Clinical features and outcome of SIL/TAL1-positive T-cell acute lymphoblastic leukemia in children and adolescents: a 10-year experience of the AIEOP group

Characteristics and therapeutic approaches for patients diagnosed with T-ALL/LBL exhibiting t(8;14)(q24;q11)/TCRA/D:MYC translocation

T-acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) patients with t(8;14)(q24;q11)/TCRA/D::MYC translocation represent a rare subgroup, with an aggressive course. In our retrospective analysis of 14 patients, all were identified during refractory or relapsed stages (5 primary tumor, 9 relapse). Notably, extramedullary invasion was detected in most patients. Four exhibited STIL::TAL1 translocation, and six demonstrated CDKN2A/B gene loss. The therapeutic outcomes were notably poor for all seven patients who received only chemotherapy or allogeneic hematopoietic stem cell transplantation (HSCT); all eventually succumbed to the disease with a median OS of 3 months. In the application of CD7 CAR-T therapy in six patients, five achieved CR. Of the four patients who underwent HSCT following CAR-T therapy, all have remained disease-free. The prognosis for T-ALL/LBL patients with t(8;14) translocation remains bleak, but interventions involving CD7 CAR-T may offer a potential pathway to CR. HSCT following CAR-T could be a viable strategy for long-term survival.

S1P-S1PR3-RAS promotes the progression of S1PR3hi TAL1+ T-cell acute lymphoblastic leukemia that can be effectively inhibited by an S1PR3 antagonist

TAL1+ T-cell acute lymphoblastic leukemia (T-ALL) is a distinct subtype of leukemia with poor outcomes. Through the cooperation of co-activators, including RUNX1, GATA3, and MYB, the TAL1 oncoprotein extends the immature thymocytes with autonomy and plays an important role in the development of T-ALL. However, this process is not yet well understood. Here, by investigating the transcriptome and prognosis of T-ALL from multiple cohorts, we found that S1PR3 was highly expressed in a subset of TAL1+ T-ALL (S1PR3hi TAL1+ T-ALL), which showed poor outcomes. Through pharmacological and genetic methods, we identified a specific survival-supporting role of S1P-S1PR3 in TAL1+ T-ALL cells. In T-ALL cells, TAL1-RUNX1 up-regulated the expression of S1PR3 by binding to the enhancer region of S1PR3 gene. With hyperactivated S1P-S1PR3, T-ALL cells grew rapidly, partly by activating the KRAS signal. Finally, we assessed S1PR3 inhibitor TY-52156 in T-ALL patient-derived xenografts (PDXs) mouse model. We found that TY-52156 attenuated leukemia progression efficiently and extended the lifespan of S1PR3hi TAL1+ T-ALL xenografts. Our findings demonstrate that S1PR3 plays an important oncogenic role in S1PR3hi TAL1+ T-ALL and may serve as a promising therapeutic target.

Proteomics in Childhood Acute Lymphoblastic Leukemia: Challenges and Opportunities

Acute lymphoblastic leukemia (ALL) is the most common cancer in children and one of the success stories in cancer therapeutics. Risk-directed therapy based on clinical, biologic and genetic features has played a significant role in this accomplishment. Despite the observed improvement in survival rates, leukemia remains one of the leading causes of cancer-related deaths. Implementation of next-generation genomic and transcriptomic sequencing tools has illustrated the genomic landscape of ALL. However, the underlying dynamic changes at protein level still remain a challenge. Proteomics is a cutting-edge technology aimed at deciphering the mechanisms, pathways, and the degree to which the proteome impacts leukemia subtypes. Advances in mass spectrometry enable high-throughput collection of global proteomic profiles, representing an opportunity to unveil new biological markers and druggable targets. The purpose of this narrative review article is to provide a comprehensive overview of studies that have utilized applications of proteomics in an attempt to gain insight into the pathogenesis and identification of biomarkers in childhood ALL.

Harnessing the MYB-dependent TAL1 5'super-enhancer for targeted therapy in T-ALL

The acquisition of genetic abnormalities engendering oncogene dysregulation underpins cancer development. Certain proto-oncogenes possess several dysregulation mechanisms, yet how each mechanism impacts clinical outcome is unclear. Using T-cell acute lymphoblastic leukemia (T-ALL) as an example, we show that patients harboring 5'super-enhancer (5'SE) mutations of the TAL1 oncogene identifies a specific patient subgroup with poor prognosis irrespective of the level of oncogene dysregulation. Remarkably, the MYB dependent oncogenic 5'SE can be targeted using Mebendazole to induce MYB protein degradation and T-ALL cell death. Of note Mebendazole treatment demonstrated efficacy in vivo in T-ALL preclinical models. Our work provides proof of concept that within a specific oncogene driven cancer, the mechanism of oncogene dysregulation rather than the oncogene itself can identify clinically distinct patient subgroups and pave the way for future super-enhancer targeting therapy.

Optimizing Molecular Minimal Residual Disease Analysis in Adult Acute Lymphoblastic Leukemia

Minimal/measurable residual disease (MRD) evaluation has resulted in a fundamental instrument to guide patient management in acute lymphoblastic leukemia (ALL). From a methodological standpoint, MRD is defined as any approach aimed at detecting and possibly quantifying residual neoplastic cells beyond the sensitivity level of cytomorphology. The molecular methods to study MRD in ALL are polymerase chain reaction (PCR) amplification-based approaches and are the most standardized techniques. However, there are some limitations, and emerging technologies, such as digital droplet PCR (ddPCR) and next-generation sequencing (NGS), seem to have advantages that could improve MRD analysis in ALL patients. Furthermore, other blood components, namely cell-free DNA (cfDNA), appear promising and are also being investigated for their potential role in monitoring tumor burden and response to treatment in hematologic malignancies. Based on the review of the literature and on our own data, we hereby discuss how emerging molecular technologies are helping to refine the molecular monitoring of MRD in ALL and may help to overcome some of the limitations of standard approaches, providing a benefit for the care of patients.

Clinico-Hematological Profile and Copy Number Abnormalities in a Cohort of STIL-TAL1 and NUP214-ABL1 Positive Pediatric T-Cell Acute Lymphoblastic Leukemia

T cell acute lymphoblastic leukaemia (T-ALL) is a genetically heterogeneous and aggressive form of malignancy. Although a number of recurrent fusion genes are reported in T-ALL, their involvement in disease stratification and therapeutic intervention is still controversial. Considering the prognostic value of STIL-TAL1 fusion and tyrosine kinase inhibitor (TKI) based therapeutic potential of NUP214-ABL1, the present study aimed to investigate their frequency and clinical correlation in pediatric T-ALL cases. Our cohort consisted of 48 T-ALL pediatric cases (age ≤ 12 years) with a median age of 6 years and male to female ratio of 20.5:1. The median TLC of the study group was noted to be 220,000/ cu mm with a range from 26,810/cu mm to 785,430/cu mm. By MLPA and RT-PCR analysis we observed that 11/48 cases (23%) showed STIL-TAL1 fusion and 4/48 cases (8.3%) had NUP214-ABL1 fusion gene. Both of the fusion genes did not show any significant correlation with any of the clinico-hematological or treatment outcome parameters. However, upon analysis of copy number variations (CNVs) with other clinically relevant genes, we found significant correlation between LEF1 (p = 0.024) and PTEN (p = 0.049) gene deletions with STIL/TAL1 fusion in T-ALL patients. NUP214-ABL1 fusion gene did not reveal any association with either CNVs or with survival. Although limited with the small cohort size and follow up, our study supports the similar frequency of these fusions as compared to other Asian and Western studies and also highlights utility of MLPA technique as a good diagnostic modality to screen for both STIL-TAL1 and NUP214-ABL1 fusions in a single assay with additional data on secondary copy number changes.

STIL Endows Oncogenic and Stem-Like Attributes to Colorectal Cancer Plausibly by Shh and Wnt Signaling

The discovery of a potent gene regulating tumorigenesis and drug resistance is of high clinical importance. STIL is an oncogene; however, its molecular associations and role in colorectal oncogenesis are unknown. In this study, we have explored the role of STIL gene in tumorigenesis and studied its molecular targets in colorectal cancer (CRC). STIL silencing reduced proliferation and tumor growth in CRC. Further, STIL was found to regulate stemness markers CD133 and CD44 and drug resistant markers thymidylate synthase, ABCB1, and ABCG2 both in in-vitro and in-vivo CRC models. In addition, high expression of STIL mRNA was found to be associated with reduced disease-free survival in CRC cases. Interestingly, we observed that STIL-mediated regulation of stemness and drug resistant genes is not exclusively governed by Sonic hedgehog (Shh) signaling. Remarkably, we found STIL regulate β-catenin levels through p-AKT, independent of Shh pathway. This partially answers Shh independent regulatory mechanism of cancer stem cell (CSC) markers by STIL. Our study suggests an instrumental role of STIL in molecular manifestation of CRC and progression.

Genetic Alterations in Childhood Acute Lymphoblastic Leukemia: Interactions with Clinical Features and Treatment Response

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. This aggressive cancer comprises multiple molecular subtypes, each harboring a distinct constellation of somatic, and to a lesser extent, inherited genetic alterations. With recent advances in genomic analyses such as next-generation sequencing techniques, we can now clearly identify >20 different genetic subtypes in ALL. Clinically, identifying these genetic subtypes will better refine risk stratification and determine the optimal intensity of therapy for each patient. Underpinning each genetic subtype are unique clinical and therapeutic characteristics, such as age and presenting white blood cell (WBC) count. More importantly, within each genetic subtype, there is much less variability in treatment response and survival outcomes compared with current risk factors such as National Cancer Institute (NCI) criteria. We review how this new taxonomy of genetic subtypes in childhood ALL interacts with clinical risk factors used widely, i.e., age, presenting WBC, IKZF1del, treatment response, and outcomes.

Interstitial Deletions Generating Fusion Genes

A fusion gene is the physical juxtaposition of two different genes resulting in a structure consisting of the head of one gene and the tail of the other. Gene fusion is often a primary neoplasia-inducing event in leukemias, lymphomas, solid malignancies as well as benign tumors. Knowledge about fusion genes is crucial not only for our understanding of tumorigenesis, but also for the diagnosis, prognostication, and treatment of cancer. Balanced chromosomal rearrangements, in particular translocations and inversions, are the most frequent genetic events leading to the generation of fusion genes. In the present review, we summarize the existing knowledge on chromosome deletions as a mechanism for fusion gene formation. Such deletions are mostly submicroscopic and, hence, not detected by cytogenetic analyses but by array comparative genome hybridization (aCGH) and/or high throughput sequencing (HTS). They are found across the genome in a variety of neoplasias. As tumors are increasingly analyzed using aCGH and HTS, it is likely that more interstitial deletions giving rise to fusion genes will be found, significantly impacting our understanding and treatment of cancer.

Early T-cell precursor acute lymphoblastic leukemia and other subtypes: a retrospective case report from a single pediatric center in China

PURPOSE

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is rare in China and case reports are varied. We conducted an in-depth analysis of newly diagnosed children with T-ALL from January 1999 to April 2015 in our center, to show the biological differences between Chinese ETP-ALL children and other immune types of T-ALL.

METHODS

The newly diagnosed children with T-ALL were divided into four groups according to their immunophenotype: ETP-ALL, early non-ETP-ALL, cortical T-ALL and medullary T-ALL. Disease-free survival (DFS), event-free survival (EFS), and overall survival (OS) rates were estimated by the Kaplan-Meier method. The Cox regression model was used for multivariate analysis.

RESULTS

A total of 117 newly diagnosed children with T-ALL were enrolled in this study. The 10-year EFS and OS rates for all patients were 59.0 ± 4.7% and 61.0 ± 4.7%, respectively, with a median follow-up of 64 (5-167) months. Univariate analysis showed that ETP-ALL patients had the lowest 10-year DFS rate of 32.1 ± 11.7%, while cortical T-ALL had the highest DFS rate of 81.3 ± 8.5% compared with early non-ETP-ALL (61.6 ± 7.0%) and medullary T-ALL (59.1 ± 10.6%). Multivariate analysis demonstrated that only ETP-ALL and involvement of the central nervous system were independent prognostic factors.

CONCLUSION

Compared with other subtypes, pediatric ETP-ALL had a poor treatment response and high recurrence rate while cortical T-ALL appeared to have much better outcome. Our observations highlight the need for an individualized treatment regime for ETP-ALL.

Minimal Residual Disease in Acute Lymphoblastic Leukemia: Technical and Clinical Advances

Introduction: Acute lymphoblastic leukemia (ALL) is the first neoplasm where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has proven to be a fundamental tool to guide therapeutic choices. The most standardized methods to study MRD in ALL are multi-parametric flow cytometry (MFC) and polymerase chain reaction (PCR) amplification-based methods. Emerging technologies hold the promise to improve MRD detection in ALL patients. Moreover, novel therapies, such as monoclonal antibodies, bispecific T-cell engagers, and chimeric antigen receptor T cells (CART) represent exciting advancements in the management of B-cell precursor (BCP)-ALL.

Aims: Through a review of the literature and in house data, we analyze the current status of MRD assessment in ALL to better understand how some of its limitations could be overcome by emerging molecular technologies. Furthermore, we highlight the future role of MRD monitoring in the context of personalized protocols, taking into account the genetic complexity in ALL.

Results and Conclusions: Molecular rearrangements (gene fusions and immunoglobulin and T-cell receptor-IG/TR gene rearrangements) are widely used as targets to detect residual leukemic cells in ALL patients. The advent of novel techniques, namely next generation flow cytometry (NGF), digital-droplet-PCR (ddPCR), and next generation sequencing (NGS) appear important tools to evaluate MRD in ALL, since they have the potential to overcome the limitations of standard approaches. It is likely that in the forthcoming future these techniques will be incorporated in clinical trials, at least at decisional time points. Finally, the advent of new powerful compounds is further increasing MRD negativity rates, with benefits in long-term survival and a potential reduction of therapy-related toxicities. However, the prognostic relevance in the setting of novel immunotherapies still needs to be evaluated.

Clinical use of SNP-microarrays for the detection of genome-wide changes in haematological malignancies

Single nucleotide polymorphism (SNP) microarrays are commonly used for the clinical investigation of constitutional genomic disorders; however, their adoption for investigating somatic changes is being recognised. With increasing importance being placed on defining the cancer genome, a shift in technology is imperative at a clinical level. Microarray platforms have the potential to become frontline testing, replacing or complementing standard investigations such as FISH or karyotype. This 'molecular karyotype approach' exemplified by SNP-microarrays has distinct advantages in the investigation of several haematological malignancies. A growing body of literature, including guidelines, has shown support for the use of SNP-microarrays in the clinical laboratory to aid in a more accurate definition of the cancer genome. Understanding the benefits of this technology along with discussing the barriers to its implementation is necessary for the development and incorporation of SNP-microarrays in a clinical laboratory for the investigation of haematological malignancies.

The Key Roles of PTEN in T-Cell Acute Lymphoblastic Leukemia Development, Progression, and Therapeutic Response

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive blood cancer that comprises 10–15% of pediatric and ~25% of adult ALL cases. Although the curative rates have significantly improved over the past 10 years, especially in pediatric patients, T-ALL remains a challenge from a therapeutic point of view, due to the high number of early relapses that are for the most part resistant to further treatment. Considerable advances in the understanding of the genes, signaling networks, and mechanisms that play crucial roles in the pathobiology of T-ALL have led to the identification of the key drivers of the disease, thereby paving the way for new therapeutic approaches. PTEN is critical to prevent the malignant transformation of T-cells. However, its expression and functions are altered in human T-ALL. PTEN is frequently deleted or mutated, while PTEN protein is often phosphorylated and functionally inactivated by casein kinase 2. Different murine knockout models recapitulating the development of T-ALL have demonstrated that PTEN abnormalities are at the hub of an intricate oncogenic network sustaining and driving leukemia development by activating several signaling cascades associated with drug-resistance and poor outcome. These aspects and their possible therapeutic implications are highlighted in this review.

Origins of STIL-TAL1 fusion genes in children who later developed paediatric T-cell acute lymphoblastic leukaemia: An investigation of neonatal blood spots

SCL/TAL1 interrupting locus (STIL)-T-cell acute leukaemia (TAL1) fusion genes are present in approximately 11-27% of children with paediatric T-cell acute lymphoblastic leukaemia (T-ALL), but the developmental timing of the rearrangement is still unknown. To investigate whether the fusion gene can be detected in neonatal blood spots (NBSs) from paediatric patients diagnosed with T-cell ALL, we analysed DNA from 38 paediatric patients with T-ALL by nested polymerase chain reaction and electrophoresis. The STIL-TAL1 fusion gene was not detected in NBSs from any of the 38 patients with T-ALL, suggesting that STIL-TAL1 fusion genes are most probably postnatal events in paediatric T-ALL.

Identification of NMU as a potential gene conferring alectinib resistance in non-small cell lung cancer based on bioinformatics analyses

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, and adjuvant targeted therapy has shown great benefits for the NSCLC patients with specific genomic mutations. Alectinib, a selective anaplastic lymphoma kinase (ALK) inhibitor, has been clinically used for the NSCLC patients with ALK-rearrangement, however, irreversible therapeutic resistance for the patients receiving alectinib treatment frequently occurs. Here we show that neuromedin U (NMU) may confer the alectinib resistance in NSCLC via multiple mechanisms based on the integrative bioinformatics analyses. Through employing the bioinformatics analyses of three microarray datasets, NMU, overexpressed in both NSCLC tissues and alectinib-resistant NSCLC cells, was initially identified as potential candidate for causing alectinib resistance in NSCLC. The resistance function of NMU in NSCLC was validated by performing protein/gene interactions and biological process annotation analyses, and further validated by analyzing the transcription factors targeting NMU mRNA. Collectively, these results indicated that NMU may confer alectinib resistance in NSCLC.

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.

MAP3K7 is recurrently deleted in pediatric T-lymphoblastic leukemia and affects cell proliferation independently of NF-κB

BACKGROUND

Deletions of 6q15-16.1 are recurrently found in pediatric T-cell acute lymphoblastic leukemia (T-ALL). This chromosomal region includes the mitogen-activated protein kinase kinase kinase 7 (MAP3K7) gene which has a crucial role in innate immune signaling and was observed to be functionally and prognostically relevant in different cancer entities. Therefore, we correlated the presence of MAP3K7 deletions with clinical parameters in a cohort of 327 pediatric T-ALL patients and investigated the function of MAP3K7 in the T-ALL cell lines CCRF-CEM, Jurkat and MOLT-4.

METHODS

MAP3K7 deletions were detected by multiplex ligation-dependent probe amplification (MLPA). T-ALL cell lines were transduced with adeno-associated virus (AAV) vectors expressing anti-MAP3K7 shRNA or a non-silencing shRNA together with a GFP reporter. Transduction efficiency was measured by flow cytometry and depletion efficiency by RT-PCR and Western blots. Induction of apoptosis was measured by flow cytometry after staining with PE-conjugated Annexin V. In order to assess the contribution of NF-κB signaling to the effects of MAP3K7 depletion, cells were treated with TNF-α and cell lysates analyzed for components of the NF-κB pathway by Western blotting and for expression of the NF-κB target genes BCL2, CMYC, FAS, PTEN and TNF-α by RT-PCR.

RESULTS

MAP3K7 is deleted in approximately 10% and point-mutated in approximately 1% of children with T-ALL. In 32 of 33 leukemias the deletion of MAP3K7 also included the adjacent CASP8AP2 gene. MAP3K7 deletions were associated with the occurrence of SIL-TAL1 fusions and a mature immunophenotype, but not with response to treatment and outcome. Depletion of MAP3K7 expression in T-ALL cell lines by shRNAs slowed down proliferation and induced apoptosis, but neither changed protein levels of components of NF-κB signaling nor NF-κB target gene expression after stimulation with TNF-α.

CONCLUSIONS

This study revealed that the recurrent deletion of MAP3K7/CASP8AP2 is associated with SIL-TAL1 fusions and a mature immunophenotype, but not with response to treatment and risk of relapse. Homozygous deletions of MAP3K7 were not observed, and efficient depletion of MAP3K7 interfered with viability of T-ALL cells, indicating that a residual expression of MAP3K7 is indispensable for T-lymphoblasts.

The impact of immunological and biomolecular investigations on the outcome of children with acute lymphoblastic leukemia - experience of IIIrd Paediatric Clinic Timisoara

Introduction. The unsatisfactory results of the survival in patients with acute lymphoblastic leukemia (ALL) until 2000 in our center have led us to improve the approach of diagnosis and therapy. Since 2003 in all patients the following have been performed: flow cytometry, conventional genetic diagnosis, FISH (fluorescent in situ hybridization), and molecular biology. Objectives. Our aims were to identify solutions to increase patients’ survival. Patients and method. It is a single-center, retrospective study of 136 patients with ALL treated at 3rd Pediatric Clinic of Timisoara, over a period of 10 years (2003-2012), where survival was assessed. Results. Morphologically, 86% of the patients were L1 type, 13% L2 type and 1% L3 type. Flow citometry revealed that 68% were ALL with B precursors, and 19% with T immunophenotype. Acute leukemia with mixed phenotype (biphenotypic) was identified in 2.3% of patients and 10.7% of the forms were acute leukemia with myeloid markers. In 27.7% of patients, mutations were detected by the RT-PCR method, the most commonly identified was TEL-AML1 (ETV6- RUNX1) accounting for 12.7% of the cases. Relapse-free survival at 5 years for the entire group was 59%, and for the group treated between 2008 and 2012 it was 72%. Conclusion. Our analysis confirms the decisive value of laboratory investigations for the prognosis and improvement of supportive therapy.

Glucocorticoid resistance is reverted by LCK inhibition in pediatric T-cell acute lymphoblastic leukemia

Pediatric T-acute lymphoblastic leukemia (T-ALL) patients often display resistance to glucocorticoid (GC) treatment. These patients, classified as prednisone poor responders (PPR), have poorer outcome than do the other pediatric T-ALL patients receiving a high-risk adapted therapy. Because glucocorticoids are administered to ALL patients during all the different phases of therapy, GC resistance represents an important challenge to improving the outcome for these patients. Mechanisms underlying resistance are not yet fully unraveled; thus our research focused on the identification of deregulated signaling pathways to point out new targeted approaches. We first identified, by reverse-phase protein arrays, the lymphocyte cell-specific protein-tyrosine kinase (LCK) as aberrantly activated in PPR patients. We showed that LCK inhibitors, such as dasatinib, bosutinib, nintedanib, and WH-4-023, are able to induce cell death in GC-resistant T-ALL cells, and remarkably, cotreatment with dexamethasone is able to reverse GC resistance, even at therapeutic drug concentrations. This was confirmed by specific LCK gene silencing and ex vivo combined treatment of cells from PPR patient-derived xenografts. Moreover, we observed that LCK hyperactivation in PPR patients upregulates the calcineurin/nuclear factor of activated T cells signaling triggering to interleukin-4 (IL-4) overexpression. GC-sensitive cells cultured with IL-4 display an increased resistance to dexamethasone, whereas the inhibition of IL-4 signaling could increase GC-induced apoptosis in resistant cells. Treatment with dexamethasone and dasatinib also impaired engraftment of leukemia cells in vivo. Our results suggest a quickly actionable approach to supporting conventional therapies and overcoming GC resistance in pediatric T-ALL patients.

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.

An update on PCR use for minimal residual disease monitoring in acute lymphoblastic leukemia

INTRODUCTION

Acute lymphoblastic leukemia (ALL) is the first neoplasm where the assessment of early response to therapy by minimal residual disease (MRD) monitoring has proven to be a fundamental tool for guiding therapeutic choices. In recent years, thanks to real-time quantitative PCR (qPCR), MRD monitoring has further achieved higher levels of sensitivity and standardization. However, some outstanding issues still remain to be addressed and emerging technologies hold the promise of improving MRD detection in ALL patients. Areas covered: Through a comprehensive review of the literature, we analyze the state-of-the-art of molecular MRD assessment in ALL to better understand how, in the upcoming years, some of its limitations could be tackled by emerging molecular technologies. Furthermore, we highlight the future role of molecular MRD monitoring in the context of personalized protocols, taking into account the growing genetic complexity in ALL. Expert commentary: Although new molecular technologies are promising tools for MRD assessment, qPCR still remains the gold standard for evaluating MRD in ALL. High-throughput sequencing and droplet digital PCR allow to identify new prognostic factors and/or MRD targets at diagnosis and to perform earlier MRD evaluations, thereby optimizing patient stratification and earlier MRD-based clinical intervention to improve ALL patient outcomes.

A neoplasm with FIP1L1-PDGFRA fusion presenting as pediatric T-cell lymphoblastic leukemia/lymphoma without eosinophilia

The 2016 World Health Organization (2016 WHO) classification of hematopoietic malignancies classifies neoplasms with a fusion between the FIP1L1 and PDGFRA genes in 4q12 into a group called "myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1 or with PCM1-JAK2". Neoplasms characterized by this fusion are pluripotent stem cell disorders that can show both myeloid and lymphoid differentiation. They typically occur in adult patients and most are characterized by eosinophilia. We describe identification of a FIP1L1-PDGFRA fusion in a 13-year-old boy who presented with T-lymphoblastic leukemia/lymphoma without eosinophilia. Detection of FIP1L1-PDGFRA driven neoplasms at diagnosis is usually critical for proper treatment, since almost all reported cases responded to tyrosine kinase inhibitors. However, our patient's leukemia was refractory to standard chemotherapy, and did not show a meaningful response to tyrosine kinase inhibitor therapy. Testing for a FIP1L1-PDGFRA rearrangement is at present limited to patients with idiopathic hypereosinophilia, and we hypothesize that this abnormality may be under-diagnosed in children with acute leukemias.

Recurrent Cytogenetic Abnormalities in Acute Lymphoblastic Leukemia

Both B-cell and T-cell acute lymphoblastic leukemia (ALL) exhibit recurrent cytogenetic alterations, many with prognostic implications. This chapter overviews the major recurrent categories of cytogenetic abnormalities associated with ALL, with an emphasis on the detection and characterization of these cases by G-band and FISH analyses.

Pediatric T-cell acute lymphoblastic leukemia

The most common pediatric malignancy is acute lymphoblastic leukemia (ALL), of which T-cell ALL (T-ALL) comprises 10-15% of cases. T-ALL arises in the thymus from an immature thymocyte as a consequence of a stepwise accumulation of genetic and epigenetic aberrations. Crucial biological processes, such as differentiation, self-renewal capacity, proliferation, and apoptosis, are targeted and deranged by several types of neoplasia-associated genetic alteration, for example, translocations, deletions, and mutations of genes that code for proteins involved in signaling transduction, epigenetic regulation, and transcription. Epigenetically, T-ALL is characterized by gene expression changes caused by hypermethylation of tumor suppressor genes, histone modifications, and miRNA and lncRNA abnormalities. Although some genetic and gene expression patterns have been associated with certain clinical features, such as immunophenotypic subtype and outcome, none has of yet generally been implemented in clinical routine for treatment decisions. The recent advent of massive parallel sequencing technologies has dramatically increased our knowledge of the genetic blueprint of T-ALL, revealing numerous fusion genes as well as novel gene mutations. The challenges now are to integrate all genetic and epigenetic data into a coherent understanding of the pathogenesis of T-ALL and to translate the wealth of information gained in the last few years into clinical use in the form of improved risk stratification and targeted therapies. Here, we provide an overview of pediatric T-ALL with an emphasis on the acquired genetic alterations that result in this disease. © 2016 Wiley Periodicals, Inc.

Early T-cell precursor acute lymphoblastic leukaemia in children treated in AIEOP centres with AIEOP-BFM protocols: a retrospective analysis

BACKGROUND

Early T-cell precursor acute lymphoblastic leukaemia was recently recognised as a distinct leukaemia and reported as associated with poor outcomes. We aimed to assess the outcome of early T-cell precursor acute lymphoblastic leukaemia in patients from the Italian Association of Pediatric Hematology Oncology (AIEOP) centres treated with AIEOP-Berlin-Frankfurt-Münster (AIEOP-BFM) protocols.

METHODS

In this retrospective analysis, we included all children aged from 1 to less than 18 years with early T-cell precursor acute lymphoblastic leukaemia immunophenotype diagnosed between Jan 1, 2008, and Oct 31, 2014, from AIEOP centres. Early T-cell precursors were defined as being CD1a and CD8 negative, CD5 weak positive or negative, and positive for at least one of the following antigens: CD34, CD117, HLADR, CD13, CD33, CD11b, or CD65. Treatment was based on AIEOP-BFM acute lymphoblastic leukaemia 2000 (NCT00613457) or AIEOP-BFM acute lymphoblastic leukaemia 2009 protocols (European Clinical Trials Database 2007-004270-43). The main differences in treatment and stratification of T-cell acute lymphoblastic leukaemia between the two protocols were that in the 2009 protocol only, pegylated L-asparaginase was substituted for Escherichia coli L-asparaginase, patients with prednisone poor response received an additional dose of cyclophosphamide at day 10 of phase IA, and high minimal residual disease at day 15 assessed by flow cytometry was used as a high-risk criterion. Outcomes were assessed in terms of event-free survival, disease-free survival, and overall survival.

FINDINGS

Early T-cell precursor acute lymphoblastic leukaemia was diagnosed in 49 patients. Compared with overall T-cell acute lymphoblastic leukaemia, it was associated with absence of molecular markers for PCR detection of minimal residual disease in 25 (56%) of 45 patients; prednisone poor response in 27 (55%) of 49 patients; high minimal residual disease at day 15 after starting therapy in 25 (64%) of 39 patients (bone marrow blasts ≥ 10%, by flow cytometry); no complete remission after phase IA in 7 (15%) of 46 patients (bone marrow blasts ≥ 5%, morphologically); and high PCR minimal residual disease (≥ 5 × 10(-4)) at day 33 after starting therapy in 17 (85%) of 20 patients with markers available. Overall, 38 (78%) of 49 patients are in continuous complete remission, including 13 of 18 after haemopoietic stem cell transplantation, with three deaths in induction, five deaths after haemopoietic stem cell transplantation, and three relapses. Severe adverse events in the 2009 study were reported in 10 (30%) of 33 patients with early T-cell precursor acute lymphoblastic leukaemia versus 24 (15%) of 164 patients without early T-cell precursor acute lymphoblastic leukaemia and life-threatening events in induction phase IA occurred in 4 (12%) of 33 patients with early T-cell precursor acute lymphoblastic leukaemia versus 7 (4%) of 164 patients without early T-cell precursor acute lymphoblastic leukaemia. No difference was seen in the subsequent consolidation phase IB of protocol I.

INTERPRETATION

Early T-cell precursor acute lymphoblastic leukaemia is characterised by poor early response to conventional induction treatment. Consolidation phase IB, based on cyclophosphamide, 6-mercaptopurine, and ara-C at conventional (non-high) doses is effective in reducing minimal residual disease. Although the number of patients and observational time are limited, patients with early T-cell precursor acute lymphoblastic leukaemia treated with current BFM stratification and treatment strategy have a favourable outcome compared with earlier reports. The role of innovative therapies and haemopoietic stem cell therapy in early T-cell precursor acute lymphoblastic leukaemia needs to be assessed.

FUNDING

None.