Bone marrow fibrosis in childhood acute lymphoblastic leukemia correlates to biological factors, treatment response and outcome

Impact of bone marrow fibrosis on outcomes of allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia

Bone marrow fibrosis (BMF) of unknown etiology was common in hematological malignancies, but its prognostic value for acute myeloid leukemia (AML) is unclear. We interrogated data from 532 newly diagnosed subjects with AML receiving allogeneic hematological stem cell transplantation to evaluate the prognostic impact of BMF on transplant outcomes. Using the European consensus on the grading of BMF at diagnosis, 255 (48%) subjects were BMF-0, 209 (39%), BMF-1 and 68 (13%), BMF-2-3. Subjects with BMF-2-3 had poor overall survival (P < 0.001), disease-free survival (P < 0.001) and a higher incidence of relapse (CIR, P < 0.001). Multi-variable analyses in subjects achieving pre-transplant complete remission showed BMF-2-3 was an independent risk factor for CIR (Hazard Ratio [HR] = 2.17, (95% CI, 1.11, 4,24); P = 0.02). Furthermore, BMF-2-3 group showed delayed neutrophil and platelet engraftment and delayed B cell recovery post-transplantation. These findings demonstrate the significance of BMF in transplant outcomes and attract more attention to AML with BMF.

Bone marrow fibrosis is associated with non-response to CD19 CAR T-cell therapy in B-acute lymphoblastic leukemia

CD19 directed CAR T-cell therapy is used to treat relapsed/refractory B-cell acute lymphoblastic leukemia. The role of the pre-CAR bone marrow (BM) stromal microenvironment in determining response to CAR T-cell therapy has been understudied. We performed whole transcriptome analysis, reticulin fibrosis assessment and CD3 T-cell infiltration on BM core biopsies from pre- and post-CAR timepoints for 61 patients, as well as on a cohort of 54 primary B-ALL samples. Pathways of fibrosis, extracellular matrix development, and associated transcription factors AP1 and TGF-β3, were enriched and upregulated in nonresponders (NR) even prior to CAR T cell therapy. NR showed significantly higher levels of BM fibrosis compared to complete responders by both clinical reticulin assessment and AI-assisted digital image scoring. CD3+ T cells showed a trend toward lower infiltration in NR. NR had significantly higher levels of pre-CAR fibrosis compared to primary B-ALL. High levels of fibrosis were associated with lower overall survival after CAR T-cell therapy. In conclusion, BM fibrosis is a novel mechanism mediating nonresponse to CD19-directed CAR T-cell therapy in B-ALL. A widely used clinically assay for quantitating myelofibrosis can be repurposed to determine patients at high risk of non-response. Genes and pathways associated with BM fibrosis are a potential target to improve response.

Continuous Indexing of Fibrosis (CIF): improving the assessment and classification of MPN patients

The grading of fibrosis in myeloproliferative neoplasms (MPN) is an important component of disease classification, prognostication and monitoring. However, current fibrosis grading systems are only semi-quantitative and fail to fully capture sample heterogeneity. To improve the quantitation of reticulin fibrosis, we developed a machine learning approach using bone marrow trephine (BMT) samples (n = 107) from patients diagnosed with MPN or a reactive marrow. The resulting Continuous Indexing of Fibrosis (CIF) enhances the detection and monitoring of fibrosis within BMTs, and aids MPN subtyping. When combined with megakaryocyte feature analysis, CIF discriminates between the frequently challenging differential diagnosis of essential thrombocythemia (ET) and pre-fibrotic myelofibrosis with high predictive accuracy [area under the curve = 0.94]. CIF also shows promise in the identification of MPN patients at risk of disease progression; analysis of samples from 35 patients diagnosed with ET and enrolled in the Primary Thrombocythemia-1 trial identified features predictive of post-ET myelofibrosis (area under the curve = 0.77). In addition to these clinical applications, automated analysis of fibrosis has clear potential to further refine disease classification boundaries and inform future studies of the micro-environmental factors driving disease initiation and progression in MPN and other stem cell disorders.

Cancer-associated fibroblasts in acute leukemia

Although the prognosis for acute leukemia has greatly improved, treatment of relapsed/refractory acute leukemia (R/R AL) remains challenging. Recently, increasing evidence indicates that the bone marrow microenvironment (BMM) plays a crucial role in leukemogenesis and therapeutic resistance; therefore, BMM-targeted strategies should be a potent protocol for treating R/R AL. The targeting of cancer-associated fibroblasts (CAFs) in solid tumors has received much attention and has achieved some progress, as CAFs might act as an organizer in the tumor microenvironment. Additionally, over the last 10 years, attention has been drawn to the role of CAFs in the BMM. In spite of certain successes in preclinical and clinical studies, the heterogeneity and plasticity of CAFs mean targeting them is a big challenge. Herein, we review the heterogeneity and roles of CAFs in the BMM and highlight the challenges and opportunities associated with acute leukemia therapies that involve the targeting of CAFs.

Establishment and characterization of HXWMF-1: the first mouse fibroblastic tumor cell line derived from leukemia-associated fibroblasts

Background

Chemo-resistance is still a major obstacle in leukemia treatment. Accumulating evidence indicates that cancer-associated fibroblasts (CAFs), the most abundant stromal cells in tumor microenvironment (TME), play a crucial role in cancer progression and response to chemotherapy. To Figure out the role of leukemia-associated fibroblasts (LAFs) in relapsed/refractory leukemia, we constructed the first leukemia-associated fibroblastic tumor cell line, HXWMF-1.

Methods

A cell culture technique was used to establish the leukemia-associated fibroblastic tumor cell line. Molecular and cellular biological techniques including flow cytometry, MTT assay, western blotting, and short tandem repeat (STR) analysis were used to characterize the cell line. Nude mice were used for xenograft studies.

Results

We established a LAFs derived tumor cell line HXWMF-1, originated from the subcutaneous xenografts of HXEX-ALL1, a cell line originated from a patient with acute lymphoblastic leukemia (ALL) at the second relapse. The HXWMF-1 cell line was authenticated as a tumor cell line and being derived from CAFs based on morphologic, immunophenotypic, cytogenetic and STR analyses and tumorigenicity test in nude mice. To clarify the reliability of the method, we got the LAFs derived tumor cells from three different tumor mass of HXEX-ALL1 xenografts.

Conclusions

To our knowledge, HXWMF-1 is the first fibroblastic tumor cell line derived from LAFs or CAFs. In addition, the cell line provided firm evidence for that leukemia cells may induce LAFs/CAFs malignant transformation, which may help to develop brand new theory and therapeutic strategies for patients with relapsed /refractory ALL.

Disease detection methodologies in relapsed B-cell acute lymphoblastic leukemia: Opportunities for improvement

BACKGROUND

Accurate disease detection is integral to risk stratification in B-cell acute lymphoblastic leukemia (ALL). The gold standard used to evaluate response in the United States includes morphologic evaluation and minimal residual disease (MRD) testing of aspirated bone marrow (BM) by flow cytometry (FC). This MRD assessment is usually made on a single aspirate sample that is subject to variability in collection techniques and sampling error. Additionally, central nervous system (CNS) assessments for ALL include evaluations of cytopathology and cell counts, which can miss subclinical involvement.

PROCEDURE

We retrospectively compared BM biopsy, aspirate, and FC samples obtained from children and young adults with relapsed/refractory ALL to identify the frequency and degree of disease discrepancies in this population. We also compared CNS FC and cytopathology techniques.

RESULTS

Sixty of 410 (14.6%) BM samples had discrepant results, 41 (10%) of which were clinically relevant as they resulted in a change in the assignment of marrow status. Discrepant BM results were found in 28 of 89 (31.5%) patients evaluated. Additionally, cerebrospinal fluid (CSF) FC identified disease in 9.7% of cases where cytopathology was negative.

CONCLUSIONS

These results support further investigation of the role of concurrent BM biopsy, with aspirate and FC evaluations, and the addition of FC to CSF evaluations, to fully assess disease status and response, particularly in patients with relapsed/refractory ALL. Prospective studies incorporating more comprehensive analysis to evaluate the impact on clinical outcomes are warranted.

Immune-Based Therapies in Acute Leukemia

Treatment resistance remains a leading cause of acute leukemia-related deaths. Thus, there is an unmet need to develop novel approaches to improve outcome. New immune-based therapies with chimeric antigen receptor (CAR) T cells, bi-specific T cell engagers (BiTEs), and immune checkpoint blockers (ICBs) have emerged as effective treatment options for chemoresistant B cell acute lymphoblastic leukemia (B-ALL) and acute myeloid leukemia (AML). However, many patients show resistance to these immune-based approaches. This review describes crucial lessons learned from immune-based approaches targeting high-risk B-ALL and AML, such as the leukemia-intrinsic (e.g., target antigen loss, tumor heterogeneity) and -extrinsic (e.g., immunosuppressive microenvironment) mechanisms that drive treatment resistance, and discusses alternative approaches to enhance the effectiveness of these immune-based treatment regimens.

Simple deep sequencing-based post-remission MRD surveillance predicts clinical relapse in B-ALL

Background

Next-generation sequencing (NGS) of the rearranged immunoglobulin heavy-chain gene has emerged as a highly sensitive method to detect minimal residual disease (MRD) in B acute lymphoblastic leukemia/lymphoma (B-ALL). However, a sensitive and easily implemented NGS methodology for routine clinical laboratories is lacking and clinical utility of NGS-MRD surveillance in a post-remission setting to predict clinical relapse has not been determined.

Methods

Here we described a simple and quantitative NGS platform and assessed its performance characteristics, quantified NGS-MRD levels in 122 B-ALL samples from 30 B-ALL patients, and explored the clinical merit of NGS-based MRD surveillance.

Results

The current NGS platform has an analytic sensitivity of 0.0001% with excellent specificity and reproducibility. Overall, it performs better than routine multi-color flow cytometry (MCF) in detecting MRD. Utilizing this assay in MRD surveillance in a post-remission setting showed that it detected conversion to positive MRD (CPMRD) in patients with NGS-based molecular remission much earlier than MCF, and that positive MRD conversion could be detected as early as 25.6 weeks prior to clinical relapse in closely surveilled patients. Post-remission CPMRD, but not NGS-based MRD positivity at end of induction, can accurately predict clinical relapse in our limited cohort of B-ALL patients.

Conclusions

This pilot proof-of-concept study illustrates the clinical utility of a simple, sensitive, and clinically feasible MRD detection platform in post-remission NGS-based MRD surveillance and early relapse detection in B-ALL patients.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0652-y) contains supplementary material, which is available to authorized users.

Concurrent Acute Myelofibrosis and Acute Lymphoblastic Leukemia in Childhood: Case Report and Review of the Literature

Myelofibrosis is associated with a wide variety of neoplastic and non-neoplastic bone marrow diseases, predominately myeloproliferative neoplasms and acute myeloid leukemia. The following case documents an unusual patient presenting with pancytopenia and acute myelofibrosis accompanied by precursor B-cell acute lymphoblastic leukemia. This very rare clinical presentation raises questions concerning the relationship between concurrent occurrence of acute myelofibrosis and acute lymphoblastic leukemia.

Bone marrow fibrosis at diagnosis predicts survival for primary acute myeloid leukemia

PURPOSE

As a desmoplastic reaction, tissue fibrosis played crucial roles in solid tumor progression, chemo-resistance, and consequently heralded poor clinical outcome. Previous studies implied the effects of marrow fibrosis on prognosis for acute lymphoblastic leukemia were disputable. In this study, we aimed to investigate the potential role of bone marrow fibrosis on clinical survival in acute myeloid leukemia (AML) patients.

METHODS

Bone marrow fibrosis (evaluated as reticulin fiber density, RFD) in bone marrow sections was evaluated at diagnosis via computer technology. Receiver operating characteristic curve (ROC) was used to analyze the predictive value of RFD for relapse and survival status. Kaplan-Meier method was used to estimate survival rates per subgroup between patients with different RFD. Cox proportional hazard regression was used to model the overall survival.

RESULTS

High RFD at diagnosis in bone marrow sections from primary AML might predict early relapse and shorter survival (P = 0.003 and 0.001, respectively). The optimal cutoff value of RFD at diagnosis was determined to be 7.2%. Furthermore, the Kaplan-Meier analysis indicated that patients with high marrow RFD had shorter relapse-free survival (RFS) and overall survival (OS) than patients with low RFD (P = 0.007 and 0.000, respectively). Multivariate analysis suggested that similar with cytogenetics, marrow RFD at diagnosis was an independent prognostic factor for RFS [HR 0.564, 95% confidence interval (CI) 0.338-0.940, P = 0.028] and OS (HR 0.457, 95% CI 0.225-0.929, P = 0.031) in primary AML patients.

CONCLUSIONS

Our data suggest that marrow RFD before treatment should be seemed as prognostic factor in primary AML, it may provide valuable clues for developing new targeted therapy.

Growth differentiation factor 15 contributes to cancer-associated fibroblasts-mediated chemo-protection of AML cells

BACKGROUND

Chemo-resistance is still a major obstacle in efforts to overcome acute myeloid leukemia (AML). An emerging concept has proposed that interactions between the bone marrow (BM) microenvironment and leukemia cells reduce the sensitivity of the leukemia cells to chemotherapy. As an important element of the tumor microenvironment, the cancer-associated fibroblasts (CAFs) are considered to be activated modulators in the chemo-resistance of many solid tumors. But their contribution to AML has yet to be fully understood. Here we report a critical role for CAFs which were thought to be a survival and chemo-protective factor for leukemia cells.

METHODS

A retrospective study on the BM biopsies from 63 primary AML patients and 59 normal controls was applied to quantitative analysis the fiber stroma in the BM sections. Then immunohistochemistry on the BM biopsies were used to detect the makers of the CAFs. Their effects on drug resistance of leukemia cells were further to be assessed by co-cultured experiments in vitro. Moreover, the possible mechanisms involved in CAF-mediated chemo-protection of AML cells was investigated by antibody neutralization and siRNA knockdown experiments, with particular emphasis on the role of GDF15.

RESULTS

In our study, excessive reticular fibers in the BM led to higher frequency of relapse and mortality in primary AML patients, bringing the inspiration for us to investigate the functional roles of the fiber-devied cells. We declared that the CAF cells which expressed higher levels of FSP1, α-SMA or FAP protein were widely distributed in the marrow of AML. Then in vitro co-cultured tests showed that these CAFs could protect leukemia cell lines (THP-1/K562) from chemotherapy. Interestingly, this effect could be decreased by either treatment with a neutralizing anti-GDF15 antibody or knockdown GDF15 (with siGDF15) in CAFs. Furthermore, we also confirmed that the GDF15(+) cells mainly co-localized with FAP, which was identified as the typical phenotype of CAFs in the BM stroma.

CONCLUSIONS

We firstly demonstrate that the functional CAFs are widespread within the BM of AML patients and should be a critical chemo-protective element for AML cells by producing amount of GDF15.

High expression of connective tissue growth factor accelerates dissemination of leukaemia

To improve treatment of acute lymphoblastic leukaemia (ALL), a better understanding of disease development is needed to tailor new therapies. Connective tissue growth factor (CTGF/CCN2) is highly expressed in leukaemia cells from the majority of paediatric patients with B-lineage ALL (pre-B ALL). CTGF is a matricellular protein and plays a role in aggressive cancers. Here we have genetically engineered leukaemia cells to modulate CTGF expression levels. Elevated CTGF levels accelerated disease dissemination and reduced survival in NOD/SCID mice. In vitro studies showed that CTGF protein induces stromal cell proliferation, promotes adhesion of leukaemia cells to stromal cells and leads to overexpression of genes associated with cell cycle and synthesis of extracellular matrix (ECM). Corresponding data from our leukaemia xenograft models demonstrated that CTGF leads to increased proliferation of non-leukaemia cells and deposition of ECM in the bone marrow. We document for the first time a functional role of CTGF in altering disease progression in a lymphoid malignancy. The findings provide support for targeting the bone marrow microenvironment in aggressive forms of leukaemia.

Bone Marrow Recovery by Morphometry during Induction Chemotherapy for Acute Lymphoblastic Leukemia in Children

Bone marrow architecture is grossly distorted at the diagnosis of ALL and details of the morphological changes that accompany response to Induction chemotherapy have not been reported before. While marrow aspirates are widely used to assess initial response to ALL therapy and provide some indications, we have enumerated marrow components using morphometric analysis of trephine samples with the aim of achieving a greater understanding of changes in bone marrow niches. Morphometric analyses were carried out in the bone marrow trephine samples of 44 children with ALL, using a NanoZoomer HT digital scanner. Diagnostic samples were compared to those of 32 control patients with solid tumors but without marrow involvement. Samples from patients with ALL had significantly increased fibrosis and the area occupied by bony trabeculae was lower than in controls. Cellularity was higher in ALL samples due to leukemic infiltration while the percentage of normal elements such as megakaryocytes, adipocytes, osteoblasts and osteoclasts were all significantly lower. During the course of Induction therapy, there was a decrease in the cellularity of ALL samples at day 15 of therapy with a further decrease at the end of Induction and an increase in the area occupied by adipocytes and the width of sinusoids. Reticulin fibrosis decreased throughout Induction. Megakaryocytes increased, osteoblasts and osteoclasts remained unchanged. No correlation was found between clinical presentation, early response to treatment and morphological changes. Our results provide a morphological background to further studies of bone marrow stroma in ALL.

Study of prognostic significance of marrow angiogenesis assessment in patients with de novo acute leukemia

BACKGROUND

Angiogenesis is the highly ordered formation of new blood vessels from pre-existing vessels. It is seen throughout growth, in wound healing, menses, and is important in cancer, where pro- and antiangiogenic signals can be released by cancer cells, endothelial cells, stromal cells, blood, and the extracellular matrix. Aim of the study is to use standardized method for counting blood vessels to verify the significance and prognostic value of assessing marrow angiogenesis at diagnosis of de novo acute leukemia.

SUBJECTS AND METHODS

The study included 70 newly diagnosed acute leukemia cases and a control group composed of 35 bone marrow biopsy sections obtained from breast cancer patients. Examination of CD34 immunohistochemically stained sections for the assessment of marrow angiogenesis by quantification of its microvessel density (MVD).

RESULTS

MVD was significantly increased in acute leukemia patients in comparison to control group (P-value <0.001). Increased MVD was associated with unfavorable outcome.

CONCLUSION

The study demonstrated an evidence of increased angiogenesis in acute leukemia detected by high bone marrow MVD which may play a significant role in leukemic process. Understanding its role may help in designing new therapeutic strategies for acute leukemia.

Leukemia propagating cells rebuild an evolving niche in response to therapy

Residence of cancer-propagating cells (CPCs) within preferential microenvironmental niches has a major part in evading therapy. However, the nature of niches involved and the mechanisms protecting CPCs remain largely unknown. We addressed these issues in mouse transplantation models of acute lymphoblastic leukemia (ALL). When the engrafted leukemic cells substantially damaged adjacent microenvironment in the bone marrow (BM), after chemotherapy small foci of CPCs were retained, surrounded by sheaths of supporting cells that comprise a protective niche. We investigated patients' BM biopsies and found evidence of a similar process in patients receiving induction therapy. The efficacy of chemotherapy was enhanced by interfering with the niche formation or function. We therefore identified a therapy-induced niche that protects CPCs.

High modal number and triple trisomies are highly correlated favorable factors in childhood B-cell precursor high hyperdiploid acute lymphoblastic leukemia treated according to the NOPHO ALL 1992/2000 protocols

Between 1992 and 2008, 713 high hyperdiploid acute lymphoblastic leukemias in children aged 1-15 years were diagnosed and treated according to the Nordic Society for Pediatric Hematology and Oncology acute lymphoblastic leukemia 1992/2000 protocols. Twenty (2.8%) harbored t(1;19), t(9;22), der(11q23), or t(12;21). The median age of patients with "classic" high hyperdiploidy was lower than that of patients with translocation-positive high hyperdiploidy (P<0.001). Cases with triple trisomies (+4, +10, +17), comprising 50%, had higher modal numbers than the triple trisomy-negative cases (P<0.0001). The probabilities of event-free survival and overall survival were lower for those with white blood cell counts ≥ 50 × 10(9)/L (P=0.017/P=0.009), ≥ 5% bone marrow blasts at day 29 (P=0.001/0.002), and for high-risk patients (P<0.001/P=0.003), whereas event-free, but not overall, survival, was higher for cases with gains of chromosomes 4 (P<0.0001), 6 (P<0.003), 17 (P=0.010), 18 (P=0.049), and 22 (P=0.040), triple trisomies (P=0.002), and modal numbers >53/55 (P=0.020/0.024). In multivariate analyses, modal number and triple trisomies were significantly associated with superior event-free survival in separate analyses with age and white blood cell counts. When including both modal numbers and triple trisomies, only low white blood cell counts were significantly associated with superior event-free survival (P=0.009). We conclude that high modal chromosome numbers and triple trisomies are highly correlated prognostic factors and that these two parameters identify the same subgroup of patients characterized by a particularly favorable outcome.

Early lymphoid development and microenvironmental cues in B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) is a hematological disorder characterized by malignant and uncontrolled proliferation of B-lymphoid precursor cells in bone marrow. Over the last few years remarkable advances have been made in identifying genetic aberrations, patterns of abnormal transcriptional activity controlling early fate decisions and environmental cues that may influence leukemic development. In this review we focus on the structure of the early lymphoid system and the current knowledge about cell composition and function of the hematopoietic microenvironment that might control progenitor cell activity and lead to differentiation, proliferation and survival of developing B leukemic precursors. Learning the biology of special leukemic niches is central to understanding the pathogenesis of B-ALL and for the development of novel therapies.

Interactions between acute lymphoblastic leukemia and bone marrow stromal cells influence response to therapy

The cure rate for pediatric patients with B precursor acute lymphoblastic leukemia (pre-B ALL) is steadily improving, however relapses do occur despite initial response to therapy. To identify links between drug resistance and gene deregulation we used oligonucleotide microarray technology and determined in 184 pre-B ALL specimen genes differentially expressed compared to normal CD34(+) specimens. We identified 20 signature genes including CTGF, BMP-2, CXCR4 and IL7R, documented to regulate interactions in the bone marrow. We recorded remarkably similar levels of expression in three independent patient cohorts, and found distinct patterns in cytogenetically defined subgroups of pre-B ALL. The canonical pathways that were affected are involved in inter- and intra-cellular communication, regulating signaling within the microenvironment. We tested experimentally whether interaction with stromal cells conferred protection to four drugs used in current ALL therapy, and demonstrated that bone marrow stromal cells significantly influenced resistance to vincristine and cytosine arabinoside. Compounds designed to block the identified cellular interactions within the bone marrow microenvironment are expected to mobilise the leukemic cells and make them more accessible to contemporary antileukemic agents. The data provide novel insight into the pathobiology of ALL and indicate new therapeutic targets for patients with ALL.

Reticulin fibres anchor leukaemic blasts in the marrow of patients with acute lymphoblastic leukaemia

Reticulin fibrosis has been recognized in childhood ALL at diagnosis as part of the altered stromal structure in the bone marrow (BM). Increased fibre density is correlated with a higher concentration of leukaemia cells in the BM and lower numbers of blasts in peripheral blood. We hypothesize that these fibres anchor the leukaemia cells within the BM in close proximity to BM stromal cells (BMSC). The BMSC are a rich source of growth factors and cytokines which enhance leukaemia cell growth and provide protection against chemotherapy. Mobilizing the cells by breaking the 'anchoring ropes' could lead to greater exposure to apoptotic signals.

The impact of bone marrow fibrosis on the outcome of hematopoietic stem cell transplantation

We retrospectively analyzed the data of 175 patients who underwent autologous (n = 69) or allogeneic hematopoietic stem cell transplantation (HCT) (n = 106) including 19 (27.5%) and 38 (35.8%) recipients who had bone marrow fibrosis (BMF) prior to transplantation, respectively. We investigated the effects of BMF on engraftment, graft-versus-host disease (GVHD), early posttransplant complications, and survival. Pretransplantation BMF did not delay engraftment and showed no impact either on early posttransplant complications or on the development of acute and/or chronic GVHD. Probability of 1-year overall survival (OS) and progression-free survival (PFS) of autologous HCT recipients were similar, namely 76.7% versus 88.6% (P > .005) and 26.33% versus 16.5% (P > .05) among patients with versus without fibrosis, respectively. In allogeneic HCT recipients, the probability of 1-year OS was 35.2% among patients with versus 48.9% among those without fibrosis (P = .004) PFS at 1 year was inferior among allogeneic HCT recipients with BMF: 27.8% versus 51.2% (P = .0008). Cox regression analysis revealed BMF to be independently associated with age, Sorror comorbidity index, primary disease, and disease status during HCT (P = .045).

High hyperdiploid childhood acute lymphoblastic leukemia

High hyperdiploidy (51-67 chromosomes) is the most common cytogenetic abnormality pattern in childhood B-cell precursor acute lymphoblastic leukemia (ALL), occurring in 25-30% of such cases. High hyperdiploid ALL is characterized cytogenetically by a nonrandom gain of chromosomes X, 4, 6, 10, 14, 17, 18, and 21 and clinically by a favorable prognosis. Despite the high frequency of this karyotypic subgroup, many questions remain regarding the epidemiology, etiology, presence of other genetic changes, the time and cell of origin, and the formation and pathogenetic consequences of high hyperdiploidy. However, during the last few years, several studies have addressed some of these important issues, and these, as well as previous reports on high hyperdiploid childhood ALL, are reviewed herein.

Transient myelofibrosis with autoimmune pancytopenia: a case report

INTRODUCTION

Myelofibrosis associated with myelodysplasia is thought to herald poor prognosis in myelodysplastic syndrome (MDS).

CASE REPORT

A 7-month-old boy presented with fever (39 degrees C), pancytopenia, and slight hepatosplenomegaly (3 and 2 cm, respectively). Bone marrow showed hypercellularity, hyperplasia of erythroblasts, and also myelofibrosis. IgG was 1,136 mg/dL, IgA was 131 mg/dL, and IgM was 89 mg/dL. Antinuclear and antineutrophil antibodies, red-blood-cell-associated IgG, antiplatelet antibodies, and Coombs test were positive. Karyotype was 46XY. No viral cause was evidenced. Mild myelodysplasia was revealed two months later, but was insufficient to support a diagnosis of MDS. The boy was treated with transfusion of packed cells, prednisolone 2 mg/kg/day for 3 weeks associated with intravenous gammaglobulin 400 mg/kg/day for 5 days. Direct Coombs remained positive 1 month after treatment for 5 months, myelofibrosis persisted for 3 months, and neutropenia for 21 months. After 3-year follow-up, hematological data were normal without any therapeutic intervention.

CONCLUSION

Myelofibrosis associated with mild myelodysplasia and pancytopenia can have a benign evolution in infants and young children.

Vascular density in childhood acute lymphoblastic leukaemia correlates to biological factors and outcome

The issue of angiogenesis and its clinical relevance in childhood acute lymphoblastic leukaemia (ALL) is controversial. In the present study, microvessel density (MVD), analysed in 185 diagnostic bone marrow biopsies, was higher in T-cell ALL compared to B-cell precursor (BCP)-ALL (P = 0.013). In the BCP group, cases with t(12;21) were characterized by a low MVD while patients with high-hyperdiploid leukaemia (HeH, 51-61 chromosomes) showed a high MVD compared to other BCP patients (P = 0.001 and 0.002 respectively). There was a correlation between MVD and white blood cell (WBC) count in high-risk BCP patients (P = 0.021). In addition, BCP patients with a high marrow reticulin fibre density and high MVD had an unfavourable outcome compared to the other BCP patients (P = 0.002). The fraction of vessels in which lumina were filled with blasts (blast congested vessel fraction) correlated strongly with WBC count (P < 0.001). These findings indicate that the angiogenic process interacts with other stroma-factors, such as reticulin fibre density, in its effect on outcome, and is coupled to both the ALL genotype and phenotype. One possible implication is that different subtypes of childhood ALL may respond differently to anti-angiogenic drugs as a supplement in first-line treatment.

Unrelated stem cell transplant for infantile idiopathic myelofibrosis

Idiopathic myelofibrosis (IMF) is a rare disease in children that can present during infancy and have a protracted course. The only known curative approach for this disease in adult patients is allogeneic stem cell transplant. We present two cases of IMF during infancy that did not resolve with supportive care measures. Both patients underwent unrelated stem cell transplant with complete resolution of their hematologic manifestations and resolution of the bone marrow fibrosis.