Childhood Acute Leukemias in Developing Nations: Successes and Challenges

Prevalence and Treatment Outcomes of Childhood Acute Lymphoblastic Leukemia in Kosovo

Advances in research, including novel biomarker identification and patient stratification, have significantly improved the therapy for childhood acute lymphoblastic leukemia (ALL), though access to improved healthcare services varies across geographical regions. In an effort to evaluate the advances in therapeutic approaches, we performed a retrospective analysis of childhood ALL in Kosovo. Our retrospective analysis included 225 cases diagnosed between 2008 and 2023, representing 52% of 429 diagnosed childhood cancers. The average annual incidence was 14, with a median age diagnosis of seven years, and a male predominance (59.54%). Patients were categorized into risk groups, with the majority (43%) in the standard-risk category. We identified five different treatment protocols for this study period. Over 61% of patients achieved remission after the first chemotherapy cycle and we observed a 20% mortality rate. Survival analysis showed that 55% and 40% of patients achieved 2-year and 5-year event-free survival (EFS), respectively, with significant differences across risk groups. Treatment advancements significantly correlated with improved survival rates, achieving a 5-year overall survival (OS) of 88% in the currently used standardized AIEOP-BFM-2009 protocol. Our study emphasizes the need for continued research and customized care strategies to enhance clinical outcomes.

Effect of American genomic ancestry on severe toxicities in children with acute lymphoblastic leukemia in the Amazon region

BACKGROUND

Acute Lymphoblastic Leukemia (ALL) is a neoplasm of the hematopoietic system characterized by a clonal expansion of abnormal lymphocyte precursor cells. ALL is the most common form of cancer in children, but despite advances in treatment, it can still be fatal. Ethnic differences influence survival rates, and genomic ancestry plays an important role, especially in mixed-race populations such as Latin America. This study aims to analyze the influence of genomic ancestry on toxicity in children with ALL in the Amazon region.

METHODS

The study included 171 patients (protocol number 119,649/2012-Ethics Committee) with ALL treated at a pediatric treatment center in Belém do Pará, in the Brazilian Amazon. The patients were submitted to the BFM protocol of induction therapy for ALL. Toxicity was assessed based on laboratory tests and adverse events, classified according to the CTC-NCI guide. Genomic ancestry was determined using autosomal informative markers.

RESULTS

The majority of children (94.74%) developed some type of toxicity during treatment, 87.04% of which were severe. Infectious toxicity was the most common, present in 84.8% of cases, 77.24% of which were severe. Amerindian ancestry showed an association with the risk of severe general toxicity and severe infectious toxicity, with a contribution of 35.0% demonstrating a significant increase in risk. In addition, post-induction refractoriness and relapse were also associated with an increased risk of death.

CONCLUSION

This study highlights the influence of Amerindian genomic ancestry on response to therapy and toxicity in children with ALL in the Amazon region. Understanding these associations can contribute to personalizing treatment and improving clinical outcomes.

Implementation of a roadmap for the comprehensive diagnosis, follow-up, and research of childhood leukemias in vulnerable regions of Mexico: results from the PRONAII Strategy

The main objective of the National Project for Research and Incidence of Childhood Leukemias is to reduce early mortality rates for these neoplasms in the vulnerable regions of Mexico. This project was conducted in the states of Oaxaca, Puebla, and Tlaxcala. A key strategy of the project is the implementation of an effective roadmap to ensure that leukemia patients are the target of maximum benefit of interdisciplinary collaboration between researchers, clinicians, surveyors, and laboratories. This strategy guarantees the comprehensive management of diagnosis and follow-up samples of pediatric patients with leukemia, centralizing, managing, and analyzing the information collected. Additionally, it allows for a precise diagnosis and monitoring of the disease through immunophenotype and measurable residual disease (MRD) studies, enhancing research and supporting informed clinical decisions for the first time in these regions through a population-based study. This initiative has significantly improved the diagnostic capacity of leukemia in girls, boys, and adolescents in the regions of Oaxaca, Puebla, and Tlaxcala, providing comprehensive, high-quality care with full coverage in the region. Likewise, it has strengthened collaboration between health institutions, researchers, and professionals in the sector, which contributes to reducing the impact of the disease on the community.

Association between genetic variants of membrane transporters and the risk of high-grade hematologic adverse events in a cohort of Mexican children with B-cell acute lymphoblastic leukemia

Background

Advances in the understanding of the pathobiology of childhood B-cell acute lymphoblastic leukemia (B-ALL) have led towards risk-oriented treatment regimens and markedly improved survival rates. However, treatment-related toxicities remain a major cause of mortality in developing countries. One of the most common adverse effects of chemotherapy in B-ALL is the hematologic toxicity, which may be related to genetic variants in membrane transporters that are critical for drug absorption, distribution, and elimination. In this study we detected genetic variants present in a selected group genes of the ABC and SLC families that are associated with the risk of high-grade hematologic adverse events due to chemotherapy treatment in a group of Mexican children with B-ALL.

Methods

Next generation sequencing (NGS) was used to screen six genes of the ABC and seven genes of the SLC transporter families, in a cohort of 96 children with B-ALL. The grade of hematologic toxicity was classified according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) version 5.0, Subsequently, two groups of patients were formed: the null/low-grade (grades 1 and 2) and the high-grade (grades 3 to 5) adverse events groups. To determine whether there is an association between the genetic variants and high-grade hematologic adverse events, logistic regression analyses were performed using co-dominant, dominant, recessive, overdominant and log-additive inheritance models. Odds ratio (OR) and 95% confidence intervals (95% CI) were calculated.

Results

We found two types of associations among the genetic variants identified as possible predictor factors of hematologic toxicity. One group of variants associated with high-grade toxicity risk: ABCC1 rs129081; ABCC4 rs227409; ABCC5 rs939338, rs1132776, rs3749442, rs4148575, rs4148579 and rs4148580; and another group of protective variants that includes ABCC1 rs212087 and rs212090; SLC22A6 rs4149170, rs4149171 and rs955434.

Conclusion

There are genetic variants in the SLC and ABC transporter families present in Mexican children with B-ALL that can be considered as potential risk markers for hematologic toxicity secondary to chemotherapeutic treatment, as well as other protective variants that may be useful in addition to conventional risk stratification for therapeutic decision making in these highly vulnerable patients.

Subclassification of B-acute lymphoblastic leukemia according to age, immunophenotype and microenvironment, predicts MRD risk in Mexican children from vulnerable regions

Introduction

The decisive key to disease-free survival in B-cell precursor acute lymphoblastic leukemia in children, is the combination of diagnostic timeliness and treatment efficacy, guided by accurate patient risk stratification. Implementation of standardized and high-precision diagnostic/prognostic systems is particularly important in the most marginalized geographic areas in Mexico, where high numbers of the pediatric population resides and the highest relapse and early death rates due to acute leukemias are recorded even in those cases diagnosed as standard risk.

Methods

By using a multidimensional and integrated analysis of the immunophenotype of leukemic cells, the immunological context and the tumor microenvironment, this study aim to capture the snapshot of acute leukemia at disease debut of a cohort of Mexican children from vulnerable regions in Puebla, Oaxaca and Tlaxcala and its potential use in risk stratification.

Results and discussion

Our findings highlight the existence of a distinct profile of ProB-ALL in children older than 10 years, which is associated with a six-fold increase in the risk of developing measurable residual disease (MRD). Along with the absence of CD34+ seminal cells for normal hematopoiesis, this ProB-ALL subtype exhibited several characteristics related to poor prognosis, including the high expression level of myeloid lineage markers such as MPO and CD33, as well as upregulation of CD19, CD34, CD24, CD20 and nuTdT. In contrast, it showed a trend towards decreased expression of CD9, CD81, CD123, CD13, CD15 and CD21. Of note, the mesenchymal stromal cell compartment constituting their leukemic niche in the bone marrow, displayed characteristics of potential suppressive microenvironment, such as the expression of Gal9 and IDO1, and the absence of the chemokine CXCL11. Accordingly, adaptive immunity components were poorly represented. Taken together, our results suggest, for the first time, that a biologically distinct subtype of ProB-ALL emerges in vulnerable adolescents, with a high risk of developing MRD. Rigorous research on potential enhancing factors, environmental or lifestyle, is crucial for its detection and prevention. The use of the reported profile for early risk stratification is suggested.

Long-term experience in treatment of acute promyelocytic leukemia in Mexican children in a tertiary care hospital

Introduction

Acute promyelocytic leukemia (APL) is a rare myeloid leukemia subtype affecting adult and pediatric populations. APL constitutes 15-20% of all childhood AML in Latin America, compared to 7% in the non-Latino population. This leukemia has unique characteristics, such as its association with chromosomal translocations involving the retinoid acid receptor α (RARA) gene on chromosome 17. In addition, APL is also distinct from other AML subtypes due to its response to all-trans-retinoic acid (ATRA), which induces terminal granulocytic differentiation of blasts. Overall 5-year survival rates are generally reported to be greater than 80%.

Materials and methods

A study was conducted from January 2008 to December 2022 applying the IC-APL 2006 treatment protocol. This case series reports the clinical results of 22 children with APL. In all cases, the diagnosis was made by bone marrow aspiration and evaluation of the t(15:17) or t(11:17) transcripts.

Results

We identified 22 patients with APL, of whom 10 were female and 12 were male. Twelve patients debuted with coagulation abnormalities. The doses of anthracyclines varied according to the risk, with an average of 496.8 mgm2. The cardiological assessment was performed before and after chemotherapy, finding 2/22 patients with moderate sisto-diastolic dysfunction and one with mild pulmonary insufficiency at the end of treatment. There were 6/22 patients with complications related to ATRA treatment, the most frequent being pseudotumor cerebri. All complications were transitory and treated immediately without complications. In this series of cases, an overall survival of 90.6% and a relapse-free survival of 90.6% were recorded. The follow-up mean was 9.1 ± 3.8 years.

Conclusion

APL is a highly curable disease when combined with ATRA and anthracyclines. In this series of cases, good long-term results were observed with the IC-APL 2006 protocol. However, in Latin America, the availability of drugs such as arsenic trioxide as the first line of treatment is an unresolved challenge.

A new hope for early T cell precursor acute lymphoblastic leukemia therapy based on STAT5+ leukemic stem cell targeting

Leukemia stem cells are known to drive tumor progression, drug resistance, microenvironmental shift, and relapse, which would make them a perfect therapeutic target. However, their phenotypic and functional similarity to their normal counterparts leaves limited road maps for their selective elimination. Tremblay et al. recently unraveled the fundamental role of overactivated pSTAT5 as a functional marker of early T cell precursor acute lymphoblastic leukemia stem cells driving leukemic progression and highlighted its potential use as a therapeutic target to prevent fatal outcomes.

Triple-hit explanation for the worse prognosis of pediatric acute lymphoblastic leukemia among Mexican and Hispanic children

Acute lymphoblastic leukemia (ALL) is the most common malignancy among Mexican and Hispanic children and the first cause of death by disease in Mexico. We propose a "triple-hit" explanation for the survival gap affecting this population. The first hit can be attributed to epidemiology and social, cultural, and economic burdens. The second hit refers to cancer biology, with a high incidence of unfavorable genetic characteristics associated with an unfavorable response to treatment and, subsequently, poor survival. Finally, the third hit relates to sub-optimal treatment and support. Society and culture, leukemia biology, and treatment approach limitations are key factors that should not be seen apart and must be considered comprehensively in any strategy to improve the prognosis of Mexican and Hispanic children with ALL.

Patient-Derived Bone Marrow Spheroids Reveal Leukemia-Initiating Cells Supported by Mesenchymal Hypoxic Niches in Pediatric B-ALL

B-cell acute lymphoblastic leukemia (B-ALL) results from the expansion of malignant lymphoid precursors within the bone marrow (BM), where hematopoietic niches and microenvironmental signals provide leukemia-initiating cells (LICs) the conditions to survive, proliferate, initiate disease, and relapse. Normal and malignant lymphopoiesis are highly dependent on the BM microenvironment, particularly on CXCL12-abundant Reticular (CAR) cells, which provide a niche for maintenance of primitive cells. During B-ALL, leukemic cells hijack BM niches, creating a proinflammatory milieu incompetent to support normal hematopoiesis but favoring leukemic proliferation. Although the lack of a phenotypic stem cell hierarchy is apparent in B-ALL, LICs are a rare and quiescent population potentially responsible for chemoresistance and relapse. Here, we developed novel patient-derived leukemia spheroids (PDLS), an ex vivo avatar model, from mesenchymal stromal cells (MSCs) and primary B-ALL cells, to mimic specialized niche structures and cell-to-cell intercommunication promoting normal and malignant hematopoiesis in pediatric B-ALL. 3D MSC spheroids can recapitulate CAR niche-like hypoxic structures that produce high levels of CXCL10 and CXCL11. We found that PDLS were preferentially enriched with leukemia cells displaying functional properties of LICs, such as quiescence, low reactive oxygen species, drug resistance, high engraftment in immunodeficient mice, and long-term leukemogenesis. Moreover, the combination of PDLS and patient-derived xenografts confirmed a microenvironment-driven hierarchy in their leukemic potential. Importantly, transcriptional profiles of MSC derived from primary patient samples revealed two unique signatures (1), a CXCL12low inflammatory and leukemia expansion (ILE)-like niche, that likely supports leukemic burden, and (2) a CXCL11hi immune-suppressive and leukemia-initiating cell (SLIC)-like niche, where LICs are likely sustained. Interestingly, the CXCL11+ hypoxic zones were recapitulated within the PDLS that are capable of supporting LIC functions. Taken together, we have implemented a novel PDLS system that enriches and supports leukemia cells with stem cell features driven by CXCL11+ MSCs within hypoxic microenvironments capable of recapitulating key features, such as tumor reemergence after exposure to chemotherapy and tumor initiation. This system represents a unique opportunity for designing ex vivo personalized avatars for B-ALL patients to evaluate their own LIC pathobiology and drug sensitivity in the context of the tumor microenvironment.

Novel Markers in Pediatric Acute Lymphoid Leukemia: The Role of ADAM6 in B Cell Leukemia

Background

The extensive genetic heterogeneity found in the B cell precursor acute lymphoblastic leukemia (BCP-ALL) subtype of childhood ALL represents a potential repository of biomarkers. To explore this potential, we have carried out in silico analysis of publicly available ALL datasets to identify genetic biomarkers for childhood BCP-ALL, which could be used either individually or in combination as markers for early detection, risk stratification, and prognosis.

Methods

To explore novel genes that show promising clinical and molecular signatures, we examined the cBioPortal online tool for publicly available datasets on lymphoid cancers. Three studies on lymphoblastic and lymphoid leukemia with 1706 patients and 2144 samples of which were identified. Only B-Lymphoblastic Leukemia/Lymphoma samples (n = 1978) were selected for further analysis. Chromosomal changes were assessed to determine novel genomic loci to analyze clinical and molecular profiles for the leukemia of lymphoid origin using cBioPortal tool.

Results

ADAM6 gene homozygous deletions (HOM:DEL) were present in 59.60% of the profiled patients and were associated with poor ten years of overall patients’ survival. Moreover, patients with ADAM6 HOM:DEL showed a distinguished clinical and molecular profile with higher Central Nervous System (CNS) sites of relapse. In addition, ADAM6 HOM:DEL was significantly associated with unique microRNAs gene expression patterns.

Conclusion

ADAM6 has the potential to be a novel biomarker for the development and progress of BCP- ALL.