A temporal in vivo catalog of chromatin accessibility and expression profiles in pineoblastoma reveals a prevalent role for repressor elements.

Pediatric pineoblastomas (PBs) are rare and aggressive tumors of grade IV histology. Although some oncogenic drivers are characterized, including germline mutations in RB1 and DICER1, the role of epigenetic deregulation and cis-regulatory regions in PB pathogenesis and progression is largely unknown. Here, we generated genome-wide gene expression, chromatin accessibility, and H3K27ac profiles covering key time points of PB initiation and progression from pineal tissues of a mouse model of CCND1-driven PB. We identified PB-specific enhancers and super-enhancers, and found that in some cases, the accessible genome dynamics precede transcriptomic changes, a characteristic that is underexplored in tumor progression. During progression of PB, newly acquired open chromatin regions lacking H3K27ac signal become enriched for repressive state elements and harbor motifs of repressor transcription factors like HINFP, GLI2, and YY1. Copy number variant analysis identified deletion events specific to the tumorigenic stage, affecting, among others, the histone gene cluster and Gas1, the growth arrest specific gene. Gene set enrichment analysis and gene expression signatures positioned the model used here close to human PB samples, showing the potential of our findings for exploring new avenues in PB management and therapy. Overall, this study reports the first temporal and in vivo cis-regulatory, expression, and accessibility maps in PB.

A regional virtual case discussion forum in pediatric oncology: Experience of the Pediatric Oncology East and Mediterranean Group.

BACKGROUND: The Pediatric Oncology East and Mediterranean (POEM) group that aims to share expertise among pediatric oncology providers across the Middle East, North Africa, and East Asia region initiated a virtual Case Discussion Forum (CDF) in 2013. METHODS: Meeting records from September 2013 till June 2021 were reviewed. Detailed minutes were available starting August 2016; case data were analyzed including diagnoses, purpose of presentation and recommendations. A 38-item survey assessing perception of benefits, challenges, and opportunities of the forum was distributed to members of the POEM group and results analyzed. RESULTS: A total of 140 cases were presented from 14 countries. After August 2016, 67 cases were presented, and those were analyzed regarding reasons for discussion, barriers, and recommendations. Details are presented in this report, and the most common challenges identified were related to histopathologic/molecular diagnosis (24%), imaging interpretation (18%), resource limitations (12%), and surgical difficulties (9%). A survey was distributed to all POEM members in 28 countries, and 76 responded. The main benefit reported was the provision of recommendations regarding treatment and evaluation, while the main challenges reported were time zone difference and workload. Recognized opportunities included conducting regionally relevant research studies based on clinical problems identified during discussions, and setting guidelines for resource-adapted treatment regimens. CONCLUSIONS: The POEM CDF identified areas for multi-institutional regional studies and led to a twinning project between two centers in the region for improving diagnostic infrastructure. Such forums can identify specific resource limitations in pediatric cancer and direct efforts for targeted capacity building.

Development of EPAT: An assessment tool for pediatric hematology/oncology training programs.

PURPOSE: In the absence of a standardized tool to assess the quality of pediatric hematology/oncology training programs, the Education Program Assessment Tool (EPAT) was conceptualized as a user-friendly and adaptable tool to evaluate and identify areas of opportunity, pinpoint needed modifications, and monitor progress for training programs around the world. METHODS: The development of EPAT consisted of three main phases: operationalization, consensus, and piloting. After each phase, the tool was iteratively modified based on feedback to improve its relevance, usability, and clarity. RESULTS: The operationalization process led to the development of 10 domains with associated assessment questions. The two-step consensus phase included an internal consensus phase to validate the domains and a subsequent external consensus phase to refine the domains and overall function of the tool. EPAT domains for programmatic evaluation are hospital infrastructure, patient care, education infrastructure, program basics, clinical exposure, theory, research, evaluation, educational culture, and graduate impact. EPAT was piloted in five training programs in five countries, representing diverse medical training and patient care contexts for proper validation of the tool. Face validity was confirmed by a correlation between the perceived and calculated scores for each domain (r = 0.78, p < .0001). CONCLUSIONS: EPAT was developed following a systematic approach, ultimately leading to a relevant tool to evaluate the different core elements of pediatric hematology/oncology training programs across the world. With EPAT, programs will have a tool to quantitatively evaluate their training, allowing for benchmarking with centers at the local, regional, and international level.

Using comprehensive genomic and functional analyses for resolving genotype-phenotype mismatches in children with suspected CMMRD in Lebanon: an IRRDC study.

Constitutional mismatch repair deficiency (CMMRD) is an aggressive and highly penetrant cancer predisposition syndrome. Because of its variable clinical presentation and phenotypical overlap with neurofibromatosis, timely diagnosis remains challenging, especially in countries with limited resources. Since current tests are either difficult to implement or interpret or both we used a novel and relatively inexpensive functional genomic assay (LOGIC) which has been recently reported to have high sensitivity and specificity in diagnosing CMMRD. Here we report the clinical and molecular characteristics of nine patients diagnosed with cancer and suspected to have CMMRD and highlight the challenges with variant interpretation and immunohistochemical analysis that led to an uncertain interpretation of genetic findings in 6 of the 9 patients. Using LOGIC, we were able to confirm the diagnosis of CMMRD in 7 and likely exclude it in 2 patients, resolving ambiguous result interpretation. LOGIC also enabled predictive testing of asymptomatic siblings for early diagnosis and implementation of surveillance. This study highlights the varied manifestations and practical limitations of current diagnostic criteria for CMMRD, and the importance of international collaboration for implementing robust and low-cost functional assays for resolving diagnostic challenges.

Heritable cancer predisposition testing in pediatric cancer patients excluding retinoblastoma in a middle-income country.

Resource-limited settings often have financial barriers to genetic testing for heritable cancer. This retrospective study investigated the pattern of heritable cancer predisposition testing in a middle-income country over the period 2014-2021, excluding retinoblastoma. After establishing a specific fund in 2019, rate of tests increased from 1.1% to 10.9% of new diagnoses. Most common testing was for constitutional mismatch repair deficiency (CMMRD), rhabdoid predisposition syndrome, TP53 (tumor protein 53) mutation, and hereditary cancer panel. Of 33 patients, 13 (39%) tested positive, 12 (36%) negative, and eight (24%) had variants of unknown significance. Positivity rate was 43% for a clinical phenotype and 44% for a tumor type indication.

Pediatric oncology infrastructure and workforce training needs: a report from the Pediatric Oncology East and Mediterranean (POEM) Group.

BACKGROUND: Inadequate numbers of trained healthcare providers (HCPs), contribute to poor pediatric oncology (PO) outcomes, particularly in low- and lower middle-income countries (L/LMICs). An understanding of the characteristics of the workforce challenges are vital for addressing these problems. METHODS: The Pediatric Oncology East and Mediterranean (POEM) Group surveyed PO centers in countries of the North Africa, Middle East, Central Asia and Indian subcontinent on infrastructure and workforce capacity, service availability, and training opportunities for HCPs. Participating centers were categorized by the World Bank income levels for their countries and correlated with services, workload and staffing characteristics, and training needs. RESULTS: Fifty of 82 member-centers (61%) from 21 countries responded to the survey. 299 pediatric oncologists and 1,176 nurses treated 12,496 new PO patients/year, with a 1,451 beds utilization. The majority (71%) of new cases occurred in L/LMICs. The availability of HCPs correlated with country income level, as did pediatric subspecialty access, while availability of support services was unrelated. Twenty-five centers in 11 countries offered PO fellowship training for physicians, whereas 13 PO nurse training centers in 9 countries had the capacity to train 273 nurses annually. The survey respondents indicated that, among their existing workforce, an average of 3·5 physicians and 14 nurses per institution would benefit from additional PO training opportunities. CONCLUSIONS: The participating centers exhibited intra-regional heterogeneity in financial resources, infrastructure, workload, workforce, and medical services. Our findings provide insight into the disparities and regional resources available to POEM, which can be mobilized to rectify specific deficiencies. This article is protected by copyright. All rights reserved.

Global Neuroblastoma Network: An international multidisciplinary neuroblastoma tumor board for resource-limited countries.

BACKGROUND: Tumor boards are part of standard care of patients with complex cancers, but appropriate multidisciplinary expertise and infrastructure are often not available in low- and middle-income countries (LMIC) for pediatric cancers, such as neuroblastoma. Our goal was to review results of a Global Neuroblastoma Network (GNN) tumor board accessible to LMIC. METHODS: De-identified clinical cases presented via internet conference during a weekly GNN virtual tumor board from 2010 through 2020 were evaluated in a standardized format, including diagnostic imaging, pathology, therapy information, resource limitations, and questions for discussion. Information summarized included the presentations, a survey of the impact on care, and a resource questionnaire. RESULTS: Registered GNN participants included 575 individuals from 77 countries, with a median of 39 participants per session. Total 412 cases were presented from 32 countries, including 351 unique neuroblastoma patients, 52 follow-up cases, and nine non-neuroblastoma diagnoses. Twenty-eight educational sessions were presented. Limited critical resources for diagnostics and staging of cases included MYCN analysis (54.7%), metaiodobenzylguanidine (MIBG) scans (38.7%), and International Neuroblastoma Pathology Classification (49%). Therapies were also limited, with markedly decreased use of radiation and autologous stem cell transplant for high-risk cases, and no availability of anti-GD2 antibody in LMIC. Limited sampling with a post-presentation survey showed that 100% found the GNN helpful, and 70% altered the care plan based on the discussion. CONCLUSION: This report shows the utility of an international tumor board for LMIC focused on a challenging solid tumor where local expertise may be limited, with international multidisciplinary expert participation and educational sessions.

Vincristine-induced neurotoxicity in pediatric patients with rhabdomyosarcoma: A retrospective analysis of clinical features and outcome.

Vincristine is an essential component of rhabdomyosarcoma treatment. However, it can cause motor neurotoxicity, necessitating dose reductions. We retrospectively reviewed the rates and patterns of vincristine-induced motor neuropathy in children treated for rhabdomyosarcoma, and investigated effects on outcome. Fifteen of 43 patients (35%) developed motor neuropathies necessitating dose reductions, which ranged from 1.7% to 58% of planned cumulative dose. Older age was the only significant clinical risk factor. Almost half (47%) recovered during treatment with subsequent dose escalation. Most patients had complete resolution of symptoms upon follow-up. There was no discernible effect of treatment reduction on survival or relapse rates.

Signaling pathways in Rhabdomyosarcoma invasion and metastasis.

Rhabdomyosarcoma (RMS) is an aggressive childhood mesenchymal tumor with two major molecular and histopathologic subtypes: fusion-positive (FP)RMS, characterized by the PAX3-FOXO1 fusion protein and largely of alveolar histology, and fusion-negative (FN)RMS, the majority of which exhibit embryonal tumor histology. Metastatic disease continues to be associated with poor overall survival despite intensive treatment strategies. Studies on RMS biology have provided some insight into autocrine as well as paracrine signaling pathways that contribute to invasion and metastatic propensity. Such pathways include those driven by the PAX3-FOXO1 fusion oncoprotein in FPRMS and signaling pathways such as IGF/RAS/MEK/ERK, PI3K/AKT/mTOR, cMET, FGFR4, and PDGFR in both FP and FNRMS. In addition, specific cytoskeletal proteins, G protein coupled receptors, Hedgehog, Notch, Wnt, Hippo, and p53 pathways play a role, as do specific microRNA. Paracrine factors, including secreted proteins and RMS-derived exosomes that carry cargo of protein and miRNA, have also recently emerged as potentially important players in RMS biology. This review summarizes the known factors contributing to RMS invasion and metastasis and their implications on identifying targets for treatment and a better understanding of metastatic RMS.

Pediatric oncology infrastructure and workforce training needs: A report from the Pediatric Oncology East and Mediterranean (POEM) Group.

BACKGROUND: Inadequate numbers of trained health care providers (HCPs) contribute to poor pediatric oncology (PO) outcomes, particularly in low- and lower middle-income countries (L/LMICs). An understanding of the characteristics of the workforce challenges is vital for addressing these problems. METHODS: The Pediatric Oncology East and Mediterranean (POEM) Group surveyed PO centers in countries of North Africa, Middle East, Central Asia, and Indian subcontinent on infrastructure and workforce capacity, service availability, and training opportunities for HCPs. Participating centers were categorized by the World Bank income levels for their countries and correlated with services, workload and staffing characteristics, and training needs. RESULTS: Fifty of 82 member centers (61%) from 21 countries responded to the survey. Two hundred ninety-nine pediatric oncologists and 1176 nurses treated 12 496 new PO patients/year, with a 1451-bed utilization. The majority (71%) of new cases occurred in L/LMICs. The availability of HCPs correlated with country income level, as did pediatric subspecialty access, while availability of support services was unrelated. Twenty-five centers in 11 countries offered PO fellowship training for physicians, whereas 13 PO nurse training centers in nine countries had the capacity to train 273 nurses annually. The survey respondents indicated that, among their existing workforce, an average of 3.5 physicians and 14 nurses per institution would benefit from additional PO training opportunities. CONCLUSIONS: The participating centers exhibited intraregional heterogeneity in financial resources, infrastructure, workload, workforce, and medical services. Our findings provide insight into the disparities and regional resources available to POEM, which can be mobilized to rectify specific deficiencies.

Treatment-induced cerebral sinus venous thrombosis in childhood acute lymphoblastic malignancies: New risk factors to consider.

BACKGROUND: Cerebral sinus venous thrombosis (CSVT) is one of the many side effects encountered during acute lymphoblastic leukemia (ALL) therapy. Due to the rarity of cases, lack of data, and consensus management, no recommendations exist to target the population at risk. METHODS: This is a retrospective chart review of 229 consecutive patients diagnosed with ALL with an age range of 1-21 years, treated at the Children's Cancer Center of Lebanon between October 2007 and February 2018. RESULTS: The incidence of CSVT was 10.5%. Using univariate analysis, increased risk of CSVT was observed with male gender, age >10 years, T-cell immunophenotype, intermediate/high-risk disease, maximum triglyceride (TG) level of >615 mg/dl, presence of mediastinal mass, and larger body surface area (BSA). With multivariate analysis, the only statistically significant risk factors were maximum TG level, BSA, presence of mediastinal mass, and risk stratification (intermediate/high risk). CONCLUSION: Our study was able to unveil TG level of >615 mg/dl, mediastinal mass, and a larger BSA as novel risk factors that have not been previously discussed in the literature.

Impact of the coronavirus disease 2019 (COVID-19) pandemic on pediatric oncology care in the Middle East, North Africa, and West Asia region: A report from the Pediatric Oncology East and Mediterranean (POEM) group.

BACKGROUND: Childhood cancer is a highly curable disease when timely diagnosis and appropriate therapy are provided. A negative impact of the coronavirus disease 2019 (COVID-19) pandemic on access to care for children with cancer is likely but has not been evaluated. METHODS: A 34-item survey focusing on barriers to pediatric oncology management during the COVID-19 pandemic was distributed to heads of pediatric oncology units within the Pediatric Oncology East and Mediterranean (POEM) collaborative group, from the Middle East, North Africa, and West Asia. Responses were collected on April 11 through 22, 2020. Corresponding rates of proven COVID-19 cases and deaths were retrieved from the World Health Organization database. RESULTS: In total, 34 centers from 19 countries participated. Almost all centers applied guidelines to optimize resource utilization and safety, including delaying off-treatment visits, rotating and reducing staff, and implementing social distancing, hand hygiene measures, and personal protective equipment use. Essential treatments, including chemotherapy, surgery, and radiation therapy, were delayed in 29% to 44% of centers, and 24% of centers restricted acceptance of new patients. Clinical care delivery was reported as negatively affected in 28% of centers. Greater than 70% of centers reported shortages in blood products, and 47% to 62% reported interruptions in surgery and radiation as well as medication shortages. However, bed availability was affected in <30% of centers, reflecting the low rates of COVID-19 hospitalizations in the corresponding countries at the time of the survey. CONCLUSIONS: Mechanisms to approach childhood cancer treatment delivery during crises need to be re-evaluated, because treatment interruptions and delays are expected to affect patient outcomes in this otherwise largely curable disease.

Isolated Central Nervous System Relapse Following Treatment Reduction in Low-risk Acute Lymphoblastic Leukemia at the Children's Cancer Center of Lebanon.

The aim of this trial was to decrease the incidence of life-threatening infections by decreasing the dose and the duration of dexamethasone treatment during maintenance therapy. This was a prospective, nonrandomized trial of low-risk acute lymphoblastic leukemia patients 1 to 18 years of age who were treated at the Children's Cancer Center of Lebanon (CCCL). Patients consecutively diagnosed between 2002 and 2013 were divided into groups 1 and 2 receiving total dexamethasone doses of 1144 and 618 mg/m, respectively. A total of 84 patients were assigned to group 1 and 33 patients to group 2. The 5-year cumulative incidence of isolated central nervous system relapse increased from (n=0% [95% confidence interval: 0%-4.4%]) in group 1 to 9.1% [95% confidence interval: 3%-23%]; P=0.021) in group 2. Decreasing cumulative dose of dexamethasone for low-risk childhood acute lymphoblastic leukemia patients aiming to avoid serious viral infections led to a significant increase in isolated central nervous system relapse.

Proteomic Profiling of Rhabdomyosarcoma-Derived Exosomes Yield Insights into Their Functional Role in Paracrine Signaling.

Exosomes are important intercellular communication vehicles, secreted into body fluids by multiple cell types, including tumor cells. They have been demonstrated to contribute to the metastatic progression of tumor cells through paracrine signaling. Tumor exosomes contain intact and functional proteins, mRNA and miRNA that may alter the cellular environment to favor tumor growth. We evaluated the protein cargo of exosomes derived from the childhood tumor rhabdomyosarcoma (RMS) and the molecular pathways they are implicated in to decipher their role in the progression of this aggressive disease. We conducted a mass spectrometry analysis of exosome content isolated from five RMS cell lines: three of embryonal RMS (ERMS) and two of alveolar RMS (ARMS) histology and verified results by multiple reaction monitoring and western blot analyses. Results revealed 161 common proteins in ERMS-derived exosomes and 122 common proteins in ARMS-derived exosomes, of which 81 proteins were common to both subtypes. Using both PANTHER gene classification and Pathway Studio software, we assessed the perturbed biological processes and altered pathways in which the exosomal proteins are involved. The 81 commonly expressed proteins included those involved in "cell-signaling," "cell-movement," and "cancer." Pathways engaging the identified proteins revealed 37 common pathways including "integrin signaling pathway," "inflammation mediated by chemokine and cytokine signaling pathway," and "angiogenesis." Finally, a comparison of exosomal proteins of RMS cells with publicly available datasets from other cancer cells revealed that 36 proteins are specific and endogenous to the RMS-exosomes. Taken together, our results reveal that RMS-derived exosomes carry a protein cargo that contributes to conserved cellular signaling networks across multiple cell lines, and we also identify RMS exosome-specific proteins that should be further evaluated as possible novel biomarkers for this tumor.

Identifying barriers to treatment of childhood rhabdomyosarcoma in resource-limited settings: A literature review.

We performed a literature review to examine barriers for rhabdomyosarcoma treatment in low-resource settings, and identified 29 articles from 14 middle-income countries, with none from low-income countries. Notable findings included inconsistent use of local control modalities, lack of diagnostics in some settings, and high rate of abandonment specifically in low middle-income countries. Reported limitations included lack of surgical expertise and/or radiation therapy, advanced stage of disease, and absence of health insurance. Although very poor outcomes were prevalent in several settings, good outcomes were achievable in others when multidisciplinary therapy and financial coverage of medical care were made available.

Establishment of a formal program for retinoblastoma: Feasibility of clinical coordination across borders and impact on outcome.

Retinoblastoma is an ocular tumor that occurs in young children, in either heritable or sporadic manner. The relative rarity of retinoblastoma, and the need for expensive equipment, anesthesia, and pediatric ophthalmologic expertise, are barriers for effective treatment in developing countries. Also, with an average age-adjusted incidence of two to five cases per million children, patient number limits development of local expertise in countries with small populations. Lebanon is a small country with a population of approximately 4.5 million. In 2012, a comprehensive retinoblastoma program was formalized at the Children's Cancer Institute (CCI) at the American University of Beirut Medical Center, and resources were allocated for efficient interdisciplinary coordination to attract patients from neighboring countries such as Syria and Iraq, where such specialized therapy is also lacking. Through this program, care was coordinated across hospitals and borders such that patients would receive scheduled chemotherapy at their institution, and monthly retinal examinations and focal laser therapy at the CCI in Lebanon. Our results show the feasibility of successful collaboration across borders, with excellent patient and physician adherence to treatment plans. This was accompanied by an increase in patient referrals, which enables continued expertise development. However, the majority of patients presented with advanced intraocular disease, necessitating enucleation in 90% of eyes in unilateral cases, and more than 50% of eyes in bilateral cases. Future efforts need to focus on expanding the program that reaches to additional hospitals in both countries, and promoting early diagnosis, for further improvement of globe salvage rates.

Illness cognition and health anxiety in parents of children with cancer.

Purpose: Health anxiety is a clinical entity characterized by a pathological fear of illness. Illness cognition refers to persistent positive or negative thoughts an individual has towards illness. Evidence has shown that patients with chronic conditions who possess negative illness cognitions experience greater social, emotional, and physical difficulties than patients with positive illness cognitions. This study aims to measure the prevalence of health anxiety in a population of parents of children with cancer, and investigate the association between positive and negative illness cognitions and health anxiety. Methods: We interviewed 105 parents of children with cancer and administered Arabic versions of the Illness Cognition Questionnaire - Parent Version and the Short Health Anxiety Inventory. Results: The mean parental age was 37.7 years with the majority of participants being mothers (78.1%) and married (94.3%) and with 35.2% having completed university education. The average age of the child with cancer was 8.4 years, with the largest proportion of children suffering from leukemia. The prevalence of health anxiety among parents of children with cancer was 21%. The following two dimensions of illness cognition were significantly associated with health anxiety: Helplessness (B = 0.222, p = 0.021) and lower Acceptance (B = -0.242, p = 0.008). Other variables associated with health anxiety were perceived inadequate income (B = -0.238, p = 0.021) and personal illness or illness of a family member/close friend (B = 0.251, p = 0.013). Conclusions: Parents of children with cancer may experience health anxiety. Predictors of health anxiety include feelings of helplessness, lower acceptance, inadequate income, and extended family illnesses.

Displaced children with cancer in Lebanon: A sustained response to an unprecedented crisis.

BACKGROUND: The unrest in Syria has resulted in an escalating refugee crisis. The postwar lack of health care infrastructure in Iraq has also resulted in Iraqis seeking health care in neighboring countries. Pediatric cancer is largely curable, although its treatment is expensive and complex. Strategies to implement pediatric cancer care with curative intent in these vulnerable populations are lacking. METHODS: To assess the feasibility of a collaborative approach for the provision of care to displaced children with cancer, this study reviewed the experience of the authors over the past 6 years in Lebanon, the country with the highest number of refugees per capita in the world. RESULTS: The American University of Beirut Medical Center and the Children's Cancer Center of Lebanon Foundation, in partnership with St. Jude Children's Research Hospital and the American Lebanese Syrian Associated Charities, established 3 successive funding programs to treat displaced children with cancer along with a continuous assessment of resource utilization. Between 2011 and 2017, 575 non-Lebanese children suspected to have cancer were evaluated. Of those, 311 received direct medical support, with 107 receiving full-treatment coverage and 204 receiving limited-workup/specialty services; the remaining 264 patients received medical consultations. CONCLUSIONS: In addition to providing lifesaving humanitarian support, the coordination of care delivery, including the establishment of guidelines for prioritization, can help direct future efforts. Many patients continue to be in dire need of support, and this should be addressed via collaboration among governmental, nongovernmental, and health care organizations. Cancer 2018;124:1464-72. © 2018 American Cancer Society.

Genetic polymorphisms in candidate genes are not associated with increased vincristine-related peripheral neuropathy in Arab children treated for acute childhood leukemia: a single institution study.

OBJECTIVE: The aim of this study was to evaluate the potential association between candidate genetic polymorphisms and vincristine-related peripheral neuropathy in Arab children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: This is a retrospective evaluation of 133 Arab children treated for ALL at the Children's Cancer Center of Lebanon. Incidence and severity of, as well as the timing (in weeks) at which grade 2 or higher peripheral neuropathy occurred were recorded. Genotyping for ABCB1 (rs1045642), ABCB1 (rs1128503), ABCC2 (rs717620), CEP72 (rs924607), ETAA1 (rs17032980), and MTNR1B (rs12786200) was performed. RESULTS: A total of 26 (19.5%) individuals developed peripheral neuropathy, three of which occurred during the induction phase. No statistically significant associations were revealed for any of the polymorphisms with either incidence of vincristine-related toxicity, toxicity severity, or time to the first episode of grade 2 or higher vincristine-related peripheral neuropathy. CONCLUSION: This study presents the first pharmacogenetic analysis of vincristine-related peripheral neuropathy in children with ALL in an Arab country. We have shown that genetic polymorphisms in candidate genes are not associated with peripheral neuropathy secondary to chronic therapy with high-dose vincristine (2 mg/m) during the continuation phase. Concerning CEP72, our results are in line with the findings from the St Jude cohort of children treated for ALL with higher vincristine doses during chronic treatment. Larger high-throughput genetic analyses may be warranted to evaluate variants in other candidate genes such as CYP3A5 and reveal new nonpreviously reported alleles that may be peculiar to this region of the world.