Infection Complications in Patients with Multiple Myeloma Treated with New-Drug Combinations Including Thalidomide.

Abstract 2828

Poster Board II-804

Studies including thalidomide showed a rate of severe infection that can be life-threatening complication or compromise compliance to therapy ranging from 6% to 22%. 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 patients treated with thalidomide based combinations within controlled trials in order to assess time, type and outcome of infections. We analysed the main demographic and disease related variables to search for factors affecting onset of infections during induction and build a risk model in order to perform targeted prophylaxis.

Two hundred and twenty four patients were eligible for this study. Median age was 70 years (range 31-90 years) and 141 patients (63%) had more than 65 years. Fifty three percent of patients had de novo MM whereas the remaining had received thalidomide as second or subsequent lines of therapy. ISS stage 2-3 and renal impairment were present in 156 (69%) and 38 (17%) of patients, respectively. Induction therapy consisted in the following protocols: ThaDD (160 patients: 71.5%), ThaDD-V (42 patients: 19%), VMPT (9 patients: 4%), TD (8 patients: 3.5%) and VTD (5 patients: 2%). Prophylaxis for infections was administered to 168 patients (75%) and consisted of quinolones (72%) or thrimethoprim-sulphamethoxazole (28%).

Eighty six patients (38.5%) developed an infection resulting of grade 3-4 in 39 of them (17.5%) (12% grade 3, 5.5% grade 4). Probability of infection at six months was 39% although that of severe infection was 20% (18% at 4 months and just 2% from 4 to 6 months). Among the 39 patients with severe infection, 23 (59%) developed pneumonia, 9 FUO (23%), 6 bacteremia (1 septic shock) and 1 an orbital abscess. Aetiology of severe infection was recognized in 7 patients (4 Gram-negative bacteria, 1 Gram-positive bacteria, 1 CMV and 1 probable fungal infection). Eighty percent of severe infections occurred during the first 3 courses of induction therapy and only 12% during neutropenia. Fifteen percent of patients undergoing antibiotic prophylaxis developed infection vs 25% of patients who did not (p= 0.084). There were no difference between quinolones and thrimethoprim-sulphamethoxazole prophylaxis regarding incidence of infections. The majority of infections were empirically treated and cured with wide spectrum antibiotic therapy except when a specific aetiology was recognized. Only one patient died because of septic shock during neutropenia and 2 patients withdrawn from protocol because of infection. In univariate analysis monoclonal component > 2 g (p=0.021), platelets < 130.000/ml (p= 0.005), newly diagnosed MM (p=0.083) and antibiotic prophylaxis (p=0.061) were factors predicting severe infection development whereas age, sex, ECOG performance status, MM type, D-S stage, plasmacell infiltration in bone marrow, haemoglobin concentration, serum b2-microglobulin, serum albumin, ISS, serum C-Reactive Protein, serum creatinine, previous stem cell transplantation were not. Cox regression analysis selected monoclonal component > 2 g (p=0.015 HR= 1.8) and platelets < 130.000/ml (p=0.003 HR= 2.3) as covariates associated to severe infection. The 25 patients without adverse factors, the 125 with 1 and the 74 with 2 adverse factors had a probability of severe infection equal to 4%, 17% and 32 % (p= 0.023), respectively. This model remains useful apart from prophylaxis since the probability of severe infection in patients with at least 1 risk factors receiving prophylaxis is 17% vs 4% in patients without risk factors. Of note, patients developing severe infection had a significantly higher incidence of deep venous thrombosis (DVT) compared with patients who did not (20.5% vs 9%: p= 0.041). DVT occurred after a median time of 0.9 months (range 0.1-5 months; 75% within 2 months) from infection onset.

In conclusion, despite antibiotic prophylaxis, patients receiving thalidomide combination therapy can develop severe infections particularly pneumonia. Wide spectrum antibiotic therapy is effective in the majority of cases since viral or fungal infections are very rare. Patients with large size of disease, represented by high MC and low platelets count, are at higher risk of severe infection that in turn significantly increase the risk of DVT. Therefore, these patients at high-risk should receive more suitable antimicrobial prophylaxis.