91. Differential Impact of Cytomegalovirus (CMV) Donor (D) Serostatus on Rates and Kinetics of CMV Viremia among CMV Seropositive Recipients (R+) of Ex vivo T-cell Depleted (TCD) and Unmodified (CONV) Hematopoietic Cell Transplants (HCT)

BACKGROUND: In unmodified (CONV) HCT, CMV donor seropositivity (D+) conveys partial protection against CMV disease mediated by the transfer of donor CMV T-cell immunity through the allograft. Ex vivo T-cell depletion by CD34 selection affords a stringent depletion of donor T cells, thus transfer of donor T-cell immunity to CMV would be negligible. We evaluate the impact of CMV D serostatus on rates and kinetics of CMV viremia by Day (D)100 post-HCT in a contemporary cohort of CONV and TCD recipients from a single center. METHODS: A retrospective cohort study of R+ adult recipients of first peripheral blood or marrow HCT for hematologic malignancies (excluding multiple myeloma) from June 2010 to December 2017 at MSKCC. Routine CMV monitoring by a quantitative PCR assay occurred weekly from D14 through D100. Patients were treated preemptively. CMV viral burden was assessed as the time-averaged area under the viremia curve over 100 days from HCT (AAUC) calculated as the sum of the area of trapezoids of AUC viral loads divided by the number of weeks of follow-up viremia. The median AAUC for all patients with CMV reactivation (AAUC50) was used to classify patients as CMV controllers (AAUC ≤ AAUC50) or noncontrollers (AAUC >AAUC50). RESULTS: Of 509 R+, 290 (57%) patients received CONV and 219 (43%) TCD HCT; from 300 (59%) D+ and 209 (41%) D− donors. In CONV, CMV viremia occurred with similar frequency in D+ (65%) and D− (62%), P = 0.6. In contrast, in TCD, CMV viremia occurred more frequently in D+ compared with D− (83% vs. 71%, P = 0.03). Among CONV, D+ was associated with lower CMV burden (median AAUC) compared with D− (0.791 vs. 1.13, respectively, P = 0.0004). In contrast, in TCD, AAUC was similar between D− and D+ (1.19 vs. 1.35; P = 0.86). Among CONV with CMV viremia, D− were more likely to be noncontrollers compared with D+ (56% vs. 31%, respectively, P = 0.001). In contrast, among TCD with CMV viremia the proportion of noncontrollers was similar between D− and D+ (61% vs. 60%, respectively; P = 1). CONCLUSION: Donor CMV serostatus has a differential effect on rates and kinetics of CMV viremia in R+ TCD and CONV HCT recipients. D+ is associated with less CMV viremia and less CMV burden in CONV but not in TCD. Our findings, if confirmed, have implications for donor selection algorithms. [Image: see text] [Image: see text] DISCLOSURES: All Authors: No reported Disclosures.