Low- versus standard-dose post-transplant cyclophosphamide as GVHD prophylaxis for haploidentical transplantation.

Haploidentical haematopoietic cell transplantation (haplo-HCT) using post-transplant cyclophosphamide (PTCY) as graft-versus-host disease (GVHD) prophylaxis is the standard of care for various haematological malignancies. The original PTCY dose after haplo-HCT was 100 mg/kg, but no dose-finding studies have been performed to identify the optimal dose. We performed a retrospective analysis to compare standard-dose PTCY (100 mg/kg) with reduced-dose PTCY (80 mg/kg): 969 in the standard-dose group and 538 in the reduced-dose group. As there was a significant difference between the two groups regarding patient and transplant characteristics, we performed propensity score (PS) matching. After PS matching, 425 patients in each group were included. The probabilities of 2-year OS were 55.9% in the standard-dose group and 47.0% in the reduced-dose group (p = 0.36). The cumulative incidences of 2-year non-relapse mortality were 21.3% in the standard-dose group and 20.5% in the reduced-dose group (p = 0.55). There was no significant difference in the incidence of acute (grade II-IV 29.2% [95% CI, 24.9-33.6] vs. 25.3% [95% CI, 21.3-29.6]; grade III-IV 7.3% [95% CI, 5.1-10.0] vs. 6.6% [95% CI, 4.5-9.3]) or chronic GVHD. In conclusion, reduced- and standard-dose PTCY were comparable in terms of major clinical outcomes.

Superiority of BM over PBSC for recipients with pre-transplant lung dysfunction in HLA-matched allogeneic HCT.

BACKGROUND AIMS: Pre-transplant lung dysfunction is known to be a risk factor for non-relapse mortality (NRM) after allogeneic hematopoietic cell transplantation (allo-HCT). It is unclear which cell source gives better outcomes for patients with pulmonary dysfunction. METHODS: We analyzed 3289 adult patients with standard-risk disease who had received HLA-matched allo-HCT, and compared outcomes between those who received peripheral blood stem cell (PBSC) vs. bone marrow (BM) in two cohorts based on the presence of a lung score by the Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI): the Lung-scored (LS) and non-LS cohorts. RESULTS: In the LS cohort, the 2-year overall survival (OS) in the BM group tended to be higher than that in the PBSC group (72.4% vs. 61.4%; P = 0.044). In the non-LS cohort, there was no significant difference between the two groups (71.7% vs. 73.2%; P = 0.13). Multivariate analyses confirmed that PBSC was significantly associated with inferior OS in the LS cohort (hazard ratio [HR], 1.66; 95% CI, 1.09-2.54; P = 0.019). On the other hand, the cell source did not affect OS in the non-LS cohort (HR, 0.92; 95% CI, 0.76-1.12; P = 0.41). We found that PBSC was associated with an increased risk of NRM in the LS cohort (HR, 2.17; 95% CI, 1.16-4.05; P = 0.016), while the cell source did not significantly affect NRM in the non-LS cohort. PBSC was not identified as a risk factor for relapse in either cohort. CONCLUSIONS: Our results suggest that BM might be beneficial for recipients with lung dysfunction in HLA-matched allo-HCT.

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.

Phase III clinical trial of autologous CD34 + cell transplantation to accelerate fracture nonunion repair.

BACKGROUND: We previously demonstrated that CD34 + cell transplantation in animals healed intractable fractures via osteogenesis and vasculogenesis; we also demonstrated the safety and efficacy of this cell therapy in an earlier phase I/II clinical trial conducted on seven patients with fracture nonunion. Herein, we present the results of a phase III clinical trial conducted to confirm the results of the previous phase studies using a larger cohort of patients. METHODS: CD34 + cells were mobilized via administration of granulocyte colony-stimulating factor, harvested using leukapheresis, and isolated using magnetic cell sorting. Autologous CD34 + cells were transplanted in 15 patients with tibia nonunion and 10 patients with femur nonunion, who were followed up for 52 weeks post transplantation. The main outcome was a reduction in time to heal the tibia in nonunion patients compared with that in historical control patients. We calculated the required number of patients as 15 based on the results of the phase I/II study. An independent data monitoring committee performed the radiographic assessments. Adverse events and medical device failures were recorded. RESULTS: All fractures healed during the study period. The time to radiological fracture healing was 2.8 times shorter in patients with CD34 + cell transplantation than in the historical control group (hazard ratio: 2.81 and 95% confidence interval 1.16-6.85); moreover, no safety concerns were observed. CONCLUSIONS: Our findings strongly suggest that autologous CD34 + cell transplantation is a novel treatment option for fracture nonunion. TRIAL REGISTRATION: UMIN-CTR, UMIN000022814. Registered on 22 June 2016.

Unrelated female-to-male bone marrow transplantation would be preferred over cord blood transplantation in male patients.

BACKGROUND AIMS: Allogeneic hematopoietic stem cell transplantation from female donors to male recipients (female-to-male allo-HCT) is a well-established risk factor for a greater incidence of non-relapse mortality (NRM) and chronic graft-versus-host disease (GVHD). In contrast, unrelated cord blood transplantation (UCBT) is associated with a lower incidence of chronic GVHD. In this study, survival outcomes were compared between the UCBT and unrelated female-to-male bone marrow transplantation (UFMBMT) groups. METHODS: We evaluated male allo-HCT recipients who underwent UCBT or UFMBMT between 2012 and 2020 in Japan. There were 2517 cases in the UCBT group, 456 cases in the HLA-matched UFMBMT group and 457 cases in the HLA-mismatched UFMBMT group. RESULTS: HLA-mismatched UFMBMT was significantly associated with a decreased risk of relapse (hazard ratio [HR] 0.74; 95% confidence interval [CI] 0.57-0.98], P = 0.033) and HLA-matched UFMBMT had the tendency of a decreased risk of relapse (HR 0.78; 95% CI 0.61-1.01, P = 0.059). HLA-matched UFMBMT was also associated with favorable OS (HR 0.82; 95% CI 0.69-0.97, P = 0.021). The relationship between the donor sources and relapse was similarly observed in the lymphoid malignancy cohort. CONCLUSIONS: The difference of graft-versus leukemia effect by H-Y immunity according to donor sources might contribute to the difference in clinical impact. It might be desirable for patients who could sufficiently wait for donor coordination to select BMT rather than UCBT, even if only unrelated female donors are available for male recipients.

Chapter 3: Management of kidney injury caused by cancer drug therapy, from clinical practice guidelines for the management of kidney injury during anticancer drug therapy 2022.

Cisplatin should be administered with diuretics and Magnesium supplementation under adequate hydration to avoid renal impairment. Patients should be evaluated for eGFR (estimated glomerular filtration rate) during the treatment with pemetrexed, as kidney injury has been reported. Pemetrexed should be administered with caution in patients with a CCr (creatinine clearance) < 45 mL/min. Mesna is used to prevent hemorrhagic cystitis in patients receiving ifosfamide. Febuxostat is effective in avoiding hyperuricemia induced by TLS (tumor lysis syndrome). Preventative rasburicase is recommended in high-risk cases of TLS. Thrombotic microangiopathy could be triggered by anticancer drugs and there is no evidence of efficacy of plasma exchange therapy. When proteinuria occurs during treatment with anti-angiogenic agents or multi-kinase inhibitors, dose reductions or interruptions based on grading should be considered. Grade 3 proteinuria and renal dysfunction require urgent intervention, including drug interruption or withdrawal, and referral to a nephrologist should be considered. The first-line drugs used for blood pressure elevation due to anti-angiogenic agents are ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers). The protein binding of drugs and their pharmacokinetics are considerably altered in patients with hypoalbuminemia. The clearance of rituximab is increased in patients with proteinuria, and the correlation with urinary IgG suggests similar pharmacokinetic changes when using other antibody drugs. AIN (acute interstitial nephritis) is the most common cause of ICI (immune checkpoint inhibitor)-related kidney injury that is often treated with steroids. The need for renal biopsy in patients with kidney injury that occurs during treatment with ICI remains controversial.

Comparable efficacy and safety of COVID-19 vaccines for patients receiving tegafur-uracil as postoperative adjuvant chemotherapy.

PURPOSE: Many effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been developed, but a weaker response in individuals undergoing anticancer treatment has been reported. This study evaluates the immunogenic status and safety of SARS-CoV-2 vaccines for patients with non-small-cell lung cancer (NSCLC), receiving tegafur-uracil (UFT) as postoperative adjuvant chemotherapy. METHODS: The subjects of this prospective study were 40 patients who underwent surgery for NSCLC and received SARS-CoV-2 vaccines postoperatively. We compared the antibody titers of SARS-CoV-2 vaccines and the adverse events between patients who received adjuvant UFT and patients who did not. RESULTS: The mean anti-S1 IgG titers were not significantly different between the UFT and without-UFT groups (mean optimal density, 0.194 vs. 0.205; P = 0.76). Multivariate analysis identified the period after the second vaccination as an independent predictor of anti-S1 IgG titer (P = 0.049), but not the UFT status (with or without-UFT treatment; P = 0.47). The prevalence of adverse events did not differ significantly between the groups, and no severe adverse events occurred. CONCLUSIONS: The efficacy and safety of the SARS-CoV-2 vaccines for NSCLC patients who received postoperative adjuvant UFT chemotherapy were comparable to those for NSCLC patients who did not receive postoperative adjuvant UFT chemotherapy. CLINICAL TRIAL REGISTRATION: This study was registered with the University Hospital Medical Information Network (UMIN) in Japan (UMIN000047380).

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.

Disseminated cryptococcosis resembling miliary tuberculosis in a patient with acute myeloid leukemia.

Disseminated cryptococcosis, usually involving the lungs and central nervous system, carries a high risk of morbidity and mortality in immunocompromised hosts. In this report, we describe a case of miliary pulmonary cryptococcosis in a patient with acute myeloid leukemia, initially resembling miliary tuberculosis. The diagnosis of disseminated cryptococcosis was made based on transbronchial lung biopsy with subsequent detection of Cryptococcus neoformans in blood and cerebrospinal fluid. The patient was treated with liposomal amphotericin B as induction therapy, followed by fluconazole as consolidation and maintenance therapies thereafter. The infection was improved immediately, and he successfully underwent hematopoietic stem cell transplantation. The present case serves as a timely reminder that a radiological miliary pattern necessitates a thorough search for a definitive microbiological and histopathological diagnosis.

Human herpesvirus 6 encephalitis in patients administered mycophenolate mofetil as prophylaxis for graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Human herpesvirus 6 (HHV-6) encephalitis is a known life-threatening complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, few studies have focused on the occurrence of HHV-6 encephalitis in patients receiving mycophenolate mofetil (MMF) combined with a calcineurin inhibitor as prophylaxis for graft-versus-host disease (GVHD). This study aimed to investigate the impact of MMF administered for GVHD prophylaxis in the occurrence of HHV-6 encephalitis after allo-HSCT and the characteristics of this condition. METHODS AND RESULTS: We retrospectively analyzed 73 patients who underwent allo-HSCT (83 transplants) at our hospital between April 2010 and December 2015. MMF (2-3 g/d) was administered along with a calcineurin inhibitor. Seven patients (8.0%) developed encephalitis due to HHV-6. The median period from allo-HSCT to the onset of HHV-6 encephalitis was 23 days (range, 17-98 days). The cumulative incidence of HHV-6 encephalitis on day 100 after treatment was 12% and 6% in patients who underwent cord blood transplantation (CBT) and non-CBT (ie, bone marrow transplantation and peripheral blood stem cell transplantation), respectively (P = 0.344). Neurological symptoms of encephalitis were more severe in non-CBT cases than those in CBT cases. All patients diagnosed with HHV-6 encephalitis were treated with ganciclovir or foscarnet. None of the enrolled patients died from HHV-6 encephalitis. CONCLUSIONS: Mycophenolate mofetil may have the potential to increase the frequency of severe HHV-6 encephalitis in patients undergoing CBT and non-CBT. Thus, MMF should be administered with caution, and patients should be monitored closely for HHV-6 encephalitis even those who did not undergo CBT.

Discontinuation of sorafenib can lead to the emergence of FLT3-ITD-positive acute myeloid leukemia.

A 69-year-old woman who had been diagnosed with unresectable papillary thyroid cancer was referred to our hospital. We initially treated her with sorafenib, but she subsequently developed erythema multiforme, which was suspected to be a drug rush due to sorafenib; therefore, sorafenib was discontinued. At the time of discontinuation, immature blast cells were detected in her peripheral blood. Approximately two weeks later, her skin rash improved substantially, but the proportion of blasts in the peripheral blood increased. We performed a bone marrow examination, and she was diagnosed with FLT3-ITD-positive acute myeloid leukemia. FLT3-ITD expression is found in 20-25% of AML and is a known independent poor prognostic factor. To overcome the poor prognosis associated with FLT3-ITD, molecular drugs targeting FLT3-ITD are attracting much attention. Sorafenib, a multi-kinase inhibitor, also has an effect on FLT3-ITD. Although primary disease flares after tyrosine kinase inhibitor discontinuation have been reported, this is the first report to describe discontinuation of sorafenib treatment as a potential trigger of FLT3-ITD-positive acute myeloid leukemia in papillary thyroid cancer.

Delayed Socket Healing After Dental Extraction in Patients Undergoing Myelosuppressive Chemotherapy for Hematological Malignancy: Incidence and Risk Factors.

PURPOSE: The purpose of this study was to measure the frequency and identify factors associated with delayed socket healing after dental extraction in patients undergoing myelosuppressive chemotherapy for hematologic malignancy. MATERIALS AND METHODS: This prospective cohort study focused on delayed healing after extraction in patients with hematologic malignancy. Sockets with delayed healing were defined as those with intense pain and bone exposure 1 week postoperatively. Patients with and without delayed socket healing were compared using the Fisher exact test and Mann-Whitney U test with some variables. Receiver operating characteristics curve analysis was conducted to define cutoff values for delayed healing. RESULTS: One hundred ninety-four dental extractions in 93 patients (median age, 64 yr; range, 20 to 85 yr) were analyzed. The incidence of delayed socket healing was 7.5% (7 of 93 patients). There was no postoperative bleeding. Older age, type of hematologic malignancy (acute leukemia), shorter time from dental extraction to initiation of chemotherapy, low platelet count or hemoglobin level, requirement for red blood cell concentrate or platelet transfusion, and use of an absorbable hemostatic agent were statistically associated with the occurrence of delayed socket healing. Platelet and hemoglobin cutoffs were 4.6 × 104/µL and 7.7 g/dL, respectively. CONCLUSIONS: Although dental extraction can be safely performed in patients undergoing myelosuppressive chemotherapy for hematologic malignancy, oral surgeons should understand the potential risk for delayed socket healing. When considering dental extraction, patients with hematologic malignancy and low hemoglobin or platelet levels should be informed about the possibility of delayed socket healing.

MYC Amplification in the Form of Ring Chromosomes 8 in Acute Myeloid Leukemia with t(11;16)(q13;p11.2).

Oncogene amplification is uncommon in acute myeloid leukemia (AML). Cytogenetically, it is primarily found as double minute chromosomes (dmin) or homogeneously staining regions (hsr). A 62-year-old woman was admitted to our hospital because of anemia and thrombocytopenia. Her bone marrow was hypercellular with 78.6% myeloperoxidase- positive blasts. Some had micronuclei. The patient was diagnosed with AML M2 and remains in complete remission (CR) after induction therapy. G-banding at diagnosis showed 51,XX,t(11;16)(q13;p11.2),+r1,+mar1×4. Spectral karyotyping confirmed t(11;16) and revealed that the ring and the marker chromosomes were derived from multiple copies of ring chromosome 8. Fluorescence in situ hybridization (FISH) with a MYC probe at 8q24 detected amplified MYC signals on 1 large and 4 small ring chromosomes 8. One MYC signal was deleted from one of the 2 chromosomes 8. FISH with a FUS probe at 16p11.2 showed monoallelic deletion of FUS. Immunohistochemistry demonstrated MYC protein overexpression at diagnosis and almost negative expression in CR. These results indicate that MYC amplification could occur in ring chromosomes without dmin. A cryptic MYC deletion suggests that an episome model could be applicable to MYC amplification in ring chromosomes as observed for dmin and hsr. Furthermore, considering 2 further reported cases, t(11;16)(q13;p11) may be a very rare but recurrent translocation in AML.

Impact of total body irradiation on successful neutrophil engraftment in unrelated bone marrow or cord blood transplantation.

Total body irradiation (TBI) has been thought to promote donor cell engraftment in allogeneic hematopoietic cell transplantation (HCT) from alternative donors. However, recent progress in HCT strategies may affect the clinical significance of TBI on neutrophil engraftment. With the use of a Japanese transplant registry database, we analyzed 3933 adult recipients (>15 y.o.) who underwent HCT between 2006 and 2013 from an 8/8 HLA-matched unrelated bone marrow donor (MUD, n = 1367), an HLA-mismatched unrelated bone marrow donor (MMUD, n = 1102), or unrelated cord blood (CBT, n = 1464). Conditioning regimens were divided into five groups: High-TBI-(>8Gy), Low-TBI- (≤8Gy), and no-TBI-myeloablative conditioning (MAC), and Low-TBI- and no-TBI-reduced-intensity conditioning (RIC). In both MUD and MMUD, neutrophil engraftment rate was >90% in each of the five conditioning groups, and TBI was not associated with prompt neutrophil engraftment in multivariate analyses. Conversely, in CBT, TBI regimens had a higher rate of day-30 neutrophil engraftment than no-TBI-regimens: 78% in High-TBI-MAC, 83% in Low-TBI-MAC, and 76% in Low-TBI-RIC versus 65% in No-TBI-MAC, and 68% in No-TBI-RIC (P < .001). Multivariate analyses in CBT demonstrated that TBI-regimens were significantly associated with a higher rate of neutrophil engraftment. Subsequently focusing on CBT patients alone, TBI-regimens were significantly associated with a higher rate of neutrophil engraftment in patients who received CBT with a 4/6 or less HLA allele-match, or who had anti-HLA antibodies. In summary, TBI-regimens had no impact on neutrophil engraftment in the current practice of unrelated bone marrow transplantation. However, in CBT, TBI is still necessary to enhance engraftment.

NANOG Expression as a Responsive Biomarker during Treatment with Hedgehog Signal Inhibitor in Acute Myeloid Leukemia.

Aberrant activation of the Hedgehog (Hh) signaling pathway is involved in the maintenance of leukemic stem cell (LSCs) populations. PF-0444913 (PF-913) is a novel inhibitor that selectively targets Smoothened (SMO), which regulates the Hh pathway. Treatment with PF-913 has shown promising results in an early phase study of acute myeloid leukemia (AML). However, a detailed mode of action for PF-913 and relevant biomarkers remain to be elucidated. In this study, we examined bone marrow samples derived from AML patients under PF-913 monotherapy. Gene set enrichment analysis (GSEA) revealed that PF-913 treatment affected the self-renewal signature and cell-cycle regulation associated with LSC-like properties. We then focused on the expression of a pluripotency factor, NANOG, because previous reports showed that a downstream effector in the Hh pathway, GLI, directly binds to the NANOG promoter and that the GLI-NANOG axis promotes stemness and growth in several cancers. In this study, we found that a change in NANOG transcripts was closely associated with GLI-target genes and NANOG transcripts can be a responsive biomarker during PF-913 therapy. Additionally, the treatment of AML with PF-913 holds promise, possibly through inducing quiescent leukemia stem cells toward cell cycling.

Loss of CD45 expression at relapse of acute myeloid leukemia.

A 49-year-old female was initially diagnosed with acute myeloid leukemia (AML) M4 with a CD45＋CD13＋CD33＋CD34-HLA-DR＋ immunophenotype. She underwent allogeneic bone marrow transplantation, but the disease recurred. The bone marrow was infiltrated with 87.0% blasts negative for myeloperoxidase (MPO) staining. Immunophenotyping by flow cytometry identified the presence of a CD45-negative blast population. These blasts exhibited a CD13＋CD33＋CD19-CD10-CD34-HLA-DR- immunophenotype. The lack of CD45 expression is often observed in B-cell acute lymphoblastic leukemia, whereas CD45-negative AML is extremely rare; only one older male with AML-M0 has been reported. In the present case, the CD45-negative blasts had an MPO-CD13＋CD33＋ phenotype, which is similar to AML-M0.

Coexpression of NUP98/TOP1 and TOP1/NUP98 in de novo Acute Myeloid Leukemia with t(11;20)(p15;q12) and t(2;5)(q33;q31).

The t(11;20)(p15;q11∼12) translocation is a very rare but recurrent cytogenetic aberration that occurs in myelodysplastic syndrome/acute myeloid leukemia (MDS/AML). This translocation was shown to form a fusion gene between NUP98 at 11p15 and TOP1 at 20q12. Here, we describe a new case of de novo AML M2 with t(11;20) which was associated with another balanced translocation. An 81-year-old man was admitted to undergo salvage therapy for relapsed AML. G-banding and spectral karyotyping showed 46,XY,t(2;5)(q33;q31),t(11;20)(p15;q12)[20]. Expression of the NUP98/TOP1 fusion transcript was confirmed: NUP98 exon 13 was in-frame fused with TOP1 exon 8. The reciprocal TOP1/NUP98 fusion transcript was also detected: TOP1 exon 7 was fused with NUP98 exon 14. After achieving hematological complete remission, the karyotype converted to 46,XY,t(2;5)(q33;q31)[19]/46,sl,t(11;20)(p15;q12)[1]. FISH analysis demonstrated that the 5q31 breakpoint of t(2;5) was centromeric to EGR1. In all 10 cases described in the literature, the NUP98 exon 13/TOP1 exon 8 fusion transcript was expressed, indicating that it may be responsible for the pathogenesis of MDS/AML with t(11;20). On the other hand, the TOP1/NUP98 transcript was coexpressed in 4 cases of de novo AML, but not in 3 cases of therapy-related MDS. Thus, this reciprocal fusion may be associated with progression to AML.