AbstractAbstract 4496 Purpose:To investigate the impact of pre-transplant CMV serostatus of donor or recipient on outcome of patients undergoing allogeneic hematopoietic stem cell transplantation (Allo-SCT) for Multiple Myeloma (MM). Patients and methods:We retrospectively followed 99 consecutive patients who underwent reduced-intensity conditioning (RIC) Allo-SCT for MM in our cancer centre at Marseille between January 2000 and January 2012. Based upon CMV serostatus, patients were classified as low risk (donor [D]-/recipient [R]-) 17 patients (17.1%), intermediate risk (D+/R) 14 patients (14.1%), or high risk – either (D-/R+) 31 patients (31.3%) or (D+/R+), 37 patients (37.3%). Results:Cumulative incidence of CMV reactivation was 39% with a median time of 61 days (26–318). Three patients (3%) developed CMV disease. Two factors were associated with CMV reactivation: CMV serostatus group (low: 0% vs intermediate: 29% vs high: 50%; p=0.001) and the presence of grade II–IV acute GvHD (Hazard Ratio: HR=2.1 [1.1–3.9]). Thirty-six of the 39 patients (92%) with CMV reactivation did not present positive detection of CMV after a 21-day median duration preemptive treatment with ganciclovir. Cumulative incidence of day 100 grade II–IV acute GvHD, 1-year chronic GvHD and day 100 transplantation related mortality (TRM) were 37%, 36% and 9%, respectively. CMV reactivation and serostatus were not associated with increased GvHD and TRM or short survival. Only the presence of acute GvHD as a time dependent variable was significantly associated with increased TRM (p=0.005). Two-year overall and progression free survival were 56% and 34%, respectively. Conclusion:Donor and recipient CMV serostatus and acute GvHD are independent factors for increased CMV reactivation in high-risk MM patients undergoing RIC Allo-SCT. However, we did not find any influence of CMV reactivation on post transplantation outcome. CMV monitoring and pre-emptive treatment strategy could in part explain these results. Novel prophylactic measures such as immunotherapy and drug prophylaxis need to be considered in this specific group of patients, warranting further prospective studies.Table 1Patient and transplantation characteristicsPatient and transplantation characteristicsn = 99 (%)Patients Age (median) [range]53 years [27–67]Male gender59 (60)Myeloma-subtypeIgG52 (53)IgA23 (23)Light Chain12 (12)Bence jones8 (8)Other4 (4)Cytogenetics at diagnosisNormal14 (14)Del(13) or Del (17) or t(4;14)24 (24)NA61 (62)Median number of prior chemotherapies before Allo-SCT [range]2 [1–5]1 line27 (27)2 lines46 (47)3 lines15 (15)>3 lines11 (11)Median number of prior Auto-SCT [range]2 [1–4]157 (58)231 (31)> 28 (8)Status of Myeloma at Allo-SCTCR12 (12)VGPR10 (10)PR/SD66 (67)PD11 (11)Median interval between Auto- and Allo-SCT months [range]19 [1–89]Donor typeMRD73 (74)URD26 (26)Donor/recipient sex mismatch48 (48)ABO compatibilityYes63 (64)No36 (36)Donor/recipient CMV serostatusD−/R− (low risk)17 (17)D+/R− (intermediate risk)14 (14)D+/R+ (high risk)31 (31)D−/R+ (high risk)37 (37)Donor Median age years (range)46 (20–71)Conditioning regimenFlu + Bu + ATG68 (69)Flu + TBI25 (25)Other RIC6 (6)GvHD prophylaxisCSA56 (57)CSA+MMF41 (41)MMF2 (2)Stem cell sourcePeripheral Blood88 (89)Bone Marrow9 (9)Cord blood2 (2)Stem cell dose median [range]CD34+ × 106/kg5.41 [0.16–12.8]CD3+ × 106/kg299 [5–745] Legend:CR, complete remission; VGPR, very good partial remission; PR, partial remission, PD, progressive disease; Flu, fludarabine; Bu, busulfan; ATG, antithymocyte globulin; CR, complete remission; VGPR, very good partial remission; PR, partial remission, PD, progressive disease; MRD, matched related donor; URD, unrelated donor; GVHD, graft versus host disease; CSA, cyclosporine A; MMF, mycophenolate mofetyl.Table 2CMV reactivationCumulative incidence of CMV reactivationpAll patients (n=99)39%CMV serostatusLow risk (n=17)0%0.001Intermediate risk (n=14)29%High risk (n=68)50%Donor type*MRD (n=72)38%0.427URD (n=24)46%Graft source*PBSC (n=88)38%0.215Bone marrow (n=8)63%Transplantation period<2006 (n=42)33%0.368>=2006 (n=57)43%Conditioning regimen with ATGYes (n=68)43%0.164No (n=31)29%CMV detection methodpp65 (n=65)38%0.819PCR (n=34)39%Acute GVHD$HR=2.1 [1.1–3.9]0.032Chronic GVHD$HR=0.8 [0.1–8.6]0.837$The occurrence of GVHD was analysed as a time dependent variable Disclosures:No relevant conflicts of interest to declare.