Treatment-related myelodysplastic syndrome/acute myeloid leukemia in survivors of childhood cancer--an update

Genetic and epigenetic bases of long-term adverse effects of childhood cancer therapy

Over the past decade, genome-scale molecular profiling of large childhood cancer survivorship cohorts has led to unprecedented advances in our understanding of the genetic and epigenetic bases of therapy-related adverse health outcomes in this vulnerable population. To facilitate the integration of knowledge generated from these studies into formulating next-generation precision care for survivors of childhood cancer, we summarize key findings of genetic and epigenetic association studies of long-term therapy-related adverse effects including subsequent neoplasms and cardiomyopathies among others. We also discuss therapy-related genotoxicities including clonal haematopoiesis and DNA methylation, which may underlie accelerated molecular ageing. Finally, we highlight enhanced risk prediction models for survivors of childhood cancer that incorporate both genetic factors and treatment exposures, aiming to achieve enhanced accuracy in predicting risks for this population. These new insights will hopefully inspire future studies that harness both expanding omics resources and evolving data science methodology to accelerate the translation of precision medicine for survivors of childhood cancer.

Pediatric Acute Myeloid Leukemia Post Cytotoxic Therapy-Retrospective Analysis of the Patients Treated in Poland from 2005 to 2022

Acute P./myeloid leukemia post cytotoxic therapy (AML-pCT) is rare complication of cancer treatment in childhood. The objective of the study was to identify clinical characteristics and provide an analysis of the outcomes in pediatric AML-pCT. We retrospectively analyzed the data of 40 children with AML-pCT, treated from 2005 to 2020 within the Polish Pediatric Leukemia and Lymphoma Study Group. The most common primary malignancies were acute lymphoblastic leukemia (32.5%) and brain tumors (20%). The median latency period was 2.9 years (range: 0.7-12.9). Probabilities of overall (OS), event-free (EFS), and relapse-free survival (RFS) in the whole cohort were 0.49 ± 0.08, 0.43 ± 0.08, and 0.64 ± 0.10, respectively. Significant improvements in outcomes were observed in patients treated from 2015-2022 (two induction cycles followed by stem cell transplantation-SCT in 69% of patients) compared to 2005-2014 (four induction cycles followed by SCT in 49% of patients). The probability of EFS increased from 0.30 ± 0.10 to 0.67 ± 0.12 (p = 0.07) and RFS increased from 0.46 ± 0.11 to 1.0 (p = 0.01). The poorest outcome (OS and EFS 0.25 ± 0.20) was in AML post brain tumor, mainly due to deaths from toxicities. To conclude, treatment results achieved in patients with AML-pCT treated from 2015-2022, with two induction cycles followed by immediate SCT, were better than those reported by other authors, and comparable to the results in de novo AML.

The acquisition of molecular drivers in pediatric therapy-related myeloid neoplasms

Pediatric therapy-related myeloid neoplasms (tMN) occur in children after exposure to cytotoxic therapy and have a dismal prognosis. The somatic and germline genomic alterations that drive these myeloid neoplasms in children and how they arise have yet to be comprehensively described. We use whole exome, whole genome, and/or RNA sequencing to characterize the genomic profile of 84 pediatric tMN cases (tMDS: n = 28, tAML: n = 56). Our data show that Ras/MAPK pathway mutations, alterations in RUNX1 or TP53, and KMT2A rearrangements are frequent somatic drivers, and we identify cases with aberrant MECOM expression secondary to enhancer hijacking. Unlike adults with tMN, we find no evidence of pre-existing minor tMN clones (including those with TP53 mutations), but rather the majority of cases are unrelated clones arising as a consequence of cytotoxic therapy. These studies also uncover rare cases of lineage switch disease rather than true secondary neoplasms.

Therapy-related Acute Myeloid Leukemia After the Treatment of Primary Solid Cancer in Children: A Single-center Experience

Therapy-related acute myeloid leukemia (t-AML) has a dismal prognosis and is one of the most frequent second malignant neoplasms which could be encountered by pediatric oncologists. Between October 2000 and September 2016, 16 patients who had primary solid tumors were diagnosed with t-AML at the Seoul National University Children's Hospital. The median patient age at the time of diagnosis of their primary solid tumors was 9.6 years (range, 0.1 to 15.4 y), and that of t-AML was 14.0 years (range, 4.7 to 23.9 y). The median latency period from the end of the primary tumor treatment to the initial diagnosis of t-AML was 29 months (range, 6 to 130 mo). Twelve patients achieved complete remission. Of them, only 7 patients underwent hematopoietic stem cell transplantation (HSCT). The 3-year overall survival (OS) rates and event-free survival rates were 33.7±12.2% and 26.9±11.5% respectively. The patients who underwent HSCT showed favorable 5-year OS rates (57.1±18.7%), whereas the 5-year OS rates of those who did not undergo HSCT was 0%. This study demonstrates that an achievement of complete remission and a subsequent HSCT can be the optimal solution for the treatment of t-AML, and this strategy showed acceptable outcomes.

Treatment-related myelodysplastic syndrome (t-MDS)/acute myeloid leukemia (AML) in children with cancer: A single-center experience

Treatment-related myelodysplastic syndrome (t-MDS)/acute myeloid leukemia (AML) is a devastating early or late complication of treatment for childhood cancer related with a significant morbidity and mortality. We retrospectively studied survivors of childhood cancer. Overall, 287 patients were recorded in the databases and we identified three (1.04%) with t-MDS. The primary cancer diagnoses were Langerhans cell histiocytosis (one patient) and acute lymphoblastic leukemia (ALL; two patients). The mean age of patients was 12.1 years. All patients had received systemic antifungal treatment for invasive pulmonary aspergillosis successfully treated with voriconazole and liposomal amphotericin B before diagnosis of t-MDS. Two patients (66%) remain alive after a median follow-up period of 3.5 years.

Parental Tobacco Smoking and Acute Myeloid Leukemia: The Childhood Leukemia International Consortium

The association between tobacco smoke and acute myeloid leukemia (AML) is well established in adults but not in children. Individual-level data on parental cigarette smoking were obtained from 12 case-control studies from the Childhood Leukemia International Consortium (CLIC, 1974-2012), including 1,330 AML cases diagnosed at age <15 years and 13,169 controls. We conducted pooled analyses of CLIC studies, as well as meta-analyses of CLIC and non-CLIC studies. Overall, maternal smoking before, during, or after pregnancy was not associated with childhood AML; there was a suggestion, however, that smoking during pregnancy was associated with an increased risk in Hispanics (odds ratio = 2.08, 95% confidence interval (CI): 1.20, 3.61) but not in other ethnic groups. By contrast, the odds ratios for paternal lifetime smoking were 1.34 (95% CI: 1.11, 1.62) and 1.18 (95% CI: 0.92, 1.51) in pooled and meta-analyses, respectively. Overall, increased risks from 1.2- to 1.3-fold were observed for pre- and postnatal smoking (P < 0.05), with higher risks reported for heavy smokers. Associations with paternal smoking varied by histological type. Our analyses suggest an association between paternal smoking and childhood AML. The association with maternal smoking appears limited to Hispanic children, raising questions about ethnic differences in tobacco-related exposures and biological mechanisms, as well as study-specific biases.

Characteristics and Outcomes of Second Malignant Neoplasms after Childhood Cancer Treatment: Multi-Center Retrospective Survey

This retrospective study investigated the clinical characteristics and outcomes of second malignant neoplasms (SMNs) in survivors of childhood cancer from multiple institutions in Korea. A total of 102 patients from 11 institutions who developed SMN after childhood cancer treatment between 1998 and 2011 were retrospectively enrolled. The most common primary malignant neoplasms (PMNs) were central nervous system (CNS) tumors (n = 17), followed by acute lymphoblastic leukemia (n = 16), non-Hodgkin lymphoma (n = 13), and osteosarcoma (n = 12). The most common SMNs were therapy-related myeloid neoplasms (t-MNs; acute myeloid leukemia [AML], 29 cases; myelodysplastic syndrome [MDS], 12 cases), followed by thyroid carcinomas (n = 15) and CNS tumors (n = 10). The median latency period was 4.9 years (range, 0.5-18.5 years). Among 45 patients with solid tumors defined as an SMN, 15 (33%) developed the lesion in a field previously subjected to radiation. The 5-year overall survival (OS) rate of patients with an SMN was 45% with a median follow-up time of 8.6 years. Patients with AML, MDS, and CNS tumors exhibited the poorest outcomes with 5-year OS rates of 18%, 33%, and 32%, respectively, whereas those with second osteosarcoma showed comparable outcomes (64%) to patients with primary counterpart and those with second thyroid carcinoma had a 100% OS rate. Further therapeutic efforts are recommended to improve the survival outcomes in patients with SMNs, especially in cases with t-MNs and CNS tumors.

Progress and Prospects in Pediatric Leukemia

Pediatric leukemia is the single most common malignancy affecting children, representing up to 30% of all pediatric cancers. Dramatic improvements in survival for acute lymphoblastic leukemia (ALL) have taken place over the past 4 decades with outcomes approaching 90% in the latest studies. However, progress has been slower for myeloid leukemia and certain subgroups like infant ALL, adolescent/young adult ALL, and relapsed ALL. Recent advances include recognition of molecularly defined subgroups, which has ushered in precision medicine approaches. We discuss the current understanding of the biology of the various childhood leukemias, recent advances in research, and future challenges in this field.

Hematological Changes Mimicking Myelodysplastic Syndrome Following Treatment for Osteosarcoma

BACKGROUND

Therapy-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/AML) is a feared long-term complication of pediatric cancer. Few osteosarcoma patients develop t-MDS/AML, but the frequency of hematological abnormalities after therapy is unknown. We reviewed biochemistry from osteosarcoma patients up to 3 years posttreatment.

PROCEDURE

All children diagnosed with osteosarcoma at our department from 2006 to 2012 without relapse 1 month posttherapy were included (n=14). Serial blood counts posttherapy were analyzed.

RESULTS

The median increase of mean corpuscular volume (MCV) from baseline was 8 fL 6 months posttherapy and remained >5 throughout follow-up. All posttreatment levels of MCV were above 90 fL in 5 patients. Six months posttherapy, the median difference for platelets, white blood count, and absolute neutrophil count had decreased from baseline. They remained under baseline throughout follow-up. Hemoglobin remained stable. Ferritin level was associated with increased MCV. MDS with monosomy 7 was diagnosed in 1 patient. Hypoplastic refractory cytopenia was found in another patient showing spontaneous normalization of hematologic values.

CONCLUSIONS

More than a third of patients treated for osteosarcoma developed hematological abnormalities mimicking early MDS, but only 1 developed t-MDS/AML. Close hematological monitoring of patients recovering from osteosarcoma is essential and it is worth noting that hematological abnormalities are frequent and may be transitory.

Myelodysplastic syndrome: an inability to appropriately respond to damaged DNA?

Myelodysplastic syndrome (MDS) is considered a hematopoietic stem cell disease that is characterized by abnormal hematopoietic differentiation and a high propensity to develop acute myeloid leukemia. It is mostly associated with advanced age, but also with prior cancer therapy and inherited syndromes related to abnormalities in DNA repair. Recent technologic advances have led to the identification of a myriad of frequently occurring genomic perturbations associated with MDS. These observations suggest that MDS and its progression to acute myeloid leukemia is a genomic instability disorder, resulting from a stepwise accumulation of genetic abnormalities. The notion is now emerging that the underlying mechanism of this disease could be a defect in one or more pathways that are involved in responding to or repairing damaged DNA. In this review, we discuss these pathways in relationship to a large number of studies performed with MDS patient samples and MDS mouse models. Moreover, in view of our current understanding of how DNA damage response and repair pathways are affected by age in hematopoietic stem cells, we also explore how this might relate to MDS development.

Temozolomide-related idiosyncratic and other uncommon toxicities: a systematic review

Temozolomide (TMZ)-related idiosyncratic and other uncommon toxicities have been reported. To better characterize these toxicities and to identify any associated risk factors, we performed a systematic review. We searched the PubMed database, limited to the English language, published between 1999 and December 2011. We selected only those articles in which TMZ was temporally related and was the sole or main contributing chemotherapeutic drug to idiosyncratic drug reactions (IDRs) and other uncommon toxicities. Hematological IDRs are biopsy-proven aplastic anemia or grade V toxicity or grade IV toxicity with slow and incomplete hematological recovery. Seventy-three cases were identified, including 21 hematological IDRs, 31 nonhematological IDRs and uncommon infections, and 21 second primary cancers. With a caveat of publication and reporting bias, the following observations could be made. The hematological IDRs predominantly occurred in female patients (exact binomial two-tailed, P=0.0041) and most patients were receiving TMZ concomitantly with radiotherapy for glioma. The median duration of exposure to TMZ was 30 days and the median cumulative TMZ exposure was 2250 mg/m (range, 500-6900 mg/m). The sex predilection was not evident in nonhematological IDRs and other uncommon toxicities. TMZ-induced pneumonitis and cholestatic hepatitis are emerging as a nonhematological hypersensitive reaction and IDR, respectively. For TMZ-related myelodysplasia or leukemia, the cumulative dose of TMZ ranged from 1400 to 30 000 mg/m. The cumulative dose of TMZ was lower and latency was shorter with a previous exposure to other leukemogenic drugs, suggesting that TMZ may have augmented the leukemogenic potential of other drugs. Early appearance of profound myelosuppression during the course of TMZ and concurrent radiotherapy could be a hematological IDR, which warrants prompt investigations to exclude aplastic anemia. Myelodysplasia or leukemia developed after a median TMZ exposure of 15 g/m.

Cytogenetic abnormalities and monosomal karyotypes in children and adolescents with acute myeloid leukemia: correlations with clinical characteristics and outcome

The whole spectrum of chromosomal abnormalities and their prognostic significance in children and adolescents with acute myeloid leukemia (AML) has not been fully elucidated yet, although a considerable amount of knowledge has been gained recently. Moreover, the incidence and prognostic impact of monosomal karyotypes (MKs), which are new cytogenetic categories reported recently in adults with AML, are currently unknown for childhood and adolescent AML. In this study, we investigated the cytogenetic and clinical characteristics of 140 children and adolescents (≤21 y) with AML, and correlated their cytogenetic features with both the clinical characteristics and outcomes of our patient cohort. The most frequent cytogenetic abnormality found in our study was the t(15;17), followed by the t(8;21). Striking differences in the genetic abnormalities and French-American-British subtypes were found among infants, children, and adolescents. Of 124 cases, 15 (12.1%) met the criteria of the MK definition, and 12 of the 15 MKs (80%) were complex karyotypes. Of 124 cases, 27 (21.8%) had cytogenetic abnormalities sufficient to be diagnosed as AML with myelodyspastic sydrome-related features. As expected, patients with the t(15;17) had the most favorable outcomes, whereas patients with 11q23 rearrangements and monosomy 7 had the worst outcomes. These data expand our knowledge by providing novel insights into the cytogenetic features and their correlations with clinical characteristics and outcomes in childhood and adolescent AML.

Secondary acute myelogenous leukemia (AML) with trisomy 10 and del(9q) following precursor B-cell acute lymphoblastic leukemia (ALL) with a hyperdiploid karyotype

Acute myelogenous leukemia (AML) secondary to acute lymphoblastic leukemia (ALL) in children is uncommon and usually occurs within 10 years of completing therapy for ALL. A variety of recurrent cytogenetic abnormalities have been described, suggesting significant biological heterogeneity. We report a case of highly refractory secondary AML with trisomy 10 and del(9q) occurring in an adolescent female 12 years after she was treated successfully for precursor B-cell ALL with chemotherapy only.

Treatment-related myelodysplasia in patients with primary brain tumors

Treatment-related myelodysplastic syndrome (t-MDS) and treatment-related acute myelogenous leukemia (t-AML) represent rare secondary events in patients with primary tumors of the nervous system and predominantly affect those treated with alkylating agents or topoisomerase II inhibitors. Temozolomide has become the standard chemotherapeutic agent for malignant gliomas. The emergence of this alkylating agent with little acute toxicity or cumulative myelosuppression has led to off-label protracted chemotherapy for many patients with malignant and even low-grade infiltrative gliomas, raising concern for increased risk of t-MDS/t-AML in the few long-term survivors. On the basis of an extensive literature search, we provide a discussion of epidemiology, pathogenesis, clinical presentation, diagnosis, and therapy of these disorders. t-MDS/t-AML remain rare complications of chemotherapy in patients with primary brain tumors, and the vast majority of patients die of their primary neoplasm. Prospective randomized studies with long-term follow-up are required to accurately assess the risk of t-MDS/t-AML; however, unless survival in the most common gliomas substantially increases, t-MDS/t-AML incidence will likely remain low in this patient population.

Treatment-related myelodysplastic syndrome after temozolomide use in a child: first report

Temozolomide is an effective alkylating agent that is increasingly used for the treatment of pediatric brain tumors. Secondary, or treatment-related, myelodysplasia is a life-threatening complication of alkylating chemotherapy and has been reported in children with brain tumors after treatments other than temozolomide. We describe for the first time a case of temozolomide-related myelodysplasia in a child.

Toxicity and outcome of children with treatment related acute myeloid leukemia

BACKGROUND

The aim of this study was to evaluate the clinical course and outcome of children with treatment related acute myeloid leukemia (tAML) and compare them to children with primary AML (pAML).

PROCEDURE

We retrospectively reviewed the demographic, treatment, toxicity, and outcome data of children with tAML and treatment related myelodysplastic syndrome (tMDS), treated at our institution between 1975 and 2005. We compared these parameters with matched controlled children with pAML. Finally we compared overall survival (OS) for tAML with all pAML children treated at the study era in our institution.

RESULTS

Twenty-one patients with tAML (n = 19) and tMDS (n = 2) were identified. Three years event-free survival (EFS) and OS were both 14 +/- 8%. Compared to pAML patients, tAML had a higher rate of adverse cytogenetics (P < 0.008) and inferior OS (P = 0.027) but no significant difference in treatment toxicity or death. All survivors were treated with allogeneic hematopoietic stem cell transplantation (HSCT).

CONCLUSIONS

In this population based report of pediatric tAML, outcome was poor and was related to a higher probability of poor cytogenetic features rather than excessive toxicities or inability to deliver therapy. HSCT should be considered for patients with tAML. These preliminary findings should set the stage for prospective cooperative studies.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.