Use of CMV Unselected Blood Products Does Not Increase the Risk of CMV Reactivation in Patients Undergoing Hematopoetic Stem Cell Transplant (HSCT)

Introduction: Conventionally patients receiving allogeneic HSCT (AlloHSCT) have received CMV negative blood products to obviate the risk of transfusion related CMV transmission. In the era of leucodepletion with more than log 4 reduction in blood product WBC content, the utility of this practice has been questioned and, in line with SABTO (Safety of Blood, Tissues and Organs) guidance, most UK transplant centers have adopted the policy of using unselected blood products for this patient cohort.  At this center, our policy was changed to conform to recommended national practice in April 2013. This analysis was carried out to evaluate if this change has resulted in an increased incidence of CMV reactivation.

Methods: 868 (M: 561; median age:  F: 307; median age:) patients who received HSCT from January 1998 to November 2014 were included in analysis. Transplant types included AutoHSCT (n=384), AlloHSCT-Sibling (n=217) and AlloHSCT-MUD (n=267).  Diagnosis was Ac Leukaemia (n=313), Chr Leukaemia (n=36), Myeloma (n=216), Lymphoma (n=261) or other malignancies (n=42). Commonest indication for AutoHSCT was myeloma or lymphoma. TBI based condition was used in 225 AlloHSCT and 50 AutoHSCT cases. RIC was used in 268 cases and full intensity in 215 cases (unknown in 1).  Alemtuzumab or ATG was used in conditioning for 274 cases. Source of stem cell was PBSC (AutoHSCT: 363, AlloHSCT: 382), BM (AutoHSCT: 7, AlloHSCT: 97), both (AutoHSCT: 2, AlloHSCT: 9) and 8 AlloHSCT were UCB grafts.  

Results:  26, 345 blood PCR results were evaluated. 3100 tests were requested in AutoHSCT patients and 109 (3.6%) were positive. There were no differences in the incidence of positive CMV PCR results before and after use of CMV unselected blood products. Further analysis was limited to AlloHSCT patients. AlloHSCT patients were divided in two groups, GrpA: 1998 to 2013 and GrpB: 2013 to 2014 to evaluate the effect of using CMV unselected blood products.  In AlloHSCT group, 9.1% of 23278 samples tested for CMV PCR were positive (Median log: 2.7, range: 0.3 -7.3).  Incidence of CMV reactivation was not different in GrpB as compared to GrpA (47.7% vs. 48.1%, p=0.93). There was no difference with gender (M: 45.8% vs. F: 53.1%, p=0.13), type of donor (Sibling: 48.6% vs. MUD: 47.9%, p=0.98), use of Alemtuzumab/ATG (50.6% vs. 45.4%, p=0.51), source of stem cells (BM: 36.4% vs. PBSC: 51.3%, p=0.07), use of TBI (43.8% vs. 52.3%, p=0.06). Higher incidence was observed with use of RIC transplant (53.2% vs. 42.3%, p=0.02) and donor-recipient CMV mismatch (NP: 24.5%, PN: 80%, PP: 90.8%, p<0.0001).

Conclusion: This analysis suggests that the risk of CMV reactivation is related to the donor-recipient CMV mis-match and the transplant intensity. Use of CMV unselected blood products does not increase the risk of CMV reactivation and careful selection of donors using CMV sero-status is the key factor to reduce the risk of CMV reactivation post AlloHSCT.