Molecular, clinical and therapeutic determinants of outcome in NPM1 mutated AML.

Although NPM1-mutated acute myeloid leukemia (AML) carries a generally favorable prognosis, many patients still relapse and die. Previous studies identified several molecular and clinical features associated with poor outcome, however only FLT3-ITD mutation and adverse karyotype are currently used for risk stratification due to inconsistent results and uncertainty around how other factors should influence treatment, particularly given the strong prognostic impact of post-induction measurable residual disease (MRD). Here we analyzed a large group of patients with NPM1mut AML enrolled in prospective trials (NCRI AML17 and AML19, n=1357) to delineate the impact of baseline molecular and clinical features, post induction MRD status and treatment intensity on outcome. FLT3-ITD (HR 1.28, 95%CI 1.01-1.63), DNMT3A (HR 1.65, 95%CI 1.32-2.05), WT1 (HR 1.74, 95%CI 1272-2.38) and non-ABD NPM1 mutations (HR 1.64, 95%CI 1.22-2.21) were independently associated with poorer overall survival (OS). These factors were also strongly associated with MRD positivity. For patients achieving MRD negativity, these mutations (except FLT3-ITD) were associated with an increased cumulative incidence of relapse (CIR) and poorer OS. However, apart from the few patients with adverse cytogenetics, we could not identify any group of MRD negative patients with a CIR >40% or with benefit from allograft in first remission. Intensified chemotherapy with the FLAG-Ida regimen was associated with improved outcomes in all subgroups, with greater benefits observed in the highest risk molecular subgroups.

Postinduction molecular MRD identifies patients with NPM1 AML who benefit from allogeneic transplant in first remission.

ABSTRACT: Selection of patients with NPM1-mutated acute myeloid leukemia (AML) for allogeneic transplant in first complete remission (CR1-allo) remains controversial because of a lack of robust data. Consequently, some centers consider baseline FLT3-internal tandem duplication (ITD) an indication for transplant, and others rely on measurable residual disease (MRD) status. Using prospective data from the United Kingdom National Cancer Research Institute AML17 and AML19 studies, we examined the impact of CR1-allo according to peripheral blood NPM1 MRD status measured by quantitative reverse transcription polymerase chain reaction after 2 courses of induction chemotherapy. Of 737 patients achieving remission, MRD was positive in 19%. CR1-allo was performed in 46% of MRD+ and 17% of MRD- patients. We observed significant heterogeneity of overall survival (OS) benefit from CR1-allo according to MRD status, with substantial OS advantage for MRD+ patients (3-year OS with CR1-allo vs without: 61% vs 24%; hazard ratio [HR], 0.39; 95% confidence interval [CI], 0.24-0.64; P < .001) but no benefit for MRD- patients (3-year OS with CR1-allo vs without: 79% vs 82%; HR, 0.82; 95% CI, 0.50-1.33; P = .4). Restricting analysis to patients with coexisting FLT3-ITD, again CR1-allo only improved OS for MRD+ patients (3-year OS, 45% vs 18%; compared with 83% vs 76% if MRD-); no interaction with FLT3 allelic ratio was observed. Postinduction molecular MRD reliably identifies those patients who benefit from allogeneic transplant in first remission. The AML17 and AML19 trials were registered at www.isrctn.com as #ISRCTN55675535 and #ISRCTN78449203, respectively.

Treatment of the elderly patient with haematological cancer.

During the last two decades, novel targeted therapies, in particular, ¼small molecules« for oral administration and monoclonal antibodies, have revolutionized the treatment and prognosis of haematological cancers. Generally, these treatments are well tolerated and therefore suitable for elderly patients. This review presents a short update on the current standard-of-care treatment of elderly patients with haematological cancer.

Droplet digital PCR for sensitive relapse detection in acute myeloid leukaemia patients transplanted by reduced intensity conditioning.

INTRODUCTION: Follow-up after allogeneic transplantation in acute myeloid leukaemia (AML) is guided by measurable residual disease (MRD) testing. Quantitative polymerase chain reaction (qPCR) is the preferred MRD platform but unfortunately, 40%-60% of AML patients have no high-quality qPCR target. This study aimed to improve MRD testing by utilising droplet digital PCR (ddPCR). ddPCR offers patient-specific monitoring but concerns of tracking clonal haematopoiesis rather than malignant cells prompt further validation. METHODS: Retrospectively, we performed MRD testing on blood and bone marrow samples from AML patients transplanted by reduced-intensity conditioning. RESULTS: The applicability of ddPCR was 39/42 (92.9%). Forty-five ddPCR assays were validated with a 0.0089% median sensitivity. qPCR targeting NPM1 mutation detected relapse 46 days before ddPCR (p = .03). ddPCR detected relapse 34.5 days before qPCR targeting WT1 overexpression (p = .03). In non-relapsing patients, zero false positive ddPCR MRD relapses were observed even when monitoring targets associated with clonal haematopoiesis such as DNMT3A, TET2, and ASXL1 mutations. CONCLUSION: These results confirm that qPCR targeting NPM1 mutations or fusion transcripts are superior in MRD testing. In the absence of such targets, ddPCR is a promising alternative demonstrating (a) high applicability, (b) high sensitivity, and (c) zero false positive MRD relapses in non-relapsing patients.

Impaired fibrinolysis and increased clot strength are potential risk factors for thrombosis in lymphoma.

Thrombosis and bleeding are significant contributors to morbidity and mortality in patients with hematological cancer, and the impact of altered fibrinolysis on bleeding and thrombosis risk is poorly understood. In this prospective cohort study, we investigated the dynamics of fibrinolysis in patients with hematological cancer. Fibrinolysis was investigated before treatment and 3 months after treatment initiation. A dynamic clot formation and lysis assay was performed beyond the measurement of plasminogen activator inhibitor 1, tissue- and urokinase-type plasminogen activators (tPA and uPA), plasmin-antiplasmin complexes (PAP), α-2-antiplasmin activity, and plasminogen activity. Clot initiation, clot propagation, and clot strength were assessed using rotational thromboelastometry. A total of 79 patients were enrolled. Patients with lymphoma displayed impaired fibrinolysis with prolonged 50% clot lysis time compared with healthy controls (P = .048). They also displayed decreased clot strength at follow-up compared with at diagnosis (P = .001). A patient with amyloid light-chain amyloidosis having overt bleeding at diagnosis displayed hyperfibrinolysis, indicated by a reduced 50% clot lysis time, α-2-antiplasmin activity, and plasminogen activity, and elevated tPA and uPA. A patient with acute promyelocytic leukemia also displayed marked hyperfibrinolysis with very high PAP, indicating extreme plasmin generation, and clot formation was not measurable, probably because of the extremely fast fibrinolysis. Fibrinolysis returned to normal after treatment in both patients. In conclusion, patients with lymphoma showed signs of impaired fibrinolysis and increased clot strength, whereas hyperfibrinolysis was seen in patients with acute promyelocytic leukemia and light-chain amyloidosis. Thus, investigating fibrinolysis in patients with hematological cancer could have diagnostic value.

Prophylaxis with low dose tranexamic acid in acute myeloid leukemia patients undergoing intensive chemotherapy.

Patients suffering from acute myeloid leukemia (AML) carry a high risk of serious bleeding complications due to severe thrombocytopenia for long periods of time during treatment. Prior to prophylactic platelet transfusion becoming the standard of care, intracranial bleeding was a major contributor to death in AML patients. However, despite prophylactic platelet transfusions, up to 79% of patients with AML experience clinically significant bleeding during treatment. Antifibrinolytics are effective and well tolerated hemostatic agents widely used in many patient groups, and in this study, we investigated the effect of low dose tranexamic acid (TXA) in patients with AML and thrombocytopenia. We compared bleeding and thrombosis between 113 thrombocytopenic AML patients receiving TXA 500 mg three times daily (n = 36) versus no-TXA (n = 77). Clinical information was obtained systematically from electronic medical records, and laboratory data were collected from the laboratory information system. No difference was demonstrated in number of patients with at least one bleeding episode (TXA: 89% vs. no-TXA: 93%, p = 0.60), median number of bleeding days (TXA: 2.5 days vs. no-TXA 2.0 days, p = 0.30), bleeding location or transfusion needs between the two groups. However, platelet count was found to be a significant risk factor for bleeding, with a probability of bleeding of 35% with a platelet count below 5 × 109/L (logistic regression, p < 0.01). We found no difference in thromboembolic events between the two groups (TXA: 8% vs. no-TXA 10%, p = 0.99). In conclusion, treatment with low dose TXA is safe, but we found no evidence to suggest that it reduces bleeding in AML patients with thrombocytopenia.

Venetoclax combined with low dose cytarabine compared to standard of care intensive chemotherapy for the treatment of favourable risk adult acute myeloid leukaemia (VICTOR): Study protocol for an international, open-label, multicentre, molecularly-guided randomised, phase II trial.

BACKGROUND: For patients with acute myeloid leukaemia (AML), the only potentially curative treatment is intensive chemotherapy (IC). This is highly toxic, particularly for patients > 60 years, potentially leading to prolonged hospitalisations requiring intensive supportive care, and sometimes treatment-related death. This also results in extensive healthcare costs and negatively impacts quality of life (QoL). Venetoclax with low-dose cytarabine (VEN + LDAC) is a novel, low-intensity treatment for AML patients who cannot receive IC. VEN + LDAC is given as an outpatient and toxicity appears significantly lower than with IC. Analysis of clinical trials performed to date are promising for patients with the genotype NPM1mutFLT3 ITDneg, where remission and survival rates appear comparable to those achieved with IC. METHODS: VICTOR is an international, two-arm, open-label, multi-centre, non-inferiority, randomised-controlled phase II trial to assess VEN + LDAC compared to standard of care (IC) as first-line treatment in older patients (initially aged ≥ 60 years) with newly diagnosed AML. The trial will recruit patients with a NPM1mutFLT3 ITDneg genotype; those with a favourable risk in relation to the experimental treatment. University of Birmingham is the UK co-ordinating centre, with national hubs in Aarhus University Hospital, Denmark, and Auckland District Health Board, New Zealand. The primary outcome is molecular event-free survival time where an event is defined as failure to achieve morphological complete response (CR) or CR with incomplete blood count recovery after two cycles of therapy; molecular persistence, progression or relapse requiring treatment change; morphological relapse, or; death. Secondary outcomes include cumulative resource use at 12- and 24-months, and QoL as assessed by EORTCQLQ-C30 and EQ-5D-3L at 3-, 6-, 12-, 18- and 24-months. The trial employs an innovative Bayesian design with target sample size of 156 patients aged > 60 years. DISCUSSION: The principle underpinning the VICTOR trial is that the chance of cure for patients in the experimental arm should not be compromised, therefore, an adaptive design with regular checks on accumulating data has been employed, which will allow for a staged expansion of the trial population to include younger patients if, and when, there is sufficient evidence of non-inferiority in older patients. TRIAL REGISTRATION: EudraCT: 2020-000,273-24; 21-Aug-2020. ISRCTN: 15,567,173; 08-Dec-2020.

Cytoreductive treatment and association with platelet function and maturity in patients with essential thrombocythaemia.

Patients with essential thrombocythaemia (ET) have an increased risk of thromboembolic events, which may differ according to different cytoreductive drugs. We investigated the effect of cytoreductive treatment on platelet function and turnover in ET patients. Blood samples were obtained at 1 and 24 h after aspirin intake. Platelet function was evaluated by platelet aggregation and flow cytometry. Platelet turnover was assessed by immature platelet count, immature platelet fraction (IPF) and mean platelet volume (MPV). A total of 47 ET patients were included and grouped into 21 patients not receiving cytoreductive treatment, 15 patients receiving hydroxycarbamide and 11 patients receiving pegylated interferon alpha (peg-IFN). Patients receiving peg-IFN had significantly higher IPF and MPV than the other ET groups. Patients not receiving cytoreductive treatment had significantly higher platelet aggregation 24 h after aspirin intake than the other ET groups (p-values from 0.03 to 0.0002). Patients receiving hydroxycarbamide had significantly higher expression of platelet granule makers, P-selectin and CD63, than patients receiving peg-IFN (p-values ≤0.003). Cytoreduction provides more consistent platelet inhibition compared with no cytoreductive treatment. Moreover, peg-IFN provides superior inhibition of platelet activation markers than hydroxycarbamide, which in part may explain differences in risk of thromboembolic events in ET patients.

A national Danish proof of concept on feasibility and safety of home -based intensive chemotherapy in patients with acute myeloid leukemia.

Technological advances have made it possible to offer home-based chemotherapy to patients without health care professionals being present. Prior studies on effects of home-based treatment lack inclusion of patients with hematologic malignancies. We present data from a multicenter single-arm feasibility and safety study of home-based intensive chemotherapy in patients with newly diagnosed acute myeloid leukemia and their quality of life and psychological wellbeing. This national study included patients from six sites in Denmark who received intensive chemotherapy on programmed CADD Solis infusion pumps through a central venous catheter and were also managed as outpatients during treatment-induced pancytopenia. Data are presented from 104 patients, receiving 272 treatments with 1.096 (mean 4.57, SD 3.0) home infusion days out of 1.644 treatment days (67 %). Sixty-two of 168 (36.9 %) reinduction and consolidation treatment cycles ensuing pancytopenia phases were solely handled in the outpatient clinic. Patients reported high satisfaction with home-based treatment, which had a positive influence on their ability to be involved in their treatment and be socially and physically active. No unexpected events occurred during the intervention. Overall, patients improved in all quality of life outcomes over time. Home-based intensive chemotherapy treatment was feasible and safe in this population. ClinicalTrials.gov identifier: NCT04904211.

Lower Antiplatelet Effect of Aspirin in Essential Thrombocythemia than in Coronary Artery Disease.

Background Patients with essential thrombocythemia (ET) and coronary artery disease (CAD) have increased risk of thromboembolic complications. In addition, a reduced antiplatelet effect of aspirin has been demonstrated in both patient groups. As ET is a platelet disorder, platelets may be more important for the thromboembolic risk in ET than in CAD. We aimed to investigate the antiplatelet effect of aspirin and platelet turnover in ET versus CAD patients. Methods We included 48 ET patients and an age-matched group of 48 CAD patients. The effect of aspirin was evaluated by thromboxane B 2 (TXB 2 ) levels and platelet aggregation. Platelet turnover was assessed by immature platelet count (IPC) and immature platelet fraction (IPF). Results ET patients had reduced effect of aspirin compared with CAD patients, demonstrated by significantly higher TXB 2 levels (median of differences = 22.3 ng/mL, p < 0.0001) and platelet aggregation (median of differences = 131.0 AU*min, p = 0.0003). Furthermore, ET patients had significantly higher IPC ( p < 0.0001) and IPF ( p = 0.0004) than CAD patients. Conclusion ET patients have lower 24-hour antiplatelet effect of aspirin than CAD patients. This may be explained by an increased platelet production and turnover counteracting the antiplatelet effect of aspirin. These findings strengthen the rationale for exploring novel antiplatelet regimens in ET patients to reduce the risk of cardiovascular events.

Altered Fibrinolysis in Hematological Malignances.

Bleeding and thrombosis are well-known complications to hematological malignancies, and changes in fibrinolysis impact both these issues. In the present systematic review, we provide an overview and discussion of the current literature in regards to clinical manifestations, diagnosis, and treatment of altered fibrinolysis in patients suffering from hematological malignancies, beyond acute promyelocytic leukemia. We performed a systematic literature search employing the databases Pubmed, Embase, and Web of Science to identify original studies investigating fibrinolysis in hematological malignancies. Studies investigating fibrinolysis in acute promyelocytic leukemia or disseminated intravascular coagulation were excluded. We identified 32 studies fulfilling the inclusion criteria. A majority of the studies were published more than two decades ago, and none of the studies examined all available markers of fibrinolysis or used dynamic clot lysis assays. In acute leukemia L-asparaginase treatment induced a hypofibrinolytic state, and prior to chemotherapy there seemed to be little to no change in fibrinolysis. In studies examining fibrinolysis during chemotherapy results were ambiguous. Two studies examining multiple myeloma indicated hypofibrinolysis prior to chemotherapy, and in another plasma cell disease, amyloid light chain-amyloidosis, clear signs of hyperfibrinolysis were demonstrated. In myeloproliferative neoplasms, the studies reported signs of hypofibrinolysis, in line with the increased risk of thrombosis in this disease. Only one study regarding lymphoma was identified, which indicated no alterations in fibrinolysis. In conclusion, this systematic review demonstrated that only sparse, and mainly old, evidence exists on fibrinolysis in hematological malignancy. However, the published studies showed a tendency toward hypofibrinolysis in myeloproliferative disorders, an increased risk of hyperfibrinolysis, and bleeding in patients with AL-amyloidosis, whereas studies regarding acute leukemias were inconclusive except with regard to L-asparaginase treatment, which induced a hypofibrinolytic state.

Platelet Function and Turnover in Essential Thrombocythemia: A Systematic Review.

Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by increased platelet counts. ET has an incidence of 0.6 to 2.5 per 100,000 per year in Europe and North America. The disease is characterized by an increased thromboembolic risk, possibly caused by increased platelet counts. Furthermore, increased platelet function and/or increased platelet turnover may play a role. We aimed to explore: (1) whether platelet function and platelet turnover are increased in ET patients compared with healthy controls, and (2) whether these parameters are associated with increased thromboembolic risk and, therefore, may support decision-making on treatment in ET patients. We performed a systematic literature search on March 20, 2020 in Embase and PubMed following the Preferred Reporting Items for Systematic and Meta-Analysis (PRISMA) guidelines. In total, 1,923 articles were identified, 38 of which were included according to prespecified inclusion and exclusion criteria. Among the 38 studies, platelet activation (CD36 and CD62P) was investigated in 18 studies and was found to be increased in 12 of these. Platelet aggregation was investigated in 21 studies and was reported to be reduced in 20 of them. Platelet turnover (immature platelet count and mean platelet volume) was investigated in five studies with inconclusive results. No parameters were reported to predict the risk of thromboembolic events. In conclusion, platelet activation was increased in ET patients, but platelet aggregation was reduced. Future studies exploring markers of thromboembolic risk in ET patients are warranted.

Successful use of extracorporeal membrane oxygenation in respiratory failure due to influenza and acute myeloid leukemia.

We report the use of extracorporeal membrane oxygenation (ECMO) in a 28-year-old woman who had an influenza infection complicated with severe acute respiratory distress syndrome (ARDS) during treatment for acute myeloid leukemia. Despite ventilator management with positive end-expiratory pressure, nitrogen oxide inhalation, and prone positioning, there was severe hypoxemia. ECMO led to improvement in gas exchange and lung mechanics. This case shows that ECMO can be lifesaving in the treatment of immunocompromised patients who have hypoxemia that is refractory to conventional treatment.

Molecular MRD status and outcome after transplantation in NPM1-mutated AML.

Relapse remains the most common cause of treatment failure for patients with acute myeloid leukemia (AML) who undergo allogeneic stem cell transplantation (alloSCT), and carries a grave prognosis. Multiple studies have identified the presence of measurable residual disease (MRD) assessed by flow cytometry before alloSCT as a strong predictor of relapse, but it is not clear how these findings apply to patients who test positive in molecular MRD assays, which have far greater sensitivity. We analyzed pretransplant blood and bone marrow samples by reverse-transcription polymerase chain reaction in 107 patients with NPM1-mutant AML enrolled in the UK National Cancer Research Institute AML17 study. After a median follow-up of 4.9 years, patients with negative, low (<200 copies per 105ABL in the peripheral blood and <1000 copies in the bone marrow aspirate), and high levels of MRD had an estimated 2-year overall survival (2y-OS) of 83%, 63%, and 13%, respectively (P < .0001). Focusing on patients with low-level MRD before alloSCT, those with FLT3 internal tandem duplications(ITDs) had significantly poorer outcome (hazard ratio [HR], 6.14; P = .01). Combining these variables was highly prognostic, dividing patients into 2 groups with 2y-OS of 17% and 82% (HR, 13.2; P < .0001). T-depletion was associated with significantly reduced survival both in the entire cohort (2y-OS, 56% vs 96%; HR, 3.24; P = .0005) and in MRD-positive patients (2y-OS, 34% vs 100%; HR, 3.78; P = .003), but there was no significant effect of either conditioning regimen or donor source on outcome. Registered at ISRCTN (http://www.isrctn.com/ISRCTN55675535).

Clinical Use of Measurable Residual Disease in Acute Myeloid Leukemia.

OPINION STATEMENT: Treatment of acute myeloid leukemia (AML) remains a high-risk venture for the patient suffering from the disease. There is a real risk of succumbing to the treatment rather than the disease, and even so, cure is much less than certain. Since the establishment of complete remission as a prerequisite for cure in the 1960s, a number of years passed before advanced techniques for detecting minute amounts of disease matured sufficiently for clinical implementation. The two main techniques for detection of measurable residual disease (MRD) remain qPCR and multicolor flow cytometry. When performed in expert laboratories, both these modalities offer treating physicians excellent opportunity to follow the amount of residual disease upon treatment and offer unparalleled prognostication. In some AML and age group subsets, evidence now exist to support the choice of both proceeding to allogeneic transplant and not doing so. In other AML subgroups, MRD has sufficient discriminative power to identify patients likely to benefit from allogeneic transplant and patients likely not to. After treatment or transplantation, follow-up by molecular techniques can, with high certainty, predict relapse months before bone marrow function deterioration. On the other hand, options upon so-called molecular relapse are less well tested but recent evidence supports the use of azacitidine both in transplanted patients and patients consolidated with chemotherapy. In conclusion, MRD testing during treatment is a superb prognosticator and a major tool when choosing whether a patient should be transplanted or not. The exact use of MRD testing after treatment is less well defined but evidence is mounting for the instigation of treatment upon rising MRD levels (pre-emptive treatment) before morphologically detectable relapse.

Monitoring minimal residual disease in acute myeloid leukaemia: a review of the current evolving strategies.

Several disease-monitoring techniques are available for the physician treating acute myeloid leukaemia (AML). Besides immunohistochemistry assisted light microscopy, the past 20 years have seen the development and preclinical perfection of a number of techniques, most notably quantitative polymerase chain reaction (PCR) and multicolor flow cytometry. Late additions to the group of applicable assays include next generation sequencing and digital PCR. In this review the principles of use of these modalities at three different time points during the AML disease course are discussed, namely at the time of treatment evaluation, pretransplantation and postconsolidation. The drawbacks and pitfalls of each different technique are delineated. The evidence or lack of evidence for minimal residual disease guided treatment decisions is discussed. Lastly, future strategies in the MRD field are suggested and commented upon.

Fatal haemolytic crisis with microvascular pulmonary obstruction mimicking a pulmonary embolism in a young African man with glucose-6-phosphate dehydrogenase deficiency.

We report a fatal case of haemolytic crisis mimicking a pulmonary embolism in a previously healthy 42-year-old African man. The patient was admitted to hospital with fatigue, shortness of breath and jaundice lasting for 2 days. Laboratory tests were consistent with haemolysis and inflammation. The patient was treated as having a mycoplasma pneumonia. His condition deteriorated rapidly, with respiratory distress and circulatory failure. Echocardiography showed pulmonary hypertension and right heart dilation. Despite the fact that he was given fibrinolysis for suspected pulmonary embolism, he developed cardiac arrest and died after a long-lasting resuscitation attempt. Postmortem examinations revealed that the patient had a glucose-6-phosphate dehydrogenase deficiency and disseminated intravascular coagulation with pulmonary microthrombi. To the best of our knowledge, this is the first case of death caused by right heart failure due to microvascular obstruction resulting from multiple microvascular thrombosis in a patient with acute haemolysis due to glucose-6-phosphate dehydrogenase deficiency.

Delineation of known and new transcript variants of the SETMAR (Metnase) gene and the expression profile in hematologic neoplasms.

SET domain and mariner transposase fusion gene (SETMAR), also known as Metnase, has previously been shown to suppress the formation of chromosomal translocation in mouse fibroblasts. Despite the fact that hematologic malignancies are often characterized by chromosomal rearrangements, no studies have hitherto investigated the expression pattern of the gene in these disorders. We hypothesized that a high expression of SETMAR protected the cells from chromosomal rearrangements; thus, we examined the mRNA expression of SETMAR transcript variants in hematologic patients. We identified six transcript variants (var1, var2, var5, varA, varB, varC), of which three had not been reported previously. Expression levels were quantified by transcript-specific quantitative polymerase chain reaction in 15 healthy individuals, 70 acute myeloid leukemia (AML) patients (translocation positive, n= 30 [AML(TPos)], translocation negative, n = 40 [AML(TNeg)]), seven patients with mantle cell lymphoma (t [11,14] positive), and 13 patients with chronic myeloid leukemia (t [9,22] positive). All variants were significantly overexpressed in both subgroups of AML compared with healthy individuals (var1 and var2: p < 0.00001 for both AML subgroups, varA and varB: p = 0.0002, var5: p = 0.0008, and varC: p = 0.0001 for AML(TNeg); varA: p = 0.0048, varB and var5: p = 0.0001, varC: p = 0.0017). When comparing the expression in AML(TNeg) and AML(TPos), we found a significantly increased expression of the full length SETMAR in AML(TNeg) (var1: p = 0.047), suggesting a protective effect of high SETMAR expression on formation of chromosomal translocations. In conclusion, we have found known and novel SETMAR splice variants to be significantly increased in AML. To our knowledge, this is the first study that describes an expression profile of SETMAR in subgroups of hematologic malignancies, which can be linked to the incidence of chromosomal rearrangements.

A novel RT-qPCR assay for quantification of the MLL-MLLT3 fusion transcript in acute myeloid leukaemia.

OBJECTIVES: Patients with acute myeloid leukaemia (AML) of the monocytic lineage often lack molecular markers for minimal residual disease (MRD) monitoring. The MLL-MLLT3 fusion transcript found in patients with AML harbouring t(9;11) is amenable to RT-qPCR quantification but because of the heterogeneity of translocation break points, the MLL-MLLT3 fusion gene is a challenging target. We hypothesised that MRD monitoring using MLL-MLLT3 as a RT-qPCR marker is feasible in the majority of patients with t(9;11)-positive AML. METHODS: Using a locked nucleic acid probe, we developed a sensitive RT-qPCR assay for quantification of the most common break point region of the MLL-MLLT3 fusion gene. Five paediatric patients with t(9;11)-positive AML were monitored using the MLL-MLLT3 assay. RESULTS: A total of 43 bone marrow (BM) and 52 Peripheral blood (PB) samples were collected from diagnosis until follow-up. Two patients relapsed, and both were MRD positive in BM after first induction course. A total of three relapses occurred, and they were detected by RT-qPCR 3 wks before haematological relapse was diagnosed. CONCLUSION: This MLL-MLLT3 RT-qPCR assay could be useful in MRD monitoring of a group of patients with AML who often lack reliable MRD markers.