Background: RSV remains a leading cause of infant hospitalization worldwide, and the recently approved nirsevimab could represent an effective and safe prophylactic strategy to prevent severe infections in the general neonatal population. Objectives: We conducted a retrospective observational monocentric pilot study in a mixed preterm/term birth cohort to add real-world evidence of the efficacy and safety of nirsevimab in preventing severe RSV infection. Methods: We included a total of 2035 consecutive infants admitted to the Neonatal Unit, University Hospital “San Giovanni di Dio e Ruggi d’Aragona”, Salerno, Italy, from November 2024 to April 2025. We evaluated 30-day safety profiles and season-wide RSV infection rates, and the outcomes were also compared to newborns’ birth rate in the two previous seasons (2022–2023 and 2023–2024). Results: After the introduction of nirsevimab, a lower RSV infection rate was reported compared to previous seasons, and no adverse effects were observed. Compared to previous seasons, the clinical outcomes were more favorable, as only one unvaccinated neonate with RSV infection required invasive ventilation. Conclusions: In this real-world analysis, we demonstrated a good short-term safety profile of nirsevimab, as well as a potentially high efficacy in the general neonatal population with lower RSV infection incidence. However, future studies are needed to better assess its long-term safety and season-wide efficacy.

Background/Objectives: Clonal evolution is mainly defined based on the appearance or expansion of clones harboring specific somatic mutations and/or cytogenetic abnormalities, whereas few studies have investigated immunophenotypic heterogeneity assessed by flow cytometry and its relationship with disease progression. In this study, flow cytometry immunophenotyping of acute myeloid leukemia (AML) was carried out to identify phenotypic subclones based on antigen expression and to investigate clonal sweep. Methods: A total of 24 patients diagnosed with AML followed at the Hematology and Transplant Center of Salerno were included. Bone marrow or peripheral blood specimens were subjected to flow cytometry immunophenotyping and leukemic cell characterization. Phenotypic profiles were also compared to molecular alterations detected by next-generation sequencing. Results: We found that flow cytometry-defined clonal heterogeneity was more complex than molecular heterogeneity at diagnosis and disease relapse. Flow cytometry enabled the identification of small phenotypic subclones that were not detected by molecular profiling and that, in several cases, expanded over time, consistent with a phenotypic clonal sweep. The presence of small clones was associated with shorter progression-free survival and overall survival. Conclusions: Flow cytometric clonal heterogeneity, especially the presence of small clones (defined by antigen expression from 2 to 30%), may serve as an additional prognostic factor in AML. Immunophenotyping integrated with molecular data may improve risk stratification, enhance measurable residual disease assessment, and contribute to a more personalized disease monitoring strategy.

Background/Objectives: Hematogones, B cell precursors, are considered a clock of bone marrow reconstitution after chemotherapy and hematopoietic stem cell transplantation (HSCT). Methods: In this retrospective observational monocentric study, we investigated the prognostic role of hematogone expansion after allogeneic HSCT and its association with clinical and molecular features. Results: Using a cut-off value of 0.1%, hematogones were detected in 60% of patients at the first re-evaluation after HSCT (median, 2.4%; range, 0.2–9.0%) and in 63% of subjects at the most recent evaluation (MRR) (median, 1.4%; range, 0.1–5.1%). In particular, prolonged hematogone expansion was associated with longer overall survival (p = 0.0043) and relapse-free survival (p = 0.0002). No associations were described between hematogone frequency and stem cell sources or acute or chronic graft versus host disease incidence. Conclusions: In conclusion, our results confirmed that hematogones mirrored bone marrow fitness and reconstitution ability; thus, they could be used as a prognostic marker of HSCT outcomes.

Background: Nirsevimab, a long-acting monoclonal antibody targeting respiratory syncytial virus (RSV), has recently been introduced as universal prophylaxis in newborns and infants. Although clinical trials have shown high efficacy and a favorable safety profile, real-world evidence remains limited. Objectives: Our Italian multicenter observational study included newborns eligible for nirsevimab prophylaxis during the 2025–2026 season and aimed to assess nirsevimab coverage, timing of administration, and short-term safety in routine clinical practice. The association between perinatal and environmental factors and neonatal intensive care unit (NICU) admission was also investigated, while RSV occurrence was evaluated as a descriptive and exploratory outcome. Methods: Eligible newborns were from four Italian hospitals during the 2025–2026 RSV season. We assessed nirsevimab coverage, timing of administration, RSV incidence, adverse events, and selected neonatal, perinatal, and maternal risk factors. Results: Among 1554 eligible newborns, 1462 received nirsevimab, corresponding to a coverage rate of 94.0%. The median age at administration was 3.0 days (IQR 2-6 days), with significantly delayed prophylaxis in preterm compared with term infants. During the observation period, two laboratory-confirmed RSV-associated bronchiolitis cases occurred, corresponding to a cumulative incidence of 0.13%. One case occurred in the immunized group and one in the non-immunized group. No adverse events following immunization were recorded. Conclusions: Nirsevimab prophylaxis achieved high coverage and showed a reassuring short-term safety profile in this real-world multicenter cohort. RSV infections were uncommon, and their very limited number prevents definitive conclusions regarding comparative effectiveness between immunized and non-immunized newborns. Prematurity was associated with delayed administration and greater need for intensive care, underscoring the importance of timely prophylaxis in vulnerable newborns.