Loss of or decrease in CD30 expression in four patients with anaplastic large cell lymphoma after brentuximab vedotin-containing therapy.

Brentuximab vedotin (BV), CD30 specific antibody drug conjugate, has been used to treat anaplastic large cell lymphoma (ALCL) and classic Hodgkin lymphoma (CHL); it is also used in the treatment of other CD30-positive peripheral T-cell lymphomas. We aimed to investigate the incidence and clinicopathological characteristics of patients with ALCL or CHL with loss of or decrease in CD30 expression after BV-containing therapy. Twelve and nine patients with refractory/relapsed CHL and ALCL, respectively, were analyzed after receiving BV-containing therapy. In four ALCL patients (44%), CD30 expression was lost/decreased in re-biopsy materials, including one with complete loss and three with a reduction of less than 20%. All 12 CHL patients showed consistent CD30 expression levels after BV treatment. Compared with five ALCL patients with consistent CD30 expression, four ALCL patients with a loss of/decrease in CD30 expression received a higher cumulative dose of BV (P = 0.014) and revealed a lower intensity of CD30 expression in initial biopsy materials (P = 0.017). The subtypes of ALCL (ALK positive, ALK negative, and primary cutaneous) were not related to the loss of/decrease in CD30 expression. In conclusion, 44% of ALCL patients, regardless of histological subtypes, showed a loss of/decrease in CD30 expression after receiving BV-containing therapy, but this phenomenon was not observed in CHL patients. A higher cumulative dose of BV and a lower amount of CD30 antigen in tumor cells in the initial biopsy materials might be predictors of a loss of/decrease in CD30 expression in ALCL patients.

Exploring the mechanistic link between SF3B1 mutation and ring sideroblast formation in myelodysplastic syndrome.

Acquired sideroblastic anemia, characterized by bone marrow ring sideroblasts (RS), is predominantly associated with myelodysplastic syndrome (MDS). Although somatic mutations in splicing factor 3b subunit 1 (SF3B1), which is involved in the RNA splicing machinery, are frequently found in MDS-RS, the detailed mechanism contributing to RS formation is unknown. To explore the mechanism, we established human umbilical cord blood-derived erythroid progenitor-2 (HUDEP-2) cells stably expressing SF3B1K700E. SF3B1K700E expressing cells showed higher proportion of RS than the control cells along with erythroid differentiation, indicating the direct contribution of mutant SF3B1 expression in erythroblasts to RS formation. In SF3B1K700E expressing cells, ABCB7 and ALAS2, known causative genes for congenital sideroblastic anemia, were downregulated. Additionally, mis-splicing of ABCB7 was observed in SF3B1K700E expressing cells. ABCB7-knockdown HUDEP-2 cells revealed an increased frequency of RS formation along with erythroid differentiation, demonstrating the direct molecular link between ABCB7 defects and RS formation. ALAS2 protein levels were obviously decreased in ABCB7-knockdown cells, indicating decreased ALAS2 translation owing to impaired Fe-S cluster export by ABCB7 defects. Finally, RNA-seq analysis of MDS clinical samples demonstrated decreased expression of ABCB7 by the SF3B1 mutation. Our findings contribute to the elucidation of the complex mechanisms of RS formation in MDS-RS.

Congenital sideroblastic anemia model due to ALAS2 mutation is susceptible to ferroptosis.

X-linked sideroblastic anemia (XLSA), the most common form of congenital sideroblastic anemia, is caused by a germline mutation in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene. In XLSA, defective heme biosynthesis leads to ring sideroblast formation because of excess mitochondrial iron accumulation. In this study, we introduced ALAS2 missense mutations on human umbilical cord blood-derived erythroblasts; hereafter, we refer to them as XLSA clones. XLSA clones that differentiated into mature erythroblasts showed an increased frequency of ring sideroblast formation with impaired hemoglobin biosynthesis. The expression profiling revealed significant enrichment of genes involved in ferroptosis, which is a form of regulated cell death induced by iron accumulation and lipid peroxidation. Notably, treatment with erastin, a ferroptosis inducer, caused a higher proportion of cell death in XLSA clones. XLSA clones exhibited significantly higher levels of intracellular lipid peroxides and enhanced expression of BACH1, a regulator of iron metabolism and potential accelerator of ferroptosis. In XLSA clones, BACH1 repressed genes involved in iron metabolism and glutathione synthesis. Collectively, defective heme biosynthesis in XLSA clones could confer enhanced BACH1 expression, leading to increased susceptibility to ferroptosis. The results of our study provide important information for the development of novel therapeutic targets for XLSA.

TM5614, an Inhibitor of Plasminogen Activator Inhibitor-1, Exerts an Antitumor Effect on Chronic Myeloid Leukemia.

Chronic myeloid leukemia (CML) is triggered by t(9;22)(q34;q11.2) translocation, leading to the formation of the BCR-ABL1 fusion gene. Although the development of BCR-ABL1 tyrosine kinase inhibitors (TKIs) has dramatically improved the prognosis of CML, the disease could often relapse, presumably because leukemic stem cell fraction of CML (CML-LSC) may reside in specific niches, and also acquire an ability to resist the cytotoxic agents. Recently a study indicated that pharmacological inhibition of plasminogen activator inhibitor-1 (PAI-1, also known as SERPINE1) would cause detachment of CML-LSCs from their niche by inducing maturation of membrane-type matrix metalloprotease-1 (MT1-MMP), leading to increased susceptibility of CML-LSCs against TKIs. However, the direct antitumor effect of PAI-1 inhibition in CML remains unclear. Because PAI-1 mRNA expression was lower in CML cell line (K562) than bone marrow mononuclear cells derived from CML patients, we established K562 cell clones stably expressing exogenous PAI-1 (K562/PAI-1). We found that TM5614 treatment significantly suppressed cell proliferation and induced apoptosis in K562/PAI-1 cells, accompanied by increased activity of Furin protease, which is a known target of PAI-1. Besides processing mature MT1-MMP, Furin is in charge of cleaving the NOTCH receptor to form a heterodimer before exporting it to the cell surface membrane. In K562/PAI-1 cells, TM5614 treatment increased NOTCH1 intracellular domain (NICD) protein expression as well as NOTCH1 target of HEY1 mRNA levels. Finally, forced expression of either Furin or NICD in K562/PAI-1 cells significantly inhibited cell proliferation and induced apoptosis. Collectively, PAI-1 inhibition may have an antitumor effect by modulating the Furin/NICD pathway.

JAK2 mutation-positive polycythaemia vera associated with IgA vasculitis and nephrotic syndrome: a case report.

We report a case of polycythaemia vera (PV) associated with IgA vasculitis. A 45-year-old man was admitted for evaluation of abdominal pain and palpable purpura. IgA vasculitis was diagnosed, and oral prednisolone therapy (30 mg/day) was initiated. On day 6, the patient developed left hemiparesis, and magnetic resonance imaging revealed acute cerebral infarction. Bone marrow biopsy results and the identification of a Janus kinase 2 (JAK2) mutation led to the diagnosis of PV. Despite steroid therapy, urine protein levels increased to 15 g/g・Cre. Renal biopsy demonstrated mild mesangial proliferation with IgA deposits, but immunosuppressive therapy was partially effective. This case suggests that PV can be a complication of IgA vasculitis and that preventive measures for thrombosis should be taken in such cases.

Umbilical Cord Blood Transplantation Using Reduced-Intensity Conditioning without Antithymocyte Globulin in Adult Patients with Severe Aplastic Anemia.

Umbilical cord blood transplantation (UCBT) is a possible option for patients with aplastic anemia (AA) without a related or unrelated HLA-matched donor, particularly if immunosuppressive therapy (IST) has failed or transplantation is urgently needed. However, a higher rate of graft failure after UCBT remains a major problem, and the optimal conditioning regimen for stable engraftment after UCBT has not been established. Here we investigated 6 adult patients with AA who underwent UCBT using a reduced-intensity conditioning (RIC) regimen comprising fludarabine 125 mg/m2, cyclophosphamide 120 mg/kg, and 4 Gy of total body irradiation (Flu/CY/TBI4Gy) without antithymocyte globulin (ATG). Five patients underwent UCBT after IST failure, and 1 patient underwent UCBT as a first-line treatment due to a fulminant clinical finding of a neutrophil count of 0, despite granulocyte colony-stimulating factor administration. Regarding graft-versus-host disease (GVHD) prophylaxis, 2 patients received tacrolimus plus short-term methotrexate and 4 patients received tacrolimus plus mycophenolate mofetil, and all patients achieved sustained engraftment of both neutrophils and platelets, at a median of 17.5 days (range, 14 to 37 days) and 38.5 days (range, 31 to 86 days), respectively, with complete donor chimerism confirmed in all patients at a median of 14 days (range, 14 to 32 days). Three patients developed grade II acute GVHD (aGVHD), but grade III/IV aGVHD was not observed, whereas 4 patients developed chronic GVHD involving only skin. At the time of this report, all 6 patients were alive without the need for blood transfusion, at a median follow-up of 16 months (range, 12 to 131 months). Although further study is needed, our findings suggest that conditioning with Flu/CY/TBI4Gy without ATG might allow stable engraftment in UCBT for adults with AA.

Post-allogeneic stem cell transplant extramedullary relapse of acute megakaryoblastic leukemia initially detected by elevated WT1 mRNA levels in peripheral blood.

An 18-year-old male was admitted to our hospital for fever, and was diagnosed with acute megakaryoblastic leukemia (AML M7) based on the presence of CD42a and CD61 positive myeloblasts in peripheral blood (PB). Induction chemotherapy at our hospital resulted in complete remission (CR). Subsequently, he underwent unrelated HLA-DR one locus-mismatched allogeneic bone marrow (BM) transplantation. Although CR was maintained without development of graft-versus-host disease (GvHD), the WT1 mRNA level in PB was elevated on post-transplant day 134. As BM aspiration performed 1 week later confirmed maintenance of CR, and because the WT1 mRNA level in BM was not high in comparison with PB, we suspected extramedullary relapse. PET-CT demonstrated a thymic tumor and a gastric tumor with abnormal accumulation of FDG, and biopsy confirmed both to be extramedullary relapse of AML M7. Induction chemotherapy following local radiation therapy achieved a second CR, following which he received HLA haploidentical peripheral blood stem cell transplantation on day 256 after the first transplant. The patient is currently surviving free from both relapse and GvHD. High WT1 mRNA levels in PB as compared with BM should raise suspicion of extramedullary relapse, and PET-CT is very useful for whole body evaluation in such cases.

Prognostic Significance of New-Onset Atrial Fibrillation in Patients With Non-Hodgkin's Lymphoma Treated With Anthracyclines.

Cancer therapeutics-related cardiac dysfunction induced by anthracycline is highly problematic, and its early recognition is of importance. Atrial fibrillation (AF) is sometimes seen after anthracycline chemotherapy. We aimed to test whether new-onset AF predicts anthracycline-induced heart failure. We prospectively studied 249 lymphoma patients who received anthracyclines. The patients were followed up with a frequent electrocardiographic examination. Fifteen patients (6%) newly developed AF after the chemotherapy, and during a mean follow-up of 34 months, they had a higher incidence of acute heart failure (40% vs 3.8%; p <0.001) and greater all-cause mortality (60% vs 14.1%; p <0.001) than those without AF. The onset of AF preceded the development of heart failure by a mean of 2.4 months. New-onset AF was independently associated with both acute heart failure (hazard ratio 12.78; p <0.001) and all-cause mortality (hazard ratio 4.77; p <0.001). The cumulative anthracycline dose did not differ between the patients with and without heart failure, yet it was another independent predictor of the mortality. In conclusion, new-onset AF may predict unfavorable outcomes after anthracycline chemotherapy in patients with malignant lymphoma.