Acute lymphoblastic leukemia of the central nervous system: on the role of PBX1

The advances of E2A-PBX1 fusion in B-cell acute lymphoblastic Leukaemia

The E2A-PBX1 gene fusion is a common translocation in B-cell acute lymphoblastic leukaemia. Patients harbouring the E2A-PBX1 fusion gene typically exhibit an intermediate prognosis. Furthermore, minimal residual disease has unsatisfactory prognostic value in E2A-PBX1 B-cell acute lymphoblastic leukaemia. However, the mechanism of E2A-PBX1 in the occurrence and progression of B-cell acute lymphoblastic leukaemia is not well understood. Here, we mainly review the roles of E2A and PBX1 in the differentiation and development of B lymphocytes, the mechanism of E2A-PBX1 gene fusion in B-cell acute lymphoblastic leukaemia, and the potential therapeutic approaches.

Low Prevalence of ETV6::RUNX1 Fusion Gene in a Hispanic Population

ETV6::RUNX1 is a genetic rearrangement of good prognosis in children with acute lymphoblastic leukemia (ALL). In Mexico, its prevalence is low in comparison with Caucasian populations. We developed a novel TaqMan one-step RT-qPCR approach to assess the prevalence of four genetic rearrangements in a cohort of Hispanic children with ALL from Mexico City. The prevalence of common fusion gene transcripts was as follows: TCF3::PBX1 7.7%; BCR::ABL1p 190 3.3%; and KMT2A::AFF1 2.8%, and ETV6::RUNX1was observed with low prevalence (10.5%) in comparison to that reported for developed countries. This is consistent with previous findings on Mexican children with ALL and similar to those reported on children from Hispanic populations. The confirmation of a low prevalence of ETV6::RUNX1 in children of a Hispanic origin represents an advancement in the description of genetic factors of ALL in these populations.

Co-occurrence of TCF3-PBX1 gene fusion, and chromosomal aberration in a pediatric pre-B cell acute lymphoblastic leukemia with clitoris swelling: A case report and literature review

RATIONALE

Clitoris swelling as the initial clinical presentation of acute lymphoblastic leukemia (ALL) is extremely rare. These patients may be misdiagnosed with acute myeloid leukemia or solid tumor, and the main treatment can also be delayed.

PATIENT CONCERNS

A 2.10-year-old girl was referred to the pediatric surgery clinic with a worsening onset of clitoris swellings. The patient was afebrile and well appearing. Multiple retroperitoneal mass were confirmed by computed tomography (CT) and high serum neuron-specific enolase level was high. She was scheduled for an abdominal biopsy from the retroperitoneal mass suspicious of neuroblastoma.

DIAGNOSES

The child was eventually diagnosed as having precursor B cell ALL with central nervous system involved, with TCF3-PBX1 fusion gene and additional chromosomal aberrations, based on examinations of the bone marrow and brain magnetic resonance imaging.

INTERVENTIONS

Before the diagnosis of leukemia, the patient was given symptomatic treatment for 1 week. She was treated with chemotherapy in accordance with the Chinese Children's Cancer Group protocol 2015 after confirmed diagnosis.

OUTCOMES

After induction chemotherapy for ALL, although the girl had transiently clinical remission, the bone marrow aspirate indicated a poor outcome. Our patient discontinued treatment and discharged. From literature review, there was only 1 case of in acute myeloid leukemia with clitoris swelling as the initial symptom.

LESSONS

The clinical symptoms of ALL with clitoris swelling are not typical, with a high rate of misdiagnosis. When the cause of clitoris swelling is unknown, ALL should be considered. Bone marrow aspiration must be done before doing a more invasive investigation like biopsy.

Cerebrospinal Fluid Biomarkers in Childhood Leukemias

Involvement of the central nervous system (CNS) in childhood leukemias remains a major cause of treatment failures. Analysis of the cerebrospinal fluid constitutes the most important diagnostic pillar in the detection of CNS leukemia and relies primarily on cytological and flow-cytometry studies. With increasing survival rates, it has become clear that treatments for pediatric leukemias pose a toll on the developing brain, as they may cause acute toxicities and persistent neurocognitive deficits. Preclinical research has demonstrated that established and newer therapies can injure and even destroy neuronal and glial cells in the brain. Both passive and active cell death forms can result from DNA damage, oxidative stress, cytokine release, and acceleration of cell aging. In addition, chemotherapy agents may impair neurogenesis as well as the function, formation, and plasticity of synapses. Clinical studies show that neurocognitive toxicity of chemotherapy is greatest in younger children. This raises concerns that, in addition to injury, chemotherapy may also disrupt crucial developmental events resulting in impairment of the formation and efficiency of neuronal networks. This review presents an overview of studies demonstrating that cerebrospinal fluid biomarkers can be utilized in tracing both CNS disease and neurotoxicity of administered treatments in childhood leukemias.

Involvement of the central nervous system in acute lymphoblastic leukemia: opinions on molecular mechanisms and clinical implications based on recent data

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. One of the major clinical challenges is adequate diagnosis and treatment of central nervous system (CNS) involvement in this disease. Intriguingly, there is little solid evidence on the mechanisms sustaining CNS disease in ALL. Here, we present and discuss recent data on this topic, which are mainly derived from preclinical model systems. We thereby highlight sites and routes of leukemic CNS infiltration, cellular features promoting infiltration and survival of leukemic cells in a presumably hostile niche, and dormancy as a potential mechanism of survival and relapse in CNS leukemia. We also focus on the impact of ALL cytogenetic subtypes on features associated with a particular CNS tropism. Finally, we speculate on new perspectives in the treatment of ALL in the CNS, including ideas on the impact of novel immunotherapies.

New attempts for central nervous infiltration of pediatric acute lymphoblastic leukemia

The cure rate of acute lymphoblastic leukemia (ALL), the commonest childhood cancer, has been sharply improved and reached almost 90% ever since the central nervous system (CNS)-directed therapy proposed in the 1960s. However, relapse, particularly in the central nervous system (CNS), is still a common cause of treatment failure. Up to now, the classic CNS-directed treatment for CNS leukemia (CNSL) has been aslant from cranial radiation to high-dose system chemotherapy plus intrathecal (IT) chemotherapy for the serious side effects of cranial radiation. The neurotoxic effects of chemotherapy and IT chemotherapy have been reported in recent years as well. For better prevention and treatment of CNSL, plenty of studies have tried to improve the detection sensitivity for CNSL and prevent CNSL from happening by targeting cytokines and chemokines which could be key factors for the traveling of ALL cells into the CNS. Other studies also have aimed to completely kill ALL cells (including dormant cells) in the CNS by promoting the entering of chemotherapy drugs into the CNS or targeting the components of the CNS niche which could be in favor of the survival of ALL cells in CNS. The aim of this review is to discuss the imperfection of current diagnostic methods and treatments for CNSL, as well as new attempts which could be significant for better elimination of CNSL.

Evaluation of multiplexed biomarkers in assessment of CSF infiltration in pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a very common pediatric malignancy with high survival rates. The course of treatment is modified according to the occurrence of central nervous system (CNS) disease. Aim: To relate serum and cerebrospinal fluid levels of five biomarkers (matrix metalloprotienase 9, CCL-2, sVCAM-1, IFN-γ and inducible protein 10) at diagnosis to the development of CNS infiltration. Methods: The present study was carried on 64 children with ALL and 20 controls. Multiplexed cytokines were measured by Luminex technology (Matrix metalloprotienase 9, CCL-2, sVCAM-1, IFN-γ and inducible protein 10). Results: Significantly higher sMMP-9 and lower sCCL2 were found in patients who developed CNS leukemia. Conclusion: Serum multiplexed parameters at diagnosis of childhood ALL may predict of development of CNS leukemia.

Exon sequencing reveals that missense mutation of PBX1 gene may increase the risk of non-syndromic cleft lip/palate

OBJECTIVE

Non-syndromic oral cleft (NSOC) is one of the most common multifactorial birth defects. A previous animal study showed PBX1 gene knockout mice consequently exhibited complete cleft lip/palate (CL/P). However, little is known about the association between PBX1 and NSOC in humans. This study investigated the role of the PBX1 gene in NSOC in the Han Chinese population.

METHODS

In all, 287 NSOCs were recruited for this study. First, exons in the PBX1 gene were sequenced among 50 non-syndromic cleft lip and palate cases to screen for variations by the Sanger sequencing method. Then, we selected four SNPs to replicate among 237 NSOC trios and analyzed the data by using TDT and parent of origin effect methods.

RESULTS

Exon sequencing identified six variants of the PBX1 gene. Among them, four variants were common variants. TDT analysis revealed allele G at rs2275558 and allele T at rs3835581 were over-transmitted in NSCL/P (P=0.039 and 0.038, respectively), which could increase the risk for NSCL/P. Parent of origin effect analysis indicated that allele G at rs2275558 was paternally over-transmitted for NSCL/P (P=0.0091).

CONCLUSION

This is the first report that the PBX1 gene is associated with NSCL/P, which indicates that it is a promising candidate gene for NSCL/P.

Excellent outcome of acute lymphoblastic leukaemia with TCF3-PBX1 rearrangement in Hong Kong

OBJECTIVE

The aim of this study was to review clinical outcomes and prognosis of paediatric patients with acute lymphoblastic leukaemia (ALL) with TCF3-PBX1 rearrangement.

PATIENTS

All children in Hong Kong diagnosed with ALL with TCF3-PBX1 rearrangement over the past two decades were included.

METHODS

Six hundred and twenty-four newly diagnosed patients with ALL from four consecutive studies were enrolled from 1997 to 2016. Patients carrying TCF3-PBX1 rearrangement and patients at intermediate risk without the gene expression were compared for clinical characteristics, overall survival and event-free survival (EFS).

RESULTS

The TCF3-PBX1 rearrangement was detected in 30 of 624 patients (4.8%). Results were consistent across the consecutive clinical trials employed in the past two decades. Compared with 239 intermediate risk patients without TCF3-PBX1 rearrangement, the 5-year overall survival and EFS for patients with TCF3-PBX1 rearrangement was superior, with both at 100% (P = 0.12 and P = 0.029).

CONCLUSION

This population-based study over the past 20 years demonstrated that patients with TCF3-PBX1 rearrangement had favourable EFS compared with other intermediate risk patients treated with a similar chemotherapy backbone.

Approved CAR T cell therapies: ice bucket challenges on glaring safety risks and long-term impacts

Two autologous chimeric antigen receptor (CAR) T cell therapies (Kymriah™ and Yescarta™) were recently approved by the FDA. Kymriah™ is for the treatment of pediatric patients and young adults with refractory or relapse (R/R) B cell precursor acute lymphoblastic leukemia and Yescarta™ is for the treatment of adult patients with R/R large B cell lymphoma. In common, both are CD19-specific CAR T cell therapies lysing CD19-positive targets. Their dramatic efficacy in the short term has been highlighted by many media reports. By contrast, their glaring safety gaps behind the miracles remain much less addressed. Here, we focus on addressing the crucial challenges in relation to the gaps.

Characteristics and Therapeutic Targeting of Minimal Residual Disease in Childhood Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. Early response to therapy, especially the measurement of minimal residual disease (MRD), remains the most reliable and strongest independent prognostic parameter. Intriguingly, little is known on the mechanisms sustaining MRD in that disease. Here, we summarize existing evidence on the influences of molecular genetics and clonal architecture of childhood ALL on disease persistence. Also, the impact of the leukemic niche on residual leukemia cells in the bone marrow and extramedullary compartments is reviewed. We further discuss existing in vivo models of minimal residual disease based on different cellular labelling strategies and engraftment of ALL cells in immunodeficient mouse strains. We finally draw some conclusions on potential strategies targeting residual ALL cells, with a focus on cellular and antibody-based immunotherapy.