NOTCH1 and FBXW7 mutations have a favorable impact on early response to treatment, but not on outcome, in children with T-cell acute lymphoblastic leukemia (T-ALL) treated on EORTC trials 58881 and 58951

NGS-based stratification refines the risk stratification in T-ALL and identifies a very-high-risk subgroup of patients

ABSTRACT

We previously reported a better outcome in adult and pediatric T-cell acute lymphoblastic leukemia (T-ALL) harboring NOTCH1 and/or FBXW7 mutations without alterations of K-N-RAS and PTEN genes. Availability of high-throughput next-generation sequencing (NGS) strategies led us to refine the outcome prediction in T-ALL. Targeted whole-exome sequencing of 72 T-ALL-related oncogenes was performed in 198 adults with T-ALLs in first remission from the GRAALL-2003/2005 protocols and 242 pediatric patients with T-ALLs from the FRALLE2000T. This approach enabled the identification of, to our knowledge, the first NGS-based classifier in T-ALL, categorizing low-risk patients as those with N/F, PHF6, or EP300 mutations, excluding N-K-RAS, PI3K pathway (PTEN, PIK3CA, and PIK3R1), TP53, DNMT3A, IDH1/2, and IKZF1 alterations, with a 5-year cumulative incidence of relapse (CIR) estimated at 21%. Conversely, the remaining patients were classified as high risk, exhibiting a 5-year CIR estimated at 47%. We externally validated this stratification in the pediatric cohort. NGS-based classifier was highly prognostic independently of minimal residual disease (MRD) and white blood cell (WBC) counts, in both adult and pediatric cohorts. Integration of the NGS-based classifier into a comprehensive risk-stratification model, including WBC count at diagnosis and MRD at the end of induction, enabled the identification of an adverse-risk subgroup (25%) with a 5-year CIR estimated at 51%, and a favorable-risk group (32%) with a 5-year CIR estimated at 12%. NGS-based stratification combined with WBC and MRD sharpens the prognostic classification in T-ALL and identifies a new subgroup of patients who may benefit from innovative therapeutic approaches. The GRAALL-2003/2005 studies were registered at www.ClinicalTrials.gov as #NCT00222027 and #NCT00327678.

Emerging Epigenetic and Posttranslational Mechanisms Controlling Resistance to Glucocorticoids in Acute Lymphoblastic Leukemia

Glucocorticoids are extensively used for the treatment of acute lymphoblastic leukemia as they pressure cancer cells to undergo apoptosis. Nevertheless, glucocorticoid partners, modifications, and mechanisms of action are hitherto poorly characterized. This hampers our understanding of therapy resistance, frequently occurring in leukemia despite the current therapeutic combinations using glucocorticoids in acute lymphoblastic leukemia. In this review, we initially cover the traditional view of glucocorticoid resistance and ways of targeting this resistance. We discuss recent progress in our understanding of chromatin and posttranslational properties of the glucocorticoid receptor that might be proven beneficial in our efforts to understand and target therapy resistance. We discuss emerging roles of pathways and proteins such as the lymphocyte-specific kinase that antagonizes glucocorticoid receptor activation and nuclear translocation. In addition, we provide an overview of ongoing therapeutic approaches that sensitize cells to glucocorticoids including small molecule inhibitors and proteolysis-targeting chimeras.

The role of SF3B1 and NOTCH1 in the pathogenesis of leukemia

The discovery of new genes/pathways improves our knowledge of cancer pathogenesis and presents novel potential therapeutic options. For instance, splicing factor 3b subunit 1 (SF3B1) and NOTCH1 genetic alterations have been identified at a high frequency in hematological malignancies, such as leukemia, and may be related to the prognosis of involved patients because they change the nature of malignancies in different ways like mediating therapeutic resistance; therefore, studying these gene/pathways is essential. This review aims to discuss SF3B1 and NOTCH1 roles in the pathogenesis of various types of leukemia and the therapeutic potential of targeting these genes or their mutations to provide a foundation for leukemia treatment.

Integrated clinical genotype-phenotype characteristics of early T-cell precursor acute lymphoblastic leukemia

BACKGROUND

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinct subtype of T-ALL with a unique immunophenotype and high treatment failure rate. The molecular genetic abnormalities and their prognostic impact in ETP-ALL patients are poorly understood.

METHODS

The authors performed systematic analyses of the clinicopathologic features with an emphasis on molecular genetic aspects of 32 patients with ETP-ALL.

RESULTS

The median age was 43 years (range, 16-71). The blasts were positive for cytoplasmic CD3 and CD7 and negative for CD1a and CD8. Other markers expressed included CD34 (88%), CD33 (72%), CD117 (68%), CD13 (58%), CD5 (partial, 56%), CD2 (38%), CD10 (25%), CD56 (partial, 19%), and CD4 (6%). Cytogenetic analyses revealed a diploid karyotype in 10 patients, simple (1-2) abnormalities in 10 patients, and complex karyotype in 10 patients. Next-generation sequencing for 21 patients demonstrated that all had gene mutations (median, four mutations per patient). The most frequently mutated genes were WT1 (38%), NOTCH1 (29%), NRAS (29%), PHF6 (25%), TP53 (24%), ASXL1 (19%), FLT3 (19%), and IKZF1 (19%). All patients except one received multi-agent chemotherapy, and 22 patients underwent allogeneic stem cell transplantation. Thrombocytopenia, an abnormal karyotype, and TP53 mutation were associated with markedly shortened overall survival. Stem cell transplantation significantly improved overall survival.

CONCLUSIONS

Patients with ETP-ALL often have high mutation burden with increased genomic instability. TP53 mutation was the only molecular prognostic marker and was associated with complex karyotype and greater than or equal to five mutations. These patients may benefit from stem cell transplantation, and recurrent gene mutations may be novel therapeutic markers.

Molecular genetic abnormalities in patients with T-cell acute lymphoblastic leukemia: a literature review

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL) is an aggressive hematological disease. Modern polychemotherapy protocols allow achieving a 5-year overall survival of 60–90 % in different age groups, however, relapses and refractory forms of T-ALL remain incurable. Over the past decades, the pathogenesis of this variant of leukemia has been studied in many trials, and it has been found that various signaling pathways are involved in the multi-step process of leukemogenesis. This opens the way for targeted therapy.In this review, we provide an update on the pathogenesis of T-ALL, opportunities for introducing targeted therapies, and issues that remain to be addressed.

Oncogenetic landscape of T-cell lymphoblastic lymphomas compared to T-cell acute lymphoblastic leukemia

In the latest 2016 World Health Organization classification of hematological malignancies, T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) are grouped together into one entity called T-cell lymphoblastic leukemia/lymphoma (T-LBLL). However, the question of whether these entities represent one or two diseases remains. Multiple studies on driver alterations in T-ALL have led to a better understanding of the disease while, so far, little data on genetic profiles in T-LBL is available. We sought to define recurrent genetic alterations in T-LBL and provide a comprehensive comparison with T-ALL. Targeted whole-exome next-generation sequencing of 105 genes, multiplex ligation-dependent probe amplification, and quantitative PCR allowed comprehensive genotype assessment in 818, consecutive, unselected, newly diagnosed patients (342 T-LBL vs. 476 T-ALL). The median age at diagnosis was similar in T-LBL and T-ALL (17 vs. 15 years old, respectively; p = 0.2). Although we found commonly altered signaling pathways and co-occurring mutations, we identified recurrent dissimilarities in actionable gene alterations in T-LBL as compared to T-ALL. HOX abnormalities (TLX1 and TLX3 overexpression) were more frequent in T-ALL (5% of T-LBL vs 13% of T-ALL had TLX1 overexpression; p = 0.04 and 6% of T-LBL vs 17% of T-ALL had TLX3 overexpression; p = 0.006). The PI3K signaling pathway was significantly more frequently altered in T-LBL as compared to T-ALL (33% vs 19%; p < 0.001), especially through PIK3CA alterations (9% vs 2%; p < 0.001) with PIK3CA^H1047 as the most common hotspot. Similarly, T-LBL genotypes were significantly enriched in alterations in genes coding for the EZH2 epigenetic regulator and in TP53 mutations (respectively, 13% vs 8%; p = 0.016 and 7% vs 2%; p < 0.001). This genetic landscape of T-LBLL identifies differential involvement of recurrent alterations in T-LBL as compared to T-ALL, thus contributing to better understanding and management of this rare disease.

Hyperprogression, a challenge of PD-1/PD-L1 inhibitors treatments: potential mechanisms and coping strategies

Immunotherapy is now a mainstay in cancer treatments. Programmed cell death 1 (PD-1)/programmed cell death ligand 1 (PD-L1) immune checkpoint inhibitor (ICI) therapies have opened up a new venue of advanced cancer immunotherapy. However, hyperprogressive disease (HPD) induced by PD-1/PD-L1 inhibitors caused a significant decrease in the overall survival (OS) of the patients, which compromise the efficacy of PD-1/PD-L1 inhibitors. Therefore, HPD has become an urgent issue to be addressed in the clinical uses of PD-1/PD-L1 inhibitors. The mechanisms of HPD remain unclear, and possible predictive factors of HPD are not well understood. In this review, we summarized the potential mechanisms of HPD and coping strategies that can effectively reduce the occurrence and development of HPD.

Overcoming Steroid Resistance in Pediatric Acute Lymphoblastic Leukemia-The State-of-the-Art Knowledge and Future Prospects

Acute lymphoblastic leukemia (ALL) is the most common malignancy among children. Despite the enormous progress in ALL therapy, resulting in achieving a 5-year survival rate of up to 90%, the ambitious goal of reaching a 100% survival rate is still being pursued. A typical ALL treatment includes three phases: remission induction and consolidation and maintenance, preceded by a prednisone prephase. Poor prednisone response (PPR) is defined as the presence of ≥1.0 × 10⁹ blasts/L in the peripheral blood on day eight of therapy and results in significantly frequent relapses and worse outcomes. Hence, identifying risk factors of steroid resistance and finding methods of overcoming that resistance may significantly improve patients' outcomes. A mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK-ERK) pathway seems to be a particularly attractive target, as its activation leads to steroid resistance via a phosphorylating Bcl-2-interacting mediator of cell death (BIM), which is crucial in the steroid-induced cell death. Several mutations causing activation of MAPK-ERK were discovered, notably the interleukin-7 receptor (IL-7R) pathway mutations in T-cell ALL and rat sarcoma virus (Ras) pathway mutations in precursor B-cell ALL. MAPK-ERK pathway inhibitors were demonstrated to enhance the results of dexamethasone therapy in preclinical ALL studies. This report summarizes steroids' mechanism of action, resistance to treatment, and prospects of steroids therapy in pediatric ALL.

T-Cell Acute Lymphoblastic Leukemia: Biomarkers and Their Clinical Usefulness

T-cell acute lymphoblastic leukemias (T-ALL) are immature lymphoid tumors localizing in the bone marrow, mediastinum, central nervous system, and lymphoid organs. They account for 10-15% of pediatric and about 25% of adult acute lymphoblastic leukemia (ALL) cases. It is a widely heterogeneous disease that is caused by the co-occurrence of multiple genetic abnormalities, which are acquired over time, and once accumulated, lead to full-blown leukemia. Recurrently affected genes deregulate pivotal cell processes, such as cycling (CDKN1B, RB1, TP53), signaling transduction (RAS pathway, IL7R/JAK/STAT, PI3K/AKT), epigenetics (PRC2 members, PHF6), and protein translation (RPL10, CNOT3). A remarkable role is played by NOTCH1 and CDKN2A, as they are altered in more than half of the cases. The activation of the NOTCH1 signaling affects thymocyte specification and development, while CDKN2A haploinsufficiency/inactivation, promotes cell cycle progression. Among recurrently involved oncogenes, a major role is exerted by T-cell-specific transcription factors, whose deregulated expression interferes with normal thymocyte development and causes a stage-specific differentiation arrest. Hence, TAL and/or LMO deregulation is typical of T-ALL with a mature phenotype (sCD3 positive) that of TLX1, NKX2-1, or TLX3, of cortical T-ALL (CD1a positive); HOXA and MEF2C are instead over-expressed in subsets of Early T-cell Precursor (ETP; immature phenotype) and early T-ALL. Among immature T-ALL, genomic alterations, that cause BCL11B transcriptional deregulation, identify a specific genetic subgroup. Although comprehensive cytogenetic and molecular studies have shed light on the genetic background of T-ALL, biomarkers are not currently adopted in the diagnostic workup of T-ALL, and only a limited number of studies have assessed their clinical implications. In this review, we will focus on recurrent T-ALL abnormalities that define specific leukemogenic pathways and on oncogenes/oncosuppressors that can serve as diagnostic biomarkers. Moreover, we will discuss how the complex genomic profile of T-ALL can be used to address and test innovative/targeted therapeutic options.

T-cell lymphoblastic lymphoma and leukemia: different diseases from a common premalignant progenitor?

T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) represent malignancies that arise from the transformation of immature precursor T cells. Similarities in T-LBL and T-ALL have raised the question whether these entities represent 1 disease or reflect 2 different diseases. The genetic profiles of T-ALL have been thoroughly investigated over the last 2 decades, whereas fairly little is known about genetic driver mutations in T-LBL. Nevertheless, the comparison of clinical, immunophenotypic, and molecular observations from independent T-LBL and T-ALL studies lent strength to the theory that T-LBL and T-ALL reflect different presentations of the same disease. Alternatively, T-LBL and T-ALL may simultaneously evolve from a common malignant precursor cell, each having their own specific pathogenic requirements or cellular dependencies that differ among stroma-embedded blasts in lymphoid tissues compared with solitary leukemia cells. This review aims to cluster recent findings with regard to clinical presentation, genetic predisposition, and the acquisition of additional mutations that may give rise to differences in gene expression signatures among T-LBL and T-ALL patients. Improved insight in T-LBL in relation to T-ALL may further help to apply confirmed T-ALL therapies to T-LBL patients.

Integrative genomic analysis of pediatric T-cell lymphoblastic lymphoma reveals candidates of clinical significance

T-cell lymphoblastic lymphoma (T-LBL) is a heterogeneous malignancy of lymphoblasts committed to T-cell lineage. The dismal outcomes (15%-30%) after T-LBL relapse warrant establishing risk-based treatment. To our knowledge, this study presents the first comprehensive, systematic, integrated, genome-wide analysis including relapsed cases that identifies molecular markers of prognostic relevance for T-LBL. NOTCH1 was identified as the putative driver for T-LBL. An activated NOTCH/PI3K-AKT signaling axis and alterations in cell cycle regulators constitute the core oncogenic program for T-LBL. Mutated KMT2D was identified as a prognostic marker. The cumulative incidence of relapse was 47% ± 17% in patients with KMT2D mutations, compared with 14% ± 3% in wild-type KMT2D. Structural analysis of the mutated domains of KMT2D revealed a plausible impact on structure and functional consequences. These findings provide new insights into the pathogenesis of T-LBL, including high translational potential. The ongoing LBL 2018 trial (www.clinicaltrials.gov #NCT04043494) allows for prospective validation and subsequent fine tuning of the stratification criteria for T-LBL risk groups to improve survival of pediatric patients.

The Role of Notch, Hedgehog, and Wnt Signaling Pathways in the Resistance of Tumors to Anticancer Therapies

Resistance to therapy is the major hurdle in the current cancer management. Cancer cells often rewire their cellular process to alternate mechanisms to resist the deleterious effect mounted by different therapeutic approaches. The major signaling pathways involved in the developmental process, such as Notch, Hedgehog, and Wnt, play a vital role in development, tumorigenesis, and also in the resistance to the various anticancer therapies. Understanding how cancer utilizes these developmental pathways in acquiring the resistance to the multi-therapeutic approach cancer can give rise to a new insight of the anti-therapy resistance mechanisms, which can be explored for the development of a novel therapeutic approach. We present a brief overview of Notch, Hedgehog, and Wnt signaling pathways in cancer and its role in providing resistance to various cancer treatment modalities such as chemotherapy, radiotherapy, molecular targeted therapy, and immunotherapy. Understanding the importance of these molecular networks will provide a rational basis for novel and safer combined anticancer therapeutic approaches for the improvement of cancer treatment by overcoming drug resistance.

The FBXW7-NOTCH interactome: A ubiquitin proteasomal system-induced crosstalk modulating oncogenic transformation in human tissues

BACKGROUND

Ubiquitin ligases or E3 ligases are well programmed to regulate molecular interactions that operate at a post-translational level. Skp, Cullin, F-box containing complex (or SCF complex) is a multidomain E3 ligase known to mediate the degradation of a wide range of proteins through the proteasomal pathway. The three-dimensional domain architecture of SCF family proteins suggests that it operates through a novel and adaptable "super-enzymatic" process that might respond to targeted therapeutic modalities in cancer.

RECENT FINDINGS

Several F-box containing proteins have been characterized either as tumor suppressors (FBXW8, FBXL3, FBXW8, FBXL3, FBXO1, FBXO4, and FBXO18) or as oncogenes (FBXO5, FBXO9, and SKP2). Besides, F-box members like βTrcP1 and βTrcP2, the ones with context-dependent functionality, have also been studied and reported. FBXW7 is a well-studied F-box protein and is a tumor suppressor. FBXW7 regulates the activity of a range of substrates, such as c-Myc, cyclin E, mTOR, c-Jun, NOTCH, myeloid cell leukemia sequence-1 (MCL1), AURKA, NOTCH through the well-known ubiquitin-proteasome system (UPS)-mediated degradation pathway. NOTCH signaling is a primitive pathway that plays a crucial role in maintaining normal tissue homeostasis. FBXW7 regulates NOTCH protein activity by controlling its half-life, thereby maintaining optimum protein levels in tissue. However, aberrations in the FBXW7 or NOTCH expression levels can lead to poor prognosis and detrimental outcomes in patients. Therefore, the FBXW7-NOTCH axis has been a subject of intense study and research over the years, especially around the interactome's role in driving cancer development and progression. Several studies have reported the effect of FBXW7 and NOTCH mutations on normal tissue behavior. The current review attempts to critically analyze these mutations prognostic value in a wide range of tumors. Furthermore, the review summarizes the recent findings pertaining to the FBXW7 and NOTCH interactome and its involvement in phosphorylation-related events, cell cycle, proliferation, apoptosis, and metastasis.

CONCLUSION

The review concludes by positioning FBXW7 as an effective diagnostic marker in tumors and by listing out recent advancements made in cancer therapeutics in identifying protocols targeting the FBXW7-NOTCH aberrations in tumors.

Progress in research on childhood T-cell acute lymphocytic leukemia, Notch1 signaling pathway, and its inhibitors: A review

Childhood leukemia is cancer that seriously threatens the life of children in China. Poor sensitivity to chemotherapy and susceptibility to drug resistance are the reasons for the treatment of T-cell acute lymphocytic leukemia (T-ALL) being extremely difficult. Moreover, traditional intensive chemotherapy regimens cause great damage to children. Therefore, it is highly important to search for targeted drugs and develop a precise individualized treatment for child patients. There are activating mutations in the NOTCH1 gene in more than 50% of human T-ALLs and the Notch signaling pathway is involved in the pathogenesis of T-ALL. In this review, we summarize the progress in research on T-ALL and Notch1 signaling pathway inhibitors to provide a theoretical basis for the clinical treatment of T-ALL.

Pediatric Acute Lymphoblastic Leukemia, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

DNA Methylation in T-Cell Acute Lymphoblastic Leukemia: In Search for Clinical and Biological Meaning

Distinct DNA methylation signatures, related to different prognosis, have been observed across many cancers, including T-cell acute lymphoblastic leukemia (T-ALL), an aggressive hematological neoplasm. By global methylation analysis, two major phenotypes might be observed in T-ALL: hypermethylation related to better outcome and hypomethylation, which is a candidate marker of poor prognosis. Moreover, DNA methylation holds more than a clinical meaning. It reflects the replicative history of leukemic cells and most likely different mechanisms underlying leukemia development in these T-ALL subtypes. The elucidation of the mechanisms and aberrations specific to (epi-)genomic subtypes might pave the way towards predictive diagnostics and precision medicine in T-ALL. We present the current state of knowledge on the role of DNA methylation in T-ALL. We describe the involvement of DNA methylation in normal hematopoiesis and T-cell development, focusing on epigenetic aberrations contributing to this leukemia. We further review the research investigating distinct methylation phenotypes in T-ALL, related to different outcomes, pointing to the most recent research aimed to unravel the biological mechanisms behind differential methylation. We highlight how technological advancements facilitated broadening the perspective of the investigation into DNA methylation and how this has changed our understanding of the roles of this epigenetic modification in T-ALL.

Identification of prognostic factors in childhood T-cell acute lymphoblastic leukemia: Results from DFCI ALL Consortium Protocols 05-001 and 11-001

BACKGROUND/OBJECTIVES

While outcomes for pediatric T-cell acute lymphoblastic leukemia (T-ALL) are favorable, there are few widely accepted prognostic factors, limiting the ability to risk stratify therapy.

DESIGN/METHODS

Dana-Farber Cancer Institute (DFCI) Protocols 05-001 and 11-001 enrolled pediatric patients with newly diagnosed B- or T-ALL from 2005 to 2011 and from 2012 to 2015, respectively. Protocol therapy was nearly identical for patients with T-ALL (N = 123), who were all initially assigned to the high-risk arm. End-induction minimal residual disease (MRD) was assessed by reverse transcription polymerase chain reaction (RT-PCR) or next-generation sequencing (NGS), but was not used to modify postinduction therapy. Early T-cell precursor (ETP) status was determined by flow cytometry. Cases with sufficient diagnostic DNA were retrospectively evaluated by targeted NGS of known genetic drivers of T-ALL, including Notch, PI3K, and Ras pathway genes.

RESULTS

The 5-year event-free survival (EFS) and overall survival (OS) for patients with T-ALL was 81% (95% CI, 73-87%) and 90% (95% CI, 83-94%), respectively. ETP phenotype was associated with failure to achieve complete remission, but not with inferior OS. Low end-induction MRD (<10-4 ) was associated with superior disease-free survival (DFS). Pathogenic mutations of the PI3K pathway were mutually exclusive of ETP phenotype and were associated with inferior 5-year DFS and OS.

CONCLUSIONS

Together, our findings demonstrate that ETP phenotype, end-induction MRD, and PI3K pathway mutation status are prognostically relevant in pediatric T-ALL and should be considered for risk classification in future trials. DFCI Protocols 05-001 and 11-001 are registered at www.clinicaltrials.gov as NCT00165087 and NCT01574274, respectively.

A Molecular Test for Quantifying Functional Notch Signaling Pathway Activity in Human Cancer

Simple Summary

The Notch signal transduction pathway is important for various physiological processes, including immune responses, and plays a role in many diseases, for example cancer. We have developed a new assay to quantitatively measure Notch pathway activity, and we validated it using data from various human cancer cell lines. The assay can be applied across different cell types, and offers numerous possibilities to explore the contribution of the Notch pathway to tumor formation and the stratification of cancer patients. We assessed Notch pathway activity in a cohort of T cell acute lymphoblastic leukemia (T-ALL) patient samples, and found that the pathway activity score more accurately reflects Notch pathway activity than a prediction on the basis of NOTCH1 mutations alone. Finally, we found that patients with low Notch pathway activity had a significantly shorter event-free survival compared to patients who had T-ALL cells with higher activity.

Abstract

Background: The Notch signal transduction pathway is pivotal for various physiological processes, including immune responses, and has been implicated in the pathogenesis of many diseases. The effectiveness of various targeted Notch pathway inhibitors may vary due to variabilities in Notch pathway activity among individual patients. The quantitative measurement of Notch pathway activity is therefore essential to identify patients who could benefit from targeted treatment. Methods: We here describe a new assay that infers a quantitative Notch pathway activity score from the mRNA levels of generally conserved direct NOTCH target genes. Following the calibration and biological validation of our Notch pathway activity model over a wide spectrum of human cancer types, we assessed Notch pathway activity in a cohort of T-ALL patient samples and related it to biological and clinical parameters, including outcome. Results: We developed an assay using 18 select direct target genes and high-grade serous ovarian cancer for calibration. For validation, seven independent human datasets (mostly cancer series) were used to quantify Notch activity in agreement with expectations. For T-ALL, the median Notch pathway activity was highest for samples with strong NOTCH1-activating mutations, and T-ALL patients of the TLX subtype generally had the highest levels of Notch pathway activity. We observed a significant relationship between ICN1 levels and the absence/presence of NOTCH1-activating mutations with Notch pathway activity scores. Patients with the lowest Notch activity scores had the shortest event-free survival compared to other patients. Conclusions: High Notch pathway activity was not limited to T-ALL samples harboring strong NOTCH1 mutations, including juxtamembrane domain mutations or hetero-dimerization combined with PEST-domain or FBXW7 mutations, indicating that additional mechanisms may activate Notch signaling. The measured Notch pathway activity was related to intracellular NOTCH levels, indicating that the pathway activity score more accurately reflects Notch pathway activity than when it is predicted on the basis of NOTCH1 mutations. Importantly, patients with low Notch pathway activity had a significantly shorter event-free survival compared to patients showing higher activity.

PEST domain NOTCH mutations confer a poor relapse free survival in pediatric T-ALL: Data from a tertiary care centre in India

A comprehensive genotype-phenotype analysis of pediatric T-ALL data was performed. 33 confirmed pediatric (≤12 y) T-ALL samples were evaluated for oncogenic transcripts: TLX-1, TLX-3, common fusion of STIL-TAL1, NOTCH1 mutations and copy number variations (CNVs). Mean WBC was 235.69 × 10³/μL. TLX1 and TLX-3 overexpression detected in 1 (3%) and 7 (21%) patients and STIL-TAL1 in 8 (27%). NOTCH1 mutations were noted in 17 (52%), of which 12 (71%) in HD domain and 6 (35%) in PEST domain (including one case with mutations in all three domains). Commonest CNVs were CDKN2A (85%) and CDKN2B (75%). Relapse occurred in 8 (24%) patients. The median follow-up was 15 months (range: 0.5-36). Bulky liver (p = 0.025), day 35 marrow (p = 0.004) and NOTCH mutation (p = 0.046) were predictive of time to an event. RFS was significantly poor for cases with PEST Vs. HD domain mutations (50% Vs. 85%) (p = 0.0009). Though cases with PEST domain NOTCH mutations had poor RFS, the OS was not influenced by NOTCH mutation positivity.

The Physiopathology of T- Cell Acute Lymphoblastic Leukemia: Focus on Molecular Aspects

T-cell acute lymphoblastic leukemia/lymphoma is an aggressive hematological neoplasm whose classification is still based on immunophenotypic findings. Frontline treatment encompass high intensity combination chemotherapy with good overall survival; however, relapsing/refractory patients have very limited options. In the last years, the understanding of molecular physiopathology of this disease, lead to the identification of a subset of patients with peculiar genetic profile, namely “early T-cell precursors” lymphoblastic leukemia, characterized by dismal outcome and indication to frontline allogeneic bone marrow transplant. In general, the most common mutations occur in the NOTCH1/FBXW7 pathway (60% of adult patients), with a positive prognostic impact. Other pathogenic steps encompass transcriptional deregulation of oncogenes/oncosuppressors, cell cycle deregulation, kinase signaling (including IL7R-JAK-STAT pathway, PI3K/AKT/mTOR pathway, RAS/MAPK signaling pathway, ABL1 signaling pathway), epigenetic deregulation, ribosomal dysfunction, and altered expression of oncogenic miRNAs or long non-coding RNA. The insight in the genomic landscape of the disease paves the way to the use of novel targeted drugs that might improve the outcome, particularly in relapse/refractory patients. In this review, we analyse available literature on T-ALL pathogenesis, focusing on molecular aspects of clinical, prognostic, and therapeutic significance.

Measurable Residual Disease Assessed by Flow-Cytometry Is a Stable Prognostic Factor for Pediatric T-Cell Acute Lymphoblastic Leukemia in Consecutive SEHOP Protocols Whereas the Impact of Oncogenetics Depends on Treatment

Robust and applicable risk-stratifying genetic factors at diagnosis in pediatric T-cell acute lymphoblastic leukemia (T-ALL) are still lacking, and most protocols rely on measurable residual disease (MRD) assessment. In our study, we aimed to analyze the impact of NOTCH1, FBXW7, PTEN, and RAS mutations, the measurable residual disease (MRD) levels assessed by flow cytometry (FCM-MRD) and other reported risk factors in a Spanish cohort of pediatric T-ALL patients. We included 199 patients treated with SEHOP and PETHEMA consecutive protocols from 1998 to 2019. We observed a better outcome of patients included in the newest SEHOP-PETHEMA-2013 protocol compared to the previous SHOP-2005 cohort. FCM-MRD significantly predicted outcome in both protocols, but the impact at early and late time points differed between protocols. The impact of FCM-MRD at late time points was more evident in SEHOP-PETHEMA 2013, whereas in SHOP-2005 FCM-MRD was predictive of outcome at early time points. Genetics impact was different in SHOP-2005 and SEHOP-PETHEMA-2013 cohorts: NOTCH1 mutations impacted on overall survival only in the SEHOP-PETHEMA-2013 cohort, whereas homozygous deletions of CDKN2A/B had a significantly higher CIR in SHOP-2005 patients. We applied the clinical classification combining oncogenetics, WBC count and MRD levels at the end of induction as previously reported by the FRALLE group. Using this score, we identified different subgroups of patients with statistically different outcome in both Spanish cohorts. In SHOP-2005, the FRALLE classifier identified a subgroup of high-risk patients with poorer survival. In the newest protocol SEHOP-PETHEMA-2013, a very low-risk group of patients with excellent outcome and no relapses was detected, with borderline significance. Overall, FCM-MRD, WBC count and oncogenetics may refine the risk-stratification, helping to design tailored approaches for pediatric T-ALL patients.

RAS and TP53 can predict survival in adults with T-cell lymphoblastic leukemia treated with hyper-CVAD

Adult T-cell acute lymphoblastic leukemia (T-ALL) is a heterogeneous group of acute leukemias that account for about one third of all cases of Philadelphia chromosome (Ph)-negative ALL. Recently, a molecular classifier using the mutational status of NOTCH1, FBXW7, RAS, and PTEN (NFRP) has been shown to distinguish low- vs high-risk groups in adult T-ALL patients treated using the Berlin-Frankfurt-Münster ALL protocol. However, it is unknown if this molecular classifier can stratify adult T-ALL patients treated with hyper-CVAD ± nelarabine. We identified a relatively small cohort of 27 adults with T-ALL who were uniformly treated with hyper-CVAD ± nelarabine with available mutational analysis at time of diagnosis. The most commonly mutated genes in this group were NOTCH1 (52%), NRAS (22%), DNMT3A (19%), KRAS (15%), and TP53 (7%). The NFRP molecular classifier failed to stratify overall survival (OS; P = .84) and relapse-free survival (RFS; P = .18) in this cohort. We developed a new stratification model combining K/NRAS and TP53 mutations as high-risk factors and showed that mutations in these genes predicted poorer OS (P = .03) and RFS (P = .04). While the current study is limited by cohort size, these data suggest that the NFRP molecular classifier might not be applicable to adult T-ALL patients treated with hyper-CVAD ± nelarabine. RAS/TP53 mutation status, however, was useful in risk stratification in adults with T-ALL.

The Profile of Immunophenotype and Genotype Aberrations in Subsets of Pediatric T-Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a biologically heterogeneous malignancy, which reflects distinctive stages of T-cell differentiation arrest. We have revisited a cohort of pediatric T-ALL, in order to test if immunophenotypes associated with molecular alterations would predict the patient's outcome. Genetic mutations, translocations and copy number alterations were identified through Sanger sequencing, RT-PCR, FISH and multiplex ligation-dependent probe amplification (MLPA). We defined 8 immunophenotypic T-ALL subtypes through multiparametric flow cytometry: early T-cell precursor (ETP, n = 27), immature (n = 38), early cortical (n = 15), cortical (n = 50), late cortical (n = 53), CD4/CD8 double negative mature (n = 31), double positive mature (n = 35) and simple positive mature (n = 31) T-ALL. Deletions (del) or amplifications (amp) in at least one gene were observed in 87% of cases. The most frequent gene alterations were CDKN2A/B^del (71.4%), NOTCH1^mut (47.6%) and FBXW7^mut (17%). ETP-ALL had frequent FLT3^mut (22.2%) and SUZ12^del (16.7%) (p < 0.001), while CDKN2A/B^del were rarely found in this subtype (p < 0.001). The early cortical T-ALL subtype had high frequencies of NOTCH1^mut and IL7R^mut (71%, 28.6%, respectively), whereas, mature T-ALL with double positive CD4/CD8 had the highest frequencies of STIL-TAL1 (36.7%), LEF1^del (27.3%) and CASP8AP2^del (22.7%). The co-existence of two groups of T-ALL with NOTCH1^mut/IL7R^mut, and with TLX3/SUZ12^del/NF1^del/IL7R^mut, were characterized with statistical significance (p < 0.05) but only STIL-TAL1 (pOS 47.5%) and NOTCH1^WT/FBXW7^WT (pOS 55.3%) are predictors of poor T-ALL outcomes. In conclusion, we have observed that 8 T-ALL subgroups are characterized by distinct molecular profiles. The mutations in NOTCH1/FBXW7 and STIL-TAL1 rearrangement had a prognostic impact, independent of immunophenotype.

NOTCH1 pathway activating mutations and clonal evolution in pediatric T-cell acute lymphoblastic leukemia

Molecular mechanisms involved in the relapse of T‐cell acute lymphoblastic leukemia (T‐ALL) are not fully understood, although activating NOTCH1 signaling due to NOTCH1/FBXW7 alterations is a major oncogenic driver. To unravel the relevance of NOTCH1/FBXW7 mutations associated with relapse, we performed whole–exome sequencing in 30 pediatric T‐ALL cases, among which 11 diagnosis‐relapse paired cases were further investigated to track the clonal evolution of relapse using amplicon–based deep sequencing. NOTCH1/FBXW7 alterations were detected in 73.3% (diagnosis) and 72.7% (relapse) of cases. Single nucleotide variations in the heterodimerization domain were the most frequent (40.0%) at diagnosis, whereas proline, glutamic acid, serine, threonine–rich (PEST) domain alterations were the most frequent at relapse (54.5%). Comparison between non–relapsed and relapsed cases at diagnosis showed a predominance of PEST alterations in relapsed cases (P = .045), although we failed to validate this in the TARGET cohort. Based on the clonal analysis of diagnosis‐relapse samples, we identified NOTCH1 “switching” characterized by different NOTCH1 mutations in a major clone between diagnosis and relapse samples in 2 out of 11 diagnosis‐relapse paired cases analyzed. We found another NOTCH1 “switching” case in a previously reported Berlin‐Frankfurt‐Münster cohort (n = 13), indicating NOTCH1 importance in both the development and progression of T‐ALL. Despite the limitations of having a small sample size and a non–minimal residual disease–based protocol, our results suggest that the presence of NOTCH1 mutations might contribute to the disease relapse of T‐ALL.

Clinical and biological relevance of genetic alterations in pediatric T-cell acute lymphoblastic leukemia in Taiwan

BACKGROUND

The leukemogenesis of T-cell acute lymphoblastic leukemia (T-ALL) involves multistep processes of genetic alterations. We aimed to determine the genetic alterations including common fusion transcripts, overexpression of T-cell transcription factor oncogenes, and deletion or mutation of targeted genes in pediatric T-ALL in Taiwan as well as their impact on outcomes in those treated with the Taiwan Pediatric Oncology Group-ALL-2002 protocol.

PROCEDURE

Between 1995 and 2015, bone marrow samples obtained from 102 children aged <18 years consecutively diagnosed with T-ALL were examined. Thirty-two genetic alterations were examined by reverse transcription polymerase chain reaction (PCR) assays-PCR-based assays-followed by direct sequencing, real time quantitative PCR with TaqMan assays, or multiplex ligase probe amplification.

RESULTS

TAL1 overexpression, CDKN2A/2B deletions, and NOTCH1 mutation were the most frequent aberrations while none had NF1, SUZ12 deletion, JAK1 or JAK2 mutations, or NUP214-ABL1 fusion in our cohort. The most frequent cooperating occurrence of genetic alterations included CDKN2A/2B and MTAP, MTAP and CDKN2B, LEF1 and PTPN2, and HOX11L2 and PHF6 mutation/deletion. NOTCH1 mutations conferred a favorable overall survival, whereas SIL-TAL1 fusion, TAL overexpression, LEF1 deletion, and PHF6 deletion/mutation were associated with an inferior outcome. By multivariate analysis, PHF6 mutation/deletion was the only independent predictor for inferior overall survival.

CONCLUSIONS

The present study showed that the frequencies of genetic alterations in Taiwanese children with T-ALL differed considerably from those reported in Western countries. PHF6 mutation/deletion was an independently adverse predictor.

CRLF2 expression associates with ICN1 stabilization in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematopoietic malignancy with few molecular alterations showing a consensual prognostic value. CRLF2 overexpression was recently identified in high-risk T-ALL patients. For these cases, no genomic abnormality was found to be associated with CRLF2 overexpression. IKZF1 has been recently shown to be a direct transcriptional regulator of CRLF2 expression. Moreover, it is known that NOTCH1 antagonizes IKZF1 in T-ALL. In light of these pieces of evidence, we reasoned that IKZF1 binding perturbation and CRLF2 upregulation could be associated in T-ALL. We evaluated two independent series of pediatric T-ALL cases (PHOP, n = 57 and TARGET, n = 264) for the presence of common T-ALL molecular abnormalities, such as NOTCH1/FBXW7 mutations. We also assessed CRLF2 and IKZF1 gene expression. CRLF2 overexpression was observed in 14% (PHOP) and 16% (TARGET) of T-ALL patients. No correlation was found between mRNA expression of CRLF2 and IKZF1 in both cohorts. Interestingly, we show that patients with mutations affecting NOTCH1-PEST domain and/or FBXW7 had higher CRLF2 expression (P = .04). In summary, we demonstrate for the first time that only mutations resulting in ICN1 (intracellular domain of NOTCH1) stabilization are associated with CRLF2 overexpression.

Recent Advances in the Biology and Treatment of T Cell Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

This article provides an overview of the current knowledge regarding the biology and treatment of T cell acute lymphoblastic leukemia (T-ALL) and highlights the most recent findings in this field over the past 5 years.

RECENT FINDINGS

Remarkable progress has been made in the genomic landscape of T-ALL over the past few years. The discovery of activating mutations of NOTCH1 and FBXW7 in a majority of patients has been a seminal observation, with several early phase clinical trials currently exploring these as potential therapeutic targets. Characterization of early T cell precursor ALL, incorporation of minimal residual disease assessment into therapeutic protocols, and use of pediatric-intensive regimens along with judicious use of allogeneic HCT have significantly improved risk stratification and treatment outcomes. Improved risk stratification and the use of novel targeted therapies based on recent genomic discoveries are expected to change the therapeutic landscape of T-ALL and hopefully improve the outcomes of this historically poor prognosis disease.

The depletion of PHF6 decreases the drug sensitivity of T-cell acute lymphoblastic leukemia to prednisolone

Mutation of PHF6 has been identified in Börjeson-Forssman-Lehmann syndrome and some types of subsets of childhood leukemia. However, the molecular function and the relationship of PHF6 mutation with glucocorticoid drug resistance during T-ALL treatment remains elusive. Here we report the influence of PHF6 expression on the drug response of T-ALL to prednisolone, and the underlying mechanism of this. Through sanger sequencing and western blotting assays, we identified two T-ALL cell lines with wild-type PHF6 expression, including SIL-ALL and CCRF-CEM, and two T-ALL cell lines without PHF6 expression, including TALL-1 and HPB-ALL, due to the nonsense and frameshift mutations in the coding region of PHF6. MTT assays showed that SIL-ALL and CCRF-CEM were much more sensitive to prednisolone. However, TALL-1 and HPB-ALL were much more resistance to prednisolone. Further knockout of PHF6 led to the resistant of both SIL-ALL and CCRF-CEM cells to prednisolone. On the contrary, the correction of the PHF6 point mutation in HPB-ALL cells with CRISPR-CAS9 method increased the sensibility of both cell lines to prednisolone. Then we found that PHF6 repress p21 expression through direct binding and recruiting RBPP4 to its promoter region. Finally, the co-treatment of p21 inhibitor increased the sensitivity of TALL-1 and HPB-ALL cells to prednisolone. Collectively, our findings not only enrich our understanding of the relationship between PHF6 mutation and drug resistance but also indicate a new therapeutic potential for those T-ALL patients containing the PHF6 mutation.

Clinical significance of cytogenetic changes in childhood T-cell acute lymphoblastic leukemia: results of the multicenter group Moscow-Berlin (MB)

The prognostic significance of genetic lesions in T-cell ALL still needs to be elucidated. Karyotyping and FISH were performed in samples from 120 patients with T-cell ALL registered in the trial Moscow-Berlin 2008. Most frequent rearrangements were TLX3 (N = 29; 24%) and TAL1 (N = 18; 15%), followed by KMT2A (N = 6; 5%), TLX1 (N = 5; 4.2%), and 11p13-15 (N = 5; 4.2%). In 16.7% of patients, the karyotype was normal, and in 30.8% 'other' aberrations were seen. Patients with a normal karyotype, TAL1, or KMT2A rearrangements had the most favorable outcome (probability of event free survival (pEFS): 82% ± 6%), while prognosis for patients with TLX3 and TLX1 rearrangements and 'other' aberrations was less favorable (pEFS: 62% ± 6%). Worst outcome was observed for five patients with 11p rearrangements (pEFS: 20% ± 18%). In summary, three subgroups of patients with T-cell ALL with significantly different outcomes could be defined by cytogenetic profiling.

Notch in Leukemia

Notch is commonly activated in lymphoid malignancies through ligand-independent and ligand-dependent mechanisms. In T-cell acute lymphoblastic leukemia/lymphoma (T-ALL), ligand-independent activation predominates. Negative Regulatory Region (NRR) mutations trigger supraphysiological Notch1 activation by exposing the S2 site to proteolytic cleavage in the absence of ligand. Subsequently, cleavage at the S3 site generates the activated form of Notch, intracellular Notch (ICN). In contrast to T-ALL, in mature lymphoid neoplasms such as chronic lymphocytic leukemia (CLL), the S2 cleavage site is exposed through ligand-receptor interactions. Thus, agents that disrupt ligand-receptor interactions might be useful for treating these malignancies. Notch activation can be enhanced by mutations that delete the C-terminal proline (P), glutamic acid (E), serine (S), and threonine (T) (PEST) domain. These mutations do not activate the Notch pathway per se, but rather impair degradation of ICN. In this chapter, we review the mechanisms of Notch activation and the importance of Notch for the genesis and maintenance of lymphoid malignancies. Unfortunately, targeting the Notch pathway with pan-Notch inhibitors in clinical trials has proven challenging. These clinical trials have encountered dose-limiting on-target toxicities and primary resistance. Strategies to overcome these challenges have emerged from the identification and improved understanding of direct oncogenic Notch target genes. Other strategies have arisen from new insights into the "nuclear context" that selectively directs Notch functions in lymphoid cancers. This nuclear context is created by factors that co-bind ICN at cell-type specific transcriptional regulatory elements. Disrupting the functions of these proteins or inhibiting downstream oncogenic pathways might combat cancer without the intolerable side effects of pan-Notch inhibition.

Clinical impact of miR-223 expression in pediatric T-Cell lymphoblastic lymphoma

Although probability of event-free survival in pediatric lymphoblastic T-cell lymphoma (T-LBL) is about 75%, survival in relapsed patients is very poor, so the identification of new molecular markers is crucial for treatment optimization. Here, we demonstrated that the over-expression of miR-223 promotes tumor T-LBL cell growth, migration and invasion in vitro. We found out that SIK1, an anti-metastatic protein, is a direct target of miR-223 and consequently is significantly reduced in miR-223-overexpressing tumor cells. We measured miR-223 expression levels at diagnosis in tumor biopsies from 67 T-LBL pediatric patients for whom complete clinical and follow up data were available, and we found that high miR-223 expression (above the median value) is associated with worse prognosis (PFS 66% vs 94%, P=0.0036). In addition, the multivariate analysis, conducted taking into account miR-223 expression level and other molecular and clinical characteristics, showed that only high level of miR-223 is an independent factor for worse prognosis. MiR-223 represents a promising marker for treatment stratification in pediatric patients with T-LBL and we provide the first evidence of miR-223 potential role as oncomir by SIK1 repression.

Oncogenic Notch signaling in T-cell and B-cell lymphoproliferative disorders

PURPOSE OF REVIEW

This article highlights recent discoveries about Notch activation and its oncogenic functions in lymphoid malignancies, and discusses the therapeutic potential of Notch inhibition.

RECENT FINDINGS

NOTCH mutations arise in a broad spectrum of lymphoid malignancies and are increasingly scrutinized as putative therapeutic targets. In T-cell acute lymphoblastic leukemia (T-ALL), NOTCH1 mutations affect the extracellular negative regulatory region and lead to constitutive Notch activation, although mutated receptors remain sensitive to Notch ligands. Other NOTCH1 mutations in T-ALL and NOTCH1/2 mutations in multiple B-cell malignancies truncate the C-terminal proline (P), glutamic acid (E), serine (S), threonine (T)-rich (PEST) domain, leading to decreased Notch degradation after ligand-mediated activation. Thus, targeting Notch ligand-receptor interactions could provide therapeutic benefits. In addition, we discuss recent reports on clinical testing of Notch inhibitors in T-ALL that influenced contemporary thinking on the challenges of targeting Notch in cancer. We review advances in the laboratory to address these challenges in regards to drug targets, the Notch-driven metabolome, and the sophisticated protein-protein interactions at Notch-dependent superenhancers that underlie oncogenic Notch functions.

SUMMARY

Notch signaling is a recurrent oncogenic pathway in multiple T- and B-cell lymphoproliferative disorders. Understanding the complexity and consequences of Notch activation is critical to define optimal therapeutic strategies targeting the Notch pathway.

Oncogenetic mutations combined with MRD improve outcome prediction in pediatric T-cell acute lymphoblastic leukemia

Risk stratification in childhood T-cell acute lymphoblastic leukemia (T-ALL) is mainly based on minimal residual disease (MRD) quantification. Whether oncogenetic mutation profiles can improve the discrimination of MRD-defined risk categories was unknown. Two hundred and twenty FRALLE2000T-treated patients were tested retrospectively for NOTCH1/FBXW7/RAS and PTEN alterations. Patients with NOTCH1/FBXW7 (N/F) mutations and RAS/PTEN (R/P) germ line (GL) were classified as oncogenetic low risk (gLoR; n = 111), whereas those with N/F GL and R/P GL mutations or N/F and R/P mutations were classified as high risk (gHiR; n = 109). Day 35 MRD status was available for 191 patients. Five-year cumulative incidence of relapse (CIR) and disease-free survival were 36% and 60% for gHiR patients and 11% and 89% for gLoR patients, respectively. Importantly, among the 60% of patients with MRD <10^-4, 5-year CIR was 29% for gHiR patients and 4% for gLoR patients. Based on multivariable Cox models and stepwise selection, the 3 most discriminating variables were the oncogenetic classifier, MRD, and white blood cell (WBC) count. Patients harboring a WBC count ≥200 × 10⁹/L, gHiR classifier, and MRD ≥10^-4 demonstrated a 5-year CIR of 46%, whereas the 58 patients (30%) with a WBC count <200 × 10⁹/L, gLoR classifier, and MRD <10^-4 had a very low risk of relapse, with a 5-year CIR of only 2%. In childhood T-ALL, the N/F/R/P mutation profile is an independent predictor of relapse. When combined with MRD and a WBC count ≥200 × 10⁹/L, it identifies a significant subgroup of patients with a low risk of relapse.

Initial Diagnostic Workup of Acute Leukemia: Guideline From the College of American Pathologists and the American Society of Hematology

CONTEXT

- A complete diagnosis of acute leukemia requires knowledge of clinical information combined with morphologic evaluation, immunophenotyping and karyotype analysis, and often, molecular genetic testing. Although many aspects of the workup for acute leukemia are well accepted, few guidelines have addressed the different aspects of the diagnostic evaluation of samples from patients suspected to have acute leukemia.

OBJECTIVE

- To develop a guideline for treating physicians and pathologists involved in the diagnostic and prognostic evaluation of new acute leukemia samples, including acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemias of ambiguous lineage.

DESIGN

- The College of American Pathologists and the American Society of Hematology convened a panel of experts in hematology and hematopathology to develop recommendations. A systematic evidence review was conducted to address 6 key questions. Recommendations were derived from strength of evidence, feedback received during the public comment period, and expert panel consensus.

RESULTS

- Twenty-seven guideline statements were established, which ranged from recommendations on what clinical and laboratory information should be available as part of the diagnostic and prognostic evaluation of acute leukemia samples to what types of testing should be performed routinely, with recommendations on where such testing should be performed and how the results should be reported.

CONCLUSIONS

- The guideline provides a framework for the multiple steps, including laboratory testing, in the evaluation of acute leukemia samples. Some aspects of the guideline, especially molecular genetic testing in acute leukemia, are rapidly changing with new supportive literature, which will require on-going updates for the guideline to remain relevant.

Meta-analysis of the clinical characteristics and prognostic relevance of NOTCH1 and FBXW7 mutation in T-cell acute lymphoblastic leukemia

The NOTCH1 signaling pathway is crucial for T-cell development, and NOTCH1 and/or FBXW7 mutations are frequently detected in T-cell acute lymphoblastic leukemia (T-ALL). We performed a systematic review and meta-analysis of 18 randomized controlled trials (RCTs) to assess the prognostic impact of mutations in the NOTCH1 pathway. After retrieving relevant articles from PubMed, EMBASE, and the Cochrane Library, we investigated overall survival (OS) and event-free survival (EFS) with hazard ratios (HRs) using fixed-effects or random-effects models and conducted subgroup analyses based on population and mutation status. NOTCH1/FBXW7 mutations correlated significantly with better prognosis (5-year EFS: HR, 0.57; 95% confidence interval [CI], 0.46 to 0.68; P < 0.001 and 5-year OS: HR, 0.61; 95% CI, 0.51 to 0.74; P < 0.001). The HR for 5-year EFS and OS with NOTCH1 mutations were 0.63 (95% CI, 0.53 to 0.75) and 0.76 (95% CI, 0.60 to 0.95), respectively; with FBXW7 mutations, they were 0.82 (95% CI, 0.60 to 1.11) and 0.79 (95% CI, 0.55 to 1.12), respectively. However, differences between children and adults showed no significance. We conclude that the presence of NOTCH1/FBXW7 mutations is an independent prognostic factor for 5-year EFS and 5-year OS.

Management of adults with T-cell lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (ALL) is a rare disease in adults with inferior survival outcomes compared with those seen in pediatric patients. Although potentially curable with ∼50% survival at 5 years, adult patients with relapsed disease have dismal outcomes with <10% of patients surviving long term. This review will discuss the diagnosis and management of adult patients with newly diagnosed T-cell ALL with an emphasis on the immunophenotypic and genetic analyses required to assign prognosis, risk stratify, and guide post-remission therapy. The evidence for the main components of complex T-cell ALL treatment regimens is described. The importance of monitoring minimal residual disease is emphasized, with a discussion of the different methods used. The results of hematopoietic cell transplantation are analyzed, and recommendations made about which patients should be considered for this intervention. The treatment of the adolescent and young adult group is delineated, and the role of using “pediatric-inspired” regimens in older adults considered. We also describe the current data and potential future options for the use of novel therapies, including nelarabine and γ-secretase inhibitors, in adult patients with T-cell ALL.

Identification of a genetically defined ultra-high-risk group in relapsed pediatric T-lymphoblastic leukemia

In the search for genes that define critical steps of relapse in pediatric T-cell acute lymphoblastic leukemia (T-ALL) and can serve as prognostic markers, we performed targeted sequencing of 313 leukemia-related genes in 214 patients: 67 samples collected at the time of relapse and 147 at initial diagnosis. As relapse-specific genetic events, we identified activating mutations in NT5C2 (P=0.0001, Fisher's exact test), inactivation of TP53 (P=0.0007, Fisher's exact test) and duplication of chr17:q11.2-24.3 (P=0.0068, Fisher's exact test) in 32/67 of T-ALL relapse samples. Alterations of TP53 were frequently homozygous events, which significantly correlated with higher rates of copy number alterations in other genes compared with wild-type TP53 (P=0.0004, Mann–Whitney's test). We subsequently focused on mutations with prognostic impact and identified genes governing DNA integrity (TP53, n=8; USP7, n=4; MSH6, n=4), having key roles in the RAS signaling pathway (KRAS, NRAS, n=8), as well as IL7R (n=4) and CNOT3 (n=4) to be exclusively mutated in fatal relapses. These markers recognize 24/49 patients with a second event. In 17 of these patients with mostly refractory relapse and dire need for efficient treatment, we identified candidate targets for personalized therapy with p53 reactivating compounds, MEK inhibitors or JAK/STAT-inhibitors that may be incorporated in future treatment strategies.

Genomic characterization of pediatric T-cell acute lymphoblastic leukemia reveals novel recurrent driver mutations

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy with variable prognosis. It represents 15% of diagnosed pediatric ALL cases and has a threefold higher incidence among males. Many recurrent alterations have been identified and help define molecular subgroups of T-ALL, however the full range of events involved in driving transformation remain to be defined. Using an integrative approach combining genomic and transcriptomic data, we molecularly characterized 30 pediatric T-ALLs and identified common recurrent T-ALL targets such as FBXW7, JAK1, JAK3, PHF6, KDM6A and NOTCH1 as well as novel candidate T-ALL driver mutations including the p.R35L missense mutation in splicesome factor U2AF1 found in 3 patients and loss of function mutations in the X-linked tumor suppressor genes MED12 (frameshit mutation p.V167fs, splice site mutation g.chrX:70339329T>C, missense mutation p.R1989H) and USP9X (nonsense mutation p.Q117*). In vitro functional studies further supported the putative role of these novel T-ALL genes in driving transformation. U2AF1 p.R35L was shown to induce aberrant splicing of downstream target genes, and shRNA knockdown of MED12 and USP9X was shown to confer resistance to apoptosis following T-ALL relevant chemotherapy drug treatment in Jurkat leukemia cells. Interestingly, nearly 60% of novel candidate driver events were identified among immature T-ALL cases, highlighting the underlying genomic complexity of pediatric T-ALL, and the need for larger integrative studies to decipher the mechanisms that contribute to its various subtypes and provide opportunities to refine patient stratification and treatment.

Targeting Notch degradation system provides promise for breast cancer therapeutics

Notch receptor signaling pathways play an important role, not only in normal breast development but also in breast cancer development and progression. As a group of ligand-induced proteins, different subtypes of mammalian Notch (Notch1-4) are sensitive to subtle changes in protein levels. Thus, a clear understanding of mechanisms of Notch protein turnover is essential for understanding normal and pathological mechanisms of Notch functions. It has been suggested that there is a close relationship between the carcinogenesis and the dysregulation of Notch degradation. However, this relationship remains mostly undefined in the context of breast cancer, as protein degradation is mediated by numerous signaling pathways as well as certain molecule modulators (activators/inhibitors). In this review, we summarize the published data regarding the regulation of Notch family member degradation in breast cancer, while emphasizing areas that are likely to provide new therapeutic modalities for mechanism-based anti-cancer drugs.

Impact of PTEN abnormalities on outcome in pediatric patients with T-cell acute lymphoblastic leukemia treated on the MRC UKALL2003 trial

PTEN gene inactivation by mutation or deletion is common in pediatric T-cell acute lymphoblastic leukemia (T-ALL), but the impact on outcome is unclear, particularly in patients with NOTCH1/FBXW7 mutations. We screened samples from 145 patients treated on the MRC UKALL2003 trial for PTEN mutations using heteroduplex analysis and gene deletions using single nucleotide polymorphism arrays, and related genotype to response to therapy and long-term outcome. PTEN loss-of-function mutations/gene deletions were detected in 22% (PTEN(ABN)). Quantification of mutant level indicated that 67% of mutated cases harbored more than one mutant, with up to four mutants detected, consistent with the presence of multiple leukemic sub-clones. Overall, 41% of PTEN(ABN) cases were considered to have biallelic abnormalities (mutation and/or deletion) with complete loss of PTEN in a proportion of cells. In addition, 9% of cases had N- or K-RAS mutations. Neither PTEN nor RAS genotype significantly impacted on response to therapy or long-term outcome, irrespective of mutant level, and there was no evidence that they changed the highly favorable outcome of patients with double NOTCH1/FBXW7 mutations. These results indicate that, for pediatric patients treated according to current protocols, routine screening for PTEN or RAS abnormalities at diagnosis is not warranted to further refine risk stratification.

Notch and Wnt signaling pathway in cancer: Crucial role and potential therapeutic targets (Review)

There is no radical cure for all cancer types. The most frequently used therapies are surgical treatment, radiotherapy and chemotherapy. However, recrudescence, radiation resistance and chemotherapy resistance are the most challenging issues in clinical practice. To address these issues, they should be further studied at the molecular level, and the signaling pathways involved represent a promising avenue for this research. In the present review, we mainly discuss the components and mechanisms of activation of the Notch and Wnt signaling pathways, and we summarize the recent research efforts on these two pathways in different cancers. We also evaluate the ideal drugs that could target these two signaling pathways for cancer therapy, summarize alterations in the Notch and Wnt signaling pathways in cancer, and discuss potential signaling inhibitors as effective drugs for cancer therapy.

Different outcome of T cell acute lymphoblastic leukemia with translocation t(11;14) treated in two consecutive children leukemia group EORTC trials

Acute lymphoblastic leukemia of T cell lineage (T-ALL) is an aggressive malignant disease which accounts for 15 % of childhood ALL. T(11;14) is the more frequent chromosomal abnormality in childhood T-ALL, but its prognostic value remained controversial. Our aim was to analyze the outcome of childhood T-ALL with t(11;14) to know if the presence of this translocation is associated with a poor prognosis. We conducted a retrospective study from a series of 20 patients with t(11;14), treated in two consecutive trials from the European Organization for Research and Treatment of Cancer Children Leukemia Group over a 19-year period from 1989 to 2008. There were no significant differences between the 2 consecutive groups of patients with t(11;14) regarding the clinical and biological features at diagnosis. Among 19 patients who reached complete remission, 9 patients relapsed. We noticed 7 deaths all relapse- or failure-related. In the 58881 study, a presence of t(11;14) was associated with a poor outcome with an event-free survival at 5 years at 22.2 % versus 65.1 % for the non-t(11;14) T-ALL (p = 0.0004). In the more recent protocol, the outcome of T-ALL with t(11;14) reached that of non-t(11;14) T-ALL with an event-free survival at 5 years at 65.5 versus 74.9 % (p = 0.93). The presence of t(11;14) appeared as a poor prognostic feature in the 58881 trial whereas this abnormality no longer affected the outcome in the 58951 study. This difference is probably explained by the more intensive chemotherapy in the latest trial.