1. M. Offidani 1, A. Savini 1, L. Corvatta 2, C. Polloni 1, S. Gentili 1, A. Brioni 3, G. Visani 2, P. Galieni 2, F. Alesiani 2, M. Brunori, M. Catarini 2, A. Mele 2, M. Burattini 2, A. Samori 2, R. Centurioni 2, N. Blasi 2, M. Ferranti 2, P. Fraticelli 2, R. Rizzi 2, P. Leoni 1 1 Clinica di Ematologia, Azienda Ospedaliero-Universitaria Ospedali Riuniti Ancona, Ancona, Italy; 2 Marche Multiple Myeloma Network, GEMaMM, Italy; 3 Istituto di Ematologia e Oncologia Medica Seragnoli, Bologna, Italy Studies including thalidomide showed a rate of severe infectious complications, ranging from 6% to 22%, that maybe represent life-threatening adverse event or compromise compliance to therapy. Therefore antibacterial prophylaxis has become a routine clinical practice despite its role in the new-drugs era has to be defined. We performed a post-hoc analysis of 224 patients treated with thalidomide based combinations in order to: 1. assess time, type and outcome of infections 2. search for factors affecting onset of infections during induction and build a risk model in order to perform targeted prophylaxis. CharacteristicsAge > 65 yrs Disease status newly diagnosed relapsed/refractory PS (ECOG) 0 1-2 3-4ISS II-III Prior lines of therapy 1 > 2 Renal failure Unfavourable cytogenetic Antiinfective prophylaxis No (%) 141 (63) 119 (53) 105 (47) 77 (34) 129 (58) 18 (8) 156 (69) 49 (22) 55 (25) 38 (17) 45 (32) 168 (75) Median (range) 70 (31-91)CONCLUSIONS ParametersAge  65 > 65 SexMF Performance status 0-12-4ImmunophenotypeIgAOther Previous DVT YesNo Bone marrow plasmacells  30% > 30% Monoclonal component  2 gr/dL > 2 gr/dL Hb level < 11 gr/dL  11 gr/dL PLT count < 130000/  l  130000/  l  2-microglobulin  3.5 mg/dL > 3.5 mg/dL Albumin  3.5 g/dL > 3.5 g/dL ISS12-3CRPnormalabnormalCreatinine  2 mg/dL > 2 mg/dL Disease status newly diagnosed relapsed/refractory Prior ASCT yesnoProphylaxisYesNo%17182014172017173216162010211619221217181618231617161816132216181525OR0.9201.5830.8030.9720.3920.7560.4080.8230.4810.9801.1431.6051.1341.1500.5540.8750.524p0.8200.2000.5600.9500.0520.5190.5200.5930.0470.9560.7170.1960.7460.7720.0960.7700.084 UNIVARIATE ANALYSIS OF FACTORS AFFECTING INFECTIONS  86 patients (38,5%) developed an infection  39 patients (17,5%) developed grade 3-4 infection 23 pneumonia (1 CMV, 1 probable fungal infection) 9 FUO 6 bacteremia (all due to Gram- bacteria) 1 orbital abscess INDUCTION THERAPY: 42 patients ThaDD-V 42 patients ThaDD-V 160 patients ThaDD 160 patients ThaDD 5 patients VDT 5 patients VDT 8 patients TD 8 patients TD 9 patients VMPT 9 patients VMPT INTERMEDIATE RISK GROUP p= 0,921 Probability of infection months Patients without prophylaxis Patients with prophylaxis HIGH RISK GROUP p= 0,004 Probability of infection months Patients without prophylaxis Patients with prophylaxis 18%2% months Probability of severe infection p=0,023 months High risk group (3 risk factors) Intermediate risk group (2 risk factors) Low risk group (1 risk factor) Probability of severe infection months Progression free survival Patients without infection Patients with infection months pneumonia Despite antibiotic prophylaxis, patients receiving thalidomide combination therapy develop infections particularly pneumonia bulk disease Higher risk patients are those with bulk disease, represented by high MC and low platelets count Infections don’t compromise both compliance to therapy and outcome but they worse patients QoL and significantly increase costs of care DVT Severe infections increase the risk of DVT High risk patients should receive more suitable antimicrobial prophylaxis Cumulative risk infection Probability of infection DVT Probability of DVT months Infectious complications in patients with Multiple Myeloma treated with new-drug combinations including Thalidomide