Along with the evolution of immunophenotypic and molecular diagnostics, the assessment of Minimal Residual Disease (MRD) has progressively become a keystone in the clinical management of hematologic malignancies, enabling valuable post-therapy risk stratifications and guiding risk-adapted therapeutic approaches. However, specific prognostic values of MRD in different hematological settings, as well as its appropriate clinical uses (basically, when to measure it and how to deal with different MRD levels), still need further investigations, aiming to improve standardization and harmonization of MRD monitoring protocols and MRD-driven therapeutic strategies. Currently, MRD measurement in hematological neoplasms with bone marrow involvement is based on advanced highly sensitive methods, able to detect either specific genetic abnormalities (by PCR-based techniques and next-generation sequencing) or tumor-associated immunophenotypic profiles (by multiparametric flow cytometry, MFC). In this review, we focus on the growing clinical role for MFC-MRD diagnostics in hematological malignancies—from acute myeloid and lymphoblastic leukemias (AML, B-ALL and T-ALL) to chronic lymphocytic leukemia (CLL) and multiple myeloma (MM)—providing a comparative overview on technical aspects, clinical implications, advantages and pitfalls of MFC-MRD monitoring in different clinical settings.

Monocyte Distribution Width (MDW), a new cytometric parameter correlating with cytomorphologic changes occurring upon massive monocyte activation, has recently emerged as promising early biomarker of sepsis. Similar to sepsis, monocyte/macrophage subsets are considered key mediators of the life-threatening hyper-inflammatory disorder characterizing severe COVID-19. In this study, we longitudinally analyzed MDW values in a cohort of 87 COVID-19 patients consecutively admitted to our hospital, showing significant correlations between MDW and common inflammatory markers, namely CRP (p < 0.001), fibrinogen (p < 0.001) and ferritin (p < 0.01). Moreover, high MDW values resulted to be prognostically associated with fatal outcome in COVID-19 patients (AUC = 0.76, 95% CI: 0.66–0.87, sensitivity 0.75, specificity 0.70, MDW threshold 26.4; RR = 4.91, 95% CI: 1.73–13.96; OR = 7.14, 95% CI: 2.06–24.71). This pilot study shows that MDW can be useful in the monitoring of COVID-19 patients, as this innovative hematologic biomarker is: (1) easy to obtain, (2) directly related to the activation state of a fundamental inflammatory cell subset (i.e. monocytes, pivotal in both cytokine storm and sepsis immunopathogenesis), (3) well correlated with clinical severity of COVID-19-associated inflammatory disorder, and, in turn, (4) endowed with relevant prognostic significance. Additional studies are needed to define further the clinical impact of MDW testing in the management of COVID-19 patients.

Nucleophosmin (NPM1) gene mutations rarely occur in non-acute myeloid neoplasms (MNs) with <20% blasts. Among nearly 10,000 patients investigated so far, molecular analyses documented NPM1 mutations in around 2% of myelodysplastic syndrome (MDS) cases, mainly belonging to MDS with excess of blasts, and 3% of myelodysplastic/myeloproliferative neoplasm (MDS/MPN) cases, prevalently classified as chronic myelomonocytic leukemia. These uncommon malignancies are associated with an aggressive clinical course, relatively rapid progression to overt acute myeloid leukemia (AML) and poor survival outcomes, raising controversies on their classification as distinct clinico-pathologic entities. Furthermore, fit patients with NPM1-mutated MNs with <20% blasts could benefit most from upfront intensive chemotherapy for AML rather than from moderate intensity MDS-directed therapies, although no firm conclusion can currently be drawn on best therapeutic approaches, due to the limited available data, obtained from small and mainly retrospective series. Caution is also suggested in definitely diagnosing NPM1-mutated MNs with blast count <20%, since NPM1-mutated AML cases frequently present dysplastic features and multilineage bone marrow cells showing abnormal cytoplasmic NPM1 protein delocalization by immunohistochemical staining, therefore belonging to NPM1-mutated clone regardless of blast morphology. Further prospective studies are warranted to definitely assess whether NPM1 mutations may become sufficient to diagnose AML, irrespective of blast percentage.

The Philadelphia-negative myeloproliferative neoplasms (MPNs) are malignancies of the hematopoietic stem cell (HSC) arising as a consequence of clonal proliferation driven by somatically acquired driver mutations in discrete genes (JAK2, CALR, MPL). In recent years, along with the advances in molecular characterization, the role of immune dysregulation has been achieving increasing relevance in the pathogenesis and evolution of MPNs. In particular, a growing number of studies have shown that MPNs are often associated with detrimental cytokine milieu, expansion of the monocyte/macrophage compartment and myeloid-derived suppressor cells, as well as altered functions of T cells, dendritic cells and NK cells. Moreover, akin to solid tumors and other hematological malignancies, MPNs are able to evade T cell immune surveillance by engaging the PD-1/PD-L1 axis, whose pharmacological blockade with checkpoint inhibitors can successfully restore effective antitumor responses. A further interesting cue is provided by the recent discovery of the high immunogenic potential of JAK2V617F and CALR exon 9 mutations, that could be harnessed as intriguing targets for innovative adoptive immunotherapies. This review focuses on the recent insights in the immunological dysfunctions contributing to the pathogenesis of MPNs and outlines the potential impact of related immunotherapeutic approaches.

Kaposi sarcoma herpesvirus/human herpesvirus-8 (HHV-8) neoplastic and non-neoplastic disease in solid organ transplant (SOT) recipients can be life-threatening. We evaluated the seroprevalence of HHV-8 infection among donors (D) and recipients (R), the incidence of HHV-8 transmission/reactivation, and the clinical characteristics, management, and outcomes of HHV-8-related diseases, including Kaposi sarcoma herpesvirus-associated inflammatory cytokine syndrome (KICS), in consecutive SOT patients from 2011 to 2023. HHV-8 seroprevalence was 3.3% in 1349 donors and 8.4% in 1856 recipients screened (p<0.0001). Among the D+/R- group (n=49), 13 patients developed HHV-8-related diseases: 7 liver recipients had KICS, and 1 lung recipient had Kaposi sarcoma (KS) with subsequent KICS. Four KICS patients treated with rituximab survived, while the 3 patients not treated with rituximab died. Within the D-/R- group, out of 5 (0.3%) patients with non-donor-derived primary HHV-8 infection, 3 liver recipients developed KICS. In the R+ patients (n=155), 3 developed KS. In our cohort, 25/944 (2.6%) liver transplant recipients had a primary HHV-8 infection, and 10 of them (40%) developed KICS; 40% (4/10) of HHV-8 seropositive heart transplant recipients developed reactivation and 2 of them (50%) had fatal KS. Serologic screening and molecular surveillance of D+/R- patient groups facilitate early recognition and effective therapy of KICS.

(2015). NPM1 mutations may reveal acute myeloid leukemia in cases otherwise morphologically diagnosed as myelodysplastic syndromes or myelodysplastic/myeloproliferative neoplasms. Leukemia & Lymphoma: Vol. 56, No. 11, pp. 3222-3226.