Background/Objectives: Myeloproliferative neoplasms are a group of clonal myeloid malignancies that affect bone marrow and include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). PV is caused in most patients by the JAK2-V617F mutation and is characterized at the phenotypic level by overproduction and accumulation of red blood cells. PV is associated with significant morbidity, including risk of thrombotic events and of hematologic evolution (myelofibrotic or leukemic transformation) and reduced survival. In addition to the JAK2-V617F mutation, PV patients display additional molecular abnormalities. The aim of this study is to review recent studies investigating molecular abnormalities observed in PV. Methods: An extensive search of the most recent literature was performed, selecting and critically analyzing the most relevant studies. Results: The studies carried out in recent years have provided an extensive molecular analysis of PV, showing its heterogeneity, characterized in many patients by the presence of additional cytogenetic and gene mutations that contribute to the disease development and evolution. Conclusions: PV is a complex disease that needs to be carefully characterized at the molecular level at diagnosis, to be monitored in time to predict the risk for thrombotic complications and hematologic evolution and to receive an adequate treatment.

Blastic plasmocytoid dendritic cell neoplasm (BPDCN) is a rare myeloid malignancy, characterized by the involvement of multiple organs, including the skin, bone marrow and blood, lymph nodes and the central nervous system. According to tumor location, the disease is classified as skin-only, systemic-only, and skin and systemic. The cutaneous manifestations of disease are typical and are represented by violaceous single tumors or multiple plaques present in sun-exposed cutaneous areas. BPDCN is issued from the malignant transformation of dendritic cell progenitors and is diagnosed using the classical immunophenotypes CD123, CD4 and CD56 in addition to specific membrane markers of plasmocytoid dendritic cells. BPDCN is an aggressive disease and is associated with a short survival. Upfront therapies involve either chemotherapy regimens in fit patients and CD123-targeted therapies, including interleukin-3 conjugated with diphtheria toxin (Tagraxofusp, SL-401), or Pivekimab sunirine, an anti-IL-3R-drug conjugate, for both fit and unfit patients. Targeted treatments limit the toxicities of chemotherapy and allow the bridging of a consistent proportion of patients to hematopoietic stem cell transplantation, the only treatment associated with potential long-term survival.

Background/Objectives: Myeloproliferative neoplasms are a group of clonal myeloid malignancies that affect bone marrow and include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). PV is caused in most of patients by the JAK2-V617F mutation and is characterized at phenotypic level by overproduction and accumulation of red blood cells. PV is associated with significant morbidity, including risk of thrombotic events and of hematologic evolution (myelofibrotic or leukemic transformation) and reduced survival. In addition to JAK2-V617F mutation, PV patients display additional molecular abnormalities. The aim of this study is to review recent studies investigating molecular abnormalities observed in PV. Methods: An extensive search of the most recent literature was performed, selecting and critically analyzing the most relevant studies. Results: The studies carried out in the last years have provided an extensive molecular characterization of PV, showing its heterogeneity, characterized in many patients by the presence of additional cytogenetic and non-driver gene mutations that contribute to the disease development and evolution. Conclusions: PV is a complex disease that needs to be carefully characterized at molecular level at diagnosis, to be monitored in time to predict the risk for thrombotic complications and hematologic evolution and to receive an adequate treatment.

Background/Objectives: A complex karyotype (CK) in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) is defined as the presence of three or more unrelated chromosomal abnormalities in the absence of defining core-binding factor translocations. Frequently involved chromosomes include losses/deletions on chromosomes 5, 7 and 17. It is heavily associated with TP53 mutations, with 70-80% of CK cases in MDS/AML harboring TP53 mutations- Methods: An extensive literature search of the studies carried out in the last two decades has shown a consistent development of experimental and clinical studies aiming to characterize the biological properties and the clinical features of AML and MDS bearing CK and TP53 mutations. Results: These studies have greatly contributed to identify as separate entities AML and MDS bearing CK and or TP53 alterations. Particularly, the improvement in the methods of detection of chromosome aberrations has contributed to define the specific nature of the various chromosome abnormalities and to decipher the mechanisms of catastrophic events leading to gene rearrangements. Two types of CK were identified in AML and MDS, one more frequent associated with TP53 mutations (with poor prognosis) and another less frequent without TP53 mutations (with relatively better prognosis) Conclusions: The treatment of AML and MDS with CK and/or TP53 mutations alterations remains extremely challenging and the prognosis of these patients is dismal. The main aim of the various induction treatments explored in these patients is to bridge patients to allo-HSCT, the only therapeutic approach able to improve the survival of at least a part of these patients.

Background/Objectives: In recent years there has been a consistent development of clinical studies surrounding the incorporation of the B-cell lymphoma 2 (BCL-2) inhibitor venetoclax (VEN) into the treatment of acute myeloid leukemia (AML) Methods: A search of the literature showed a tremendous development of experimental and clinical studies evaluating the impact of VEN-based regimens in the treatment of AML patients. This review comprehensively analyzes the available scientific evidence—including prospective clinical trials, retrospective cohorts, and real-world studies—to summarize current knowledge on the efficacy and safety of venetoclax-based regimens in AML patients. Results: Recent studies have evaluated VEN-based regimens in newly diagnosed (ND) and refractory/relapsed (R/R) AML patients, showing the efficacy of these treatments. VEN with hypomethylating agents (HMAs) became the standard-of-care for elderly/unfit AML patients. Recent studies strongly support the effectiveness of VEN-based regimens in frontline treatment of adult AML patients eligible for intensive treatments. VEN-based therapies were also used in combination with targeted therapies, thus generating triplet therapeutic regimens that are under evaluation for the treatment of some AML subtypes. However, the response to VEN+HMAs is highly variable and in part depends on tumor genetics; some patients are resistant or relapse following VEN-based treatments and future studies will be required to develop therapeutic strategies able to circumvent resistance and to identify patients at high risk of relapse. Prospective randomized trials are required to establish the real efficacy of VEN in various clinical settings and to refine maintenance and discontinuation strategies, aiming to improve long-term outcomes and to make more safe treatments based on VEN.

Background/Objectives: Acute myeloid leukemia (AML) with myelodysplasia-related gene mutations (AML-MR), often referred to as secondary AML (s-AML) or AML-MRC, is an aggressive form of leukemia that typically arises from an antecedent myelodysplastic syndrome (MDS) but may also originate de novo. It is characterized by mutations in key genes associated with MDS that include some epigenetic regulators (ASXL1 and EZH2), splicing factors (SF3B1, SRSF2, U2AF1, and ZRSR2), and transcription factors (BCOR, RUNX1, and STAG2). The main objective of this review paper consists of analyzing recent studies that have improved the criteria for the characterization, definition, and classification of AML-MR. Methods: An extensive search of the most recent literature on the topic was performed, selecting and critically analyzing the most relevant studies. Results. The studies carried out in the last few years have provided an extensive molecular characterization of AML-MR, supporting sounder criteria for identification and a better definition with respect to other AML subtypes, particularly with respect to TP53-mutant AML. Conclusions: A unifying classification of AML-MR is now possible, allowing its identification as a unique, well-defined, and separate entity.

β-thalassemia and sickle cell disease are two inherited hematological diseases due to defective hemoglobin synthesis or to the production of hemoglobin with altered properties. These two conditions have prolonged survival with modern support therapies, albeit life-long, complex, expensive and resource-consuming. Studies carried out in the last three decades have shown that allogeneic hematopoietic stem cell transplantation (allo-HSCT) and gene therapy may offer a curative approach for these diseases. Allo-HSCT should be performed early in life to reduce disease-related complications like irreversible tissue damage due to iron overload in patients with transfusion-dependent β-thalassemia (TDT) and systemic vasculopathy in patients with sickle cell disease (SCD). HSCTs from a matched-sibling donor or a matched-unrelated donor represent the best therapeutic option; however, haploidentical HSCT in both TDT and SCD is now increasingly performed as a valuable and viable option for a larger number of these patients. An alternative curative strategy is based on gene therapy. These curative approaches, particularly those of gene therapy, are available only in a part of the world. Gene therapy diffusion is strongly limited by its high technological and infrastructure requirements and its very high cost. Criteria must be defined for the optimal selection of TDT and SCD patients for allo-HSCT or gene therapy.

Background: Chromosomal rearrangements involving lysine methyltransferase 2A (KMT2A) define a genetically distinct subset of acute myeloid leukemia (AML) in 10% of cases in adult patients; the frequency of KMT2A-r is higher in pediatric AML. Translocations involving the KMT2A locus at chromosome 11q23 result in the formation of a chimeric oncogene partner, where the N-terminal part of KMT2A is fused to a variety of translocation partners. The leukemogenic activity of KMT2A-fusion partners is related to their capacity to hyperactivate the expression of HOX-A and MEIS1 target genes, which stimulate the proliferation of hematopoietic stem cells. The oncogenic activity of KMT2A fusion proteins requires the binding with Menin, and this interaction can be targeted pharmacologically by small molecules acting as potent and selective Menin inhibitors. Methods: A search of the literature showed a marked development of experimental studies exploring the molecular pathogenesis of AML with KMT2A-r and of clinical studies evaluating new induction intensive treatments and the development of a targeted therapy based on Menin inhibitors. Results and Conclusions: In the present review article, we summarize our current understanding of the biology of KMT2A-r in AML development and the recent consistent progress made in the treatment of KMT2A-r AML through new chemotherapy regimens and targeted therapy using Menin inhibitors. However, the prognosis of older KMT2A-r AML patients remains poor and could be improved by drug combination studies including Menin inhibitors. Many encouraging observations derived from ongoing clinical trials with Menin inhibitors need to be confirmed through randomized clinical trials.

Complete or partial deletions of chromosome 7 (-7/del7q) represent the most frequent chromosomal abnormalities observed in myeloid neoplasms (MNs) and are associated with a poor prognosis. -7/del7q is observed in 10–15% of adult patients with myelodysplasia (MDS) or with acute myeloid leukemia (AML). The occurrence of -7/del7q is particularly frequent in pediatric MDS, often associated with germline mutations of GATA2 or SAMD9/SAMD9L genes. The disease biology of -7/del7q and the genes driving leukemic development have not been completely elucidated, but the haploinsufficiency of tumor suppressor genes located in chromosome 7 deleted regions seems to play a relevant role. The response to standard treatments based either on chemotherapy or hypomethylating agents plus Venetoclax is limited. No approved targeted therapies exist for patients with -7/del7q; however, some recent studies have discovered some vulnerabilities of these myeloid neoplasms than can be efficiently targeted.

Background/Objectives: Sickle cell disease (SCD) and β-thalassemia are autosomal recessive disorders of erythroid cells due to gene mutations occurring at the level of the β-globin gene. The severe forms of these hemoglobinopathies observed in individuals homozygous for these defective genes need intensive treatments, are associated with a poor quality of life, and allogeneic hematopoietic stem cell represents the only curative treatment option that can be offered to a limited proportion of patients. Methods: This work is a narrative review supported by a systematic literature search and analysis. Results: To bypass this limitation, autologous hematopoietic stem cell transplantation has been developed in these patients, in which patients' HSCs are harvested and genetically modified ex vivo, then transplanted back into patients after conditioning for stem cell transplantation. There are two different approaches for gene therapy of hemoglobinopathies, one based on gene addition or gene silencing using lentiviruses as vectors and the other based on gene editing strategies using CRISPR-Caspase 9 technology or base editing. Several gene therapy products have been successfully evaluated in these patients, achieving transfusion independence and correction of hematological abnormalities durable over time. Conclusions: Several gene therapy products have been approved for the treatment of SCD and β-thalassemic patients and offer potentially curative treatment for these patients.

The only cytogenetic alteration defining a subtype of a myelodysplastic syndrome is represented by the deletion of the long arm of chromosome 5 (del(5q)), now classified as MDS with isolated del(5q). This subtype is associated with a peculiar phenotype mainly dependent on the haploinsufficiency of several genes located on the deleted arm of chromosome 5. These patients show a good prognosis and respond to treatment with lenalidomide, but some cases progress to acute myeloid leukemia. Molecular studies have, in part, elucidated the heterogeneity of MDS with isolated del(5q), mainly related to the association with different co-mutations that may affect leukemic transformation and survival. In other MDS patients, del(5q) is combined with other chromosomal abnormalities, giving rise to a condition of complex karyotype, associated with frequent TP53 mutations and with a poor prognosis. Two different molecular pathways seem to be responsible for the generation of MDS with isolated del(5q) or of MDS with del(5q) associated with a complex karyotype.

The development of molecular profiling approaches for AML patients such as whole genome sequencing, whole exome sequencing and transcriptomic sequencing have greatly contributed to better understanding of leukemia development, progression and treatment responsiveness/resistance. These studies have generated a new knowledge about driver events operating in AML that can be translated into clinics, thus favoring the mutations; using this approach, more than 50% of older AML patients display molecular alterations, such as IDH1, IDH2, FLT3 (FLT3-TKD and FLT3-ITD), NPM1 and KMT2A rearrangements that can be targeted by specific drugs. Preclinical and clinical studies have supported the use of drugs targeting these molecular alterations as first-line therapy in association with induction chemotherapy in chemotherapy-fit patients or with a hypomethylating agent in association with a Bcl-2 inhibitor (Venetoclax) in chemotherapy-unfit patients. These studies have shown promising results that need to be confirmed through randomized clinical studies specifically involving the enrollment of older AML patients.

Acute myeloid leukemia (AML) is characterized by the clonal expansion of myeloid progenitors blocked at various stages of their differentiation process, and drugs that bypass this differentiation block are therapeutically efficient, as shown by retinoic acid and arsenic trioxide in acute promyelocytic leukemia. However, the successful application of differentiation therapy in APL has not translated into clinical benefit for other non-APL subtypes of AML, in which intensive chemotherapy regimens represent the standard of care. However, the development of molecular studies has led to the identification of therapeutic targets (such as mutated proteins and deregulated pathways) and has led to the generation of a new category of specific pharmacologic agents. Some of these agents, such as inhibitors of mutant isocitrate dehydrogenase (IDH1 and IDH2), lysine-specific demethylase-1 (LSD1), and Menin, have shown the capacity to induce leukemic cell differentiation and with significant therapeutic efficacy.

Multiple myeloma is a disease related to the proliferation of malignant plasma cells; in most patients, the disease is confined to the level of bone marrow. However, in a minority of patients, the malignant plasma cells are also localized outside the bone marrow, either at the level of peripheral blood (plasma cell leukemia) or at the level of soft tissues (extramedullary multiple myeloma). These two rare forms of aggressive MM (ultrahigh-risk (uHR) MM as MM leading to death within 24-36 months) are both associated with some molecular features and with a limited response to current treatments.

Chimeric antigen receptor (CAR) T-cell therapy has improved the outcomes of patients with relapsed/refractory B-cell lymphomas, B-cell acute lymphoblastic leukemia, and multiple myeloma. However, CAR-T cell therapy is also associated with distinct toxicities that contribute to morbidity and mortality. A large number of studies now define the different toxicities associated with CAR-T cell therapy and have, in part, clarified their mechanisms. In particular, cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are the two main acute toxicity events that occur after CAR-T cell infusion. Other CAR-T-related toxicities occur later after CAR-T cell infusion and include B-cell aplasia, hypogammaglobulinemia, infections, and cytopenias. Infections represent the main cause of non-relapse death observed in patients undergoing CAR-T cell therapy. Second primary malignancies are rare and are mainly represented by myeloid malignancies.

Plasma cell leukemia (PCL) is a rare and aggressive form of multiple myeloma (MM), characterized by the presence of malignant plasma cells in the peripheral blood. Until 2021, PCL was defined as plasmacytosis comprising at least 20% of the differential white blood cell count in peripheral blood. (CPCs). PCL was found in 2-4% of newly diagnosed MM cases. It can also develop from a preexisting, usually end-stage, MM, known as secondary PCL (sPCL), which exhibits distinct biological and clinical features. Both primary plasma cell leukemia (pPCL) and secondary plasma cell leukemia (sPCL) are very rare presentations of MM. According to the International Myeloma Working Group, plasma cell leukemia is generally diagnosed when the percentage of CPCs in peripheral blood exceeds 5%. PCL has a more aggressive clinical presentation than MM, involving more severe cytopenia, hypercalcemia, and renal failure. Higher tumor burden and proliferation activity in PCL are reflected by elevated levels of B2- B2-microglobulin and lactate dehydrogenase (LDH). Extramedullary localization at diagnosis is more common in pPCL and sPCL than in MM. Conversely, osteolytic lesions are less frequent in pPCL. The immunophenotype of PCL expresses the common MM markers, CD38 and CD138, but exhibits a more immature phenotype than MM. Molecularly, PCL lacks a specific marker but shows a markedly lower frequency of hyperploidy and significantly increased gains of chromosome 1 and translocations t(14;16) or t(14;20). Additionally, it has also been reported that the t(11;14) translocation occurs more frequently and is associated with a better prognosis. The recent therapy of PCL is similar to that of other high-grade myelomas, taking advantage of anti-proteasome, like bortezomib, an immunomodulator, like lenalidomide, and dexamethasone triplet + anti-CD38 antibody and/or cyclophosphamide, and hematopoietic stem cell transplantation. However, the results are not as good as in the other forms of myeloma.

Iron is required for several vital biological processes in all human cells. In mammals, a considerable number of proteins are involved in iron metabolism and utilize iron in many essential cellular processes, such as oxygen transport, mitochondrial respiration, gene regulation, and DNA synthesis or repair. Iron metabolism is a complex system finely regulated at both systemic and cellular levels. It involves the development of specialized mechanisms for iron absorption, transport, recycling, storage, and export, and protection against toxic compounds that can be generated during iron redox cycling in the presence of oxygen. The erythropoietic compartment consumes the majority of iron to support the high demand for hemoglobin synthesis. A tightly regulated system enables efficient iron uptake by erythroid cells and its subsequent processing for the synthesis of large amounts of heme, which is then incorporated into hemoglobin. A bidirectional regulatory system between erythropoiesis and iron metabolism ensures precise coordination between the two processes. This regulation is often disrupted in various anemic conditions.

The clinical use of T lymphocytes engineered with chimeric antigen receptors (CARs) has revolutionized the treatment of patients with refractory or relapsed hematological malignancies. CAR natural killer (CAR-NK) cells are NK cells engineered with CARs to specifically target cell antigens expressed on the membrane of tumor cells. CAR-NK cells could offer some advantages with respect to CAR-T cells, related to their specific and innate anti-tumor activity, availability as an “off the shelf” cellular therapy, reduced costs, and improved safety. Promising efficacy of CAR-Nk cell therapy was observed in clinical trials based on the treatment of some hematological malignancies. However, to date, the clinical experience of CAR-NK cell therapy has been preliminary, with the evaluation of only a limited number of patients. Furthermore, CAR-NK cell therapy has been limited by the short persistence of these cells and by the suboptimal cytotoxic activity of some CAR-NK preparations. Therefore, studies based on the enrollment of a number of patients is required to carefully assess and confirm the safety and the efficacy of CAR-NK cell therapy in hematological malignancies and to compare their efficacy with respect to allogeneic CAR-T cells.

Acute myeloid leukemia (AML), a heterogeneous and aggressive clonal disease, is predominantly observed in older individuals, with a median age at diagnosis of 68–69 years. With the aging population, there is a significant increase in the occurrence of some genetic alterations, including detrimental gene mutations and cytogenetic abnormalities, and a higher incidence of secondary AML (s-AML) and therapy-related AML (t-AML), compared to younger AML patients. Outcomes of AML patients and their response to therapy are associated with the molecular features of AML subtypes and with individual variables. The current criteria for risk classification predict outcomes in younger AML patients treated with intensive chemotherapy but are less predictive for older AML patients treated with lower-intensity treatments. Thus, this review analyzes and discusses the development of new risk stratification models adapted to the study of older AML patients and how these new criteria may significantly contribute to a more rational classification and treatment of older AML patients.

Background/Objectives: Sickle cells disease (SCD) and -thalassemia are autosomal recessive disorders of erythroid cells due to gene mutations occurring at the level of the -globin gene. The severe forms of these hemoglobinopathies observed in individuals homozygous for these defective genes need intensive treatments, are associated with a poor quality of life and allogeneic hematopoietic stem cell represents the only curative treatment option that can be offered only to a limited proportion of patients. Methods: This work is a narrative review supported by a systematic literature search and analysis. Results: To bypass this limitation, autologous hematopoietic stem cell transplantation has been developed in these patients in which patients’ HSCs are harvested and genetically modified ex vivo, then transplanted back into patients after conditioning for stem cell transplantation. There are two different approaches for gene therapy of hemoglobinopathies’, one based on gene addition or gene silencing using lentiviruses as vectors and the other based on gene editing strategies using CRISPR-Caspase 9 technology or base editing. Several gene therapy products have been successfully evaluated in these patients achieving transfusion independence and correction of hematological abnormalities durable in the time. Conclusions Several gene therapy products have been approved for the treatment of SCD and -thalassemic patients and offer a potentially curative treatment for these patients.