Clinical and biological landscape of constitutional mismatch-repair deficiency syndrome: an International Replication Repair Deficiency Consortium cohort study

BACKGROUND

Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare and aggressive cancer predisposition syndrome. Because a scarcity of data on this condition contributes to management challenges and poor outcomes, we aimed to describe the clinical spectrum, cancer biology, and impact of genetics on patient survival in CMMRD.

METHODS

In this cohort study, we collected cross-sectional and longitudinal data on all patients with CMMRD, with no age limits, registered with the International Replication Repair Deficiency Consortium (IRRDC) across more than 50 countries. Clinical data were extracted from the IRRDC database, medical records, and physician-completed case record forms. The primary objective was to describe the clinical features, cancer spectrum, and biology of the condition. Secondary objectives included estimations of cancer incidence and of the impact of the specific mismatch-repair gene and genotype on cancer onset and survival, including after cancer surveillance and immunotherapy interventions.

FINDINGS

We analysed data from 201 patients (103 males, 98 females) enrolled between June 5, 2007 and Sept 9, 2022. Median age at diagnosis of CMMRD or a related cancer was 8·9 years (IQR 5·9-12·6), and median follow-up from diagnosis was 7·2 years (3·6-14·8). Endogamy among minorities and closed communities contributed to high homozygosity within countries with low consanguinity. Frequent dermatological manifestations (117 [93%] of 126 patients with complete data) led to a clinical overlap with neurofibromatosis type 1 (35 [28%] of 126). 339 cancers were reported in 194 (97%) of 201 patients. The cumulative cancer incidence by age 18 years was 90% (95% CI 80-99). Median time between cancer diagnoses for patients with more than one cancer was 1·9 years (IQR 0·8-3·9). Neoplasms developed in 15 organs and included early-onset adult cancers. CNS tumours were the most frequent (173 [51%] cancers), followed by gastrointestinal (75 [22%]), haematological (61 [18%]), and other cancer types (30 [9%]). Patients with CNS tumours had the poorest overall survival rates (39% [95% CI 30-52] at 10 years from diagnosis; log-rank p<0·0001 across four cancer types), followed by those with haematological cancers (67% [55-82]), gastrointestinal cancers (89% [81-97]), and other solid tumours (96% [88-100]). All cancers showed high mutation and microsatellite indel burdens, and pathognomonic mutational signatures. MLH1 or MSH2 variants caused earlier cancer onset than PMS2 or MSH6 variants, and inferior survival (overall survival at age 15 years 63% [95% CI 55-73] for PMS2, 49% [35-68] for MSH6, 19% [6-66] for MLH1, and 0% for MSH2; p<0·0001). Frameshift or truncating variants within the same gene caused earlier cancers and inferior outcomes compared with missense variants (p<0·0001). The greater deleterious effects of MLH1 and MSH2 variants as compared with PMS2 and MSH6 variants persisted despite overall improvements in survival after surveillance or immune checkpoint inhibitor interventions.

INTERPRETATION

The very high cancer burden and unique genomic landscape of CMMRD highlight the benefit of comprehensive assays in timely diagnosis and precision approaches toward surveillance and immunotherapy. These data will guide the clinical management of children and patients who survive into adulthood with CMMRD.

FUNDING

The Canadian Institutes for Health Research, Stand Up to Cancer, Children's Oncology Group National Cancer Institute Community Oncology Research Program, Canadian Cancer Society, Brain Canada, The V Foundation for Cancer Research, BioCanRx, Harry and Agnieszka Hall, Meagan's Walk, BRAINchild Canada, The LivWise Foundation, St Baldrick Foundation, Hold'em for Life, and Garron Family Cancer Center.

Pediatric oncology provider perspectives and patient/family perceptions of chemotherapy-induced nausea and vomiting management: Experiences at an academic medical center

BACKGROUND

Chemotherapy-induced nausea and vomiting (CINV) is common in children undergoing cancer treatment, and significantly impacts quality of life. Clinical practice guidelines (CPGs) have been developed to guide CINV management, though many patients do not receive guideline-concordant care. Few studies have examined provider perspectives on CINV management or preferred improvement approaches, or pediatric patient perception of CINV control.

METHODS

A cross-sectional study of pediatric oncology providers was conducted at a large freestanding children's hospital. Providers completed an anonymous online survey about CINV control in patients admitted for scheduled chemotherapy, and their knowledge and utilization of CINV CPGs. A survey of English and Spanish-speaking pediatric oncology patients admitted for scheduled chemotherapy was conducted to assess CINV management, with key demographics used to understand association with perceptions and adherence to antiemetic guidelines.

RESULTS

For providers, 75% of respondents felt CINV management could be moderately or extremely improved, significantly more so by chemotherapy prescribers and pediatric medical residents than nurses. Over half of respondents did not have awareness of CINV CPGs, particularly pediatric medical residents. For patients, nausea was reported to be extremely well controlled in 44% of cases, and vomiting extremely well controlled in 50% of cases. There were no significant differences in patient-reported CINV across demographics, when considering emetogenicity of chemotherapy received, or concordance to guidelines.

CONCLUSIONS

Implementing education in this area may help to improve provider comfort, and ultimately, the patient experience. Future studies will expand upon this novel patient perception, and develop and evaluate CINV management interventions.

Bosutinib in Resistant and Intolerant Pediatric Patients With Chronic Phase Chronic Myeloid Leukemia: Results From the Phase I Part of Study ITCC054/COG AAML1921

PURPOSE

Bosutinib is approved for adults with chronic myeloid leukemia (CML): 400 mg once daily in newly diagnosed (ND); 500 mg once daily in resistant/intolerant (R/I) patients. Bosutinib has a different tolerability profile than other tyrosine kinase inhibitors (TKIs) and potentially less impact on growth (preclinical data). The primary objective of this first-in-child trial was to determine the recommended phase II dose (RP2D) for pediatric R/I and ND patients.

PATIENTS AND METHODS

In the phase I part of this international, open-label trial (ClinicalTrials.gov identifier: NCT04258943), children age 1-18 years with R/I (per European LeukemiaNet 2013) Ph+ CML were enrolled using a 6 + 4 design, testing 300, 350, and 400 mg/m2 once daily with food. The RP2D was the dose resulting in 0/6 or 1/10 dose-limiting toxicities (DLTs) during the first cycle and achieving adult target AUC levels for the respective indication. As ND participants were only enrolled in phase II, the ND RP2D was selected based on data from R/I patients.

RESULTS

Thirty patients were enrolled; 27 were evaluable for DLT: six at 300 mg/m2, 11 at 350 mg/m2 (one DLT), and 10 at 400 mg/m2 (one DLT). The mean AUCs at 300 mg/m2, 350 mg/m2, and 400 mg/m2 were 2.20 μg h/mL, 2.52 μg h/mL, and 2.66 μg h/mL, respectively. The most common adverse event was diarrhea (93%; ≥grade 3: 11%). Seven patients stopped because of intolerance and eight because of insufficient response. Complete cytogenetic and major molecular response to bosutinib appeared comparable with other published phase I/II trials with second-generation TKIs in children.

CONCLUSION

Bosutinib was safe and effective. The pediatric RP2D was 400 mg/m2 once daily (max 600 mg/d) with food in R/I patients and 300 mg/m2 once daily (max 500 mg/d) with food in ND patients, which achieved targeted exposures as per adult experience.

BCR/ABL-Positive Chronic Myeloid Leukemia in Children: Current Treatment Approach

PURPOSE OF REVIEW

The purpose of this review is to summarize the most updated treatment recommendations for pediatric CML, and to discuss current areas of investigation.

RECENT FINDINGS

There is new phase 1 data to support the safety of the non-ATP competitive tyrosine kinase inhibitor (TKI) asciminib in the pediatric cohort. Ongoing studies are investigating the role of treatment-free remission in children. Chronic phase CML in children is managed with lifelong TKI therapy; however, evidence of deeper remissions sustained with second-generation TKIs may permit shorter treatment courses. Use of more specific TKIs may mitigate some of the side effects specific to the pediatric cohort. Children with advanced phase CML should achieve a complete hematologic remission with use of a second-generation TKI prior to transplant to achieve the best outcome.

Efficacy and manageable safety of tagraxofusp in blastic plasmacytoid dendritic cell neoplasm: a case series of pediatric and adolescent/young adult patients

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) predominantly occurs in adults ≥60 years old; 10-20% of cases are pediatric or adolescent/young adult (AYA) patients. Tagraxofusp (TAG, Elzonris®) is the only approved treatment for BPDCN; in the United States it is approved for patients aged ≥2 years. Data on treating pediatric and AYA BPDCN patients are limited. We present a case series of pediatric and AYA patients with BPDCN treated with TAG. Eight patients (five newly diagnosed; three relapsed/refractory [R/R]), aged 2-21 years, received 12 mcg/kg TAG. Seven patients were female; most had skin (n = 6) and/or bone marrow (n = 4) involvement. No new safety signals were identified. Grade 3 adverse events were headache (n = 1) and transaminitis (n = 2). Three patients with newly diagnosed BPDCN achieved complete response, one achieved partial response, and one had stable disease (SD). One patient with R/R BPDCN achieved a minor response; one had SD. Seven patients (88%) were bridged to stem cell transplant: 80% of newly diagnosed patients and 100% of R/R patients. Five patients remained alive at last follow-up. These cases highlight the efficacy and safety of TAG in pediatric and AYA patients for whom there is no other approved BPDCN therapy.

Nivolumab Plus 5-Azacitidine in Pediatric Relapsed/Refractory Acute Myeloid Leukemia (AML): Phase I/II Trial Results from the Therapeutic Advances in Childhood Leukemia and Lymphoma (TACL) Consortium

Improvements in survival have been made over the past two decades for childhood acute myeloid leukemia (AML), but the approximately 40% of patients who relapse continue to have poor outcomes. A combination of checkpoint-inhibitor nivolumab and azacitidine has demonstrated improvements in median survival in adults with AML. This phase I/II study with nivolumab and azacitidine in children with relapsed/refractory AML (NCT03825367) was conducted through the Therapeutic Advances in Childhood Leukemia & Lymphoma consortium. Thirteen patients, median age 13.7 years, were enrolled. Patients had refractory disease with multiple reinduction attempts. Twelve evaluable patients were treated at the recommended phase II dose (established at dose level 1, 3 mg/kg/dose). Four patients (33%) maintained stable disease. This combination was well tolerated, with no dose-limiting toxicities observed. Grade 3-4 adverse events (AEs) were primarily hematological. Febrile neutropenia was the most common AE ≥ grade 3. A trend to improved quality of life was noted. Increases in CD8+ T cells and reductions in CD4+/CD8+ T cells and demethylation were observed. The combination was well tolerated and had an acceptable safety profile in pediatric patients with relapsed/refractory AML. Future studies might explore this combination for the maintenance of remission in children with AML at high risk of relapse.

The long-term efficacy and safety of nilotinib in pediatric patients with CML: a 5-year update of the DIALOG study

The efficacy and safety of nilotinib in pediatric patients with imatinib/dasatinib resistant/intolerant (R/I) or newly diagnosed (ND) Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia in chronic phase (CML-CP) was demonstrated in the phase 2, open-label DIALOG study. In this final analysis, long-term efficacy and safety are presented for patients who completed 66 cycles (of 28 days) of treatment with nilotinib (230 mg/m2 twice daily) or discontinued early. Overall, 59 patients were enrolled and 58 were treated (R/I, n = 33; ND, n = 25; median time on treatment: 60.5 and 51.9 months, respectively). In the R/I cohort, the cumulative major molecular response (MMR; BCR::ABL1 international scale [IS] ≤ 0.1%) rate was 60.6%, and no patients had a confirmed loss of MMR. Among ND patients, the best overall MMR rate was 76.0%; 3 patients had a confirmed loss of MMR. The cumulative molecular response MR4 (BCR::ABL1IS ≤ 0.01%) and MR4.5 (BCR::ABL1IS ≤ 0.0032%) rates by 66 cycles were 27.3% and 12.1% in the R/I cohort, and 56.0% and 44.0% in the ND cohort, respectively. The safety profile of nilotinib was consistent with those of earlier reports. No on-treatment deaths occurred. These long-term (up to ∼5 years) data support the efficacy and safety of nilotinib in pediatric patients with Ph+ CML-CP. This trial was registered at www.clinicaltrials.gov.uk as #NCT01844765.

Integration of Genomic Sequencing Drives Therapeutic Targeting of PDGFRA in T-Cell Acute Lymphoblastic Leukemia/Lymphoblastic Lymphoma

PURPOSE

Patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) or lymphoblastic lymphoma (T-LBL) have limited therapeutic options. Clinical use of genomic profiling provides an opportunity to identify targetable alterations to inform therapy.

EXPERIMENTAL DESIGN

We describe a cohort of 14 pediatric patients with relapsed or refractory T-ALL enrolled on the Leukemia Precision-based Therapy (LEAP) Consortium trial (NCT02670525) and a patient with T-LBL, discovering alterations in platelet-derived growth factor receptor-α (PDGFRA) in 3 of these patients. We identified a novel mutation in PDGFRA, p.D842N, and used an integrated structural modeling and molecular biology approach to characterize mutations at D842 to guide therapeutic targeting. We conducted a preclinical study of avapritinib in a mouse patient-derived xenograft (PDX) model of FIP1L1-PDGFRA and PDGFRA p.D842N leukemia.

RESULTS

Two patients with T-ALL in the LEAP cohort (14%) had targetable genomic alterations affecting PDGFRA, a FIP1-like 1 protein/PDGFRA (FIP1L1-PDGFRA) fusion and a novel mutation in PDGFRA, p.D842N. The D842N mutation resulted in PDGFRA activation and sensitivity to tested PDGFRA inhibitors. In a T-ALL PDX model, avapritinib treatment led to decreased leukemia burden, significantly prolonged survival, and even cured a subset of mice. Avapritinib treatment was well tolerated and yielded clinical benefit in a patient with refractory T-ALL.

CONCLUSIONS

Refractory T-ALL has not been fully characterized. Alterations in PDGFRA or other targetable kinases may inform therapy for patients with refractory T-ALL who otherwise have limited treatment options. Clinical genomic profiling, in real time, is needed for fully informed therapeutic decision making.

Asciminib in the Treatment of Philadelphia Chromosome-Positive Chronic Myeloid Leukemia: Focus on Patient Selection and Outcomes

Tyrosine kinase inhibitors (TKIs) have significantly changed the treatment of chronic myeloid leukemia (CML) and improved outcomes for patients with CML in chronic phase (CML-CP) and accelerated phase (AP). Now armed with numerous effective therapeutic options, clinicians must consider various patient- and disease-specific factors when selecting the most appropriate TKI across lines of therapy. While most patients with CML expected to have a near-normal life expectancy due to the success of TKIs, emphasis has expanded beyond response and survival to include factors like quality of life, tolerability, and long-term toxicity management. Importantly, a subset of patients can achieve sustained deep molecular response and can attain treatment-free remission. Despite these successes, unmet needs remain related to CML treatment, including the persistent challenge of treatment resistance and intolerance, broadening treatment options for patients with resistance mutations or serious comorbidities, and focus on specific populations such as children and young adults. In particular, the only previously available treatments for patients with CML-CP with the T315I mutation were ponatinib, olverembatinib (exclusively approved for use in China at the time of this writing), omacetaxine, and hematopoietic stem cell transplantation. Asciminib has entered the CML treatment landscape as a new option for adult patients with CML-CP who have received ≥2 prior TKIs or those with the T315I mutation. Asciminib's unique mechanism of action, Specifically Targeting the ABL Myristoyl Pocket, sets it apart from traditional adenosine triphosphate-competitive TKIs. While asciminib may overcome unmet needs for patients with CML-CP and continues to be studied in other novel settings, guidance on how to integrate asciminib in treatment algorithms is needed. This review focuses on clinical data and how asciminib can overcome current unmet needs, discusses how to individualize patient selection, and highlights future directions to investigate asciminib in earlier lines of therapy and in children and adolescents.

High-throughput Sequencing to Identify Bacteremia in Children with Cancer

Current methods to diagnose bacteremia are limited. In this pilot study of children with cancer presenting with fever, we determined the concordance between a novel high-throughput sequencing platform called BacCapSeq and blood culture. High-throughput sequencing had modest concordance with blood culture. Discordant organisms included those with both unlikely or potential clinical relevance.

Child and family perceptions of satisfaction with neutropenia management in pediatric acute myeloid leukemia

PURPOSE

Chemotherapy for pediatric acute myeloid leukemia (AML) is very intensive and many, but not all centers, require extended hospitalization until neutrophil recovery. Child and family preferences, beliefs, and experiences around hospitalization have not been systematically assessed.

PATIENTS AND METHODS

We recruited children with AML and their parents from nine pediatric cancer centers across the United States for a qualitative interview about their experiences of neutropenia management. Interviews were analyzed using a conventional content analysis approach.

RESULTS

Of 116 eligible individuals, 86 (74.1%) agreed to participate. Interviews were conducted with 32 children and 54 parents from 57 families. Of these 57 families, 39 were cared for as inpatients and 18 were managed as outpatients. A very high proportion of respondents in both groups reported satisfaction with the discharge management strategy recommended by the treating institution: 86% (57 individuals) of respondents who experienced inpatient management and 85% (17 individuals) of respondents who experienced outpatient management expressed satisfaction. Respondent perceptions associated with satisfaction related to safety (access to emergency interventions, infection risk, close monitoring) and psychosocial concerns (family separation, low morale, social support). Respondents believed it could not be assumed that all children would have the same experience due to varied life circumstances.

CONCLUSION

Children with AML and their parents express a very high degree of satisfaction with the discharge strategy recommended by their treating institution. Respondents saw a nuanced tradeoff between patient safety and psychosocial concerns that was mediated by a child's life circumstances.

Clofarabine for Lymphodepletion Before CAR-T-Cell Infusion: A Brief Case Report

Given the shortage of fludarabine, alternative preparative lymphodepleting regimens for CAR-T-cell therapy need to be identified. We present a case of relapsed/refractory B-cell acute lymphoblastic leukemia requiring multiple lines of salvage therapy with persistent extensive disease, who underwent lymphodepletion with clofarabine and cyclophosphamide before tisagenlecleucel CD19+ CAR-T-cell infusion with eventual remission. We offer evidence of clofarabine's activity against B-cell acute lymphoblastic leukemia in combination with tisagenlecleucel therapy. In this patient, clofarabine did not decrease CAR-T-cell effectiveness, supported by presence of cytokine release syndrome and ultimate minimal residual disease negativity both on flow cytometry and next-generation sequencing.

Management of children and adolescents with chronic myeloid leukemia in blast phase: International pediatric CML expert panel recommendations

Treatment of chronic myeloid leukemia has improved significantly with the introduction of tyrosine kinase inhibitors (TKIs), and treatment guidelines based on numerous clinical trials are available for chronic phase disease. However for CML in the blast phase (CML-BP), prognosis remains poor and treatment options are much more limited. The spectrum of treatment strategies for children and adolescents with CML-BP has largely evolved empirically and includes treatment principles derived from adult CML-BP and pediatric acute leukemia. Given this heterogeneity of treatment approaches, we formed an international panel of pediatric CML experts to develop recommendations for consistent therapy in children and adolescents with this high-risk disease based on the current literature and national standards. Recommendations include detailed information on initial diagnosis and treatment monitoring, differentiation from Philadelphia-positive acute leukemia, subtype-specific selection of induction therapy, and combination with tyrosine kinase inhibitors. Given that allogeneic hematopoietic stem cell transplantation currently remains the primary curative intervention for CML-BP, we also provide recommendations for the timing of transplantation, donor and graft selection, selection of a conditioning regimen and prophylaxis for graft-versus-host disease, post-transplant TKI therapy, and management of molecular relapse. Management according to the treatment recommendations presented here is intended to provide the basis for the design of future prospective clinical trials to improve outcomes for this challenging disease.

Three-year results from phase I of ZUMA-4: KTE-X19 in pediatric relapsed/refractory acute lymphoblastic leukemia

Here we present the 3-year results of ZUMA-4, a phase I/II multicenter study evaluating the safety and efficacy of KTEX19, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in pediatric/adolescent patients with relapsed/refractory B-cell acute lymphoblastic leukemia. Phase I explored two dose levels and formulations. The primary endpoint was the incidence of dose-limiting toxicities. Thirty-one patients were enrolled; KTE-X19 was administered to 24 patients (median age 13.5 years, range 3-20; median follow-up 36.1 months). No dose-limiting toxicities were observed. All treated patients had grade ≥3 adverse events, commonly hypotension (50%) and anemia (42%). Grade 3 cytokine release syndrome rates were 33% in all treated patients, 75% in patients given the dose of 2×106 CAR T cells/kg, 27% in patients given the dose of 1×106 cells/kg in the 68 mL formulation, and 22% in patients given the dose of 1×106 cells/kg in the 40 mL formulation; the percentages of patients experiencing grade ≥3 neurologic events were 21%, 25%, 27%, and 11% respectively. Overall complete remission rates (including complete remission with incomplete hematologic recovery) were 67% in all treated patients, 75% in patients given 2×106 CAR T cells/kg, 64% in patients given 1×106 cells/kg in the 68 mL formulation, and 67% in patients given 1×106 cells/kg in the 40 mL formulation. Overall minimal residual diseasenegativity rates were 100% among responders; 88% of responders underwent subsequent allogeneic stem-cell transplantation. In the 1×106 (40 mL) group (recommended phase II dose), the median duration of remission censored at allogeneic stem-cell transplantation and median overall survival were not reached. Pediatric/adolescent patients with relapsed/refractory B-cell acute lymphoblastic leukemia achieved high minimal residual disease-negative remission rates with a manageable safety profile after a single dose of KTE-X19. Phase II of the study is ongoing at the dose of 1×106 CAR T cells/kg in the 40 mL formulation. ClinicalTrials.gov: NCT02625480.

Evaluation for Bleeding Disorders in Suspected Child Abuse

Bruising or bleeding in a child can raise the concern for child abuse. Assessing whether the findings are the result of trauma and/or whether the child has a bleeding disorder is critical. Many bleeding disorders are rare, and not every child with bruising/bleeding that may raise a concern for abuse requires an evaluation for bleeding disorders. However, in some instances, bleeding disorders can present in a manner similar to child abuse. Bleeding disorders cannot be ruled out solely on the basis of patient and family history, no matter how extensive. The history and clinical evaluation can be used to determine the necessity of an evaluation for a possible bleeding disorder, and prevalence and known clinical presentations of individual bleeding disorders can be used to guide the extent of laboratory testing. This clinical report provides guidance to pediatricians and other clinicians regarding the evaluation for bleeding disorders when child abuse is suspected.

Physician risk perceptions and surveillance practices for tyrosine kinase inhibitor long-term effects in pediatric CML

Chronic myeloid leukemia (CML) is effectively treated with long-term tyrosine kinase inhibitor (TKI) therapy, yet little is known about risks of prolonged TKI exposure in young patients, and long-term effect monitoring is not standardized. We surveyed North American pediatric oncologists (n = 119) to evaluate perceived risk of and surveillance practices for potential toxicities associated with prolonged TKI exposure in children and adolescents/young adults (AYAs) with CML. Survey domains included general and specific risk perceptions and surveillance practices for asymptomatic patients on chronic TKI therapy. We analyzed data descriptively and explored relationships between risk perceptions and surveillance. Risk perceptions varied among oncologists but were similar across six categories (thyroid, cardiac, vascular, metabolic, fertility, psychologic), with less than one-third rating each risk as moderate or high in pediatric and AYA patients. More oncologists perceived moderate or high risk of growth abnormalities in children (62% pediatric, 14% AYA) and financial toxicity in all patients (60% pediatric, 64% AYA). A greater proportion of oncologists with moderate or high perceived risk of thyroid abnormalities reported testing thyroid function compared to those with lower perceived risk; patterns for metabolic risk/lipid tests and cardiac risk/tests were similar. In summary, we found that pediatric oncologists had variable risk perceptions and surveillance practices for potential toxicities associated with prolonged TKI exposure. Standardizing surveillance would help quantify risks and refine recommendations.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.2017085 .

Obesity in children with acute promyelocytic leukemia: What is its prevalence and prognostic significance?

OBJECTIVE

To compare outcomes of obese and nonobese pediatric patients with acute promyelocytic leukemia (APL) from the Cancer and Leukemia Group B trial (CALGB) 9710 and the Children's Oncology Group trial AAML0631.

METHODS

Data including demographics, adverse events, overall and event-free survival (EFS) were analyzed.

RESULTS

The prevalence of obesity was 34% on C9710 and 35% on AAML0631. There was significantly lower overall and EFS in the obese population on multivariable analysis on AAML0631 but not on CALGB 9710. Eleven patients died during therapy or in follow-up.

CONCLUSION

The prevalence of obesity is higher in pediatric patients with APL compared to the general population. The decreased EFS and OS in obese patients on AAML0631 suggest that the presence of obesity can influence outcomes using the most current treatment. These findings support the need for further research on the potential role of obesity in pediatric APL leukemogenesis.

Genomic predictors of response to PD-1 inhibition in children with germline DNA replication repair deficiency

Cancers arising from germline DNA mismatch repair deficiency or polymerase proofreading deficiency (MMRD and PPD) in children harbour the highest mutational and microsatellite insertion–deletion (MS-indel) burden in humans. MMRD and PPD cancers are commonly lethal due to the inherent resistance to chemo-irradiation. Although immune checkpoint inhibitors (ICIs) have failed to benefit children in previous studies, we hypothesized that hypermutation caused by MMRD and PPD will improve outcomes following ICI treatment in these patients. Using an international consortium registry study, we report on the ICI treatment of 45 progressive or recurrent tumors from 38 patients. Durable objective responses were observed in most patients, culminating in a 3 year survival of 41.4%. High mutation burden predicted response for ultra-hypermutant cancers (>100 mutations per Mb) enriched for combined MMRD + PPD, while MS-indels predicted response in MMRD tumors with lower mutation burden (10–100 mutations per Mb). Furthermore, both mechanisms were associated with increased immune infiltration even in ‘immunologically cold’ tumors such as gliomas, contributing to the favorable response. Pseudo-progression (flare) was common and was associated with immune activation in the tumor microenvironment and systemically. Furthermore, patients with flare who continued ICI treatment achieved durable responses. This study demonstrates improved survival for patients with tumors not previously known to respond to ICI treatment, including central nervous system and synchronous cancers, and identifies the dual roles of mutation burden and MS-indels in predicting sustained response to immunotherapy.

Hypermutation and microsatellite burden determine responses and long-term survival following PD-1 blockade in children and young adults with refractory cancers resulting from germline DNA replication repair deficiency.

Comparison of the Transcriptomic Signatures in Pediatric and Adult CML

Simple Summary

To investigate whether pediatric and adult chronic myeloid leukemia (CML) have unique molecular characteristics, we studied the transcriptomic signature of pediatric and adult CML cells using high-throughput RNA sequencing. We identified differentially expressed genes and pathways unique to pediatric CML cells compared to adult CML cells. The Rho pathway was significantly dysregulated in pediatric CML cells compared to adult CML cells, suggesting the potential importance in the pathogenesis of pediatric CML. Our study is the first to compare transcriptome profiles of CML across different age groups. A better understanding of the biology of CML across different ages may inform future treatment approaches.

Abstract

Children with chronic myeloid leukemia (CML) tend to present with higher white blood counts and larger spleens than adults with CML, suggesting that the biology of pediatric and adult CML may differ. To investigate whether pediatric and adult CML have unique molecular characteristics, we studied the transcriptomic signature of pediatric and adult CML CD34+ cells and healthy pediatric and adult CD34+ control cells. Using high-throughput RNA sequencing, we found 567 genes (207 up- and 360 downregulated) differentially expressed in pediatric CML CD34+ cells compared to pediatric healthy CD34+ cells. Directly comparing pediatric and adult CML CD34+ cells, 398 genes (258 up- and 140 downregulated), including many in the Rho pathway, were differentially expressed in pediatric CML CD34+ cells. Using RT-qPCR to verify differentially expressed genes, VAV2 and ARHGAP27 were significantly upregulated in adult CML CD34+ cells compared to pediatric CML CD34+ cells. NCF1, CYBB, and S100A8 were upregulated in adult CML CD34+ cells but not in pediatric CML CD34+ cells, compared to healthy controls. In contrast, DLC1 was significantly upregulated in pediatric CML CD34+ cells but not in adult CML CD34+ cells, compared to healthy controls. These results demonstrate unique molecular characteristics of pediatric CML, such as dysregulation of the Rho pathway, which may contribute to clinical differences between pediatric and adult patients.

Chronic Myeloid Leukemia in Children: Immune Function and Vaccinations

Children with CML need TKI treatment for many years, and the lack of knowledge about immune dysfunction with TKI has hindered routine immunizations. This review attempts to provide an overview of the effects of TKIs licensed for children (e.g., imatinib, dasatinib, and nilotinib) on immune function, as well as its implications on immunizations. We discuss surveillance strategies (e.g., immunoglobulin blood serum levels and hepatitis B reactivation) and immunizations. All inactivated vaccines (e.g., influenza, pneumococcal, and streptococcal) can be given during the treatment of CML in the chronic phase, although their efficacy may be lower. As shown in single cases of children and adults with CML, live vaccines (e.g., varicella, measles, mumps, rubella, and yellow fever) may be administered under defined circumstances with great precautions. We also highlight important aspects of COVID-19 in this patient population (e.g., the outcome of COVID-19 infection in adults with CML and in children with varying hemato-oncological diseases) and discuss the highly dynamic field of presently available different vaccination options. In conclusion, TKI treatment for CML causes humoral and cellular immune dysfunction, which is mild in most patients, and thus infectious complications are rare. Routine immunizations are important for health maintenance of children, but vaccinations for children with CML on TKI therapy should be carefully considered.

Survival Benefit for Individuals With Constitutional Mismatch Repair Deficiency Undergoing Surveillance

Constitutional mismatch repair deficiency syndrome (CMMRD) is a lethal cancer predisposition syndrome characterized by early-onset synchronous and metachronous multiorgan tumors. We designed a surveillance protocol for early tumor detection in these individuals.

Tyrosine Kinase Inhibitors and Beyond for Chronic Myeloid Leukemia in Children

Chronic myeloid leukemia (CML) is rare in children but presents a unique challenge as recent drug innovations have turned CML into a chronic disease with implications for treatment into adulthood. With the approval of newer-generation tyrosine kinase inhibitors (TKIs) in addition to imatinib, providers have more options for the treatment of chronic-phase CML (CML-CP) in children. The second-generation TKIs approved for use in children, nilotinib and dasatinib, have higher response rates than first-generation imatinib; however, overall survival rates appear to be the same. Even more options may soon become available with ongoing investigations into the use of bosutinib and ponatinib and other new agents in children. Possible long-term side effects of TKIs, including growth failure, should be carefully acknowledged by the treating provider. Although these known associations may not preclude treatment, providers should be aware of them to guide their management of pediatric patients with CML being treated long term with TKI therapy. Treatment-free remission is a desired goal for pediatric patients and providers alike, but current recommendations are for attempts at achieving this to be restricted to clinical study settings.

Chronic Myelogenous Leukemia in Childhood

PURPOSE OF REVIEW

Chronic myelogenous leukemia (CML) is rare in children, requiring extrapolation from treatment of adults. In this review, we explore similarities and differences between adult and pediatric CML with a focus on therapeutic advances and emerging clinical questions.

RECENT FINDINGS

Pediatric CML is effectively treated with long-term targeted therapy using tyrosine kinase inhibitors (TKIs). Newly diagnosed pediatric patients in chronic phase can now be treated with imatinib, dasatinib, or nilotinib without allogeneic hematopoietic stem cell transplantation. While treatment-free remission is possible in adults in chronic phase with optimal response to therapy, data are currently insufficient to support stopping TKI in pediatrics outside of a clinical trial. Knowledge gaps remain regarding long-term and late effects of TKIs in pediatric CML. Targeted therapy has markedly improved outcomes for pediatric CML, while raising a number of clinical questions, including the possibility of treatment-free remission and long-term health implications of prolonged TKI exposure at a young age.

Distinct genetic pathways define pre-malignant versus compensatory clonal hematopoiesis in Shwachman-Diamond syndrome

To understand the mechanisms that mediate germline genetic leukemia predisposition, we studied the inherited ribosomopathy Shwachman-Diamond syndrome (SDS), a bone marrow failure disorder with high risk of myeloid malignancies at an early age. To define the mechanistic basis of clonal hematopoiesis in SDS, we investigate somatic mutations acquired by patients with SDS followed longitudinally. Here we report that multiple independent somatic hematopoietic clones arise early in life, most commonly harboring heterozygous mutations in EIF6 or TP53. We show that germline SBDS deficiency establishes a fitness constraint that drives selection of somatic clones via two distinct mechanisms with different clinical consequences. EIF6 inactivation mediates a compensatory pathway with limited leukemic potential by ameliorating the underlying SDS ribosome defect and enhancing clone fitness. TP53 mutations define a maladaptive pathway with enhanced leukemic potential by inactivating tumor suppressor checkpoints without correcting the ribosome defect. Subsequent development of leukemia was associated with acquisition of biallelic TP53 alterations. These results mechanistically link leukemia predisposition to germline genetic constraints on cellular fitness, and provide a rational framework for clinical surveillance strategies.

Access to Technology and Preferences for an mHealth Intervention to Promote Medication Adherence in Pediatric Acute Lymphoblastic Leukemia: Approach Leveraging Behavior Change Techniques

Background

Suboptimal adherence to 6-mercaptopurine (6-MP) is prevalent in pediatric acute lymphoblastic leukemia (ALL) and associated with increased risk of relapse. Rapid uptake of personal technology makes mobile health (mHealth) an attractive platform to promote adherence.

Objective

Study objectives were to examine access to mobile technology and preferences for an mHealth intervention to improve medication adherence in pediatric ALL.

Methods

A cross-sectional survey was administered in oncology clinic to parents of children with ALL as well as adolescents and young adults (AYAs) with ALL receiving maintenance chemotherapy.

Results

A total of 49 parents (median age [IQR] 39 [33-42] years; female 76% [37/49]) and 15 patients (median age [IQR] 17 [16-19]; male 80% [12/15]) participated. All parents and AYAs owned electronic tablets, smartphones, or both. Parents’ most endorsed mHealth app features included a list of medications (71%, 35/49), information about 6-MP (71%, 35/49), refill reminders (71%, 35/49), and reminders to take 6-MP (71%, 35/49). AYAs' most endorsed features included refill reminders (73%, 11/15), reminders to take 6-MP (73%, 11/15), and tracking 6-MP (73%, 11/15).

Conclusions

Parents and AYAs reported ubiquitous access to mobile technology and strong interest in multiple adherence-specific mHealth app features. Parents and AYAs provided valuable insight into preferred features for a multifunctional behavioral intervention (mHealth app) to promote medication adherence in pediatric ALL.

DYRK1A regulates B cell acute lymphoblastic leukemia through phosphorylation of FOXO1 and STAT3

DYRK1A is a serine/threonine kinase encoded on human chromosome 21 (HSA21) that has been implicated in several pathologies of Down syndrome (DS), including cognitive deficits and Alzheimer's disease. Although children with DS are predisposed to developing leukemia, especially B cell acute lymphoblastic leukemia (B-ALL), the HSA21 genes that contribute to malignancies remain largely undefined. Here, we report that DYRK1A is overexpressed and required for B-ALL. Genetic and pharmacologic inhibition of DYRK1A decreased leukemic cell expansion and suppressed B-ALL development in vitro and in vivo. Furthermore, we found that FOXO1 and STAT3, transcription factors that are indispensable for B cell development, are critical substrates of DYRK1A. Loss of DYRK1A-mediated FOXO1 and STAT3 signaling disrupted DNA damage and ROS regulation, respectively, leading to preferential cell death in leukemic B cells. Thus, we reveal a DYRK1A/FOXO1/STAT3 axis that facilitates the development and maintenance of B-ALL.

IMMU-18. FAVORABLE OUTCOME IN REPLICATION REPAIR DEFICIENT HYPERMUTANT BRAIN TUMORS TO IMMUNE CHECKPOINT INHIBITION: AN INTERNATIONAL RRD CONSORTIUM REGISTRY STUDY

Pediatric brain tumors with replication repair deficiency (RRD) are hypermutant and may respond to immune checkpoint inhibition (ICI). We performed a consortium registry study of ICI in recurrent RRD cancers. Clinical and companion biomarkers were collected longitudinally on all patients. Biomarkers included tumor mutational burden (TMB), neoantigens and genetic signatures obtained from whole genome and exome sequencing. Immune inference was obtained by RNAseq and T cell rearrangement was collected in the tumor and in blood throughout treatment. Of the 46 tumors on the study, 32 were brain tumors with glioblastoma in 96%. Rapid, objective responses (>50%) were observed in 50% of glioblastomas. Three year overall survival for the whole cohort was 48+/-8% which compares favorably with historical controls. Brain tumors fared worse with OS of 39+/-10% and late recurrences observed even after 2 years of therapy (p=0.02). Tumor size and acute “flare” constitute poor outcome throughout all cancers. While all tumors are hypermutant, TMB and predicted neoantigens correlated with response to ICI (p=0.02). Specific signatures extracted from SNVs and total mutations predicted response to ICI and favorable outcome (p=0.005). RNA inference and TCR reveal that the FLARE phenotype is mostly acute nonspecific immune response and not true progression. Finally, glioblastomas (n=8) which failed single agent ICI had favorable responses to combinational immunotherapies with prolonged survival of 65%+/-8% at one year after failure vs 0 for other patients (p=0.01). RRD glioblastomas exhibit favorable outcome and responses to ICI. Combinational therapies based on tumor and immune signatures of these cancers are necessary.

A phase I study of panobinostat in children with relapsed and refractory hematologic malignancies

Background: Panobinostat demonstrates activity against pediatric cancers in vitro. A phase I trial in children with refractory hematologic malignancies was conducted. Study design: The trial evaluated two schedules of oral panobinostat using 3 + 3 dose escalations in 28-day cycles. For children with leukemia, panobinostat was given once daily three days a week each week at 24, 30 and 34 mg/m2/day. For children with lymphoma, panobinostat was given once daily three days a week every other week at 16, 20 and 24 mg/m2/day. Cerebrospinal fluid (CSF) from Day 29 of the first cycle, when available, was evaluated for PK. The study was registered on clinicaltrials.gov (NCT01321346) Results: Twenty-two subjects enrolled with leukemia. Five enrolled at dose level 1, 6 at dose level 2, and 11 at dose level 3. There was one dose limiting toxicity (DLT) in the leukemia arm at dose level 3 (Grade 4 hypertriglyceridemia), but no maximum tolerated dose (MTD) was identified. No subjects required removal from protocol therapy for QTc prolongation. PK studies were available in 11 subjects with similar exposure in children as in adults. Four Day 29 CSF specimens were found to have panobinostat levels below the lower limit of quantification. Five subjects with lymphoma were enrolled and received study drug, and 4 were evaluable for DLT. A DLT was reported (Grade 3 enteritis) on the lymphoma arm. Conclusions: Panobinostat was tolerated in heavily pretreated pediatric subjects. Gastrointestinal effects were observed on this study. There were no cardiac findings. There were no responses.

Applying the COM-B model to patient-reported barriers to medication adherence in pediatric acute lymphoblastic leukemia

BACKGROUND

Adherence to oral chemotherapy, including 6-mercaptopurine (6-MP), is suboptimal in pediatric acute lymphoblastic leukemia (ALL), which is associated with increased risk of relapse. Study objectives were to examine self-reported adherence to 6-MP and related barriers to adherence, mapped to the capability, opportunity, motivation, and behavior (COM-B) model for behavior change.

PROCEDURE

Forty-nine parents (median, 39 years old; 76% females) and 15 patients (median, 17 years old, 20% females) completed the study survey.

RESULTS

Suboptimal adherence was reported in 43% of parents and 73% of patients. Most parents and patients (80% and 90%, respectively) reported ≥1 adherence barrier. Parents reported difficulty helping their child meet others with ALL (43%), contacting community organizations (39%), and meeting other parents (37%). Patients reported difficulty finding out what their medications are (40%), finding out what 6-MP does (47%), and meeting other patients (40%). Using the COM-B, we found that parents and patients endorsed barriers in multiple components, especially physical (55%, 67%) and social opportunity (56%, 47%), highlighting that barriers to adherence may be multifaceted.

CONCLUSIONS

Our results suggest that parents and patients with ALL face various prevalent barriers to medication adherence and provide insight into the development of behavioral interventions focused on promoting adherence, which is essential to prevent relapse and optimize health outcomes in ALL.

Results from an international phase 2 study of the anti-CD22 immunotoxin moxetumomab pasudotox in relapsed or refractory childhood B-lineage acute lymphoblastic leukemia

BACKGROUND

In a multicenter phase 1 study of children with relapsed/refractory acute lymphoblastic leukemia (ALL), moxetumomab pasudotox, an anti-CD22 immunotoxin, demonstrated a manageable safety profile and preliminary evidence of clinical activity. A phase 2 study further evaluated efficacy.

PROCEDURE

This international, multicenter, phase 2 study enrolled children with relapsed/refractory B-cell precursor ALL who received moxetumomab pasudotox 40 µg/kg intravenously every other day, for six doses per 21-day cycle. The primary objective was to evaluate the complete response (CR) rate. Secondary objectives included safety, pharmacokinetics, and immunogenicity evaluations.

RESULTS

Thirty-two patients (median age, 10 years) were enrolled at 16 sites; 30 received study drug and were evaluable for safety; 28 were evaluable for response. The objective response rate was 28.6%, with three patients (10.7%) achieving morphologic CR, and five patients (17.9%) achieving partial response. Disease progression occurred in 11 patients (39.3%). Ten patients (33.3%) experienced at least one treatment-related serious adverse event, including capillary leak syndrome (CLS; n = 6), hemolytic uremic syndrome (HUS; n = 4), and treatment-related death (n = 1) from pulmonary edema. No differences were observed in inflammatory markers in patients who did or did not develop CLS or HUS.

CONCLUSIONS

Despite a signal for clinical activity, this phase 2 study was terminated at interim analysis for a CR rate that did not reach the stage 1 target. Preclinical data suggest enhanced efficacy of moxetumomab pasudotox via continuous infusion or in combination regimens; thus, further studies designed to optimize the efficacy and safety of moxetumomab pasudotox in pediatric ALL may be warranted.

Pharmacokinetics of Nilotinib in Pediatric Patients with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia or Acute Lymphoblastic Leukemia

PURPOSE

We investigated nilotinib exposure in pediatric patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) resistant to, relapsed on, refractory to, or intolerant of previous treatment.

PATIENTS AND METHODS

Fifteen patients (aged 1-<18 years) with CML resistant to or intolerant of imatinib and/or dasatinib (n = 11) or Ph+ ALL relapsed on or refractory to standard therapy (n = 4) enrolled in this phase I study. Nilotinib (230 mg/m2 twice daily; equivalent to the adult 400-mg twice-daily dose) was administered orally in 12 or 24 cycles of 28 days. The primary objective was to characterize the pharmacokinetics of nilotinib in pediatric patients.

RESULTS

The area under the concentration-time curve at steady state was slightly lower in pediatric patients versus adults (14,751.4 vs. 17,102.9 ng/h/mL); the geometric mean ratio (GMR; pediatric:adult) was 0.86 [90% confidence interval (CI), 0.70-1.06]. Body surface area-adjusted systemic clearance was slightly higher in pediatric versus adult patients (GMR, 1.30; 90% CI, 1.04-1.62). Nilotinib was generally well tolerated. The most common adverse events were headache, vomiting, increased blood bilirubin, and rash. Three patients with CML achieved major molecular response, and three with Ph+ ALL achieved complete remission.

CONCLUSIONS

Nilotinib 230 mg/m2 twice daily in pediatric patients provided a pharmacokinetics and safety profile comparable with the adult reference dose; clinical activity was demonstrated in both CML and Ph+ ALL. This dose is recommended for further evaluation in pediatric patients. The safety profile was consistent with that in adults.

Experience with ponatinib in paediatric patients with leukaemia

Ponatinib has proven to be effective in adults with Philadelphia chromosome-positive leukaemias, but data in paediatrics are scarce. Among paediatric patients with chronic myeloid leukaemia (n = 9) or acute lymphoblastic leukaemia (n = 12) treated with varying doses of ponatinib in 13 centres, 71% showed a decrease in disease burden after a median of three months. Ponatinib was well tolerated, with grade 3 toxicities occurring in 29% of patients. Toxicities were similar to those reported in adults, with the exception of arterial thrombotic events, which were not observed. Ponatinib has a favourable safety profile in this paediatric cohort, but dose-finding studies are needed.

The TLR9 agonist (GNKG168) induces a unique immune activation pattern in vivo in children with minimal residual disease positive acute leukemia: Results of the TACL T2009-008 phase I study

Background: Preclinical studies show that TLR9 agonists can eradicate leukemia by induction of immune responses in vivo against AML and ALL. These studies demonstrated that TLR9 agonists induce an immediate NK response followed by adaptive T and B cells responses resulting in long term anti-leukemia immunity. Methods: The Therapeutic Advances in Childhood Leukemia and Lymphoma Phase I consortium performed a pilot study on 3 patients with MRD positive acute leukemia after an initial remission on conventional chemotherapy (TACL T2009-008) with the TLR 9 agonist (GNKG168). To guide future trial development, we evaluated the impact of GNKG168 by Nanostring on the expression 608 genes before and 8 days after initiation of GNKG168 therapy. Results: Twenty-three out of 578 markers on the nanostring panel showed significant difference (p ≤ 0.05). We focused on 8 markers that had the greatest differences with p < 0.01. Two genes were increased, promyelocytic leukemia protein (PML) and H-RAS, and 6 were decreased, Single Ig and TIR Domain containing (SIGIRR, IL1R8), interleukin 1 receptor 1 (IL1RL1, ST2), C-C Motif chemokine receptor 8 (CCR8), interleukin 7 R (IL7R), cluster of differentiation 8B (CD8B), and cluster of differentiation 3 (CD3D). Tumor inhibitory pathways were downregulated including the SIGIRR (IL1R8), important in IL-37 signaling and NK cell inhibition. TLR9 can induce IL-33, which is known to downregulate ST2 (IL1RL1) a receptor for IL-33. Conclusion: GNKG168 therapy is associated with immunologic changes in pediatric leukemia patients. Further work with a larger sample size is required to assess the impact of these changes on disease treatment and persistence of leukemia remission.

Management of chronic myeloid leukemia in children and adolescents: Recommendations from the Children's Oncology Group CML Working Group

Chronic myeloid leukemia (CML) accounts for 2-3% of leukemias in children under 15 and 9% in adolescents aged 15-19. The diagnosis and management of CML in children, adolescents, and young adults have several differences compared to that in adults. This review outlines the diagnosis and management of the underlying disease as well as challenges that can occur when dealing with CML in this patient population.

Cost analysis of bronchoalveolar lavage and respiratory tract biopsies in the diagnosis and management of suspected invasive fungal infection in children with cancer or who have undergone stem cell transplant

BACKGROUND

Identification of an organism is the gold standard for the diagnosis of fungal infection; however, we have previously shown that invasive procedures infrequently lead to a change in management in children with cancer or who have undergone stem cell transplant with suspected respiratory tract invasive fungal infection (RT-IFI). There is also a paucity of data on the cost of RT-IFI in this population. We therefore compared the costs of RT-IFI diagnosed based on CT scan alone versus those who underwent a bronchoalveolar lavage (BAL) or respiratory tract biopsy (RTB).

PROCEDURE

We collected cost data on patients at a single center undergoing chemotherapy or who were post-hematopoietic stem cell transplant (HSCT) and were suspected of having RT-IFI between 2007 and 2012. Cost data were included for 14 days from the day of their diagnostic CT scan or procedure.

RESULTS

Cost data were available for 76 patients. Thirty-six patients were diagnosed with suspected RT-IFI based on CT only, and 40 patients underwent BAL or RTB. Costs related to chest X-rays (CXRs), inpatient/intensive care unit (ICU) beds, anesthesia, operating room (OR) time, and procedures were significantly higher in the BAL/RTB group versus CT scan group (all P < 0.01). Costs related to CT scans were significantly higher in the CT scan group (P = 0.0002). Overall costs were significantly higher for patients who underwent BAL or RTB versus CT scan only (P < 0.0001).

CONCLUSION

Our previous data showed that BAL and RTB infrequently led to a change in management in this population. We now demonstrate that this strategy is costly as well.

Functional Repair Assay for the Diagnosis of Constitutional Mismatch Repair Deficiency From Non-Neoplastic Tissue

PURPOSE

Constitutional mismatch repair deficiency (CMMRD) is a highly penetrant cancer predisposition syndrome caused by biallelic mutations in mismatch repair (MMR) genes. As several cancer syndromes are clinically similar, accurate diagnosis is critical to cancer screening and treatment. As genetic diagnosis is confounded by 15 or more pseudogenes and variants of uncertain significance, a robust diagnostic assay is urgently needed. We sought to determine whether an assay that directly measures MMR activity could accurately diagnose CMMRD.

PATIENTS AND METHODS

In vitro MMR activity was quantified using a 3'-nicked G-T mismatched DNA substrate, which requires MSH2-MSH6 and MLH1-PMS2 for repair. We quantified MMR activity from 20 Epstein-Barr virus-transformed lymphoblastoid cell lines from patients with confirmed CMMRD. We also tested 20 lymphoblastoid cell lines from patients who were suspected for CMMRD. We also characterized MMR activity from patients with neurofibromatosis type 1, Li-Fraumeni syndrome, polymerase proofreading-associated cancer syndrome, and Lynch syndrome.

RESULTS

All CMMRD cell lines had low MMR activity (n = 20; mean, 4.14 ± 1.56%) relative to controls (n = 6; mean, 44.00 ± 8.65%; P < .001). Repair was restored by complementation with the missing protein, which confirmed MMR deficiency. All cases of patients with suspected CMMRD were accurately diagnosed. Individuals with Lynch syndrome (n = 28), neurofibromatosis type 1 (n = 5), Li-Fraumeni syndrome (n = 5), and polymerase proofreading-associated cancer syndrome (n = 3) had MMR activity that was comparable to controls. To accelerate testing, we measured MMR activity directly from fresh lymphocytes, which yielded results in 8 days.

CONCLUSION

On the basis of the current data set, the in vitro G-T repair assay was able to diagnose CMMRD with 100% specificity and sensitivity. Rapid diagnosis before surgery in non-neoplastic tissues could speed proper therapeutic management.

Generic formulations of imatinib for treatment of Philadelphia chromosome-positive leukemia in pediatric patients

Since the patent for imatinib has expired, the role of generic imatinib (GI) in the management of Philadelphia chromosome-positive (Ph+) leukemia in pediatric patients has had ongoing discussion. Some studies in adults demonstrated that equivalent doses of GI and branded imatinib (BI) result in comparable plasma concentrations and clinical efficacy. However, other studies found that GI users are more likely to stop imatinib, with intolerance and decreased persistence as the main causes. Economic factors also heavily influence GI selection. This article aims to review the present knowledge to support further discussion on the role of GI in the management of pediatric Ph+ leukemia.

USP7 Cooperates with NOTCH1 to Drive the Oncogenic Transcriptional Program in T-Cell Leukemia

PURPOSE

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease, affecting children and adults. Chemotherapy treatments show high response rates but have debilitating effects and carry risk of relapse. Previous work implicated NOTCH1 and other oncogenes. However, direct inhibition of these pathways affects healthy tissues and cancer alike. Our goal in this work has been to identify enzymes active in T-ALL whose activity could be targeted for therapeutic purposes.

EXPERIMENTAL DESIGN

To identify and characterize new NOTCH1 druggable partners in T-ALL, we coupled studies of the NOTCH1 interactome to expression analysis and a series of functional analyses in cell lines, patient samples, and xenograft models.

RESULTS

We demonstrate that ubiquitin-specific protease 7 (USP7) interacts with NOTCH1 and controls leukemia growth by stabilizing the levels of NOTCH1 and JMJD3 histone demethylase. USP7 is highly expressed in T-ALL and is transcriptionally regulated by NOTCH1. In turn, USP7 controls NOTCH1 levels through deubiquitination. USP7 binds oncogenic targets and controls gene expression through stabilization of NOTCH1 and JMJD3 and ultimately H3K27me3 changes. We also show that USP7 and NOTCH1 bind T-ALL superenhancers, and inhibition of USP7 leads to a decrease of the transcriptional levels of NOTCH1 targets and significantly blocks T-ALL cell growth in vitro and in vivo.

CONCLUSIONS

These results provide a new model for USP7 deubiquitinase activity through recruitment to oncogenic chromatin loci and regulation of both oncogenic transcription factors and chromatin marks to promote leukemia. Our studies also show that targeting USP7 inhibition could be a therapeutic strategy in aggressive leukemia.

Phase I trial of the mTOR inhibitor everolimus in combination with multi-agent chemotherapy in relapsed childhood acute lymphoblastic leukemia

BACKGROUND

We sought to determine the feasibility of co-administering everolimus with a four-drug reinduction in children and adolescents with acute lymphoblastic leukemia (ALL) experiencing a first marrow relapse.

PROCEDURE

This phase I study tested everolimus with vincristine, prednisone, pegaspargase and doxorubicin in patients with marrow relapse occurring >18 months after first complete remission (CR). The primary aim was to identify the maximum tolerated dose of everolimus. Three dose levels (DLs) were tested during dose escalation (2, 3, and 5 mg/m² /day). Additional patients were enrolled at the 3- and 5 mg/m² /day DLs to further evaluate toxicity (dose expansion).

RESULTS

Thirteen patients enrolled during dose escalation and nine during dose expansion. During dose escalation, one dose-limiting toxicity occurred (grade 4 hyperbilirubinemia) in six evaluable patients at DL3 (5 mg/m² /day). The most common grade ≥3 adverse events were febrile neutropenia, infections, transaminitis, hyperbilirubinemia, and hypophosphatemia. Two of the 12 patients treated at DL3 developed Rothia mucilaginosa meningitis. Nineteen patients (86%) achieved a second CR (CR2). Of those, 13 (68%) had a low end-reinduction minimal residual disease (MRD) level (≤10^-3 by polymerase chain reaction-based assay). The CR2 rate for patients with B-cell ALL treated at DL3 (n = 12) was 92%; 82% of these patients had low MRD.

CONCLUSIONS

Everolimus combined with four-drug reinduction chemotherapy was generally well tolerated and associated with favorable rates of CR2 and low end-reinduction MRD. The recommended phase 2 dose of everolimus given in combination with a four-drug reinduction is 5 mg/m² /day. This promising combination should be further evaluated in a larger patient cohort.

Identifying patient- and family-centered outcomes relevant to inpatient versus at-home management of neutropenia in children with acute myeloid leukemia

Efficacy of therapeutic strategies relative to patient- and family-centered outcomes in pediatric oncology must be assessed. We sought to identify outcomes important to children with acute myeloid leukemia and their families related to inpatient versus at-home management of neutropenia. We conducted qualitative interviews with 32 children ≥8 years old and 54 parents. Analysis revealed the impact of neutropenia management strategy on siblings, parent anxiety, and child sleep quality as being outcomes of concern across respondents. These themes were used to inform the design of a questionnaire that is currently being used in a prospective, multiinstitutional comparative effectiveness trial.

Dasatinib in Pediatric Patients With Chronic Myeloid Leukemia in Chronic Phase: Results From a Phase II Trial

Purpose Safe, effective treatments are needed for pediatric patients with chronic myeloid leukemia in chronic phase (CML-CP). Dasatinib is approved for treatment of adults and children with CML-CP. A phase I study determined suitable dosing for children with Philadelphia chromosome-positive (Ph+) leukemias. Methods CA180-226/NCT00777036 is a phase II, open-label, nonrandomized prospective trial of patients < 18 years of age receiving dasatinib. There are three cohorts: (1) imatinib-resistant/intolerant CML-CP, (2) imatinib-resistant/intolerant CML in accelerated/blast phase or Ph+ acute lymphoblastic leukemia (n = 17), and (3) newly diagnosed CML-CP treated with tablets or powder for oral suspension. Major cytogenetic response > 30% for imatinib-resistant/intolerant patients and complete cytogenetic response (CCyR) > 55% for newly diagnosed patients were of clinical interest. Results Of 113 patients with CML-CP, 14 (48%) who were imatinib-resistant/intolerant and 61 (73%) who were newly diagnosed remained on treatment at time of analysis. Major cytogenetic response > 30% was reached by 3 months in the imatinib-resistant/intolerant group and CCyR > 55% was reached by 6 months in the newly diagnosed CML-CP group. CCyR and major molecular response by 12 months, respectively, were 76% and 41% in the imatinib-resistant/intolerant group and 92% and 52% in newly diagnosed CML-CP group. Progression-free survival by 48 months was 78% and 93% in the imatinib-resistant/intolerant and newly diagnosed CML-CP groups, respectively. No dasatinib-related pleural or pericardial effusion, pulmonary edema, or pulmonary arterial hypertension were reported. Bone growth and development events were reported in 4% of patients. Conclusion In the largest prospective trial to date in children with CML-CP, we demonstrate that dasatinib is a safe, effective treatment of pediatric CML-CP. Target responses to first- or second-line dasatinib were met early, and deep molecular responses were observed. Safety of dasatinib in pediatric patients was similar to that observed in adults; however, no cases of pleural or pericardial effusion or pulmonary arterial hypertension were reported.

Phase II trial of dasatinib (DAS) in pediatric patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP)

10511

Background: Safe and effective treatment options for newly diagnosed (ND) or imatinib (IM) resistant/intolerant (R/I) pediatric CML pts are limited, and a large prospective study is needed. DAS has proven safety and efficacy in adults with ND or IM-R/I CML and is now being evaluated in a phase II trial of pediatric pts. Methods: CA180-226/NCT00777036 is an open-label nonrandomized prospective study of pts aged <18 y in 3 cohorts: (1) CML-CP R/I to IM treated with DAS tablets 60 mg/m2 QD, (2) IM-R/I CML-AP/BP or Ph+ ALL (enrollment closed early due to poor response), and (3) ND CML-CP treated with DAS tablets 60 mg/m2 or DAS 72 mg/m2powder for oral suspension (PFOS) QD. Primary objectives were major cytogenetic response (MCyR) for CML-CP R/I to IM and complete cytogenetic response (CCyR) for ND CML-CP (MCyR >30% and CCyR >55% considered of clinical interest). Results: 113 pediatric CML-CP pts were treated. Cumulative rate of MCyR >30% was reached as early as 3 mo (55%; [95% CI 36, 74]) for IM-R/I CML-CP. Cumulative rate of CCyR >55% was reached as early as 6 mo (64% [95% CI 53, 74] for ND CML-CP; 61% [95% CI 46, 74] for pts on tablets and 70% [95% CI 51, 84] for pts on PFOS). Estimated PFS by 48 mo was >75% for CML-CP R/I to IM and >90% for ND CML-CP. One CML-CP pt R/I to IM died 1 y after stopping DAS from gastrointestinal bleeding. AEs were consistent with those observed in adults, except no DAS-related pleural/pericardial effusion or pulmonary arterial hypertension (PAH) were reported here. Conclusions: In the largest prospective trial of pediatric pts with CML-CP, target responses were met early and increased over time with DAS treatment. The efficacy and safety of DAS were consistent with previous reports in adults, except no cases of pleural/pericardial effusion or PAH were observed. These results suggest DAS is safe and highly effective in the first- or second-line treatment of pediatric CML-CP. Clinical trial information: NCT00777036. [Table: see text]

Combination of clofarabine, cyclophosphamide, and etoposide for relapsed or refractory childhood and adolescent acute myeloid leukemia

Relapsed/refractory acute myeloid leukemia (AML) has an extremely poor prognosis. We describe 17 children and adolescents with relapsed/refractory AML who received clofarabine, cyclophosphamide, and etoposide. Seven patients (41%) responded: 4 with a complete response (CR); 1 with CR with incomplete platelet recovery; and 2 with a partial response. Additionally, 4 developed hypocellular marrow without evidence of leukemia; 5 patients had resistant disease; and 1 suffered early toxic death. After further therapy including transplantation, 4 patients (24%) are alive without evidence of disease at a median of 60 months. This anthracycline-free regimen may be studied for relapsed or refractory AML, but due to the high risk of marrow aplasia reduced doses of clofarabine and cyclophosphamide should be used.

Recognizing Endocrinopathies Associated With Tyrosine Kinase Inhibitor Therapy in Children With Chronic Myelogenous Leukemia

Side effects of tyrosine kinase inhibitor (TKI) treatment vary in children and adults with chronic myelogenous leukemia (CML). As children have a much longer life expectancy than adults, TKI therapy may continue for decades and with long-term consequences that differ from adults. Children may develop endocrinopathies related to "off-target" effects of TKIs, such as delayed growth, changes in bone metabolism, thyroid abnormalities, and effects on puberty and fertility. These endocrinopathies present additional challenges for pediatric patients with CML. This review critically evaluates the literature on long-term endocrine side effects of TKIs in the pediatric CML population and provides suggested recommendations.

The biology, pathogenesis and clinical aspects of acute lymphoblastic leukemia in children with Down syndrome

Children with Down syndrome (DS) are at a 20-fold increased risk for acute lymphoblastic leukemia (DS-ALL). Although the etiology of this higher risk of developing leukemia remains largely unclear, the recent identification of CRLF2 (cytokine receptor like factor 2) and JAK2 mutations and study of the effect of trisomy of Hmgn1 and Dyrk1a (dual-specificity tyrosine phosphorylation-regulated kinase 1A) on B-cell development have shed significant new light on the disease process. Here we focus on the clinical features, biology and genetics of ALL in children with DS. We review the unique characteristics of DS-ALL on both the clinical and molecular levels and discuss the differences in treatments and outcomes in ALL in children with DS compared with those without DS. The identification of new biological insights is expected to pave the way for novel targeted therapies.

Patterns and predictors of clustered risky health behaviors among adult survivors of childhood cancer: A report from the Childhood Cancer Survivor Study

BACKGROUND

Health complications related to childhood cancer may be influenced by risky health behaviors (RHBs), particularly when RHBs co-occur. To the authors' knowledge, only limited information is available describing how RHBs cluster among survivors of childhood cancer and their siblings and the risk factors for co-occurring RHBs.

METHODS

Latent class analysis was used to identify RHB clusters using longitudinal survey data regarding smoking, alcohol use, and physical activity from adult survivors (4184 survivors) and siblings (1598 siblings) in the Childhood Cancer Survivor Study. Generalized logistic regression was used to evaluate associations between demographic characteristics, treatment exposures, psychological distress, health conditions, and cluster membership.

RESULTS

Three RHB clusters were identified: a low-risk cluster, an insufficiently active cluster, and a high-risk cluster (tobacco and risky alcohol use and insufficient activity). Compared with siblings, survivors were more likely to be in the insufficiently active cluster (adjusted odds ratio [ORadj ], 1.17; 95% confidence interval [95% CI], 1.06-1.27) and were less likely to be in the high-risk cluster (ORadj , 0.79; 95% CI, 0.69-0.88). Risk factors for membership in the high-risk cluster included psychological distress (ORadj , 2.76; 95% CI, 1.98-3.86), low educational attainment (ORadj , 7.49; 95% CI, 5.15-10.88), income <$20,000 (ORadj , 2.62; 95% CI, 1.93-3.57), being divorced/separated or widowed (ORadj , 1.36; 95% CI, 1.03-1.79), and limb amputation (ORadj , 1.52; 95% CI, 1.03-2.24). Risk factors for the insufficiently active cluster included chronic health conditions, psychological distress, low education or income, being obese or overweight, female sex, nonwhite race/ethnicity, single marital status, cranial radiation, and cisplatin exposure.

CONCLUSIONS

RHBs co-occur in survivors of childhood cancer and their siblings. Economic and educational disadvantages and psychological distress should be considered in screening and interventions to reduce RHBs. Cancer 2016. © 2016 American Cancer Society. Cancer 2016;122:2747-2756. © 2016 American Cancer Society.

Rechallenging With Intrathecal Methotrexate After Developing Subacute Neurotoxicity in Children With Hematologic Malignancies

Methotrexate is associated with neurologic side effects. It is recommended that patients who developed neurotoxicity be rechallenged with methotrexate, but little is known about the safety of this approach. We performed a chart review to identify patients who received high-dose or intrathecal (IT) methotrexate. Twenty-one of 298 patients (7%) experienced neurologic symptoms attributed to methotrexate treatment in the premaintenance phase. Seventeen of these patients were rechallenged with IT methotrexate and 13 (76%) had no further neurotoxic events. No patients rechallenged during maintenance (n = 9) experienced recurrence of neurotoxic events. It is safe to rechallenge with IT methotrexate in maintenance.