Durable remissions in TCF3-HLF positive acute lymphoblastic leukemia with blinatumomab and stem cell transplantation

Deciphering the role of HLF in idiopathic orbital inflammation: integrative analysis via bioinformatics and machine learning techniques

Idiopathic orbital inflammation, formerly known as NSOI (nonspecific orbital inflammation), is characterized as a spectrum disorder distinguished by the polymorphic infiltration of lymphoid tissue, presenting a complex and poorly understood etiology. Recent advancements have shed light on the HLF (Human lactoferrin), proposing its critical involvement in the regulation of hematopoiesis and the maintenance of innate mucosal immunity. This revelation has generated significant interest in exploring HLF's utility as a biomarker for NSOI, despite the existing gaps in our understanding of its biosynthetic pathways and operational mechanisms. Intersecting multi-omic datasets-specifically, common differentially expressed genes between GSE58331 and GSE105149 from the Gene Expression Omnibus and immune-related gene compendiums from the ImmPort database-we employed sophisticated analytical methodologies, including Lasso regression and support vector machine-recursive feature elimination, to identify HLF. Gene set enrichment analysis and gene set variation analysis disclosed significant immune pathway enrichment within gene sets linked to HLF. The intricate relationship between HLF expression and immunological processes was further dissected through the utilization of CIBERSORT and ESTIMATE algorithms, which assess characteristics of the immune microenvironment, highlighting a noteworthy association between increased HLF expression and enhanced immune cell infiltration. The expression levels of HLF were corroborated using data from the GSE58331 dataset, reinforcing the validity of our findings. Analysis of 218 HLF-related differentially expressed genes revealed statistically significant discrepancies. Fifteen hub genes were distilled using LASSO and SVM-RFE algorithms. Biological functions connected with HLF, such as leukocyte migration, ossification, and the negative regulation of immune processes, were illuminated. Immune cell analysis depicted a positive correlation between HLF and various cells, including resting mast cells, activated NK cells, plasma cells, and CD8 T cells. Conversely, a negative association was observed with gamma delta T cells, naive B cells, M0 and M1 macrophages, and activated mast cells. Diagnostic assessments of HLF in distinguishing NSOI showed promising accuracy. Our investigation delineates HLF as intricately associated with NSOI, casting light on novel biomarkers for diagnosis and progression monitoring of this perplexing condition.

Venetoclax resistance in acute lymphoblastic leukemia is characterized by increased mitochondrial activity and can be overcome by co-targeting oxidative phosphorylation

Deregulated apoptosis signaling is characteristic for many cancers and contributes to leukemogenesis and treatment failure in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Apoptosis is controlled by different pro- and anti-apoptotic molecules. Inhibition of anti-apoptotic molecules like B-cell lymphoma 2 (BCL-2) has been developed as therapeutic strategy. Venetoclax (VEN), a selective BCL-2 inhibitor has shown clinical activity in different lymphoid malignancies and is currently evaluated in first clinical trials in BCP-ALL. However, insensitivity to VEN has been described constituting a major clinical concern. Here, we addressed and modeled VEN-resistance in BCP-ALL, investigated the underlying mechanisms in cell lines and patient-derived xenograft (PDX) samples and identified potential strategies to overcome VEN-insensitivity. Leukemia lines with VEN-specific resistance were generated in vitro and further characterized using RNA-seq analysis. Interestingly, gene sets annotated to the citric/tricarboxylic acid cycle and the respiratory electron transport chain were significantly enriched and upregulated, indicating increased mitochondrial metabolism in VEN-resistant ALL. Metabolic profiling showed sustained high mitochondrial metabolism in VEN-resistant lines as compared to control lines. Accordingly, primary PDX-ALL samples with intrinsic VEN-insensitivity showed higher oxygen consumption and ATP production rates, further highlighting that increased mitochondrial activity is a characteristic feature of VEN-resistant ALL. VEN-resistant PDX-ALL showed significant higher mitochondrial DNA content and differed in mitochondria morphology with significantly larger and elongated structures, further corroborating our finding of augmented mitochondrial metabolism upon VEN-resistance. Using Oligomycin, an inhibitor of the complex V/ATPase subunit, we found synergistic activity and apoptosis induction in VEN-resistant BCP-ALL cell lines and PDX samples, demonstrating that acquired and intrinsic VEN-insensitivity can be overcome by co-targeting BCL-2 and the OxPhos pathway. These findings of reprogrammed, high mitochondrial metabolism in VEN-resistance and synergistic activity upon co-targeting BCL-2 and oxidative phosphorylation strongly suggest further preclinical and potential clinical evaluation in VEN-resistant BCP-ALL.

B-Lymphoblastic Lymphoma in Children: A Case Series From a Single Institution

BACKGROUND

Pediatric B-lymphoblastic lymphoma is an uncommon subtype of non-Hodgkin lymphoma. Studies regarding the biology, clinical course, and approach to relapse are limited.

OBSERVATIONS

We present a series of children with B-lymphoblastic lymphoma to describe the clinical course at diagnosis and relapse as well as the role of tumor cytogenetics, immunotherapy, and hematopoietic stem cell transplant.

CONCLUSIONS

The prognostic significance of cytogenetic changes in B-lymphoblastic lymphoma is not well described but may offer improved risk stratification. Immunotherapy may offer salvage options for relapsed disease and can serve as a bridge to transplant.

Biological Markers of High-Risk Childhood Acute Lymphoblastic Leukemia

Childhood acute lymphoblastic leukemia (ALL) has witnessed substantial improvements in prognosis; however, a subset of patients classified as high-risk continues to face higher rates of relapse and increased mortality. While the National Cancer Institute (NCI) criteria have traditionally guided risk stratification based on initial clinical information, recent advances highlight the pivotal role of biological markers in shaping the prognosis of childhood ALL. This review delves into the emerging understanding of high-risk childhood ALL, focusing on molecular, cytogenetic, and immunophenotypic markers. These markers not only contribute to unraveling the underlying mechanisms of the disease, but also shed light on specific clinical patterns that dictate prognosis. The paradigm shift in treatment strategies, exemplified by the success of tyrosine kinase inhibitors in Philadelphia chromosome-positive leukemia, underscores the importance of recognizing and targeting precise risk factors. Through a comprehensive exploration of high-risk childhood ALL characteristics, this review aims to enhance our comprehension of the disease, offering insights into its molecular landscape and clinical intricacies in the hope of contributing to future targeted and tailored therapies.

Novel Biomarkers and Molecular Targets in ALL

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a widely heterogeneous disease in terms of genomic alterations, treatment options, and prognosis. While ALL is considered largely curable in children, adults tend to have higher risk disease subtypes and do not respond as favorably to conventional chemotherapy. Identifying genomic drivers of leukemogenesis and applying targeted therapies in an effort to improve disease outcomes is an exciting focus of current ALL research. Here, we review recent updates in ALL targeted therapy and present promising opportunities for future research.

RECENT FINDINGS

With the utilization of next-generation sequencing techniques, the genomic landscape of ALL has greatly expanded to encompass novel subtypes characterized by recurrent chromosomal rearrangements, gene fusions, sequence mutations, and distinct gene expression profiles. The evolution of small molecule inhibitors and immunotherapies, and the exploration of unique therapy combinations are some examples of recent advancements in the field. Targeted therapies are becoming increasingly important in the treatment landscape of ALL to improve outcomes and minimize toxicity. Significant recent advancements have been made in the detection of susceptible genomic drivers and the use of novel therapies to target them.

Updates on lymphoblastic leukemia/lymphoma classification and minimal/measurable residual disease analysis

Lymphoblastic leukemia/lymphoma (ALL/LBL), especially certain subtypes, continues to confer morbidity and mortality despite significant therapeutic advances. The pathologic classification of ALL/LBL, especially that of B-ALL, has recently substantially expanded with the identification of several distinct and prognostically important genetic drivers. These discoveries are reflected in both current classification systems, the World Health Organization (WHO) 5th edition and the new International Consensus Classification (ICC). In this article, novel subtypes of B-ALL are reviewed, including DUX4, MEF2D and ZNF384-rearranged B-ALL; the rare pediatric entity B-ALL with TLF3::HLF, now added to the classifications, is discussed; updates to the category of B-ALL with BCR::ABL1-like features (Ph-like B-ALL) are summarized; and emerging genetic subtypes of T-ALL are presented. The second half of the article details current approaches to minimal/measurable residual disease (MRD) detection in B-ALL and T-ALL and presents anticipated challenges to current approaches in the burgeoning era of antigen-directed immunotherapy.

Cytogenetics in the management of B-cell acute lymphoblastic leukemia: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Cytogenetic analysis is mandatory at initial assessment of B-cell acute lymphoblastic leukemia (B-ALL) due to its diagnostic and prognostic value. Results from chromosome banding analysis and complementary FISH are taken into account in therapeutic protocols and further completed by other techniques (RT-PCR, SNP-array, MLPA, NGS, OGM). Indeed, new genomic entities have been identified by NGS, mostly RNA sequencing, such as Ph-like ALL that can benefit from targeted therapy. Here, we have attempted to establish cytogenetic guidelines by reviewing the most recent published data including the novel 5th World Health Organization and International Consensus Classifications. We also focused on newly described cytogenomic entities and indicate alternative diagnostic tools such as NGS technology, as its importance is vastly increasing in the diagnostic setting.

Acute Lymphoblastic Leukemia Immunotherapy Treatment: Now, Next, and Beyond

Acute lymphoblastic leukemia (ALL) is a blood cancer that primarily affects children but also adults. It is due to the malignant proliferation of lymphoid precursor cells that invade the bone marrow and can spread to extramedullary sites. ALL is divided into B cell (85%) and T cell lineages (10 to 15%); rare cases are associated with the natural killer (NK) cell lineage (<1%). To date, the survival rate in children with ALL is excellent while in adults continues to be poor. Despite the therapeutic progress, there are subsets of patients that still have high relapse rates after chemotherapy or hematopoietic stem cell transplantation (HSCT) and an unsatisfactory cure rate. Hence, the identification of more effective and safer therapy choices represents a primary issue. In this review, we will discuss novel therapeutic options including bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor (CAR)-based therapies, and other promising treatments for both pediatric and adult patients.

Emerging molecular subtypes and therapies in acute lymphoblastic leukemia

Tremendous strides have been made in the molecular and cytogenetic classification of acute lymphoblastic leukemia based on gene expression profiling data, leading to an expansion of entities in the recent International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias and 2022 WHO Classification of Tumours: Haematolymphoid Tumors, 5th edition. This increased diagnostic and therapeutic complexity can be overwhelming, and this review compares nomenclature differences between the ICC and WHO 5th edition publications, compiles key features of each entity, and provides a diagnostic algorithmic approach. In covering B-lymphoblastic leukemia (B-ALL), we divided the entities into established (those present in the revised 4th edition WHO) and novel (those added to either the ICC or WHO 5th edition) groups. The established B-ALL entities include B-ALL with BCR::ABL1 fusion, BCR::ABL1-like features, KMT2A rearrangement, ETV6::RUNX1 rearrangement, high hyperdiploidy, hypodiploidy (focusing on near haploid and low hypodiploid), IGH::IL3 rearrangement, TCF3::PBX1 rearrangement, and iAMP21. The novel B-ALL entities include B-ALL with MYC rearrangement; DUX4 rearrangement; MEF2D rearrangement; ZNF384 or ZNF362 rearrangement, NUTM1 rearrangement; HLF rearrangement; UBTF::ATXN7L3/PAN3,CDX2; mutated IKZF1 N159Y; mutated PAX5 P80R; ETV6::RUNX1-like features; PAX5 alteration; mutated ZEB2 (p.H1038R)/IGH::CEBPE; ZNF384 rearranged-like; KMT2A-rearranged-like; and CRLF2 rearrangement (non-Ph-like). Classification of T-ALL is complex with some variability in how the subtypes are defined in recent literature. It was classified as early T-precursor lymphoblastic leukemia/lymphoma and T-ALL, NOS in the WHO revised 4th edition and WHO 5th edition. The ICC added an entity into early T-cell precursor ALL, BCL11B-activated, and also added provisional entities subclassified based on transcription factor families that are aberrantly activated.

Etiology of oncogenic fusions in 5,190 childhood cancers and its clinical and therapeutic implication

Oncogenic fusions formed through chromosomal rearrangements are hallmarks of childhood cancer that define cancer subtype, predict outcome, persist through treatment, and can be ideal therapeutic targets. However, mechanistic understanding of the etiology of oncogenic fusions remains elusive. Here we report a comprehensive detection of 272 oncogenic fusion gene pairs by using tumor transcriptome sequencing data from 5190 childhood cancer patients. We identify diverse factors, including translation frame, protein domain, splicing, and gene length, that shape the formation of oncogenic fusions. Our mathematical modeling reveals a strong link between differential selection pressure and clinical outcome in CBFB-MYH11. We discover 4 oncogenic fusions, including RUNX1-RUNX1T1, TCF3-PBX1, CBFA2T3-GLIS2, and KMT2A-AFDN, with promoter-hijacking-like features that may offer alternative strategies for therapeutic targeting. We uncover extensive alternative splicing in oncogenic fusions including KMT2A-MLLT3, KMT2A-MLLT10, C11orf95-RELA, NUP98-NSD1, KMT2A-AFDN and ETV6-RUNX1. We discover neo splice sites in 18 oncogenic fusion gene pairs and demonstrate that such splice sites confer therapeutic vulnerability for etiology-based genome editing. Our study reveals general principles on the etiology of oncogenic fusions in childhood cancer and suggests profound clinical implications including etiology-based risk stratification and genome-editing-based therapeutics.

T-Cell-Replete Haploidentical Hematopoietic Stem Cell Transplantation for a Patient With Tcf3-Hlf-Positive Acute Lymphoblastic Leukemia Extramedullary Relapse After Unrelated Bone Marrow Transplantation

TCF3-HLF-positive B-cell precursor acute lymphoblastic leukemia (BCP-ALL) has an extremely poor prognosis. A 2-year-old boy with TCF3-HLF-positive BCP-ALL had an isolated extramedullary relapse in multiple bones after allogeneic hematopoietic stem cells transplantation (HSCT) from a human leukocyte antigen-matched unrelated donor. In this study, he received a T-cell-replete haploidentical HSCT (TCR-haplo-HSCT) from his father when in nonremission state, which resulted in a sustained complete remission for over 3 years. Immune therapies for patients with an extramedullary relapse of TCF3-HLF-positive BCP-ALL have been attempted; however, long-term efficacies of these therapies remain unknown. Our TCR-haplo-HSCT may be an effective therapeutic option for such patients.

Modern Classification and Management of Pediatric B-cell Leukemia and Lymphoma

Although pediatric hematopathology overlaps with that of adults, certain forms of leukemia and lymphoma, and many types of reactive conditions affecting the bone marrow and lymph nodes, are unique to children. As part of this series focused on lymphomas, this article (1) details the novel subtypes of lymphoblastic leukemia seen primarily in children and described since the 2017 World Health Organization classification and (2) discusses unique concepts in pediatric hematopathology, including nomenclature changes and evaluation of surgical margins in selected lymphomas.

International Consensus Classification of acute lymphoblastic leukemia/lymphoma

The updated International Consensus Classification (ICC) of B-acute lymphoblastic leukemia (B-ALL) and T-acute lymphoblastic leukemia (T-ALL) includes both revisions to subtypes previously outlined in the 2016 WHO classification and several newly described entities. The ICC classification incorporates recent clinical, cytogenetic, and molecular data, with a particular emphasis on whole transcriptome analysis and gene expression (GEX) clustering studies. B-ALL classification is modified to further subclassify BCR::ABL1-positive B-ALL and hypodiploid B-ALL. Additionally, nine new categories of B-ALL are defined, including seven that contain distinguishing gene rearrangements, as well as two new categories that are characterized by a specific single gene mutation. Four provisional entities are also included in the updated B-ALL classification, although definitive identification of these subtypes requires GEX studies. T-ALL classification is also updated to incorporate BCL11B-activating rearrangements into early T-precursor (ETP) ALL taxonomy. Additionally, eight new provisional entities are added to the T-ALL subclassification. The clinical implications of the new entities are discussed, as are practical approaches to the use of different technologies in diagnosis. The enhanced specificity of the new classification will allow for improved risk stratification and optimized treatment plans for patients with ALL.

Infectious Complications of Targeted Therapies in Children with Leukemias and Lymphomas

Simple Summary

Targeted therapies in children with hematological malignancies moderate the effects of cytotoxic therapy, thus improving survival rates. They have emerged over the last decade and are used in combination with or after the failure of conventional chemotherapy and as bridging therapy prior to hematopoietic stem cell transplantation (HSCT). Nowadays, there is a growing interest in their efficacy and safety in pediatric patients with refractory or relapsed disease. The compromised immune system, even prior to therapy, requires prompt monitoring and treatment. In children with hematological malignancies, targeted therapies are associated with a comparable incidence of infectious complications to adults. The exact impact of these agents that have different mechanisms of action and are used after conventional chemotherapy or HSCT is difficult to ascertain. Clinicians should be cautious of severe infections after the use of targeted therapies, especially when used in combination with chemotherapy.

Abstract

The aim of this review is to highlight mechanisms of immunosuppression for each agent, along with pooled analyses of infectious complications from the available medical literature. Rituximab confers no increase in grade ≥3 infectious risks, except in the case of patients with advanced-stage non-Hodgkin lymphoma. Gemtuzumab ozogamicin links with high rates of grade ≥3 infections which, however, are comparable with historical cohorts. Pembrolizumab exhibits a favorable safety profile in terms of severe infections. Despite high rates of hypogammaglobulinemia (HGG) with blinatumomab, low-grade ≥3 infection rates were observed, especially in the post-reinduction therapy of relapsed B-acute lymphoblastic leukemia. Imatinib and nilotinib are generally devoid of severe infectious complications, but dasatinib may slightly increase the risk of opportunistic infections. Data on crizotinib and pan-Trk inhibitors entrectinib and larotrectinib are limited. CAR T-cell therapy with tisagenlecleucel is associated with grade ≥3 infections in children and is linked with HGG and the emergence of immune-related adverse events. Off-label therapies inotuzumab ozogamicin, brentuximab vedotin, and venetoclax demonstrate low rates of treatment-related grade ≥3 infections, while the addition of bortezomib to standard chemotherapy in T-cell malignancies seems to decrease the infection risk during induction. Prophylaxis, immune reconstitution, and vaccinations for each targeted agent are discussed, along with comparisons to adult studies.

International Consensus Classification of Myeloid Neoplasms and Acute Leukemias: integrating morphologic, clinical, and genomic data

The classification of myeloid neoplasms and acute leukemias was last updated in 2016 within a collaboration between the World Health Organization (WHO), the Society for Hematopathology, and the European Association for Haematopathology. This collaboration was primarily based on input from a clinical advisory committees (CACs) composed of pathologists, hematologists, oncologists, geneticists, and bioinformaticians from around the world. The recent advances in our understanding of the biology of hematologic malignancies, the experience with the use of the 2016 WHO classification in clinical practice, and the results of clinical trials have indicated the need for further revising and updating the classification. As a continuation of this CAC-based process, the authors, a group with expertise in the clinical, pathologic, and genetic aspects of these disorders, developed the International Consensus Classification (ICC) of myeloid neoplasms and acute leukemias. Using a multiparameter approach, the main objective of the consensus process was the definition of real disease entities, including the introduction of new entities and refined criteria for existing diagnostic categories, based on accumulated data. The ICC is aimed at facilitating diagnosis and prognostication of these neoplasms, improving treatment of affected patients, and allowing the design of innovative clinical trials.

The pharmacology of blinatumomab: state of the art on pharmacodynamics, pharmacokinetics, adverse drug reactions and evaluation in clinical trials

WHAT IS KNOWN AND OBJECTIVE

Bispecific drugs (BDs) belong to the family of immunotherapies along with checkpoint inhibitors and CAR-T cells. In the field of oncology, BDs are designed to simultaneously bind a tumour antigen on the one side and an antigen present on the surface of effector cells on the other. This review summarizes the information available to date on the first marketed BiTE-format bispecific antibody, blinatumomab BLINCYTO® in acute lymphoblastic leukaemia.

METHODS

A literature search was conducted in the PubMed database by including studies published in English using the term blinatumomab. Furthermore, bibliographies of selected references were also evaluated for relevant articles. Clinical trial (CT) data were retrieved from clinicaltrials.gov (ongoing trials, adverse events [AEs]) and global pharmacovigilance data were retrieved from VigiBase®.

RESULTS AND DISCUSSION

Blinatumomab is a fusion protein which consists of two single-chain variable fragments arranged in tandem: the first binds the CD19 surface antigen of all B cells and the second targets the CD3 antigen of T cells. Binding of blinatumomab to B and T cells induces apoptosis of B cells after secretion of granzymes and perforins by T cells. T-cell activation results in secretion of pro-inflammatory cytokines and upregulation of activation markers and adhesion molecules on the surface of T cells. The major CTs that led to an indication show increased overall survival with blinatumomab with better efficacy in patients in haematological remission with minimal residual disease ≥10^-3 . The major AEs are cytokine release syndrome, neurotoxicity and hypogammaglobulinemia. The three most frequent system organ classes in CTs are haematological, gastrointestinal and general disorders. These results are also found in VigiBase® but neurological disorders and infections appear more frequently in real life.

WHAT IS NEW AND CONCLUSION

This review summarizes the current knowledge of blinatumomab in the literature. The subject of many CTs is to improve the route of administration and expand the indications for treatment.

Blinatumomab in pediatric relapsed/refractory B-cell acute lymphoblastic leukemia: RIALTO expanded access study final analysis

The safety and efficacy of blinatumomab, a CD3/CD19-directed bispecific molecule, were examined in an open-label, single-arm, expanded access study (RIALTO). Children (>28 days and <18 years) with CD19+ relapsed/refractory B-cell precursor acute lymphoblastic leukemia (R/R B-ALL) received up to 5 cycles of blinatumomab by continuous infusion (cycle: 4 weeks on/2 weeks off). The primary end point was incidence of adverse events. Secondary end points included complete response (CR) and measurable residual disease (MRD) response within the first 2 cycles and relapse-free survival (RFS), overall survival (OS), and allogeneic hematopoietic stem cell transplant (alloHSCT) after treatment. At final data cutoff (10 January 2020), 110 patients were enrolled (median age, 8.5 years; 88% had ≥5% baseline blasts). A low incidence of grade 3 or 4 cytokine release syndrome (n = 2; 1.8%) and neurologic events (n = 4; 3.6%) was reported; no blinatumomab-related fatal adverse events were recorded. The probability of response was not affected by the presence of cytogenetic/molecular abnormalities. Median OS was 14.6 months (95% confidence interval [CI]: 11.0-not estimable) and was significantly better for MRD responders vs MRD nonresponders (not estimable vs 9.3; hazard ratio, 0.18; 95% CI: 0.08-0.39). Of patients achieving CR after 2 cycles, 73.5% (95% CI: 61.4%-83.5%) proceeded to alloHSCT. One-year OS probability was higher for patients who received alloHSCT vs without alloHSCT after blinatumomab (87% vs 29%). These findings support the use of blinatumomab as a safe and efficacious treatment of pediatric R/R B-ALL. This trial was registered at www.clinicaltrials.gov as #NCT02187354.

Synergistic activity of combined inhibition of anti-apoptotic molecules in B-cell precursor ALL

Targeting BCL-2, a key regulator of survival in B-cell malignancies including precursor B-cell acute lymphoblastic leukemia, has become a promising treatment strategy. However, given the redundancy of anti-apoptotic BCL-2 family proteins (BCL-2, BCL-XL, MCL-1), single targeting may not be sufficient. When analyzing the effects of BH3-mimetics selectively targeting BCL-XL and MCL-1 alone or in combination with the BCL-2 inhibitor venetoclax, heterogeneous sensitivity to either of these inhibitors was found in ALL cell lines and in patient-derived xenografts. Interestingly, some venetoclax-resistant leukemias were sensitive to the MCL-1-selective antagonist S63845 and/or BCL-XL-selective A-1331852 suggesting functional mutual substitution. Consequently, co-inhibition of BCL-2 and MCL-1 or BCL-XL resulted in synergistic apoptosis induction. Functional analysis by BH3-profiling and analysis of protein complexes revealed that venetoclax-treated ALL cells are dependent on MCL-1 and BCL-XL, indicating that MCL-1 or BCL-XL provide an Achilles heel in BCL-2-inhibited cells. The effect of combining BCL-2 and MCL-1 inhibition by venetoclax and S63845 was evaluated in vivo and strongly enhanced anti-leukemia activity was found in a pre-clinical patient-derived xenograft model. Our study offers in-depth molecular analysis of mutual substitution of BCL-2 family proteins in acute lymphoblastic leukemia and provides targets for combination treatment in vivo and in ongoing clinical studies.

Impact of Blinatumomab Treatment on Bone Marrow Function in Patients with Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia

Simple Summary

Myelosuppression is a side effect of chemotherapy, in which the production of red and white blood cells and platelets is reduced, increasing risk of infections. Blinatumomab, a bispecific T-cell engager (BiTE^®) molecule, is a novel anticancer drug that kills acute lymphoblastic leukemia (ALL) cells while sparing majority of the normal bone marrow cells. Results from our study, which compared the effects of blinatumomab treatment with chemotherapy on bone marrow function in a large number of patients with ALL, indicated that the decrease in blood cell counts was more severe and lasted longer after chemotherapy compared with blinatumomab treatment, in which the effects were transient. Survival in patients treated with blinatumomab achieving complete remission was more similar between those with incomplete recovery of blood cell counts versus those with complete blood cell counts than the corresponding survival outcomes seen with chemotherapy. In conclusion, blinatumomab treatment caused transient myelosuppression when compared with chemotherapy.

Abstract

Association of blinatumomab treatment with myelosuppression was examined in this study. Peripheral blood counts were assessed prior to, during, and after blinatumomab treatment in patients with relapsed/refractory Philadelphia chromosome-negative (Ph−) B-cell precursor (BCP) acute lymphoblastic leukemia (ALL; n = 267) and Ph+ BCP-ALL (n = 45) from the TOWER and ALCANTARA studies, respectively, or chemotherapy in patients with Ph− BCP-ALL (n = 109) from the TOWER study; all the patients with relapsed/refractory BCP-ALL and responders achieving complete remission (CR) or CR with partial/incomplete hematological recovery (CRh/CRi) were evaluated. Event-free survival (EFS) and overall survival (OS) were assessed in patients achieving CR and CRh/CRi. Median leukocyte, neutrophil, and platelet counts increased during two blinatumomab cycles but remained low longer after chemotherapy. Among the responders, there was a trend that a greater proportion of patients achieved CR with blinatumomab (Ph−, 76.5%; Ph+, 77.8%) versus with chemotherapy (Ph−, 63.6%). In the TOWER study, the survival prognosis for patients achieving CRh/CRi versus CR with blinatumomab was more similar (median OS, 11.9 (95% CI, 3.9–not estimable (NE)) vs. 15.0 (95% CI, 10.4–NE) months, p = 0.062) than with chemotherapy (5.2 (95% CI, 1.6–NE) vs. 18.9 (95% CI, 9.3–NE) months, p = 0.013). Blinatumomab treatment, with only temporary and transient myelosuppression, resulted in a greater survival benefit than chemotherapy.

The Role of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for many children with high-risk or relapsed acute leukemia (AL), thanks to the combination of intense preparative radio/chemotherapy and the graft-versus-leukemia (GvL) effect. Over the years, progress in high-resolution donor typing, choice of conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive care measures have continuously improved overall transplant outcome, and recent successes using alternative donors have extended the potential application of allotransplantation to most patients. In addition, the importance of minimal residual disease (MRD) before and after transplantation is being increasingly clarified and MRD-directed interventions may be employed to further ameliorate leukemia-free survival after allogeneic HSCT. These advances have occurred in parallel with continuous refinements in chemotherapy protocols and the development of targeted therapies, which may redefine the indications for HSCT in the coming years. This review discusses the role of HSCT in childhood AL by analysing transplant indications in both acute lymphoblastic and acute myeloid leukemia, together with current and most promising strategies to further improve transplant outcome, including optimization of conditioning regimen and MRD-directed interventions.

Biologic and Therapeutic Implications of Genomic Alterations in Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most successful paradigm of how risk-adapted therapy and detailed understanding of the genetic alterations driving leukemogenesis and therapeutic response may dramatically improve treatment outcomes, with cure rates now exceeding 90% in children. However, ALL still represents a leading cause of cancer-related death in the young, and the outcome for older adolescents and young adults with ALL remains poor. In the past decade, next generation sequencing has enabled critical advances in our understanding of leukemogenesis. These include the identification of risk-associated ALL subtypes (e.g., those with rearrangements of MEF2D, DUX4, NUTM1, ZNF384 and BCL11B; the PAX5 P80R and IKZF1 N159Y mutations; and genomic phenocopies such as Ph-like ALL) and the genomic basis of disease evolution. These advances have been complemented by the development of novel therapeutic approaches, including those that are of mutation-specific, such as tyrosine kinase inhibitors, and those that are mutation-agnostic, including antibody and cellular immunotherapies, and protein degradation strategies such as proteolysis-targeting chimeras. Herein, we review the genetic taxonomy of ALL with a focus on clinical implications and the implementation of genomic diagnostic approaches.

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.

Risk factors and outcomes in children with high-risk B-cell precursor and T-cell relapsed acute lymphoblastic leukaemia: combined analysis of ALLR3 and ALL-REZ BFM 2002 clinical trials

AIM

Outcomes of children with high-risk (HR) relapsed acute lymphoblastic leukaemia (ALL) (N = 393), recruited to ALLR3 and ALL-REZ BFM 2002 trials, were analysed. Minimal residual disease (MRD) was assessed after induction and at predetermined time points until haematopoietic stem cell transplantation (SCT).

METHODS

Genetic analyses included karyotype, copy-number alterations and mutation analyses. Ten-year survivals were analysed using Kaplan-Meier and Cox models for multivariable analyses.

RESULTS

Outcomes of patients were comparable in ALLR3 and ALL-REZ BFM 2002. The event-free survival of B-cell precursor (BCP) and T-cell ALL (T-ALL) was 22.6% and 26.2% (P = 0.94), respectively, and the overall survival (OS) was 32.6% and 28.2% (P = 0.11), respectively. Induction failures (38%) were associated with deletions of NR3C1 (P = 0.002) and BTG1 (P = 0.03) in BCP-ALL. The disease-free survival (DFS) and OS in patients with good vs poor MRD responses were 57.4% vs 22.6% (P < 0.0001) and 57.8% vs 32.0% (P = 0.0004), respectively. For BCP- and T-ALL, the post-SCT DFS and OS were 42.1% and 56.8% (P = 0.26) and 51.6% and 55.4% (P = 0.67), respectively. The cumulative incidences of post-SCT relapse for BCP- and T-ALL were 36.9% and 17.8% (P = 0.012) and of death were 10.7% and 25.5% (P = 0.013), respectively. Determinants of outcomes after SCT were acute graft versus host disease, pre-SCT MRD (≥10-3), HR cytogenetics and TP53 alterations in BCP-ALL.

CONCLUSION

Improvements in outcomes for HR ALL relapses require novel compounds in induction therapy to improve remission rates and immune targeted therapy after induction to maintain remission after SCT.

TRIAL REGISTRATION

ALLR3: NCT00967057; ALL REZ-BFM 2002: NCT00114348.

Blinatumomab in Pediatric Acute Lymphoblastic Leukemia-From Salvage to First Line Therapy (A Systematic Review)

Acute lymphoblastic leukemia is by far the most common malignancy in children, and new immunotherapeutic approaches will clearly change the way we treat our patients in future years. Blinatumomab is a bispecific T-cell-engaging antibody indicated for the treatment of relapsed/refractory acute lymphoblastic leukemia (R/R-ALL). The use of blinatumomab in R/R ALL has shown promising effects, especially as a bridging tool to hematopoietic stem cell transplantation. For heavily pretreated patients, the response to one or two cycles of blinatumomab ranges from 34% to 66%. Two randomized controlled trials have very recently demonstrated an improved reduction in minimal residual disease as well as an increased survival for patients treated with blinatumomab compared to standard consolidation treatment in first relapse. Current trials using blinatumomab frontline for high-risk patients or as a consolidation treatment post-transplant will show whether efficacy is even higher in less heavily pretreated patients. Due to the distinct pattern of adverse events compared to high-dose conventional chemotherapy, blinatumomab could play an important role for patients with a risk for severe chemotherapy-associated toxicities. This systematic review discusses all published results for blinatumomab in children as well as all ongoing clinical trials.

Epigenetic Modification of Death Receptor Genes for TRAIL and TRAIL Resistance in Childhood B-Cell Precursor Acute Lymphoblastic Leukemia

Immunotherapies specific for B-cell precursor acute lymphoblastic leukemia (BCP-ALL), such as anti-CD19 chimeric antigen receptor (CAR) T-cells and blinatumomab, have dramatically improved the therapeutic outcome in refractory cases. In the anti-leukemic activity of those immunotherapies, TNF-related apoptosis-inducing ligand (TRAIL) on cytotoxic T-cells plays an essential role by inducing apoptosis of the target leukemia cells through its death receptors (DR4 and DR5). Since there are CpG islands in the promoter regions, hypermethylation of the DR4 and DR5 genes may be involved in resistance of leukemia cells to immunotherapies due to TRAIL-resistance. We analyzed the DR4 and DR5 methylation status in 32 BCP-ALL cell lines by sequencing their bisulfite PCR products with a next-generation sequencer. The DR4 and DR5 methylation status was significantly associated with the gene and cell-surface expression levels and the TRAIL-sensitivities. In the clinical samples at diagnosis (459 cases in the NOPHO study), both DR4 and DR5 genes were unmethylated in the majority of cases, whereas methylated in several cases with dic(9;20), MLL-rearrangement, and hypodiploidy, suggesting that evaluation of methylation status of the DR4 and DR5 genes might be clinically informative to predict efficacy of immunotherapy in certain cases with such unfavorable karyotypes. These observations provide an epigenetic rational for clinical efficacy of immunotherapy in the vast majority of BCP-ALL cases.

Outcomes for Australian children with relapsed/refractory acute lymphoblastic leukaemia treated with blinatumomab

We report on the Australian experience of blinatumomab for treatment of 24 children with relapsed/refractory precursor B-cell acute lymphoblastic leukaemia (B-ALL) and high-risk genetics, resulting in a minimal residual disease (MRD) response rate of 58%, 2-year progression-free survival (PFS) of 39% and 2-year overall survival of 63%. In total, 83% (n = 20/24) proceeded to haematopoietic stem cell transplant, directly after blinatumomab (n = 12) or following additional salvage therapy (n = 8). Four patients successfully received CD19-directed chimeric antigen receptor T-cell therapy despite prior blinatumomab exposure. Inferior 2-year PFS was associated with MRD positivity (20%, n = 15) and in KMT2A-rearranged infants (15%, n = 9). Our findings highlight that not all children with relapsed/refractory B-ALL respond to blinatumomab and factors such as blast genotype may affect prognosis.

Advances in the Diagnosis and Treatment of Pediatric Acute Lymphoblastic Leukemia

The outcomes of pediatric acute lymphoblastic leukemia (ALL) have improved remarkably during the last five decades. Such improvements were made possible by the incorporation of new diagnostic technologies, the effective administration of conventional chemotherapeutic agents, and the provision of better supportive care. With the 5-year survival rates now exceeding 90% in high-income countries, the goal for the next decade is to improve survival further toward 100% and to minimize treatment-related adverse effects. Based on genome-wide analyses, especially RNA-sequencing analyses, ALL can be classified into more than 20 B-lineage subtypes and more than 10 T-lineage subtypes with prognostic and therapeutic implications. Response to treatment is another critical prognostic factor, and detailed analysis of minimal residual disease can detect levels as low as one ALL cell among 1 million total cells. Such detailed analysis can facilitate the rational use of molecular targeted therapy and immunotherapy, which have emerged as new treatment strategies that can replace or reduce the use of conventional chemotherapy.

Effect of Blinatumomab vs Chemotherapy on Event-Free Survival Among Children With High-risk First-Relapse B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial

IMPORTANCE

Blinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule with efficacy in children with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL).

OBJECTIVE

To evaluate event-free survival in children with high-risk first-relapse B-ALL after a third consolidation course with blinatumomab vs consolidation chemotherapy before allogeneic hematopoietic stem cell transplant.

DESIGN, SETTING, AND PARTICIPANTS

In this randomized phase 3 clinical trial, patients were enrolled November 2015 to July 2019 (data cutoff, July 17, 2019). Investigators at 47 centers in 13 countries enrolled children older than 28 days and younger than 18 years with high-risk first-relapse B-ALL in morphologic complete remission (M1 marrow, <5% blasts) or with M2 marrow (blasts ≥5% and <25%) at randomization.

INTERVENTION

Patients were randomized to receive 1 cycle of blinatumomab (n = 54; 15 μg/m2/d for 4 weeks, continuous intravenous infusion) or chemotherapy (n = 54) for the third consolidation.

MAIN OUTCOMES AND MEASURES

The primary end point was event-free survival (events: relapse, death, second malignancy, or failure to achieve complete remission). The key secondary efficacy end point was overall survival. Other secondary end points included minimal residual disease remission and incidence of adverse events.

RESULTS

A total of 108 patients were randomized (median age, 5.0 years [interquartile range {IQR}, 4.0-10.5]; 51.9% girls; 97.2% M1 marrow) and all patients were included in the analysis. Enrollment was terminated early for benefit of blinatumomab in accordance with a prespecified stopping rule. After a median of 22.4 months of follow-up (IQR, 8.1-34.2), the incidence of events in the blinatumomab vs consolidation chemotherapy groups was 31% vs 57% (log-rank P < .001; hazard ratio [HR], 0.33 [95% CI, 0.18-0.61]). Deaths occurred in 8 patients (14.8%) in the blinatumomab group and 16 (29.6%) in the consolidation chemotherapy group. The overall survival HR was 0.43 (95% CI, 0.18-1.01). Minimal residual disease remission was observed in more patients in the blinatumomab vs consolidation chemotherapy group (90% [44/49] vs 54% [26/48]; difference, 35.6% [95% CI, 15.6%-52.5%]). No fatal adverse events were reported. In the blinatumomab vs consolidation chemotherapy group, the incidence of serious adverse events was 24.1% vs 43.1%, respectively, and the incidence of adverse events greater than or equal to grade 3 was 57.4% vs 82.4%. Adverse events leading to treatment discontinuation were reported in 2 patients in the blinatumomab group.

CONCLUSIONS AND RELEVANCE

Among children with high-risk first-relapse B-ALL, treatment with 1 cycle of blinatumomab compared with standard intensive multidrug chemotherapy before allogeneic hematopoietic stem cell transplant resulted in an improved event-free survival at a median of 22.4 months of follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02393859.

Successful Treatment of TCF3-HLF-positive Childhood B-ALL with Chimeric Antigen Receptor T-Cell Therapy

BACKGROUND

TCF3-HLF positive leukemia represents a rare subtype of B-cell acute lymphoblastic leukemia (B-ALL), characterized by a high treatment failure rate despite intensive treatment and hematopoietic stem cell transplantation (HSCT).

PATIENTS AND METHODS

Four consecutive children with TCF-HLF3-positive B-ALL who were refractory or relapsed with initial chemotherapy were treated with CD19-specific or combined CD19-and CD22-specific chimeric antigen receptor T-cell therapy (19/22 CAR-T) after conditioning regimen with fludarabine and cyclophosphamide. Clinical features, treatment responses, toxicity, and outcomes were analyzed retrospectively.

RESULTS

Four patients received 18.0, 6.0, 5.0, and 7.4 × 10⁶ CAR-T cells per kilogram and developed grade I, III, II, and III cytokine release syndrome, respectively. They all achieved minimal residual disease-negative complete remission (CR). Two of them (patients 1 and 3) underwent haploid HSCT afterward. Patient 1 relapsed after 7.2 months of transplantation and received donor-derived 19/22 CAR-T cell infusion. He had CR2 after he experienced grade II cytokine release syndrome of the second CAR-T and underwent umbilical cord blood transplantation. Unfortunately, this child died of severe lung graft versus host disease 8.4 months after the second transplantation. Patients 2 and 4 experienced reversible neurotoxicity and had a persistent clinical response to CAR-T cells for 13.8 and 6.8 months, respectively, without HSCT. Patient 3 is in continuous CR for 10.6 months until now.

CONCLUSION

CAR-T cells can effectively treat relapsed/refractory TCF3-HLF-positive childhood B-ALL with acceptable toxicity, which could be a new treatment option for this subtype compared with chemotherapy or HSCT.

Blinatumomab in pediatric patients with relapsed/refractory B-cell precursor acute lymphoblastic leukemia

OBJECTIVE

Pediatric patients with relapsed or refractory acute lymphoblastic leukemia have a poor prognosis. We here assess the response rates, adverse events, and long-term follow-up of pediatric patients with relapsed/refractory acute lymphoblastic leukemia receiving blinatumomab.

METHODS

Retrospective analysis of a single-center experience with blinatumomab in 38 patients over a period of 10 years.

RESULTS

The median age at onset of therapy was 10 years (1-21 years). Seventy-one percent of patients had undergone at least one hematopoietic stem cell transplantation (HSCT) prior to treatment with blinatumomab. We observed a response to blinatumomab in 13/38 patients (34%). The predominant side effect was febrile reactions, nearly half of the patients developed a cytokine release syndrome. Eight events of neurotoxicity were registered over the 78 cycles (15%). To date, nine patients (24%) are alive and in complete molecular remission. All survivors underwent haploidentical HSCT after treatment with blinatumomab.

CONCLUSIONS

Despite heavy pretreatment of most of our patients, severe adverse events were rare and response rates encouraging. Blinatumomab is a valuable bridging salvage therapy for relapsed or refractory patients to a second or even third HSCT.

Concepts in immuno-oncology: tackling B cell malignancies with CD19-directed bispecific T cell engager therapies

The B cell surface antigen CD19 is a target for treating B cell malignancies, such as B cell precursor acute lymphoblastic leukemia and B cell non-Hodgkin lymphoma. The BiTE® immuno-oncology platform includes blinatumomab, which is approved for relapsed/refractory B cell precursor acute lymphoblastic leukemia and B cell precursor acute lymphoblastic leukemia with minimal residual disease. Blinatumomab is also being evaluated in combination with other agents (tyrosine kinase inhibitors, checkpoint inhibitors, and chemotherapy) in various treatment settings, including frontline protocols. An extended half-life BiTE molecule is also under investigation. Patients receiving blinatumomab may experience cytokine release syndrome and neurotoxicity; however, these events may be less frequent and severe than in patients receiving other CD19-targeted immunotherapies, such as chimeric antigen receptor T cell therapy. We review BiTE technology for treating malignancies that express CD19, analyzing the benefits and limitations of this bispecific T cell engager platform from clinical experience with blinatumomab.

Comprehensive chromosomal aberrations in a case of a patient with TCF3-HLF-positive BCP-ALL

Background

The use of high-throughput analytical techniques has enabled the description of acute lymphoblastic leukaemia (ALL) subtypes. The TCF3-HLF translocation is a very rare rearrangement in ALL that is associated with an extremely poor prognosis. The TCF3-HLF fusion gene in the described case resulted in the fusion of the homeobox-related gene of TCF3 to the leucine zipper domain of HLF. The TCF3-HLF fusion gene product acts as a transcriptional factor leading to the dedifferentiation of mature B lymphocytes into an immature state (lymphoid stem cells). This process initiates the formation of pre-leukaemic cells. Due to the rarity of this chromosomal aberration, only a few cases have been described in the literature. The advantage of this work is the presentation of an interesting case of clonal evolution of cancer cells and the cumulative implications (diagnostic and prognostic) of the patient’s genetic alterations.

Case presentation

This work presents a patient with diagnosed with TCF3-HLF-positive ALL. Moreover, the additional genetic alterations, which play a key role in the pathogenesis of ALL, were detected in this patient: deletion of a fragment from the long arm of chromosome 13 (13q12.2-q21.1) containing the RB1 gene, intragenic deletions within the PAX5 gene and NOTCH1 intragenic duplication.

Conclusions

A patient with coexistence of chromosomal alterations and the TCF3-HLF fusion has not yet been described. Identifying all these chromosomal aberrations at the time of diagnosis could be sufficient to determine the cumulative effects of the described deletions on the activity of other oncogenes or tumour suppressors, as well as on the clinical course of the disease. On the other hand, complex changes in the patient’s karyotype and clonal evolution of cancer cells call into question the effectiveness of experimental therapy.

Evidence-based review of genomic aberrations in B-lymphoblastic leukemia/lymphoma: Report from the cancer genomics consortium working group for lymphoblastic leukemia

Clinical management and risk stratification of B-lymphoblastic leukemia/ lymphoma (B-ALL/LBL) depend largely on identification of chromosomal abnormalities obtained using conventional cytogenetics and Fluorescence In Situ Hybridization (FISH) testing. In the last few decades, testing algorithms have been implemented to support an optimal risk-oriented therapy, leading to a large improvement in overall survival. In addition, large scale genomic studies have identified multiple aberrations of prognostic significance that are not routinely tested by existing modalities. However, as chromosomal microarray analysis (CMA) and next-generation sequencing (NGS) technologies are increasingly used in clinical management of hematologic malignancies, these abnormalities may be more readily detected. In this article, we have compiled a comprehensive, evidence-based review of the current B-ALL literature, focusing on known and published subtypes described to date. More specifically, we describe the role of various testing modalities in the diagnosis, prognosis, and therapeutic relevance. In addition, we propose a testing algorithm aimed at assisting laboratories in the most effective detection of the underlying genomic abnormalities.

The Leukemogenic TCF3-HLF Complex Rewires Enhancers Driving Cellular Identity and Self-Renewal Conferring EP300 Vulnerability

The chimeric transcription factor TCF3-HLF defines an incurable acute lymphoblastic leukemia subtype. Here we decipher the regulome of endogenous TCF3-HLF and dissect its essential transcriptional components and targets by functional genomics. We demonstrate that TCF3-HLF recruits HLF binding sites at hematopoietic stem cell/myeloid lineage associated (super-) enhancers to drive lineage identity and self-renewal. Among direct targets, hijacking an HLF binding site in a MYC enhancer cluster by TCF3-HLF activates a conserved MYC-driven transformation program crucial for leukemia propagation in vivo. TCF3-HLF pioneers the cooperation with ERG and recruits histone acetyltransferase p300 (EP300), conferring susceptibility to EP300 inhibition. Our study provides a framework for targeting driving transcriptional dependencies in this fatal leukemia.