108 research outputs found
Inhibition of IGF1-R overcomes IGFBP7-induced chemotherapy resistance in T-ALL
Background T-cell acute lymphoblastic leukemia (T-ALL) is a genetically
heterogeneous disease with the need for treatment optimization. Previously,
high expression of Insulin-like growth factor binding protein 7 (IGFBP7), a
member of the IGF system, was identified as negative prognostic factor in
adult T-ALL patients. Since aberrant IGFBP7 expression was observed in a
variety of neoplasia and was relevant for prognosis in T-ALL, we investigated
the functional role of IGFBP7 in Jurkat and Molt-4 cells as in vitro models
for T-ALL. Methods Jurkat and Molt-4 cells were stably transfected with an
IGFBP7 over-expression vector or the empty vector as control. Proliferation of
the cells was assessed by WST-1 assays and cell cycle status was measured by
flow-cytometry after BrDU/7-AAD staining. The effect of IGFBP7 over-expression
on sensitivity to cytostatic drugs was determined in AnnexinV/7-AAD assays.
IGF1-R protein expression was measured by Western Blot and flow-cytometric
analysis. IGF1-R associated gene expression profiles were generated from
microarray gene expression data of 86 T-ALL patients from the Microarrays
Innovations in Leukemia (MILE) multicenter study. Results IGFBP7-transfected
Jurkat cells proliferated less, leading to a longer survival in a
nutrient–limited environment. Both IGFBP7-transfected Jurkat and Molt-4 cells
showed an arrest in the G0/G1 cell cycle phase. Furthermore, Jurkat
IGFBP7-transfected cells were resistant to vincristine and asparaginase
treatment. Surface expression and whole protein measurement of IGF1-R protein
expression showed a reduced abundance of the receptor after IGFBP7
transfection in Jurkat cells. Interestingly, combination of the IGF1-R
inhibitor NPV-AEW541 restored sensitivity to vincristine in IGFBP7-transfected
cells. Additionally, IGF1-R associated GEP revealed an up-regulation of
important drivers of T-ALL pathogenesis and regulators of chemo-resistance and
apoptosis such as NOTCH1, BCL-2, PRKCI, and TP53. Conclusion This study
revealed a proliferation inhibiting effect of IGFBP7 by G0/G1 arrest and a
drug resistance-inducing effect of IGFBP7 against vincristine and asparaginase
in T-ALL. These results provide a model for the previously observed
association between high IGFBP7 expression and chemotherapy failure in T-ALL
patients. Since the resistance against vincristine was abolished by IGF1-R
inhibition, IGFBP7 could serve as biomarker for patients who may benefit from
therapies including IGF1-R inhibitors in combination with chemotherapy
FLT3 mutations in Early T-Cell Precursor ALL characterize a stem cell like leukemia and imply the clinical use of tyrosine kinase inhibitors
Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) has been identified as high-risk subgroup of acute T-lymphoblastic leukemia (T-ALL) with a high rate of FLT3-mutations in adults. To unravel the underlying pathomechanisms and the clinical course we assessed molecular alterations and clinical characteristics in a large cohort of ETP-ALL (n = 68) in comparison to non-ETP T-ALL adult patients. Interestingly, we found a high rate of FLT3-mutations in ETP-ALL samples (n = 24, 35%). Furthermore, FLT3 mutated ETP-ALL was characterized by a specific immunophenotype (CD2+/CD5-/CD13+/CD33-), a distinct gene expression pattern (aberrant expression of IGFBP7, WT1, GATA3) and mutational status (absence of NOTCH1 mutations and a low frequency, 21%, of clonal TCR rearrangements). The observed low GATA3 expression and high WT1 expression in combination with lack of NOTCH1 mutations and a low rate of TCR rearrangements point to a leukemic transformation at the pluripotent prothymocyte stage in FLT3 mutated ETP-ALL. The clinical outcome in ETP-ALL patients was poor, but encouraging in those patients with allogeneic stem cell transplantation (3-year OS: 74%). To further explore the efficacy of targeted therapies, we demonstrate that T-ALL cell lines transfected with FLT3 expression constructs were particularly sensitive to tyrosine kinase inhibitors. In conclusion, FLT3 mutated ETP-ALL defines a molecular distinct stem cell like leukemic subtype. These data warrant clinical studies with the implementation of FLT3 inhibitors in addition to early allogeneic stem cell transplantation for this high risk subgroup
An alternative CYB5A transcript is expressed in aneuploid ALL and enriched in relapse
Background: B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is a genetically heterogenous malignancy with poor prognosis in relapsed adult patients. The genetic basis for relapse in aneuploid subtypes such as near haploid (NH) and high hyperdiploid (HeH) BCP-ALL is only poorly understood. Pathogenic genetic alterations remain to be identified. To this end, we investigated the dynamics of genetic alterations in a matched initial diagnosis-relapse (ID-REL) BCP-ALL cohort. Here, we firstly report the identification of the novel genetic alteration CYB5Aalt, an alternative transcript of CYB5A, in two independent cohorts.
Methods: We identified CYB5alt in the RNAseq-analysis of a matched ID-REL BCP-ALL cohort with 50 patients and quantified its expression in various molecular BCP-ALL subtypes. Findings were validated in an independent cohort of 140 first diagnosis samples from adult BCP-ALL patients. Derived from patient material, the alternative open reading frame of CYB5Aalt was cloned (pCYB5Aalt) and pCYB5Aalt or the empty vector were stably overexpressed in NALM-6 cells. RNA sequencing was performed of pCYB5Aalt clones and empty vector controls followed by differential expression analysis, gene set enrichment analysis and complementing cell death and viability assays to determine functional implications of CYB5Aalt.
Results: RNAseq data analysis revealed non-canonical exon usage of CYB5Aalt starting from a previously undescribed transcription start site. CYB5Aalt expression was increased in relapsed BCP-ALL and its occurrence was specific towards the shared gene expression cluster of NH and HeH BCP-ALL in independent cohorts. Overexpression of pCYB5Aalt in NALM-6 cells induced a distinct transcriptional program compared to empty vector controls with downregulation of pathways related to reported functions of CYB5A wildtype. Interestingly, CYB5A wildtype expression was decreased in CYB5Aalt samples in silico and in vitro. Additionally, pCYB5Aalt NALM-6 elicited a more resistant drug response.
Conclusions: Across all age groups, CYB5Aalt was the most frequent secondary genetic event in relapsed NH and HeH BCP-ALL. In addition to its high subgroup specificity, CYB5Aalt is a novel candidate to be potentially implicated in therapy resistance in NH and HeH BCP-ALL. This is underlined by overexpressing CYB5Aalt providing first evidence for a functional role in BCL2-mediated apoptosis
Early Versus Late Allogeneic Hematopoietic Cell Transplantation in Patients with AML - Results From the Randomized AML 2003 Trial
Prognostic impact of <i>CEBPA </i>mutational subgroups in adult AML
Despite recent refinements in the diagnostic and prognostic assessment of CEBPA mutations in AML, several questions remain open, i.e. implications of different types of basic region leucin zipper (bZIP) mutations, the role of co-mutations and the allelic state. Using pooled primary data analysis on 1010 CEBPA-mutant adult AML patients, a comparison was performed taking into account the type of mutation (bZIP: either typical in-frame insertion/deletion (InDel) mutations (bZIP InDel), frameshift InDel or nonsense mutations inducing translational stop (bZIP STOP) or single base-pair missense alterations (bZIP ms), and transcription activation domain (TAD) mutations) and the allelic state (single (smCEBPA) vs. double mutant (dmCEBPA)). Only bZIP InDel patients had significantly higher rates of complete remission and longer relapse free and overall survival (OS) compared with all other CEBPA-mutant subgroups. Moreover, co-mutations in bZIP InDel patients (e.g. GATA2, FLT3, WT1 as well as ELN2022 adverse risk aberrations) had no independent impact on OS, whereas in non-bZIP InDel patients, grouping according to ELN2022 recommendations added significant prognostic information. In conclusion, these results demonstrate bZIP InDel mutations to be the major independent determinant of outcome in CEBPA-mutant AML, thereby refining current classifications according to WHO (including all dmCEBPA and smCEBPA bZIP) as well as ELN2022 and ICC recommendations (including CEBPA bZIP ms). (Figure presented.)</p
Prognostic impact of CEBPA mutational subgroups in adult AML
Despite recent refinements in the diagnostic and prognostic assessment of CEBPA mutations in AML, several questions remain open, i.e. implications of different types of basic region leucin zipper (bZIP) mutations, the role of co-mutations and the allelic state. Using pooled primary data analysis on 1010 CEBPA-mutant adult AML patients, a comparison was performed taking into account the type of mutation (bZIP: either typical in-frame insertion/deletion (InDel) mutations (bZIPInDel), frameshift InDel or nonsense mutations inducing translational stop (bZIPSTOP) or single base-pair missense alterations (bZIPms), and transcription activation domain (TAD) mutations) and the allelic state (single (smCEBPA) vs. double mutant (dmCEBPA)). Only bZIPInDel patients had significantly higher rates of complete remission and longer relapse free and overall survival (OS) compared with all other CEBPA-mutant subgroups. Moreover, co-mutations in bZIPInDel patients (e.g. GATA2, FLT3, WT1 as well as ELN2022 adverse risk aberrations) had no independent impact on OS, whereas in non-bZIPInDel patients, grouping according to ELN2022 recommendations added significant prognostic information. In conclusion, these results demonstrate bZIPInDel mutations to be the major independent determinant of outcome in CEBPA-mutant AML, thereby refining current classifications according to WHO (including all dmCEBPA and smCEBPA bZIP) as well as ELN2022 and ICC recommendations (including CEBPA bZIPms)
Mutation-Guided Therapy for CML Blast Crisis: A Case Report
The management of patients with chronic myeloid leukemia (CML) in advanced phases is challenging and requires the consideration of different treatment approaches, including targeted therapy with tyrosine kinase inhibitors, cytotoxic chemotherapy, and allogeneic stem cell transplantation. Here, we present the case of a patient with CML in mixed phenotype blast phase illustrating the integration of these strategies and demonstrating the need for close monitoring of treatment response in order to individually adjust treatment regimens
Adults with Philadelphia chromosome–like acute lymphoblastic leukemia frequently have IGH-CRLF2 and JAK2 mutations, persistence of minimal residual disease and poor prognosis
Philadelphia-like B-cell precursor acute lymphoblastic leukemia (Ph-like ALL)
is characterized by distinct genetic alterations and inferior prognosis in
children and younger adults. The purpose of this study was a genetic and
clinical characterization of Ph-like ALL in adults. Twenty-six (13%) of 207
adult patients (median age: 42 years) with B-cell precursor ALL (BCP-ALL) were
classified as having Ph-like ALL using gene expression profiling. The
frequency of Ph-like ALL was 27% among 95 BCP-ALL patients negative for BCR-
ABL1 and KMT2A-rearrangements. IGH-CRLF2 rearrangements (6/16; P=0.002) and
mutations in JAK2 (7/16; P<0.001) were found exclusively in the Ph-like ALL
subgroup. Clinical and outcome analyses were restricted to patients treated in
German Multicenter Study Group for Adult ALL (GMALL) trials 06/99 and 07/03
(n=107). The complete remission rate was 100% among both Ph-like ALL patients
(n=19) and the “remaining BCP-ALL” cases (n=40), i.e. patients negative for
BCR-ABL1 and KMT2A-rearrangements and the Ph-like subtype. Significantly fewer
Ph-like ALL patients reached molecular complete remission (33% versus 79%;
P=0.02) and had a lower probability of continuous complete remission (26%
versus 60%; P=0.03) and overall survival (22% versus 64%; P=0.006) at 5 years
compared to the remaining BCP-ALL patients. The profile of genetic lesions in
adults with Ph-like ALL, including older adults, resembles that of pediatric
Ph-like ALL and differs from the profile in the remaining BCP-ALL. Our study
is the first to demonstrate that Ph-like ALL is associated with inferior
outcomes in intensively treated older adult patients. Ph-like adult ALL should
be recognized as a distinct, high-risk entity and further research on improved
diagnostic and therapeutic approaches is needed. (NCT00199056, NCT00198991
High BAALC Expression as an Independent Adverse Risk Factor in 309 Patients with Acute Myeloid Leukemia (AML) and Normal Cytogenetics: Results of the SHG’96 Study.
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