associated with high incidence of BK-related hemorrhagic cystitis and may have long-term consequences. Further studies are warranted.