Assessment and Improvement of Gene Transfer into Human Hematopoietic Stem Cells

The application of somatic gene transfer as a potential treatment in human disease has progressed from speculation to reality in a short time [4,20,21,84,85,87,105,117,174]. In May 1989 the first clinical marker gene protocol took place [145], followed by the first gene therapy protocol for the correction of adenosine deaminase deficiency in September 1990 [3,111. Subsequently, the number of gene marking and gene therapy trials grew exponentially. In 1996 more than 200 clinical protocols were approved worldwide [51 and more than 1,500 patients are now enrolled in gene transfer trials (96). However, up to now the gene therapy trials have not brought clear clinical benefits for patients [5,31,51,98]. An important explanation for the lack of therapeutic effects is the very low gene transfer efficiency in human cells. One of the main targets for gene therapy is the hematopoietic system because of well-developed procedures for bone marrow transplantation, the many types and wide distribution of hematopoietic cells in the body and the existence of many diseases and treatments that affect hematopoietic cells. The target cell for gene transfer is the primitive hematopoietic stem cell (HSC), which is present at low frequency in the bone marrow, is responsible for long-term hematopoiesis and gives rise to all hematological and lymphoid lineages. Although many research groups have reported transfer and long-term expression of genes in a significant percentage of murine hematopoietic cells [77,142,177]' the achievements in larger outbred animals [81,93,150], nonhuman primates [14,164,1651 and humans [17,29,36,44,48,72,861 show only a small percentage of long-term expression in a limited number of recipients. The aim of this study was to develop protocols which improve gene transfer of human HSC. For this purpose suitable assays were developed to determine the frequency and proliferative capacity of different classes of human HSC. Subsequently, culture conditions for human HSC were studied. As a result, using newly developed human HSC assays and optimized culture conditions, improved human HSC gene transfer protocols could be proposed. In the presented studies we have opted for clinically relevant and acceptable protocols. This included the use of target cells which are most frequently used in clinical autologous stem cell transplantation, namely mobilized peripheral blood stem cells (PBSC) [1611 and serum-free transfection cultures in which target cells and virus-producing cells were separated

Clinical implications of measurable residual disease in AML : review of current evidence

Despite the fact that 80% of adult acute myeloid leukaemia patients reach complete morphological remission after induction chemotherapy, many of them relapse. Many studies have shown that detection of minimal residual disease (defined as 'any detectable evidence of persistent leukaemic cells during complete morphological remission') has an added value in prediction of relapse and survival, and is more than just a surrogate marker for already known risk factors in AML. As such, the behaviour of the disease during treatment might become equally or even more important to decide whether or not an upgrade of treatment (such as an allogeneic stem cell transplantation) is necessary to improve outcome. However, there are still many open issues as to what the ideal time point is to measure MRD, which threshold is clinically significant, what sample (peripheral blood or bone marrow) should be used and how we can standardize tests so that results from different labs become comparable. This review gives an overview of currently available evidence regarding technical issues, prognostic impact and MRD-directed treatment in AML

Measurable residual disease-guided therapy in intermediate-risk acute myeloid leukemia patients is a valuable strategy in reducing allogeneic transplantation without negatively affecting survival.

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Molecular characterization of mutant TP53 acute myeloid leukemia and high-risk myelodysplastic syndrome

Substantial heterogeneity within mutant TP53 acute myeloid leukemia (AML) and myelodysplastic syndrome with excess of blast (MDS-EB) precludes the exact assessment of prognostic impact for individual patients. We performed in-depth clinical and molecular analysis of mutant TP53 AML and MDS-EB to dissect the molecular characteristics in detail and determine its impact on survival. We performed next-generation sequencing on 2200 AML/MDS-EB specimens and assessed the TP53 mutant allelic status (mono- or bi-allelic), the number of TP53 mutations, mutant TP53 clone size, concurrent mutations, cytogenetics, and mutant TP53 molecular minimal residual disease and studied the associations of these characteristics with overall survival. TP53 mutations were detected in 230 (10.5%) patients with AML/MDS-EB with a median variant allele frequency of 47%. Bi-allelic mutant TP53 status was observed in 174 (76%) patients. Multiple TP53 mutations were found in 49 (21%) patients. Concurrent mutations were detected in 113 (49%) patients. No significant difference in any of the aforementioned molecular characteristics of mutant TP53 was detected between AML and MDS-EB. Patients with mutant TP53 have a poor outcome (2-year overall survival, 12.8%); however, no survival difference between AML and MDS-EB was observed. Importantly, none of the molecular characteristics were significantly associated with survival in mutant TP53 AML/MDS-EB. In most patients, TP53 mutations remained detectable in complete remission by deep sequencing (73%). Detection of residual mutant TP53 was not associated with survival. Mutant TP53 AML and MDS-EB do not differ with respect to molecular characteristics and survival. Therefore, mutant TP53 AML/MDS-EB should be considered a distinct molecular disease entity

Real-World Insights on the Management of Immune-Mediated Thrombotic Thrombocytopenic Purpura (iTTP) With Caplacizumab

peer reviewe

Ibrutinib added to 10-day decitabine for older patients with AML and higher risk MDS

The treatment of older, unfit patients with acute myeloid leukemia (AML) is challenging. Based on preclinical data of Bruton tyrosine kinase expression/phosphorylation and ibrutinib cytotoxicity in AML blasts, we conducted a randomized phase 2 multicenter study to assess the tolerability and efficacy of the addition of ibrutinib to 10-day decitabine in unfit (ie, Hematopoietic Cell Transplantation Comorbidity Index ≥3) AML patients and higher risk myelodysplasia patients (HOVON135/SAKK30/15 trial). In total, 144 eligible patients were randomly (1:1) assigned to either 10-day decitabine combined with ibrutinib (560 mg; sequentially given, starting the day after the last dose of decitabine) (n = 72) or to 10-day decitabine (n = 72). The addition of ibrutinib was well tolerated, and the number of adverse events was comparable for both arms. In the decitabine plus ibrutinib arm, 41% reached complete remission/complete remission with incomplete hematologic recovery (CR/CRi), the median overall survival (OS) was 11 months, and 2-year OS was 27%; these findings compared with 50% CR/CRi, median OS of 11.5 months, and 2-year OS of 21% for the decitabine group (not significant). Extensive molecular profiling at diagnosis revealed that patients with STAG2, IDH2, and ASXL1 mutations had significantly lower CR/CRi rates, whereas patients with mutations in TP53 had significantly higher CR/CRi rates. Furthermore, multicolor flow cytometry revealed that after 3 cycles of treatment, 28 (49%) of 57 patients with available bone marrow samples had no measurable residual disease. In this limited number of cases, measurable residual disease revealed no apparent impact on event-free survival and OS. In conclusion, the addition of ibrutinib does not improve the therapeutic efficacy of decitabine. This trial was registered at the Netherlands Trial Register (NL5751 [NTR6017]) and has EudraCT number 2015-002855-85

Age and sex associate with outcome in older AML and high risk MDS patients treated with 10-day decitabine

Treatment choice according to the individual conditions remains challenging, particularly in older patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). The impact of performance status, comorbidities, and physical functioning on survival is not well defined for patients treated with hypomethylating agents. Here we describe the impact of performance status (14% ECOG performance status 2), comorbidity (40% HCT-comorbidity index ≥ 2), and physical functioning (41% short physical performance battery &lt; 9 and 17% ADL index &lt; 6) on overall survival (OS) in 115 older patients (age ≥ 66 years) treated on a clinical trial with a 10-day decitabine schedule. None of the patient-related variables showed a significant association with OS. Multivariable analysis revealed that age &gt; 76 years was significantly associated with reduced OS (HR 1.58; p = 0.043) and female sex was associated with superior OS (HR 0.62; p = 0.06). We further compared the genetic profiles of these subgroups. This revealed comparable mutational profiles in patients younger and older than 76 years, but, interestingly, revealed significantly more prevalent mutated ASXL1, STAG2, and U2AF1 in male compared to female patients. In this cohort of older patients treated with decitabine age and sex, but not comorbidities, physical functioning or cytogenetic risk were associated with overall survival.</p

Age and sex associate with outcome in older AML and high risk MDS patients treated with 10-day decitabine

Treatment choice according to the individual conditions remains challenging, particularly in older patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). The impact of performance status, comorbidities, and physical functioning on survival is not well defined for patients treated with hypomethylating agents. Here we describe the impact of performance status (14% ECOG performance status 2), comorbidity (40% HCT-comorbidity index ≥ 2), and physical functioning (41% short physical performance battery &lt; 9 and 17% ADL index &lt; 6) on overall survival (OS) in 115 older patients (age ≥ 66 years) treated on a clinical trial with a 10-day decitabine schedule. None of the patient-related variables showed a significant association with OS. Multivariable analysis revealed that age &gt; 76 years was significantly associated with reduced OS (HR 1.58; p = 0.043) and female sex was associated with superior OS (HR 0.62; p = 0.06). We further compared the genetic profiles of these subgroups. This revealed comparable mutational profiles in patients younger and older than 76 years, but, interestingly, revealed significantly more prevalent mutated ASXL1, STAG2, and U2AF1 in male compared to female patients. In this cohort of older patients treated with decitabine age and sex, but not comorbidities, physical functioning or cytogenetic risk were associated with overall survival.</p

Age and sex associate with outcome in older AML and high risk MDS patients treated with 10-day decitabine

Treatment choice according to the individual conditions remains challenging, particularly in older patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). The impact of performance status, comorbidities, and physical functioning on survival is not well defined for patients treated with hypomethylating agents. Here we describe the impact of performance status (14% ECOG performance status 2), comorbidity (40% HCT-comorbidity index ≥ 2), and physical functioning (41% short physical performance battery &lt; 9 and 17% ADL index &lt; 6) on overall survival (OS) in 115 older patients (age ≥ 66 years) treated on a clinical trial with a 10-day decitabine schedule. None of the patient-related variables showed a significant association with OS. Multivariable analysis revealed that age &gt; 76 years was significantly associated with reduced OS (HR 1.58; p = 0.043) and female sex was associated with superior OS (HR 0.62; p = 0.06). We further compared the genetic profiles of these subgroups. This revealed comparable mutational profiles in patients younger and older than 76 years, but, interestingly, revealed significantly more prevalent mutated ASXL1, STAG2, and U2AF1 in male compared to female patients. In this cohort of older patients treated with decitabine age and sex, but not comorbidities, physical functioning or cytogenetic risk were associated with overall survival.</p