Access to innovative therapies in pediatric oncology: Report of the nationwide experience in Canada.

BACKGROUND: The need for new therapies to improve survival and outcomes in pediatric oncology along with the lack of approval and accessible clinical trials has led to "out-of-trial" use of innovative therapies. We conducted a retrospective analysis of requests for innovative anticancer therapy in Canadian pediatric oncology tertiary centers for patients less than 30 years old between 2013 and 2020. METHODS: Innovative therapies were defined as cancer-directed drugs used (a) off-label, (b) unlicensed drugs being used outside the context of a clinical trial, or (c) approved drugs with limited evidence in pediatrics. We excluded cytotoxic chemotherapy, cellular products, and cytokines. RESULTS: We retrieved data on 352 innovative therapy drug requests. Underlying diagnosis was primary CNS tumor 31%; extracranial solid tumor 37%, leukemia/lymphoma 22%, LCH 2%, and plexiform neurofibroma 6%. RAS/MAP kinase pathway inhibitors were the most frequently requested innovative therapies in 28% of all requests followed by multi-targeted tyrosine kinase inhibitors (17%), inhibitors of the PIK3CA-mTOR-AKT pathway (8%), immune checkpoints inhibitors (8%), and antibody drug conjugates (8%). In 112 out of 352 requests, innovative therapies were used in combination with another anticancer agent. 48% of requests were motivated by the presence of an actionable molecular target. Compassionate access accounted for 52% of all requests while public insurance was used in 27%. Mechanisms of funding varied between provinces. CONCLUSION: This real-world data collection illustrates an increasing use of "out-of-trial" innovative therapies in pediatric oncology. This new field of practice warrants further studies to understand the impact on patient trajectory and equity in access to innovative therapies.

Performance of the eHealth decision support tool, MIPOGG, for recognising children with Li-Fraumeni, DICER1, Constitutional mismatch repair deficiency and Gorlin syndromes.

BACKGROUND: Cancer predisposition syndromes (CPSs) are responsible for at least 10% of cancer diagnoses in children and adolescents, most of which are not clinically recognised prior to cancer diagnosis. A variety of clinical screening guidelines are used in healthcare settings to help clinicians detect patients who have a higher likelihood of having a CPS. The McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) is an electronic health decision support tool that uses algorithms to help clinicians determine if a child/adolescent diagnosed with cancer should be referred to genetics for a CPS evaluation. METHODS: This study assessed MIPOGG's performance in identifying Li-Fraumeni, DICER1, Constitutional mismatch repair deficiency and Gorlin (nevoid basal cell carcinoma) syndromes in a retrospective series of 84 children diagnosed with cancer and one of these four CPSs in Canadian hospitals over an 18-year period. RESULTS: MIPOGG detected 82 of 83 (98.8%) evaluable patients with any one of these four genetic conditions and demonstrated an appropriate rationale for suggesting CPS evaluation. When compared with syndrome-specific clinical screening criteria, MIPOGG's ability to correctly identify children with any of the four CPSs was equivalent to, or outperformed, existing clinical criteria respective to each CPS. CONCLUSION: This study adds evidence that MIPOGG is an appropriate tool for CPS screening in clinical practice. MIPOGG's strength is that it starts with a specific cancer diagnosis and incorporates criteria relevant for associated CPSs, making MIPOGG a more universally accessible diagnostic adjunct that does not require in-depth knowledge of each CPS.

COVID-19 and Sickle Cell Disease in the Province of Quebec, Canada: Outcomes after Two Years of the Pandemic.

BACKGROUND: Patients with sickle cell disease (SCD) are considered at higher risk of severe COVID-19 infection. However, morbidity and mortality rates are variable among countries. To date, there are no published reports that document outcomes of SCD patients with COVID-19 in Canada. METHODS: A web-based registry was implemented in June 2020 capturing outcomes of SCD patients with COVID-19 from March 2020 to April 2022 and comparing them to the general population of Quebec, Canada. RESULTS: After 24 months of the pandemic, 185 SCD patients with confirmed SARS-CoV-2 infection were included in the registry. Overall, the population was young (median age 12 years old) and had few comorbidities. No deaths were reported. Risk of hospitalization and admission to intensive care unit (ICU) because of COVID-19 was higher in patients with SCD than in the general population (relative risks (RR) 5.15 (95% confidence interval (95% CI) 3.84-6.91), p ˂ 0.001 and 4.56 (95% CI 2.09-9.93) p ˂ 0.001). A history of arterial hypertension or acute chest syndrome in the past 12 months was associated with a higher risk of severe disease (RR = 3.06 (95% CI 1.85-5.06) p = 0.008 and 2.27 (95% CI 1.35-3.83) p = 0.01). Hospitalized patients had lower hemoglobin F than non-hospitalized patients (12% vs. 17%, p = 0.02). For those who had access to vaccination at the time of infection, 25 out of 26 patients were adequately vaccinated and had mild disease. CONCLUSIONS: The SCD population is at higher risk of severe disease than the general population. However, we report favorable outcomes as no deaths occurred. Registries will continue to be critical to document the impact of novel COVID-19 specific therapy and vaccines for the SCD population.

Poor outcome after hematopoietic stem cell transplantation of patients with unclassified inherited bone marrow failure syndromes.

Classification of inherited bone marrow failure syndromes (IBMFSs) according to clinical and genetic diagnoses enables proper adjustment of treatment. Unfortunately, 30% of patients enrolled in the Canadian Inherited Marrow Failure Registry (CIMFR) with features suggesting hereditability could not be classified with a specific syndromic diagnosis. We analyzed the outcome of hematopoietic stem cell transplantation (HSCT) in unclassified IBMFSs (uIBMFSs) and the factors associated with outcome. Twenty-two patients with uIBMFSs and 70 patients with classified IBMFSs underwent HSCT. Five-year overall survival of uIBMFS patients after HSCT was inferior to that of patients with classified IBMFSs (56% vs 76.5%). The outcome of patients with uIBMFS who received cord blood was significantly lower than that of patients who received other stem cell sources (14.8% vs 90.9%). Engraftment failure was higher among patients with uIBMFS who received cord blood than those who received bone marrow. None of the following factors were significantly associated with poor survival: transfusion load, transplant indication, the intensity of conditioning regimen, human leukocyte antigen-identical sibling/alternative donor. We suggest that identifying the genetic diagnosis is essential to modulate the transplant procedure including conditioning agents and stem cell sources for better outcome and the standard cord blood transplantation (CBT) should be avoided in uIBMFS.

Performance of the McGill Interactive Pediatric OncoGenetic Guidelines for Identifying Cancer Predisposition Syndromes.

IMPORTANCE: Prompt recognition of a child with a cancer predisposition syndrome (CPS) has implications for cancer management, surveillance, genetic counseling, and cascade testing of relatives. Diagnosis of CPS requires practitioner expertise, access to genetic testing, and test result interpretation. This diagnostic process is not accessible in all institutions worldwide, leading to missed CPS diagnoses. Advances in electronic health technology can facilitate CPS risk assessment. OBJECTIVE: To evaluate the diagnostic accuracy of a CPS prediction tool (McGill Interactive Pediatric OncoGenetic Guidelines [MIPOGG]) in identifying children with cancer who have a low or high likelihood of having a CPS. DESIGN, SETTING, AND PARTICIPANTS: In this international, multicenter diagnostic accuracy study, 1071 pediatric (<19 years of age) oncology patients who had a confirmed CPS (12 oncology referral centers) or who underwent germline DNA sequencing through precision medicine programs (6 centers) from January 1, 2000, to July 31, 2020, were studied. EXPOSURES: Exposures were MIPOGG application in patients with cancer and a confirmed CPS (diagnosed through routine clinical care; n = 413) in phase 1 and MIPOGG application in patients with cancer who underwent germline DNA sequencing (n = 658) in phase 2. Study phases did not overlap. Data analysts were blinded to genetic test results. MAIN OUTCOMES AND MEASURES: The performance of MIPOGG in CPS recognition was compared with that of routine clinical care, including identifying a CPS earlier than practitioners. The tool's test characteristics were calculated using next-generation germline DNA sequencing as the comparator. RESULTS: In phase 1, a total of 413 patients with cancer (median age, 3.0 years; range, 0-18 years) and a confirmed CPS were identified. MIPOGG correctly recognized 410 of 412 patients (99.5%) as requiring referral for CPS evaluation at the time of primary cancer diagnosis. Nine patients diagnosed with a CPS by a practitioner after their second malignant tumor were detected by MIPOGG using information available at the time of the first cancer. In phase 2, of 658 children with cancer (median age, 6.6 years; range, 0-18.8 years) who underwent comprehensive germline DNA sequencing, 636 had sufficient information for MIPOGG application. When compared with germline DNA sequencing for CPS detection, the MIPOGG test characteristics for pediatric-onset CPSs were as follows: sensitivity, 90.7%; specificity, 60.5%; positive predictive value, 17.6%; and negative predictive value, 98.6%. Tumor DNA sequencing data confirmed the MIPOGG recommendation for CPS evaluation in 20 of 22 patients with established cancer-CPS associations. CONCLUSIONS AND RELEVANCE: In this diagnostic study, MIPOGG exhibited a favorable accuracy profile for CPS screening and reduced time to CPS recognition. These findings suggest that MIPOGG implementation could standardize and rationalize recommendations for CPS evaluation in children with cancer.

Androgen therapy in inherited bone marrow failure syndromes: analysis from the Canadian Inherited Marrow Failure Registry.

Progressive cytopenia is a serious complication among paediatric patients with inherited bone marrow failure syndromes (IBMFS). Androgens have been used to improve blood counts in different bone marrow failure conditions. Little is known about efficacy and toxicity with new androgens (i.e., danazol) in different types of IBMFS. We identified 29 patients from the Canadian Inherited Marrow Failure Registry, who received oxymetholone or danazol. Sixteen (55%) had haematological response including patients with unclassified IBMFS (45%). Danazol showed a better toxicity profile and similar efficacy compared to oxymetholone. Androgens are an effective and safe option to ameliorate bone marrow failure in IBMFS.

Canadian Pediatric Neuro-Oncology Standards of Practice.

Primary CNS tumors are the leading cause of cancer-related death in pediatrics. It is essential to understand treatment trends to interpret national survival data. In Canada, children with CNS tumors are treated at one of 16 tertiary care centers. We surveyed pediatric neuro-oncologists to create a national standard of practice to be used in the absence of a clinical trial for seven of the most prevalent brain tumors in children. This allowed description of practice across the country, along with a consensus. This had a multitude of benefits, including understanding practice patterns, allowing for a basis to compare in future research and informing Health Canada of the current management of patients. This also allows all children in Canada to receive equivalent care, regardless of location.

Reanalysing genomic data by normalized coverage values uncovers CNVs in bone marrow failure gene panels.

Inherited bone marrow failure syndromes (IBMFSs) are genetically heterogeneous disorders with cytopenia. Many IBMFSs also feature physical malformations and an increased risk of cancer. Point mutations can be identified in about half of patients. Copy number variation (CNVs) have been reported; however, the frequency and spectrum of CNVs are unknown. Unfortunately, current genome-wide methods have major limitations since they may miss small CNVs or may have low sensitivity due to low read depths. Herein, we aimed to determine whether reanalysis of NGS panel data by normalized coverage value could identify CNVs and characterize them. To address this aim, DNA from IBMFS patients was analyzed by a NGS panel assay of known IBMFS genes. After analysis for point mutations, heterozygous and homozygous CNVs were searched by normalized read coverage ratios and specific thresholds. Of the 258 tested patients, 91 were found to have pathogenic point variants. NGS sample data from 165 patients without pathogenic point mutations were re-analyzed for CNVs; 10 patients were found to have deletions. Diamond Blackfan anemia genes most commonly exhibited heterozygous deletions, and included RPS19, RPL11, and RPL5. A diagnosis of GATA2-related disorder was made in a patient with myelodysplastic syndrome who was found to have a heterozygous GATA2 deletion. Importantly, homozygous FANCA deletion were detected in a patient who could not be previously assigned a specific syndromic diagnosis. Lastly, we identified compound heterozygousity for deletions and pathogenic point variants in RBM8A and PARN genes. All deletions were validated by orthogonal methods. We conclude that careful analysis of normalized coverage values can detect CNVs in NGS panels and should be considered as a standard practice prior to do further investigations.

Molecular Profiling of Hard-to-Treat Childhood and Adolescent Cancers.

Importance: Little progress in pediatric cancer treatment has been noted in the past decade, urging the development of novel therapeutic strategies for adolescents and children with hard-to-treat cancers. Use of comprehensive molecular profiling in the clinical management of children and adolescents with cancer appears a suitable approach to improve patient care and outcomes, particularly for hard-to-treat cases. Objective: To assess the feasibility of identifying potentially actionable mutations using next-generation sequencing-based assays in a clinically relevant time frame. Design, Setting, and Participants: This diagnostic study reports the results of the TRICEPS study, a prospective genome sequencing study conducted in Québec, Canada. Participants, aged 18 years or younger at diagnosis, with refractory or relapsed childhood and adolescent cancers were enrolled from April 2014 through January 2018. Whole-exome sequencing (WES) of matched tumor normal samples and RNA sequencing of tumor were performed to identify single-nucleotide variants, fusion transcripts, differential gene expression, and copy number alterations. Results reviewed by a team of experts were further annotated, synthesized into a report, and subsequently discussed in a multidisciplinary molecular tumor board. Main Outcomes and Measures: Molecular profiling of pediatric patients with hard-to-treat cancer, identification of actionable and targetable alteration needed for the management of these patients, and proposition of targeted and personalized novel therapeutic strategies. Results: A total of 84 patients with hard-to-treat cancers were included in the analysis. These patients had a mean (range) age of 10.1 (1-21) years and a similar proportion of male (45 [54%]) and female (39 [46%]). Sixty-two patients (74%) had suitable tissues for multimodal molecular profiling (WES and RNA sequencing). The process from DNA or RNA isolation to genomic sequencing and data analysis steps took a median (range) of 24 (4-41) days. Potentially actionable alterations were identified in 54 of 62 patients (87%). Actions were taken in 22 of 54 patients (41%), and 18 (33%) either were on a second or third line of treatment, were in remission, or had stable disease and thus no actions were taken. Conclusions and Relevance: Incorporating genomic sequencing into the management of hard-to-treat childhood and adolescent cancers appeared feasible; molecular profiling may enable the identification of potentially actionable alterations with clinical implications for most patients, including targeted therapy and clinically relevant information of diagnostic, prognostic, and monitoring significance.

Survival Following Tumor Recurrence in Children With Medulloblastoma.

Medulloblastoma is the most common malignant brain tumor in children. Published survival rates for this tumor are ∼70%; however, there is limited published information on outcome after disease recurrence. This was an observational study which included all persons under the age of 18 years diagnosed with medulloblastoma from 1990 to 2009 inclusive in Canada. Data collected included date of diagnosis, age at diagnosis, sex, stage, pathology, treatment, recurrence, and current status. Survival rates were determined. In total, 550 cases were ascertained meeting the study criteria. The overall survival rate at 1 year was 83.6%±1.7%, at 3 years 77.2%±1.9%, and at 5 years 72.5%±20%. The progression-free survival rates were 78%±1.9%, 70%±2.1%, and 69±2.1% at 1, 3, and 5 years from initial diagnosis. In total, 173 (31.2%) were reported to have had tumor recurrence and 23 (11.4%) of them were alive at the time of survey with an overall survival rate at 1 year of 38.3%±4%, at 2 years of 16.9%±3.3%, and at 5 years of 12.4%±2.8%. Our data confirm that children with recurrent medulloblastoma have a poor prognosis, supporting the need for novel treatment approaches for this group.

The clinical impact of copy number variants in inherited bone marrow failure syndromes.

Inherited bone marrow failure syndromes (IBMFSs) comprise a genetically heterogeneous group of diseases with hematopoietic failure and a wide array of physical malformations. Copy number variants (CNVs) were reported in some IBMFSs. It is unclear what impact CNVs play in patients evaluated for a suspected diagnosis of IBMFS. Clinical and genetic data of 323 patients from the Canadian Inherited Marrow Failure Registry from 2001 to 2014, who had a documented genetic work-up, were analyzed. Cases with pathogenic CNVs (at least 1 kilobasepairs) were compared to cases with other mutations. Genotype-phenotype correlations were performed to assess the impact of CNVs. Pathogenic nucleotide-level mutations were found in 157 of 303 tested patients (51.8%). Genome-wide CNV analysis by single nucleotide polymorphism arrays or comparative genomic hybridization arrays revealed pathogenic CNVs in 11 of 67 patients tested (16.4%). In four of these patients, identification of CNV was crucial for establishing the correct diagnosis as their clinical presentation was ambiguous. Eight additional patients were identified to harbor pathogenic CNVs by other methods. Of the 19 patients with pathogenic CNVs, four had compound-heterozygosity of a CNV with a nucleotide-level mutation. Pathogenic CNVs were associated with more extensive non-hematological organ system involvement (p=0.0006), developmental delay (p=0.006) and short stature (p=0.04) compared to nucleotide-level mutations. In conclusion, a significant proportion of patients with IBMFSs harbor pathogenic CNVs which were associated with a more extensive non-hematological phenotype in this cohort. Patients with a phenotype suggestive of IBMFSs but without identification of pathogenic nucleotide-level mutations should undergo specific testing for CNVs.

Invasive Rothia infections in children with acute myeloid leukemia: A report from the Canadian infections in AML research group.

Rothia spp. (previously termed Stomatococcus) are normal flora that can cause invasive infections in immunocompromised hosts. The objective of this study was to describe infection characteristics and outcomes of Rothia spp. infections in a large cohort of children with newly diagnosed acute myeloid leukemia (AML). This retrospective chart review is a subanalysis of a larger study in which the aim was to identify factors associated with infection in pediatric patients with AML. Only sterile site infections occurring during chemotherapy were included. Among 578 children with AML, 17 (2.9%) children with at least 1 Rothia spp. infection were identified. All children were neutropenic at the time of infection. Eight (47%) had antecedent colitis or mucositis. Of the 17 infections, 16 were bacteremia and 1 was meningitis. Sepsis occurred in 4 patients, and 1 patient died due to infection. Rothia spp. infections are rare in pediatric AML but can cause significant morbidity and mortality. Future studies should describe trends in incidence and resistance patterns over time.

Whole Abdominal-Pelvic Radiotherapy in the Management of Primary Ewing Sarcoma of the Peritoneal Cavity.

Ewing sarcoma of the abdomen is a rare entity in pediatric oncology and represents a technical challenge both for surgeons and radiation oncologists. We document the case of a young female patient with primary disseminated, intraperitoneal Ewing sarcoma who after an excellent response to chemotherapy received preoperative whole abdominal-pelvic radiotherapy with good tolerance.

Improving diagnostic precision, care and syndrome definitions using comprehensive next-generation sequencing for the inherited bone marrow failure syndromes.

BACKGROUND: Phenotypic overlap among the inherited bone marrow failure syndromes (IBMFSs) frequently limits the ability to establish a diagnosis based solely on clinical features. >70 IBMFS genes have been identified, which often renders genetic testing prolonged and costly. Since correct diagnosis, treatment and cancer surveillance often depend on identifying the mutated gene, strategies that enable timely genotyping are essential. METHODS: To overcome these challenges, we developed a next-generation sequencing assay to analyse a panel of 72 known IBMFS genes. Cases fulfilling the clinical diagnostic criteria of an IBMFS but without identified causal genotypes were included. RESULTS: The assay was validated by detecting 52 variants previously found by Sanger sequencing. A total of 158 patients with unknown mutations were studied. Of 75 patients with known IBMFS categories (eg, Fanconi anaemia), 59% had causal mutations. Among 83 patients with unclassified IBMFSs, we found causal mutations and established the diagnosis in 18% of the patients. The assay detected mutant genes that had not previously been reported to be associated with the patient phenotypes. In other cases, the assay led to amendments of diagnoses. In 20% of genotype cases, the results indicated a cancer surveillance programme. CONCLUSIONS: The novel assay is efficient, accurate and has a major impact on patient care.

Survival of children with medulloblastoma in Canada diagnosed between 1990 and 2009 inclusive.

The treatment of medulloblastoma, the most common malignant brain tumor in children, has evolved over the last few decades. The objectives of this paper were to determine the survival of pediatric medulloblastoma in Canada, to determine if there has been an improvement in the survival rates between the years of 1990 and 2009, inclusive, and to determine prognostic factors for survival. All patients under the age of 18 years diagnosed with medulloblastoma from 1990 to 2009, inclusive, in Canada were included. Data collected included date of diagnosis, age at diagnosis, gender, stage, pathology, treatment, recurrence and current status. From these, survival rates were determined. Data were obtained on 628 eligible patients. The overall 5-year survival rate for the study time period was 69.2 ± 3.3 %. The survival rate increased during the interval of 1996-2000, then remained stable; 1990-1994: 60.2 ± 4.3 %; 1995-1999: 73.2 ± 3.5 %; 2000-2004: 68.8 ± 3.7 %; and 2005-2009: 72.1 ± 4.9 %, p = 0.05. Children over 14 years of age had a significantly better overall survival than those age 5-14 and those under 5 (85.7 ± 5.5 % vs 76.1 ± 2.7 % and 60.8 ± 3 % respectively, p = 0.001). Histologic medulloblastoma subtype and M stage of disease did not result in significant differences in survival. Despite changes in approaches to therapy, we demonstrate a steady survival rate for children with medulloblastoma after 1996. In our analyses, age over 14 years was associated with a higher survival rate.

The impact of category, cytopathology and cytogenetics on development and progression of clonal and malignant myeloid transformation in inherited bone marrow failure syndromes.

Inherited bone marrow failure syndromes are a group of rare, heterogeneous genetic disorders with a risk of clonal and malignant myeloid transformation including clonal marrow cytogenetic abnormalities, myelodysplastic syndrome and acute myeloid leukemia. The clinical characteristics, risk classification, prognostic factors and outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes are largely unknown. The aims of this study were to determine the impact of category, cytopathology and cytogenetics, the three components of the "Category Cytology Cytogenetics" classification of pediatric myelodysplastic syndrome, on the outcome of clonal and malignant myeloid transformation associated with inherited bone marrow failure. We used data from the Canadian Inherited Marrow Failure Registry. Among 327 patients with inherited bone marrow failure syndrome enrolled in the registry, the estimated risk of clonal and malignant myeloid transformation by the age of 18 years was 37%. The risk of clonal and malignant myeloid transformation varied according to the type of inherited bone marrow failure syndrome but was highest in Fanconi anemia. The development of clonal and malignant myeloid transformation significantly affected overall survival. Mortality varied based on cytopathological group. The largest group of patients had refractory cytopenia. Clonal marrow cytogenetic abnormalities were identified in 87% of patients with clonal and malignant myeloid transformation, and different cytogenetic groups had different impacts on disease progression. We conclude that category, cytopathology and cytogenetics in cases of clonal and malignant myeloid transformation associated with inherited bone marrow failure syndromes have an important impact on outcome and that the classification of such cases should incorporate these factors.

Incidence of medulloblastoma in Canadian children.

Medulloblastoma is the most common malignant brain tumor in children. There was a perception of pediatric neuro-oncologists that the incidence had declined in Canada. An epidemiological survey was undertaken to determine the incidence of this tumor in Canada and if a change had indeed occurred. All patients 14 years and under diagnosed with medulloblastoma from 1990 to 2009 inclusive in Canada were included. Data collected included date of diagnosis, age at diagnosis, gender, stage, pathology, treatment, recurrence and current status. Data were analysed for change in incidence over time. Data were obtained on 574 eligible patients. The mean overall incidence per 1,000,000 persons was 4.82 (95 % CI 4.28-5.35) for the study time period. The mean age at diagnosis was 5.8 years, and there was a male predominance. Although there was an increase in incidence over the first three time periods (24 % for 1990-1994, 27.5 % for 1995-1999, 27.7 % for 2000-2004), the most recent time period (2005-2009) showed a decrease (21 %). This was true for male children while the incidence was stable for females. The mean incidence rate was double for children under the age of 5 years (7.92 per million) compared to those over 5 years (3.64 per million).This study showed that from 1990 to 2009 the incidence of medulloblastoma was relatively stable, with a slight decrease in the last five-year time period.

Second Bacteremia During Antibiotic Treatment in Children With Acute Myeloid Leukemia: A Report From the Canadian Infections in Acute Myeloid Leukemia Research Group.

BACKGROUND: The risk of second bacteremia during antibiotic treatment for initial bacteremia is unknown in high-risk populations. Our objectives were to describe the prevalence of second bacteremia during treatment and identify risk factors in children with acute myeloid leukemia (AML). METHODS: We conducted a retrospective, population-based cohort study that included children and adolescents with de novo, non-M3 AML who were diagnosed and treated between January 1, 1995 and December 31, 2004 at 15 Canadian centers. Patients were monitored for bacteremia during chemotherapy until completion of treatment, hematopoietic stem cell transplantation, relapse, refractory disease, or death. RESULTS: There were 290 episodes of bacteremia occurring in 185 (54.3%) of 341 children. Eighteen (6.2%) had a second bacteremia while receiving antibiotic treatment. Two episodes of second bacteremia were complicated by sepsis; there were no infection-related deaths. Eleven episodes (61.1%) had either an initial Gram-positive and subsequent Gram-negative bacteremia or initial Gram-negative followed by Gram-positive bacteremia. Days receiving corticosteroids (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.07-1.12; P < .0001), cumulative dose of corticosteroids (OR, 1.04; 95% CI, 1.00-1.08; P = .035), and days of neutropenia from start of course to initial bacteremia (OR, 1.07; 95% CI, 1.02-1.12; P = .007) were significantly associated with second bacteremia. CONCLUSIONS: In pediatric AML, 6% of patients will experience a second bacteremia during antibiotic treatment; duration of corticosteroid exposure and neutropenia are risk factors. These patients remain at high risk for second bacteremia after identification of the initial bacteremia and warrant continued broad-spectrum treatment during profound neutropenia.