POEMS syndrome is a rare monoclonal plasma cell disorder with unique symptoms distinct from other plasma cell neoplasms. To identify and find the transcriptional features of clonal plasma cells in POEMS syndrome (POEMS clones), single-cell RNA sequencing was performed on patient-derived bone marrow plasma cells. POEMS clones were identified in 5 out of 10 patients, and the proportions of POEMS clones in the plasma cells were markedly smaller than that of other plasma cell malignancies such as multiple myeloma and MGUS. The transcriptional features of POEMS clones differed from those of other plasma cell diseases, and representative MM-related oncogenes were not upregulated in POEMS clones. Notably, POEMS clones are negative for CD19 and express significantly lower MHC-II levels than normal plasma cells; thus, CD19⁻ HLA-DR^lo is confirmed as a useful marker to identify POEMS clones in patients. These findings unveil the unique features of POEMS clones and contribute to the understanding of the pathogenesis of POEMS syndrome.

Pola-BR (polatuzumab vedotin, bendamustine, and rituximab) therapy received approval for relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) in Japan in March 2021. There have been few reports on the efficacy and safety of Pola-BR therapy in Japanese clinical practice. A retrospective analysis was performed on twenty-nine patients with R/R DLBCL who received Pola-BR therapy at our institution (intent to cellular immunotherapy cohort: 20 patients, stand-alone treatment cohort: nine patients). The overall response rate was 69.0% (complete response 27.6%). The median progression-free survival was 5.1 months, with a 9.5-month median overall survival. In the intent to cellular immunotherapy cohort, 11 of 19 patients received chimeric antigen receptor T-cell (CAR-T) infusions, and one patient received allogeneic stem cell transplantation. Four patients received Pola-BR therapy, including bendamustine before leukapheresis, and all produced CAR-T products successfully. 3 of the 28 patients experienced grade3 or higher adverse events, and two required treatment discontinuation. Our single institution, a real-world cohort of R/R DLBCL patients showed high efficacy outcomes and a tolerable toxicity profile for Pola-BR therapy, which is comparable to previous studies. More cases are needed to determine its impact on CAR-T therapy and stem cell transplantation.

Objective: We sought to assess the safety and feasibility of outpatient management in Japanese patients with relapsed/refractory lymphoma who had received pegfilgrastim after salvage therapy. Method: This was a single-center, open-label, non-randomized, prospective interventional analysis. Patients were completely hospitalized for cycle 1 of chemotherapy. Those who met the outpatient management criteria (outpatient group) were subsequently admitted to the hospital for chemotherapy cycles but were discharged after each cycle was completed. The inpatient group was discharged when white blood cell and platelet counts improved. Pegfilgrastim was given as a single 3.6 mg dose by subcutaneous injection 2 days after the completion of each chemotherapy cycle. Results: The percentage of outpatient management days (primary endpoint) ranged from 68.2%-75.0% in the outpatient group and 28.6%-50.0% in the inpatient group. According to the secondary endpoints, there were no hospitalizations due to febrile neutropenia during the outpatient period. There were no major safety concerns raised. Conclusions: For patients with relapsed/refractory lymphoma, pegfilgrastim administration after salvage therapy in an outpatient setting was feasible and safe for those who satisfied the outpatient management criteria.

A 69-year-old male patient was referred to our hospital for further examination of hypoglycemia, splenomegaly, and para-aortic lymphadenopathy. The patient was diagnosed with diffuse large B-cell lymphoma (DLBCL) by para-aortic lymph node biopsy. Hypoglycemia was refractory to glucose supplementation but improved shortly after chemotherapy. This situation suggested that hypoglycemia was caused by lymphoma. We compared the expression levels of glyceraldehyde 3-phosphate dehydrogenase, a glycolytic enzyme whose expression is positively correlated with the glycolytic activity of cells, between the current case and two cases of DLBCL without hypoglycemia to explore the possibility that hypoglycemia was due to intense glucose consumption by lymphoma cells through their high glycolytic activity. Results revealed substantially higher expression levels of glyceraldehyde 3-phosphate dehydrogenase in the current case than in DLBCL without hypoglycemia, suggesting that the glycolytic pathway was enhanced in the current case. These results implied that intense glucose consumption by lymphoma cells through their high glycolytic activity causes hypoglycemia.

Invasive pneumococcal diseases (IPDs) after allogeneic hematopoietic stem cell transplantation have high fatality rates and often develop late after transplantation. The patient was a 58-year-old female. Fourteen years ago, she underwent bone marrow transplantation from a HLA-DR 1-antigen mismatched unrelated donor for myelodysplastic syndrome. She developed pneumonia, chronic graft-versus-host disease, and hypogammaglobulinemia. She received 23-valent pneumococcal capsular polysaccharide vaccine 11 and 6 years earlier. She was presented to our emergency room with fever. Her blood culture was positive for pneumococcus, and she was diagnosed with an IPD. The patient received antibiotic treatment but died on the third day of hospitalization. Because of its seriousness, pneumococcal infection should receive attention even 10 or more years after transplantation. Preventive approaches such as vaccination and early intervention at the time of diagnosis are important.

The unbalanced translocation der (1;7)(q10;p10) is a characteristic cytogenetic abnormality observed in myelodysplastic syndrome (MDS). A 63-year-old man presented to our hospital with fever and lung disease. The chromosomal analysis of bone marrow cells showed 46, XY, +1, der (1;7)(q10;p10) in all four metaphases. The patient was diagnosed with MDS. Bronchoscope examination revealed organizing pneumonia. The patient’s eosinophil count rose to 39% after 30 days. His fever and dyspnea worsened, and a skin rash (systemic erythema) appeared simultaneously. Therefore, the patient was commenced on azacitidine and corticosteroids. Although treatment with both drugs could control disease progression transiently, the WT-1 value and the percentage of myeloblasts in the patient’s bone marrow increased. Therefore, the patient received hematopoietic stem cell transplantation from his haplo-identical donor daughter. Some reports have demonstrated that patients with MDS with der (1;7)(q10;p10) have better prognosis than those with other abnormalities, such as −7/7q−. However, reported cases with severe complications show very poor prognosis. MDS with der (1;7)(q10;p10) complicated by eosinophilia and organizing pneumonia have not been reported, and its prognosis is expected to be very poor. Our case suggests that such cases might quickly require hematopoietic stem cell transplantation before the disease worsens.

Double minute chromosomes (dmin) are small, acentric, and extrachromosomal fragments that frequently mediate oncogene amplification and induce rapid disease progression with poor prognosis, although they are infrequent in myeloid neoplasms. An 81-year-old woman with anemia and thrombocytopenia was admitted to our hospital. Bone marrow examination showed 54.0% of the blasts. She was diagnosed with acute myeloid leukemia (French-American-British classification, M2; World Health Organization classification, acute myeloid leukemia [AML], not otherwise specified, AML with maturation). Chromosomal analysis revealed the presence of 3-45 dmin in the background of 46 and XX in 14 out of 20 metaphases examined. Spectral karyotyping examination demonstrated that the dmins were derived from chromosome 8. Fluorescence in situ hybridization (FISH) targeting the MYC gene demonstrated that dmins contained full-length MYC genes with multiple signals. Finally, she was diagnosed with AML with dmin via MYC amplification and was administered with venetoclax plus azacitidine chemotherapy. After two cycles of the regimen, FISH found no MYC amplification signals, indicating her state being in cytogenetic remission. At present, she has finished four cycles of the regimen and remained in complete remission. Venetoclax plus azacitidine could be an effective regimen for the poor prognosis of AML with dmin through MYC amplification.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) has many subtypes with diverse clinical and biological features and outcomes. Next generation sequencing has revealed several novel subtypes, including the ZNF384 and MEF2D rearrangements. The clinical characteristics and outcomes of the largest series of BCP-ALL cases with ZNF384 and MEF2D rearrangements in an international collaborative study are described here. Patients with ZNF384 rearrangements appear to express various leukemic phenotypes, including BCP-ALL (with or without abnormal expression of myeloid markers) and B/myeloid mixed phenotype acute leukemia. We provide strong evidence that among BCP-ALL patients with a ZNF384 fusion, the partner gene is associated with demographic features and influences the outcome; particularly the EP300-ZNF384 fusion is associated with a low risk of relapse. MEF2D rearrangements have been primarily described in children and young adults with BCP-ALL. Previous research has suggested that patients with MEF2D-BCL9 fusion have a high risk of relapse. Despite having the MEF2D-HNRNPUL1 fusion gene, the prognosis was favorable. Improved diagnostic genomic testing will enable future prospective studies to clarify the clinical significance of the ZNF384 and MEF2D rearrangements in childhood and young adult BCP-ALL.

Fanconi anemia (FA), a hereditary bone marrow failure syndrome, has been suggested to be caused by a defect in DNA repair that removes endogenous DNA damage due to aldehydes. In seven Japanese children with aplastic anemia who clinically resembled FA, we identified biallelic variants of the ADH5 gene, encoding formaldehyde degrading enzyme, and a heterozygous ALDH2 variant (rs671). We conclude that the combined defects in ADH5/ALDH2 caused a new disorder now termed Aldehyde Degradation Deficiency Syndrome (ADDS). We suggest that this disease is caused by defective removal of formaldehyde produced by histone demethylation during hematopoietic cell differentiation. Therapeutic targeting of formaldehyde may reduce the hematopoietic deficits of FA as well as ADDS.

Recurrent mutations in genes encoding key splicing factors, SF3B1, SRSF2, U2AF1, and ZRSR2 have been found in a variety of cancers, particularly in hematologic malignancies, including myelodysplastic syndromes, chronic myelomonocytic leukemia, acute myeloid leukemia, and chronic lymphocytic leukemia. Global mis-splicing of mRNAs targeted by aberrant splicing factors partly contributes to leukemogenesis through decrease protein expression of tumor suppressors and epigenetic modifiers, caused by mRNAs degradation of aberrantly spliced. Some of the mis-spliced mRNAs influence intracellular oncogenic pathways and cellular processes through a dysregulated expression of associated proteins, whereas others influence the function of co-mutated genes such as aberrant transcriptional regulators. Spliceosomal disruption is common in many cancers, making spliceosome an appealing therapeutic target. The findings that spliceosomal mutant cells rely on wild-type splicing machinery for survival and that splicing factor mutations occur in a mutually exclusive manner strongly suggest that inhibiting wild-type splicing machinery causes synthetic lethality in cancer cells with these mutations. We discuss the characteristics and oncogenic mechanisms of splicing factor mutations, as well as the development of novel treatment strategies targeting aberrant splicing factors in hematologic malignancies.

Coagulation factor V (FV) is both procoagulant and anticoagulant functions. Congenital FV abnormality, which are caused by mutations in the FV gene, are characterized by a tendency to bleed. However, FV-R506Q (FV_Leiden) is the most common FV abnormality that eliminates an activated protein C (APC) cleavage site, resulting in the occurrence of deep venous thrombosis (DVT). In Japan, the thrombotic predisposition caused by FV_Leiden and FV molecular abnormalities was believed to be nonexistent. We did, however, report the first case in Japan of a young patient with FV abnormality-related thrombosis. The recurrent DVT in this case was caused by a novel mutation of FV-W1920R (FV_Nara), located in the C1 domain and far from the APC cleavage sites. We considered the possibility that there were cases of FV-related thrombotic predisposition that had gone undetected in Japan. We thoroughly examined FV-related anticoagulant function to understand the pathogenesis of thrombosis caused by FV abnormality. Furthermore, using recombinant thrombomodulin, we successfully developed a novel assay with clot waveform analysis for the rapid detection of FV deficiency with APC resistance. Other FV abnormality-related thrombosis has been reported in Japan in recent years, and we hope to further clarify the FV-related thrombotic predisposition in the future.

By carrying a systemic circulation, hematopoietic and vascular systems coordinately govern the functional organ connections in the body. Blood vessels play an important role in the development, regeneration, and maintenance of organs by acting as conduits for environmental factors in the blood to tissues and secreting organ-specific cytokines as angiocrine signals. Recently, it has become clear that vascular endothelial cells, which are the main constituent cells of the blood vessels and play a role in homeostasis, are diverse. It has also been established that the cells of stem cell fraction exist in endothelial cells. The vascular endothelial cells in various organs are functionally different. For example, it has been discovered that sinusoidal blood vessels in the liver produce coagulation factor VIII as an organ-specific vascular function. Determining how such tissue-/organ-specific function of the endothelial cells is induced is a topic of interest in the vascular field of study.

Enhancer of zeste homolog (EZH), a subunit of polycomb repressive complex 2 (PRC2), suppresses gene expression by methylation of H3K27. EZH is closely associated with B-cell development and pathogenesis of certain malignant lymphomas. In follicular lymphoma (FL), gain-of-function mutation and upregulation of EZH2 are observed in approximately 30% and 15% of cases, respectively. Moreover, one-third of diffuse large B-cell lymphomas carry an EZH2 mutation, mostly co-existing with translocation involving Bcl-2. Genome-wide trimethylation of H3K27 is a unique characteristic induced by upregulation of both EZH2 and EZH1, and is responsible for more than half of the gene suppression that occurs in adult T-cell leukemia/lymphoma (ATL). Inhibition of EZH can reduce H3K27 methylation and subsequently restore epigenetically suppressed genes. Currently, an EZH2 inhibitor and dual EZH1/2 inhibitor have been clinically used to treat relapsed/refractory FL and ATL, respectively. EZH-targeted treatment for lymphoma has only just begun, and further development of these drugs for various other malignancies, both alone and in combination with other therapeutics, is ongoing.

Adult T-cell leukemia-lymphoma (ATL) is a highly aggressive peripheral T-cell neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1) infection occurring in approximately 5% of patients after prolonged latent period. ATL relapses within a short period despite its transient response to multiagent chemotherapy and the prognosis is extremely poor due to anticancer drug resistance and immunodeficiency. Although novel agents with different mechanisms, such as molecular targeted agents, have improved the prognosis, the number of cured patients remains limited. Hematopoietic stem cell transplantation resulted in long-term remission, whereas its indication is limited due to treatment-related mortality. As most ATL patients are of advanced age, development of a lesser toxic treatment is necessary. Therefore, we developed a novel therapeutic dendritic cell vaccine targeting the HTLV-1 Tax antigen. The safety profile has been confirmed in a pilot and phase I clinical studies, and a promising long-term clinical efficacy has also been obtained. This novel vaccine is a noninvasive, long-lasting therapy for ATL and can potentially be extended to different applications for low-grade ATL and high-risk HTLV-1 carriers.