Utility of the refined EBMT diagnostic and severity criteria 2023 for sinusoidal obstruction syndrome/veno-occlusive disease.

Sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a life-threatening complication of hematopoietic stem cell transplantation (HSCT). Early diagnosis of SOS/VOD is associated with improved clinical outcomes. In 2023, the refined European Society for Blood and Marrow Transplantation diagnostic and severity criteria (refined EBMT criteria 2023) have been advocated. The revision has introduced new diagnostic categories, namely; probable, clinical, and proven SOS/VOD. In addition, the Sequential Organ Failure Assessment (SOFA) score has been newly incorporated into the SOS/VOD severity grading. We performed a retrospective analysis to evaluate the utility of these criteria. We analyzed 161 cases who underwent allogeneic HSCT. We identified 53 probable, 23 clinical, and 4 proven SOS/VOD cases. Probable SOS/VOD was diagnosed a median of 5.0 days earlier (interquartile range: 2-13 days, P < 0.001) than that of clinical SOS/VOD. The development of probable SOS/VOD alone was associated with a significantly inferior survival proportion compared to non-SOS/VOD (100-day survival, 86.2% vs. 94.3%, P = 0.012). The SOFA score contributed to the prediction of prognosis. Consequently, the refined EBMT criteria 2023 demonstrated the utility of SOS/VOD diagnosis and severity grading. Further investigations and improvements in these criteria are warranted.

Irreversible Intrathecal Chemotherapy-induced Myelopathy in a Patient with Diffuse Large B-cell Lymphoma.

Intrathecal chemotherapy is often administered for prophylaxis and treatment of central nervous system involvement in hematological malignancies. However, it may rarely cause neurotoxicity as a side effect. We herein report a 74-year-old woman with diffuse large B-cell lymphoma including a spinal lesion. She received systemic and intrathecal chemotherapy. After five doses of intrathecal chemotherapy, she developed intrathecal chemotherapy-induced myelopathy. Intrathecal treatment was discontinued, and she was administered vitamin B12 and folic acid, along with steroid pulses. However, her symptoms did not improve. Intrathecal chemotherapy-induced myelopathy is rare, but may be irreversible; therefore, clinicians should be aware of this potential complication.

RUNX1 rearrangement in mature B-cell acute lymphoblastic leukemia with non-L3 morphology.

Mature B-cell acute lymphoblastic leukemia (ALL) is defined by the expression of light chain-restricted surface immunoglobulin (sIg) and usually has features of the leukemic phase of Burkitt lymphoma including FAB-L3 morphology and MYC rearrangement. Recently, another distinct entity in childhood mature B-cell ALL has been characterized as non-L3 morphology and KMT2A rearrangement. Here we report an unusual case of mature B-cell ALL that presented with RUNX1 rearrangement. A 65-year-old male was admitted to our department for thorough examination of leukocytosis and thrombocytopenia. The patient's bone marrow was hypercellular and infiltrated with 97.8% myeloperoxidase-negative, medium-to-large-sized blasts without cytoplasmic vacuoles. Immunophenotypes were characterized by the presence of light chain-restricted sIg and the lack of immature markers, indicating a diagnosis of mature B-cell ALL with L2 morphology: sIg-κ+, CD19+, CD20+, CD22+, CD79a+, TdT-, and CD34-. G-banding combined with spectral karyotyping showed the following complex karyotype: 45,X,der(Y;10)(p10;q10),del(13)(q?),inv(21)(p13q22.1). Fluorescence in situ hybridization revealed separated signals of RUNX1 at 21q22.1, whereas rearrangements of MYC and KMT2A were not found. To our knowledge, inv(21)(p13q22.1) involving RUNX1 is a novel cytogenetic aberration and this is the first case of mature B-cell ALL that presented with RUNX1 rearrangement. Thus, RUNX1 may be implicated in the pathogenesis of mature B-cell ALL showing non-L3 morphology without MYC rearrangement.

Early diagnosis of sinusoidal obstruction syndrome after hematopoietic stem cell transplantation, with modified diagnostic criteria including refractory thrombocytopenia.

Sinusoidal obstruction syndrome (SOS) is a fatal complication of hematopoietic stem cell transplantation (HSCT). Early diagnosis for SOS can improve clinical outcomes significantly. Here, we performed a retrospective study to investigate the Cairo diagnostic criteria, in which SOS was defined as the development of two or more in seven events, including transfusion-refractory thrombocytopenia. Among 154 cases of allogeneic HSCT, 10 cases of SOS using the European Society for Blood and Marrow Transplantation criteria (EBMT16) as the reference standard were identified. The original Cairo criteria could diagnose SOS 5 days earlier than any other established criteria, with some false-positive results (sensitivity = 100.0%; specificity = 72.2%). When the cutoff was set to three events for the Cairo criteria, the diagnosis of SOS could be made 3 days earlier than that using the EBMT16 criteria, with comparable precision (specificity = 86.1%). The accuracy of the Cairo criteria improved further when the cutoff point was set to four (specificity = 93.8%). The fulfillment of the Cairo criteria was associated with high mortality. Based on our results, the Cairo criteria were also considered clinically useful, especially at three or four cutoff points. Further studies are required to validate and refine the criteria.

Safety and Accuracy of Professional Continuous Glucose Monitoring in Patients Undergoing Allogeneic Hematopoietic Stem Cell Transplantation.

Hyperglycemia in the early days following allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a well-known risk factor for acute graft-versus-host disease (GVHD) and non-relapse mortality. The FreeStyle Libre Pro, a factory calibrated continuous glucose monitoring (CGM) device, has been used for the retrospective analysis of glucose testing in patients with diabetes. We assessed the safety and accuracy of the device in patients undergoing allo-HSCT. We recruited eight patients who underwent allo-HSCT between August 2017 and March 2020. They wore the FreeStyle Libre Pro on the day before or on the day of transplantation until 28 days after transplantation. Adverse events, especially bleeding and infection, were monitored to assess safety, and blood glucose levels were measured and compared with the device values. None of the eight participants experienced bleeding that was difficult to stop from the sensor site or local infection that required antimicrobial administration. The device value was well correlated with blood glucose (correlation coefficient r=0.795, P<0.01); however, the overall mean absolute relative difference was 32.1%±16.0%. Our study demonstrated the safety of FreeStyle Libre Pro in allo-HSCT patients. However, the sensor results tended to be lower than the blood glucose levels.

Response to mRNA SARS-CoV-2 vaccination evaluated by B-cell receptor repertoire after tixagevimab/cilgavimab administration.

The use of anti-SARS-CoV-2 antibody products like tixagevimab/cilgavimab represents an important strategy to protect immunocompromised patients with haematological malignancies from COVID-19. Although patients who receive these agents should still be vaccinated, the use of tixagevimab/cilgavimab can mask the production of anti-spike antibody after vaccination, making it hard to assess vaccine response. We have newly established a quantification method to assess the response to SARS-CoV-2 vaccination at the mRNA level using B-cell receptor (BCR) repertoire assay and the Coronavirus Antibody Database (CoV-AbDab). Repeated blood samples before and after vaccination were analysed for the BCR repertoire, and BCR sequences were searched in the database. We analysed the number and percentage frequency of matched sequences. We found that the number of matched sequences increased 2 weeks after the first vaccination and quickly decreased. Meanwhile, the number of matched sequences more rapidly increased after the second vaccination. These results show that the postvaccine immune response can be assessed at the mRNA level by analysing the fluctuation in matching sequences. Finally, BCR repertoire analysis with CoV-AbDab clearly demonstrated the response to mRNA SARS-CoV-2 vaccination even after tixagevimab/cilgavimab administration in haematological malignancy patients who underwent allogeneic haematopoietic stem cell transplantation.

Efficacy and Safety of Synbiotics in Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation: A Randomized, Double-blinded, Placebo-controlled Pilot Study.

Objective High-dose chemotherapy with autologous hematopoietic stem cell transplantation (auto-HSCT) is an effective treatment option for relapsed and refractory aggressive malignant lymphoma. However, patients frequently experience treatment-induced gastrointestinal symptoms. Synbiotics, including live microorganisms and nondigestible food ingredients, reportedly ameliorate chemotherapy-induced mucosal damage. In this study, we assessed the efficacy and safety of synbiotics in patients undergoing auto-HSCT. Methods This randomized, double-blinded study included patients with malignant lymphoma eligible for auto-HSCT. The patients were randomly assigned to either a synbiotic group receiving Bifidobacterium longum (BB536) and guar gum or a placebo group receiving a placebo containing dextrin. The supplements were administered twice daily from the start of conditioning chemotherapy up to 28 days after auto-HSCT. The primary endpoint was the duration of total parenteral nutrition (TPN). Results In total, 12 patients were included and randomized. The median duration of TPN was 15 (range, 12-33) days in the synbiotic group and 17.5 (range, 0-32) days in the placebo group. The median duration of grade ≥3 diarrhea was shorter in the synbiotic group than in then placebo group (2.5 vs. 6.5 days), as was the duration of hospital stay (31.5 vs. 43 days). The oral intake and quality of life regarding diarrhea and anorexia improved in the synbiotic group after engraftment. Synbiotic infections, including bacteremia, were not observed. Conclusion Synbiotics may reduce gastrointestinal toxicity, thereby reducing nutritional problems and improving the quality of life of patients undergoing auto-HSCT, without severe adverse events.

Global longitudinal strain is superior to ejection fraction for long-term follow-up after allogeneic hematopoietic stem cell transplantation.

Global longitudinal strain (GLS), a new cardiac parameter measured by the speckle-tracking method, is reportedly more sensitive than ejection fraction (EF) in detecting slight cardiac dysfunction in heart failure patients. We validated the utility of GLS in allogeneic hematopoietic stem cell transplantation (HSCT) patients during a long-term follow-up. Medical records of patients who underwent allogeneic HSCT between 2013 and 2020 were reviewed retrospectively. We evaluated the last echocardiography performed before transplantation and those performed annually during the 5 years after transplantation. We also investigated newly diagnosed cardiac events, which developed after HSCT. Among 85 patients, 22 used cardioprotective drugs. The median follow-up duration in surviving patients was 54.1 months (range, 2.9-92.6 months). GLS significantly decreased year by year, and patients taking cardioprotective agents tended to have a better GLS at 5 years than at 3 years, while EF did not change. Fifteen patients developed newly diagnosed cardiac events. Multivariate analysis revealed that low GLS and high serum ferritin levels at baseline were independently associated with the development of cardiac events. Therefore, we need a continuous follow-up of cardiac function by GLS and prescription of cardioprotective drugs might be considered for HSCT patients with low GLS. Further research is warranted.

GSK3 inhibitor enhances gemtuzumab ozogamicin-induced apoptosis in primary human leukemia cells by overcoming multiple mechanisms of resistance.

In acute myeloid leukemia (AML), the heterogeneity of genetic and epigenetic characteristics makes treatment difficult. The prognosis for AML is therefore poor, and there is an urgent need for new treatments for this condition. Gemtuzumab ozogamicin (GO), the first antibody-drug conjugate (ADC), targets the CD33 antigen expressed in over 90% of AML cases. GO therefore has the potential to counter the heterogeneity of AML patients. However, a major clinical problem is that drug resistance to GO diminishes its effect over time. Here, we report that the inhibition of glycogen synthase kinase 3 (GSK3) alone overcomes several forms of GO resistance at concentrations without antileukemic effects. The GSK3 inhibitors tested significantly enhanced the cytotoxic effect of GO in AML cell lines. We elucidated four mechanisms of enhancement: (1) increased expression of CD33, the target antigen of GO; (2) activation of a lysosomal function essential for hydrolysis of the GO linker; (3) reduced expression of MDR1 that eliminates calicheamicin, the payload of GO; and (4) reduced expression of the anti-apoptotic factor Bcl-2. A similar combination effect was observed against patient-derived primary AML cells. Combining GO with GSK3 inhibitors may be efficacious in treating heterogeneous AML.

Unexpected appearance of KMT2A::MLLT10 fusion transcript in acute myeloid leukemia with t(5;11)(q31;q23.3).

As an uncommon but nonrandom translocation in acute myeloid leukemia (AML) t(5;11)(q31;q23) results in fusion between KMT2A at 11q23 and ARHGAP26 at 5q31. The 5q31 region has another KMT2A partner, AFF4, which was identified in acute lymphoblastic leukemia harboring ins(5;11)(q31;q13q23). We report here a 65-year-old woman with AML M5b. G-banding and spectral karyotyping demonstrated 46,XX,t(5;11)(q31;q23.3). Fluorescence in situ hybridization revealed not only separated 5' and 3' KMT2A signals but a faint 5' KMT2A signal. Reverse transcription polymerase chain reaction (RT-PCR), using a KMT2A sense primer and ARHGAP26 antisense primer, detected no band whereas RT-PCR with a AFF4 antisense primer revealed an amplified band. However, sequence analysis unexpectedly disclosed that KMT2A exon 6 was connected with MLLT10 exons 15 to 18. This may be due to cross-hybridization between MLLT10 exon 18 and AFF4 antisense primer derived from AFF4 exon 10 since both exons had eight identical bases (AAGCAGCT). The MLLT10 gene is located at 10p12.31; a faint 5' KMT2A signal was probably present at this locus. These findings indicate that in AML the 5' KMT2A fragment containing exons 1 to 6 may be cryptically inserted into MLLT10 intron 14 when a reciprocal translocation t(5;11)(q31;q23.3) involving KMT2A occurred.

Biclonal Diffuse Large B-cell Lymphoma Commonly Characterized by Partial Trisomy 18q Involving MALT1 and BCL2.

A 68-year-old man was admitted because of a left shoulder mass and swollen right testis. Pathological examinations indicated a diagnosis of diffuse large B-cell lymphoma (DLBCL) with the CD20+BCL6+MUM1+BCL2+CD10-MYC- phenotype in both lesions. G-banding of soft tissue showed 47,XY,+18, whereas testicular cells showed 47,X,+X,-Y,der (4) t (4;18) (p15;?),del (5) (q?),+13. Fluorescence in situ hybridization detected additional MALT1 and BCL2 signals in both lesions. Southern blot demonstrated different IGH rearrangements between the soft tissue and testis. The patient was diagnosed with biclonal DLBCL with different karyotypes but similar immunophenotypes. Partial trisomy 18q involving MALT1 and BCL2 may be commonly involved in the pathogenesis of this biclonal DLBCL.

A Third Dose COVID-19 Vaccination in Allogeneic Hematopoietic Stem Cell Transplantation Patients.

We previously reported that a second dose of BNT162b2 was safe and effective for allogeneic hematopoietic stem cell transplantation (HSCT) patients. Here, we investigated the safety and efficacy of a third dose of COVID-19 mRNA vaccine in allogeneic HSCT patients. Antibody titers against the S1 spike protein were measured using the QuaResearch COVID-19 Human IgM IgG ELISA kit. The previous study included 25 allogeneic HSCT patients who received two doses of BNT162b2. Following the exclusion of three patients because of the development of COVID-19 (n = 2) and loss to follow-up (n = 1), the study evaluated 22 allogeneic HSCT patients who received a third dose of COVID-19 mRNA vaccine (BNT162b2 [n = 15] and mRNA-1273 [n = 7]). Median age at the time of the first vaccination was 56 (range, 23-71) years. Five patients were receiving immunosuppressants at the third vaccination, namely calcineurin inhibitors (CI) alone (n = 1), steroids alone (n = 2), or CI combined with steroids (n = 2). Twenty-one patients (95%) seroconverted after the third dose. None of our patients had serious adverse events, new-onset graft-versus-host disease (GVHD), or GVHD exacerbation after vaccination. A third dose of the BNT162b2 and mRNA-1273 COVID-19 vaccines was safe and effective for allogeneic HSCT patients.

Promising Efficacy of a Third Dose of mRNA SARS-CoV-2 Vaccination in Patients Treated with Anti-CD20 Antibody Who Failed 2-Dose Vaccination.

Anti-CD20 antibodies react with CD20 expressed not only on malignant B cells, but also on normal B cells. It has been reported that patients treated with anti-CD20 antibodies had an insufficient response to two-dose mRNA SARS-CoV-2 vaccination. To investigate the efficacy of a third dose in these patients, we investigated serum IgG antibody titers for the S1 protein after a third vaccination in 22 patients treated with the anti-CD20 antibody who failed two-dose vaccination. Results showed that overall, 50% of patients seroconverted. Although no patient who received the third dose within 1 year of the last anti-CD20 antibody administration showed an increase in S1 antibody titer, 69% of patients who received the third dose more than 1 year after the last anti-CD20 antibody administration seroconverted. Our data show that a third dose of vaccination is effective in improving the seroconversion rate in patients treated with the anti-CD20 antibody who failed standard two-dose vaccination.

Marked recovery of cardiac function by chemotherapy and autologous stem cell transplantation of a patient with heart failure with preserved ejection fraction due to primary amyloid light-chain amyloidosis: a case report.

Background: Cardiac involvement of amyloid light-chain (AL) amyloidosis is strongly associated with poor outcome, but the early detection of cardiac involvement of AL amyloidosis can be challenging. Case summary: We present a case of 49-year-old-female with heart failure with preserved ejection fraction. Echocardiography revealed normal left ventricular (LV) ejection fraction of 63% and an enlarged left atrium with a left atrial volume index (LAVI) of 54 mL/m2. Mild LV hypertrophy with an interventricular septum of 12.3 mm and posterior wall thickness of 11.0 mm was observed, and Doppler-derived LV diastolic filling showed a restrictive filling pattern. The conventional echocardiographic findings did not unequivocally indicate typical cardiac amyloidosis, but global longitudinal strain (GLS) was as low as 14.2%, and an apical sparing pattern was observed with relative apical longitudinal strain of 1.11. Finally, the patient was diagnosed as primary AL amyloidosis including histological examination of the endomyocardial specimen. After treatment with a regime of bortezomib and dexamethasone followed by high-dose melphalan followed by autologous peripheral blood stem cell transplantation (auto-PBSCT), Doppler-derived LV diastolic filling improved to normal filling pattern, and left atrial size had also decreased with an LAVI of 31 mL/m2. Moreover, GLS improved to 19.8%, and the apical sparing pattern had disappeared with relative apical longitudinal strain of 0.62. The patient has been asymptomatic during 18-month follow-up after auto-PBSCT, and recovered LV function has been maintained. Discussion: An earlier diagnosis of cardiac amyloidosis by using apical sparing may therefore allow for earlier treatment intervention for AL amyloidosis.

The Safety and Immunogenicity of the BNT162b2 mRNA COVID-19 Vaccine in Japanese Patients after Allogeneic Stem Cell Transplantation.

Patients who have undergone hematopoietic stem cell transplantation (HSCT) for hematological disease experience high mortality when infected by coronavirus disease 2019 (COVID-19). However, the safety and efficacy of the COVID-19 vaccine in HSCT patients remain to be investigated. We prospectively evaluated the safety and immunogenicity of the BNT162b2 mRNA COVID-19 vaccine (Pfizer BioNTech) in 25 Japanese allogeneic HSCT patients in comparison with 19 healthy volunteers. While anti-S1 antibody titers in almost all healthy volunteers after the second dose were higher than the cut-off value reported previously, levels in HSCT patients after the second dose were diverse. Nineteen patients (76%) had seroconversion of anti-S1 IgG. The median optical density of antibody levels in HSCT patients with low IgG levels (<600 mg/dL), steroid treatment, or low lymphocytes (<1000/µL) was significantly lower than that in the other HSCT patients. There were no serious adverse events (>Grade 3) and no new development or exacerbation of graft-versus-host disease after vaccination. We concluded that the BNT162b2 mRNA vaccine is safe and effective in Japanese allogeneic HSCT patients.

Safety and immunogenicity of the COVID-19 vaccine BNT162b2 in patients undergoing chemotherapy for solid cancer.

BACKGROUND: Although COVID-19 severity in cancer patients is high, the safety and immunogenicity of the BNT162b2 mRNA COVID-19 vaccine in patients undergoing chemotherapy for solid cancers in Japan have not been reported. METHODS: We investigated the safety and immunogenicity of BNT162b2 in 41 patients undergoing chemotherapy for solid cancers and in healthy volunteers who received 2 doses of BNT162b2. We evaluated serum IgG antibody titers for S1 protein by ELISA at pre-vaccination, prior to the second dose and 14 days after the second vaccination in 24 cancer patients undergoing cytotoxic chemotherapy (CC group), 17 cancer patients undergoing immune checkpoint inhibitor therapy (ICI group) and 12 age-matched healthy volunteers (HV group). Additionally, inflammatory cytokine levels were compared between the HV and ICI groups at pre and the next day of each vaccination. RESULTS: Anti-S1 antibody levels were significantly lower in the ICI and CC groups than in the HV group after the second dose (median optimal density: 0.241 [0.063-1.205] and 0.161 [0.07-0.857] vs 0.644 [0.259-1.498], p = 0.0024 and p < 0.0001, respectively). Adverse effect profile did not differ among the three groups, and no serious adverse event occurred. There were no differences in vaccine-induced inflammatory cytokines between the HV and ICI groups. CONCLUSION: Although there were no significant differences in adverse events in three groups, antibody titers were significantly lower in the ICI and CC groups than in the HV group. Further protection strategies should be considered in cancer patients undergoing CC or ICI.

Limited increase in antibody titers following mRNA SARS-CoV-2 vaccination for more than 3 years after final dose of anti-CD20 antibody.

We investigated the efficacy of BNT162b2 mRNA COVID-19 vaccine in patients with B-cell malignancies treated with anti-CD20 antibody. Although T-cell-mediated immune responses were detected even in patients receiving R-CHOP treatment, the S1 antibody titer following BNT162b2 vaccination remained only marginally increased for more than 3 years after the final dose of anti-CD20 antibody. We found no relationship between the percent of B-cells and S1 antibody titer. The duration of this suppression was much longer than we anticipated. Further protection and treatment strategies against COVID-19 for these patients are warranted.

Multiple thrombosis associated with Cytomegalovirus enterocolitis in an immunocompetent patient: a case report.

BACKGROUND: Cytomegalovirus (CMV) is reported to have thrombogenic characteristics that activate factor X in vitro and stimulate the production of factor VIII and von Willebrand factor (vWF). Thrombosis associated with CMV infection is prevalent among immunocompromised patients and predominantly presents as a solitary large thrombus in the deep vein, pulmonary artery, splanchnic arteriovenous ducts, or other similar sites. Multiple thrombi, however, are rarely observed in such cases. Here, we report about an immunocompetent man with multiple microthrombi associated with CMV infection. CASE PRESENTATION: A 72-year-old Japanese man who complained of abdominal pain was hospitalized with multiple colonic stenosis. He was later diagnosed with CMV enterocolitis and treated with ganciclover from Day 27 post-admission. During hospitalization, the patient developed thrombi in his fingers. He was initially treated with anticoagulant therapy (rivaroxaban); however, the therapy was discontinued owing to a prolonged activated thromboplastin time and an elevated international normalized ratio of prothrombin time. Instead, vitamin K and fresh-frozen plasma were administered. Nevertheless, his coagulation profile remained abnormal. Eventually, he developed colonic perforation and had to undergo emergency surgery. An intraoperative specimen showed several microthrombi in the middle and small arteriovenous ducts of his small and large intestines. The patient's coagulopathy improved preoperatively, and his overall condition improved postoperatively. Since the activation of ADAMTS13 was reduced remarkably, the thrombotic tendency was determined to be a thrombotic microangiopathy-like condition owing to increased vWF. We could not attribute the coagulopathy to any other cause except CMV infection; therefore, we concluded that this was a case of multiple thrombosis associated with CMV. CONCLUSIONS: We present an extremely rare case of a patient with multiple thrombotic microangiopathy-like microthrombosis caused by CMV infection. Our findings suggest that CMV infection may be considered as a differential diagnosis for immunocompetent individuals who present with thrombosis of unspecified cause.

Expression of a novel type of KMT2A/EPS15 fusion transcript in FLT3 mutation-positive B-lymphoblastic leukemia with t(1;11)(p32;q23).

The t(1;11)(p32;q23) translocation is a rare but recurrent cytogenetic aberration in acute myeloid leukemia (AML) and B-cell acute lymphoblastic leukemia (B-ALL). This translocation was initially shown to form a fusion gene between KMT2A exon 8 at 11q23 and EPS15 exon 2 at 1p32 in AML. Activating mutations of FLT3 are frequently found in AML but are very rare in ALL. Here, we describe a 75-year-old woman who was diagnosed with B-ALL since her bone marrow was made up of 98.2% lymphoblasts. These blasts were positive for CD19, CD22, CD79a, CD13, and CD33 but negative for CD10 and myeloperoxidase. The karyotype by G-banding and spectral karyotyping was 46,XX,t(1;11)(p32;q23). Expression of KMT2A/EPS15 and reciprocal EPS15/KMT2A fusion transcripts were shown: KMT2A exon 8 was in-frame fused to EPS15 exon 12, indicating that this fusion transcript was a novel type. Considering three reported B-ALL cases, EPS15 breakpoints were markedly different between AML (exon 2) and B-ALL (exons 10-12). Furthermore, an uncommon type of FLT3 mutation in the juxtamembrane domain was detected: in-frame 4-bp deletion and 10-bp insertion. Accordingly, our results indicate that the novel type of KMT2A/EPS15 fusion transcript and FLT3 mutation may cooperate in the pathogenesis of adult B-ALL as class II and class I mutations, respectively.