The aim of this study was to identify risk factors for mortality in patients suffering from hematological malignancies (HMs) with bloodstream infections (BSIs) caused by Klebsiella pneumoniae (KP). We conducted a prospective cohort study on KP BSI in 13 Italian hematological units participating in the HEMABIS registry–SEIFEM group. The outcome measured was death within 21 days of BSI onset. Survivor and non‐survivor subgroups were compared and Cox regression analysis was conducted to identify independent predictors of mortality. A total of 278 episodes of KP BSI were included in the study between January 2010 and June 2014. We found that 161 (57.9%) KP isolates were carbapenem resistant (CRKP). The overall 21‐day mortality rate was 36.3%. It was significantly higher for patients with CRKP BSI (84/161, 52.2%) than for those with BSI caused by carbapenem susceptible KP (CSKP) (17/117, 14.5%; P < 0.001). Septic shock (HR 3.86), acute respiratory failure (HR 2.32), inadequate initial antimicrobial therapy (HR 1.87) and carbapenem resistance by KP isolates (HR 1.85) were independently associated with mortality. A subanalysis was conducted in only 149 patients with CRKP BSI who had received ≥48 hr of adequate antibiotic therapy, and combination therapy was independently associated with survival (HR 0.32). Our study shows that in recent years carbapenem resistance has dramatically increased in HM patients with KP BSI in Italy and is associated with a worse outcome. The optimal management of such infections and the definition of new empirical/targeted antimicrobial strategies in HM patients can still be considered unmet clinical needs. Am. J. Hematol. 91:1076–1081, 2016.

Acute myeloid leukemia (AML) with mutated NPM1 shows distinctive biologic and clinical features, including absent/low CD34 expression, the significance of which remains unclear. Therefore, we analyzed CD34⁺ cells from 41 NPM1-mutated AML. At flow cytometry, 31 of 41 samples contained less than 10% cells showing low intensity CD34 positivity and variable expression of CD38. Mutational analysis and/or Western blotting of purified CD34⁺ cells from 17 patients revealed NPM1-mutated gene and/or protein in all. Immunohistochemistry of trephine bone marrow biopsies and/or flow cytometry proved CD34⁺ leukemia cells from NPM1-mutated AML had aberrant nucleophosmin expression in cytoplasm. NPM1-mutated gene and/or protein was also confirmed in a CD34⁺ subfraction exhibiting the phenotype (CD34⁺/CD38⁻/CD123⁺/CD33⁺/CD90⁻) of leukemic stem cells. When transplanted into immunocompromised mice, CD34⁺ cells generated a leukemia recapitulating, both morphologically and immunohistochemically (aberrant cytoplasmic nucleophosmin, CD34 negativity), the original patient9s disease. These results indicate that the CD34⁺ fraction in NPM1-mutated AML belongs to the leukemic clone and contains NPM1-mutated cells exhibiting properties typical of leukemia-initiating cells. CD34⁻ cells from few cases (2/15) also showed significant leukemia-initiating cell potential in immunocompromised mice. This study provides further evidence that NPM1 mutation is a founder genetic lesion and has potential implications for the cell-of-origin and targeted therapy of NPM1-mutated AML.

Limited data are available on breakthrough COVID-19 in patients with hematologic malignancy (HM) after anti–severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Adult patients with HM, ≥1 dose of anti-SARS-CoV-2 vaccine, and breakthrough COVID-19 between January 2021 and March 2022 were analyzed. A total of 1548 cases were included, mainly lymphoid malignancies (1181 cases, 76%). After viral sequencing in 753 cases (49%), the Omicron variant was prevalent (517, 68.7%). Most of the patients received ≤2 vaccine doses before COVID-19 (1419, 91%), mostly mRNA-based (1377, 89%). Overall, 906 patients (59%) received COVID-19-specific treatment. After 30-day follow-up from COVID-19 diagnosis, 143 patients (9%) died. The mortality rate in patients with the Omicron variant was 7.9%, comparable to other variants, with a significantly lower 30-day mortality rate than in the prevaccine era (31%). In the univariable analysis, older age (P < .001), active HM (P < .001), and severe and critical COVID-19 (P = .007 and P < .001, respectively) were associated with mortality. Conversely, patients receiving monoclonal antibodies, even for severe or critical COVID-19, had a lower mortality rate (P < .001). In the multivariable model, older age, active disease, critical COVID-19, and 2-3 comorbidities were correlated with a higher mortality, whereas monoclonal antibody administration, alone (P < .001) or combined with antivirals (P = .009), was protective. Although mortality is significantly lower than in the prevaccination era, breakthrough COVID-19 in HM is still associated with considerable mortality. Death rate was lower in patients who received monoclonal antibodies, alone or in combination with antivirals.

To analyze the efficacy of antifungal prophylaxis (AFP) with posaconazole and itraconazole in a real-life setting of patients with acute myeloid leukemia (AML) during the first induction of remission. From January 2010 to June 2011, all patients with newly diagnosed AML were consecutively registered and prospectively monitored at 30 Italian hematological centers. Our analysis focused on adult patients who received intensive chemotherapy and a mold-active AFP for at least 5 days. To determine the efficacy of prophylaxis, invasive fungal disease (IFD) incidence, IFD-attributable mortality, and overall survival were evaluated. In total, 515 patients were included in the present analysis. Posaconazole was the most frequently prescribed drug (260 patients [50%]) followed by fluconazole (148 [29%]) and itraconazole (93 [18%]). When comparing the groups taking posaconazole and itraconazole, there were no significant differences in the baseline clinical characteristics, whereas there were significant differences in the percentage of breakthrough IFDs (18.9% with posaconazole and 38.7% with itraconazole, P< .001). The same trend was observed when only proven/probable mold infections were considered (posaconazole, 2.7% vs itraconazole, 10.7%, P= .02). There were no significant differences in the IFD-associated mortality rate, while posaconazole prophylaxis had a significant impact on overall survival at day 90 (P= .002). During the last years, the use of posaconazole prophylaxis in high-risk patients has significantly increased. Although our study was not randomized, it demonstrates in a real-life setting that posaconazole prophylaxis confers an advantage in terms of both breakthrough IFDs and overall survival compared to itraconazole prophylaxis. NCT01315925.