1763. The Use of Haploidentical Donors Compared with HLA-Matched Unrelated Donors is Associated with Increased Risk of BK Viruria and Hemorrhagic Cystitis

BACKGROUND: BK virus-associated hemorrhagic cystitis (BK-HC) is a common and often serious complication of hematopoietic cell transplantation (HCT). Studies have suggested a higher incidence of BK-HC in patients receiving haploidentical (haplo) HCTs compared with those receiving matched unrelated donor (MUD) transplants. METHODS: We retrospectively identified all adult patients receiving HCT from MUD or haplo donors at Washington University School of Medicine between January 1, 2011 and January 1, 2016. Via informatics queries, we obtained the results of every urine BK test performed on these patients. Patients with BK viruria were then evaluated for BK-HC and graded according to established criteria. The last day of follow-up was April 31, 2017. RESULTS: 503 MUDs and 140 haplos were identified for inclusion in the study. Haplo patients were significantly more likely to be nonwhite (21% vs. 5%, P < 0.001) and were younger (median age: 51.5 vs. 55, P = 0.01). Conditioning regimens were also significantly different; haplos were less likely to receive myeloablative conditioning (44% vs. 57%, P < 0.001) and busulfan-based conditioning (13% vs. 39%, P < 0.001), but were more likely to receive total body irradiation-based conditioning (83% vs. 26%, P < 0.001). Haplos were also more likely to have undergone previous allogeneic HCT (26% vs. 6%, P < 0.001). The cumulative incidence of both BK viruria and BK-HC were significantly higher in haplos (both P < 0.001). This was observed at 100 days, 180 and 365 days (Table 1). CONCLUSION: We found a significantly higher incidence of both BK viruria and BK-HC in patients receiving haplo HCT compared MUD HCT. Significant demographic and clinical imbalances exist between our two cohorts and attribution of increased risk for BK-HC to donor type vs. other factors should be further explored. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.