The genetic basis and cell of origin of mixed phenotype acute leukaemia.

Mixed phenotype acute leukaemia (MPAL) is a high-risk subtype of leukaemia with myeloid and lymphoid features, limited genetic characterization, and a lack of consensus regarding appropriate therapy. Here we show that the two principal subtypes of MPAL, T/myeloid (T/M) and B/myeloid (B/M), are genetically distinct. Rearrangement of ZNF384 is common in B/M MPAL, and biallelic WT1 alterations are common in T/M MPAL, which shares genomic features with early T-cell precursor acute lymphoblastic leukaemia. We show that the intratumoral immunophenotypic heterogeneity characteristic of MPAL is independent of somatic genetic variation, that founding lesions arise in primitive haematopoietic progenitors, and that individual phenotypic subpopulations can reconstitute the immunophenotypic diversity in vivo. These findings indicate that the cell of origin and founding lesions, rather than an accumulation of distinct genomic alterations, prime tumour cells for lineage promiscuity. Moreover, these findings position MPAL in the spectrum of immature leukaemias and provide a genetically informed framework for future clinical trials of potential treatments for MPAL.

Tumor-intrinsic and -extrinsic determinants of response to blinatumomab in adults with B-ALL.

Blinatumomab, a bispecific antibody that directs CD3+ T cells to CD19+ tumor cells, shows variable efficacy in B-progenitor acute lymphoblastic leukemia (B-ALL). To determine tumor-intrinsic and -extrinsic determinants of response, we studied 44 adults with relapsed or refractory B-ALL (including 2 minimal residual disease positive) treated with blinatumomab using bulk tumor and single-cell sequencing. The overall response rate in patients with hematological disease was 55%, with a high response rate in those with CRLF2-rearranged Philadelphia chromosome-like ALL (12 [75%] of 16). Pretreatment samples of responders exhibited a tumor-intrinsic transcriptomic signature of heightened immune response. Multiple mechanisms resulted in loss of CD19 expression, including CD19 mutations, CD19-mutant allele-specific expression, low CD19 RNA expression, and mutations in CD19 signaling complex member CD81. Patients with low hypodiploid ALL were prone to CD19- relapse resulting from aneuploidy-mediated loss of the nonmutated CD19 allele. Increased expression of a CD19 isoform with intraexonic splicing of exon 2, CD19 ex2part, at baseline or during therapy was associated with treatment failure. These analyses demonstrate both tumor-intrinsic and -extrinsic factors influence blinatumomab response. We show that CD19 mutations are commonly detected in CD19- relapse during blinatumomab treatment. Identification of the CD19 ex2part splice variant represents a new biomarker predictive of blinatumomab therapy failure.

Processes and perceptions of chemotherapy supply chain in Ethiopia: A mixed-method study.

BACKGROUND: The impact and downstream effects of the chemotherapy supply chain in Ethiopia are not well understood. The purpose of this study was to identify perceived gaps in supply chain and characterize their impact on patient care. METHODS: A concurrent mixed-method study was conducted at a large academic cancer center in Ethiopia. In-depth interviews (IDIs) and surveys were completed in collaboration with external stakeholders with knowledge about chemotherapy supply chain in Ethiopia. Thematic coding was used for qualitative analysis of IDI and descriptive statistics were used to summarize quantitative survey data. RESULTS: Six stakeholders participated in the IDIs and seven completed surveys. IDIs revealed that most chemotherapeutic agents are purchased by the Ethiopian Pharmaceutical Supply Agency (EPSA) and are distributed to cancer treatment centers. A free-market purchasing option also exists, but for chemotherapy obtained outside of government-subsidized channels, the potential for substandard or falsified chemotherapy was a concern. Participants expressed confidence that the correct treatment was administered to patients, but viewpoints on reliability and consistency of medication supply were variable. Quantitative data from the survey showed that participants were not confident that medications are prepared safely and correctly. Improper storage and manipulation of high-risk medications remain a significant risk to staff. CONCLUSIONS: This study provides insight from a healthcare staff perspective on how gaps in the chemotherapy supply chain process impact patient care in a low-income country. Inventory management, disruptions in supply chain, and product integrity were perceived as the largest gaps in the current chemotherapy supply chain structure.

Acral Skin Rash Caused by Altered Mercaptopurine Metabolism in Maintenance Therapy for B-Cell Acute Lymphoblastic Leukemia.

6-mercaptopurine is a mainstay of acute lymphoblastic leukemia treatment. It has a narrow therapeutic window, dictated by its metabolite, thioguanine and 6-methylmercaptopurine. Skin manifestations usually consist of mild facial rash or hypersensitivity exanthems. We report a child who developed a painful acral rash and mucositis while undergoing maintenance therapy for B-cell acute lymphoblastic leukemia without infectious or known drug etiology. Thiopurine metabolites were skewed toward 6-methylmercaptopurine. Two weeks after allopurinol was added and 6-mercaptopurine (6-MP) dose adjusted, the cutaneous manifestations and other constitutional symptoms resolved. We posit that the rash was because of 6-MP toxicity related to skewed metabolism, adding to the growing list of toxicity related to altered 6-MP metabolism.

Genome-wide discovery of somatic coding and noncoding mutations in pediatric endemic and sporadic Burkitt lymphoma.

Although generally curable with intensive chemotherapy in resource-rich settings, Burkitt lymphoma (BL) remains a deadly disease in older patients and in sub-Saharan Africa. Epstein-Barr virus (EBV) positivity is a feature in more than 90% of cases in malaria-endemic regions, and up to 30% elsewhere. However, the molecular features of BL have not been comprehensively evaluated when taking into account tumor EBV status or geographic origin. Through an integrative analysis of whole-genome and transcriptome data, we show a striking genome-wide increase in aberrant somatic hypermutation in EBV-positive tumors, supporting a link between EBV and activation-induced cytidine deaminase (AICDA) activity. In addition to identifying novel candidate BL genes such as SIN3A, USP7, and CHD8, we demonstrate that EBV-positive tumors had significantly fewer driver mutations, especially among genes with roles in apoptosis. We also found immunoglobulin variable region genes that were disproportionally used to encode clonal B-cell receptors (BCRs) in the tumors. These include IGHV4-34, known to produce autoreactive antibodies, and IGKV3-20, a feature described in other B-cell malignancies but not yet in BL. Our results suggest that tumor EBV status defines a specific BL phenotype irrespective of geographic origin, with particular molecular properties and distinct pathogenic mechanisms. The novel mutation patterns identified here imply rational use of DNA-damaging chemotherapy in some patients with BL and targeted agents such as the CDK4/6 inhibitor palbociclib in others, whereas the importance of BCR signaling in BL strengthens the potential benefit of inhibitors for PI3K, Syk, and Src family kinases among these patients.

Mixed Phenotype Acute Leukemia: Current Approaches to Diagnosis and Treatment.

PURPOSE OF REVIEW: Mixed phenotype acute leukemia (MPAL) is a rare subtype of acute leukemia with features of both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The review examines current definitions and controversies in classification of MPAL, new insights into genomic drivers and pathogenesis, recent evidence to support treatment recommendations, and opportunities for future research. RECENT FINDINGS: Recent collaborative efforts have made progress in understanding the genomic landscape and optimal therapy for MPAL. The preponderance of retrospective data supports beginning therapy with ALL directed regimens. Differences in prognosis for adult and children with MPAL have led to divergent approaches for therapy intensity, including use of stem cell transplantation consolidation. MPAL remains a challenging leukemia to understand, research, and treat due to low incidence, shifting and subjective approaches to classification, and innate biological heterogeneity. Ongoing research hopes to surmount these obstacles through prospective studies within large cooperative groups to provide new insight into targetable biology and further refine optimal therapy.

Results of a pre-implementation analysis of Ethiopia's National Pediatric Cancer Registry.

In Ethiopia, cancer accounts for about 5.8% of total national mortality, with an estimated annual incidence of cancer of approximately 60,960 cases and an annual mortality of over 44,000 persons. This is likely an underestimation. Survival rates for pediatric malignancies are likewise suboptimal although exact figures are unknown since a national cancer registry is unavailable. The World Health Organization (WHO) provides recommendations for the creation of cancer registries to track such data. Here we describe our pharmacist-led, pre-implementation assessment of introducing an enhanced national pediatric cancer registry in Ethiopia. Our assessment project had three specific aims around which the methods were designed: 1) characterization of the current spreadsheet-based tool across participating sites, including which variables were being collected, how these variables compared to standards set by the WHO, and a description of how the data were entered and its completeness; 2) assessment of the perceptions of an enhanced registry from hospital staff; and 3) evaluation of workflow gaps regarding documentation. The hospital staff and leadership have generally positive perceptions of an enhanced pediatric cancer registry, which were further improved by our interactions. The workflow assessment revealed several gaps, which were addressed systematically using a three-phase implementation science approach. The assessment also demonstrated that the existing spreadsheet-based tool was missing WHO-recommended variables and had inconsistent completion due to the workflow gaps. A pediatric oncology summary sheet will be implemented in upcoming trips in patient charts to better summarize the patients' journey starting from diagnosis. This document will be used by the data clerks in an enhanced-spreadsheet to have a more complete data set.

Venetoclax in combination with cytarabine with or without idarubicin in children with relapsed or refractory acute myeloid leukaemia: a phase 1, dose-escalation study.

BACKGROUND: Outcomes for children with relapsed or refractory acute myeloid leukaemia remain poor. The BCL-2 inhibitor, venetoclax, has shown promising activity in combination with hypomethylating agents and low-dose cytarabine in older adults for whom chemotherapy is not suitable with newly diagnosed acute myeloid leukaemia. We aimed to determine the safety and explore the activity of venetoclax in combination with standard and high-dose chemotherapy in paediatric patients with relapsed or refractory acute myeloid leukaemia. METHODS: We did a phase 1, dose-escalation study at three research hospitals in the USA. Eligible patients were aged 2-22 years with relapsed or refractory acute myeloid leukaemia or acute leukaemia of ambiguous lineage with adequate organ function and performance status. During dose escalation, participants received venetoclax orally once per day in continuous 28-day cycles at either 240 mg/m2 or 360 mg/m2, in combination with cytarabine received intravenously every 12 h at either 100 mg/m2 for 20 doses or 1000 mg/m2 for eight doses, with or without intravenous idarubicin (12 mg/m2) as a single dose, using a rolling-6 accrual strategy. The primary endpoint was the recommended phase 2 dose of venetoclax plus chemotherapy and the secondary endpoint was the proportion of patients treated at the recommended phase 2 dose who achieved complete remission or complete remission with incomplete haematological recovery. Analyses were done on patients who received combination therapy. The study is registered with ClinicalTrials.gov (NCT03194932) and is now enrolling to address secondary and exploratory objectives. FINDINGS: Between July 1, 2017, and July 2, 2019, 38 patients were enrolled (aged 3-22 years; median 10 [IQR 7-13]), 36 of whom received combination therapy with dose escalation, with a median follow-up of 7·1 months (IQR 5·1-11·2). The recommended phase 2 dose of venetoclax was found to be 360 mg/m2 (maximum 600 mg) combined with cytarabine (1000 mg/m2 per dose for eight doses), with or without idarubicin (12 mg/m2 as a single dose). Overall responses were observed in 24 (69%) of the 35 patients who were evaluable after cycle 1. Among the 20 patients treated at the recommended phase 2 dose, 14 (70%, 95% CI 46-88) showed complete response with or without complete haematological recovery, and two (10%) showed partial response. The most common grade 3-4 adverse events were febrile neutropenia (22 [66%]), bloodstream infections (six [16%]), and invasive fungal infections (six [16%]). Treatment-related death occurred in one patient due to colitis and sepsis. INTERPRETATION: The safety and activity of venetoclax plus chemotherapy in paediatric patients with heavily relapsed and refractory acute myeloid leukaemia suggests that this combination should be tested in newly diagnosed paediatric patients with high-risk acute myeloid leukaemia. FUNDING: US National Institutes of Health, American Lebanese Syrian Associated Charities, AbbVie, and Gateway for Cancer Research.

Safety, pharmacokinetics, and pharmacodynamics of panobinostat in children, adolescents, and young adults with relapsed acute myeloid leukemia.

BACKGROUND: Novel therapies are urgently needed for pediatric patients with relapsed acute myeloid leukemia (AML). METHODS: To determine whether the histone deacetylase inhibitor panobinostat could be safely given in combination with intensive chemotherapy, a phase 1 trial was performed in which 17 pediatric patients with relapsed or refractory AML received panobinostat (10, 15, or 20 mg/m2 ) before and in combination with fludarabine and cytarabine. RESULTS: All dose levels were tolerated, with no dose-limiting toxicities observed at any dose level. Pharmacokinetic studies demonstrated that exposure to panobinostat was proportional to the dose given, with no associations between pharmacokinetic parameters and age, weight, or body surface area. Among the 9 patients who had sufficient (>2%) circulating blasts on which histone acetylation studies could be performed, 7 demonstrated at least 1.5-fold increases in acetylation. Although no patients had a decrease in circulating blasts after single-agent panobinostat, 8 of the 17 patients (47%), including 5 of the 6 patients treated at dose level 3, achieved complete remission. Among the 8 complete responders, 6 (75%) attained negative minimal residual disease status. CONCLUSIONS: Panobinostat can be safely administered with chemotherapy and results in increased blast histone acetylation. This suggests that it should be further studied in AML.

Mixed-phenotype acute leukemia: A cohort and consensus research strategy from the Children's Oncology Group Acute Leukemia of Ambiguous Lineage Task Force.

BACKGROUND: Optimal chemotherapy for treating mixed-phenotype acute leukemia (MPAL) and the role of hematopoietic stem cell transplantation (HSCT) remain uncertain. Major limitations in interpreting available data are MPAL's rarity and the use of definitions other than the currently widely accepted criteria: the World Health Organization 2016 (WHO2016) classification. METHODS: To assess the relative efficacy of chemotherapy types for treating pediatric MPAL, the Children's Oncology Group (COG) Acute Leukemia of Ambiguous Lineage Task Force assembled a retrospective cohort of centrally reviewed WHO2016 MPAL cases selected from banking studies for acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Patients were not treated in COG trials; treatment and outcome data were captured separately. The findings were then integrated with the available, mixed literature to develop a prospective trial in pediatric MPAL. RESULTS: The central review confirmed that 54 of 70 cases fulfilled WHO2016 criteria for MPAL. ALL induction regimens achieved remission in 72% of the cases (28 of 39), whereas AML regimens achieved remission in 69% (9 of 13). The 5-year event-free survival (EFS) and overall survival (OS) rates for the entire cohort were 72% ± 8% and 77% ± 7%, respectively. EFS and OS were 75% ± 13% and 84% ± 11%, respectively, for those receiving ALL chemotherapy alone without HSCT (n = 21). CONCLUSIONS: The results of the COG MPAL cohort and a literature review suggest that ALL chemotherapy without HSCT may be the preferred initial therapy. A prospective trial within the COG is proposed to investigate this approach; AML chemotherapy and/or HSCT will be reserved for those with treatment failure as assessed by minimal residual disease. Embedded biology studies will provide further insight into MPAL genomics.

International cooperative study identifies treatment strategy in childhood ambiguous lineage leukemia.

Despite attempts to improve the definitions of ambiguous lineage leukemia (ALAL) during the last 2 decades, general therapy recommendations are missing. Herein, we report a large cohort of children with ALAL and propose a treatment strategy. A retrospective multinational study (International Berlin-Frankfurt-Münster Study of Leukemias of Ambiguous Lineage [iBFM-AMBI2012]) of 233 cases of pediatric ALAL patients is presented. Survival statistics were used to compare the prognosis of subsets and types of treatment. Five-year event-free survival (EFS) of patients with acute lymphoblastic leukemia (ALL)-type primary therapy (80% ± 4%) was superior to that of children who received acute myeloid leukemia (AML)-type or combined-type treatment (36% ± 7.2% and 50% ± 12%, respectively). When ALL- or AML-specific gene fusions were excluded, 5-year EFS of CD19+ leukemia was 83% ± 5.3% on ALL-type primary treatment compared with 0% ± 0% and 28% ± 14% on AML-type and combined-type primary treatment, respectively. Superiority of ALL-type treatment was documented in single-population mixed phenotype ALAL (using World Health Organization and/or European Group for Immunophenotyping of Leukemia definitions) and bilineal ALAL. Treatment with ALL-type protocols is recommended for the majority of pediatric patients with ALAL, including cases with CD19+ ALAL. AML-type treatment is preferred in a minority of ALAL cases with CD19- and no other lymphoid features. No overall benefit of transplantation was documented, and it could be introduced in some patients with a poor response to treatment. As no clear indicator was found for a change in treatment type, this is to be considered only in cases with ≥5% blasts after remission induction. The results provide a basis for a prospective trial.

Training pediatric hematologist/oncologists for capacity building in Ethiopia.

PURPOSE: A considerable barrier to global pediatric oncology efforts has been the scarcity and even absence of trained professionals in many low- and middle-income countries, where the majority of children with cancer reside. In 2013, no dedicated pediatric hematology-oncology (PHO) programs existed in Ethiopia despite the estimated annual incidence of 6000-12000 cases. The Aslan Project initiative was established to fill this gap in order to improve pediatric cancer care in Ethiopia. A major objective was to increase subspecialty PHO-trained physicians who were committed to practicing locally and empowered to lead programmatic development. METHODS: We designed and implemented a PHO training curriculum to provide a robust educational and clinical experience within the existing resource-constrained environment in Ethiopia. Education relied on visiting PHO faculty, a training attachment abroad, and extraordinary initiative from trainees. RESULTS: Four physicians have completed comprehensive PHO subspecialty training based primarily in Ethiopia, and all have remained local. Former fellows are now leading two PHO centers in Ethiopia with a combined capacity of 64 inpatient beds and over 800 new diagnoses per year; an additional former fellow is developing a pediatric cancer program in Nairobi, Kenya. Two fellows currently are in training. Program leadership, teaching, and advocacy are being transitioned to these physicians. CONCLUSIONS: Despite myriad challenges, a subspecialty PHO training program was successfully implemented in a low-income country. PHO training in Ethiopia is approaching sustainability through human resource development, and is accelerating the growth of dedicated PHO services where none existed 7 years ago.

Decreased relapsed rate and treatment-related mortality contribute to improved outcomes for pediatric acute myeloid leukemia in successive clinical trials.

BACKGROUND: Outcomes for children with acute myeloid leukemia (AML) have improved over the past 20 years even though the medications used for induction therapy have not changed. METHODS: This study analyzed data from patients with AML who were enrolled in successive protocols (AML97 and AML02) to determine the contributors to the improved outcomes of the latter clinical trial. RESULTS: There were significant improvements in 5-year overall survival (48.9% vs 71.2%; P < .0001) and event-free survival (43.5% vs 61.8%; P = .002) from AML97 to AML02. The 5-year cumulative incidence of early death (ED)/treatment-related mortality (TRM) was reduced for patients treated in AML02 (18.5% vs 7.9%; P = .007). Although the overall incidence of refractory disease (6.5% vs 5.6%; P = .736) and relapse (29.3% vs 21.0%; P = .12) did not differ between the 2 studies, patients with low-risk AML who were treated in AML02 had a reduced incidence of relapse (27.3% vs 8.8%; P = .036). CONCLUSIONS: The improved outcomes of the AML02 trial resulted from improved disease control for low-risk patients and overall decreased ED/TRM. These results emphasize the importance of supportive-care measures throughout chemotherapy courses and hematopoietic cell transplantation and the value of treatment intensity for patients with low-risk AML while underscoring the need for novel therapy, rather than increased therapy intensity, for children with high-risk AML. Cancer 2017;123:3791-3798. © 2017 American Cancer Society.

Metachronous T-Lymphoblastic Lymphoma and Burkitt Lymphoma in a Child With Constitutional Mismatch Repair Deficiency Syndrome.

Constitutional mismatch repair deficiency (CMMRD) is a cancer predisposition syndrome associated with a high risk of developing early-onset malignancies of the blood, brain, and intestinal tract. We present the case of a patient with T-lymphoblastic lymphoma at the age of 3 years, followed by Burkitt lymphoma 10 years later. This patient also exhibited numerous nonmalignant findings including café au lait spots, lipomas, bilateral renal nodules, a nonossifying fibroma, multiple colonic adenomas, and a rapidly enlarging pilomatrixoma. The spectrum of malignant and nonmalignant neoplasms in this patient highlights the remarkable diversity, and early onset, of lesions seen in children with CMMRD.

Variations in global prices of chemotherapy for childhood cancer: a descriptive analysis.

Background: The stark disparity in survival for children with cancer across the world has inspired a global call to expand chemotherapy access in low and middle income countries. Among the numerous barriers to success, a paucity of reliable information regarding chemotherapy pricing hinders the ability of governments and other key stakeholders to make informed budget decisions or negotiate lower medication prices. The aim of this study was to generate comparative price information on both individual chemotherapy agents and comprehensive treatment regimens for common childhood cancers using real-world data. Methods: Chemotherapy agents were selected based on their inclusion in the World Health Organization (WHO) Essential Medicines List for Children (EMLc) and their use in frontline regimens for the tracer cancer types prioritized by the WHO's Global Initiative for Childhood Cancer (GICC). Sources included IQVIA MIDAS data, obtained under license from IQVIA, and publicly available data from Management Sciences for Health (MSH). Data on chemotherapy prices and purchase volumes spanning 2012-2019 were aggregated according to WHO region and World Bank (WB) income classification. Cumulative chemotherapy prices for treatment regimens were compared across WB income classification. Findings: Data representing an estimated 1.1 billion doses of chemotherapy were obtained for 97 countries: 43 high income countries (HICs), 28 upper middle income countries (UMICs), and 26 low and lower middle income countries (LLMICs). Median drug prices in HICs were 0.9-20.4 times those of UMICs and 0.9-15.5 times those of LMICs. Regimen prices were generally higher for HICs, hematologic malignancies, non-adapted protocols, and higher risk stratification or stage, albeit with notable exceptions. Interpretation: This study represents the largest price analysis to date of chemotherapy agents used globally in childhood cancer therapy. The findings of this study form a basis for future cost-effectiveness analysis in pediatric cancer and should inform efforts of governments and stakeholders to negotiate drug prices and develop pooled purchasing strategies. Funding: NB received funding support from the American Lebanese Syrian Associated Charities and Cancer Center Support grant (CA21765) from the National Cancer Institute through the National Institutes of Health. TA received funding through the University of North Carolina Oncology K12 (K12CA120780) and the University Cancer Research Fund from the UNC Lineberger Comprehensive Cancer Center.