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.

Ensuring access to innovative therapies for children, adolescents, and young adults across Canada: The single patient study experience

Innovative therapeutic approaches are needed to alleviate the burden of life-limiting, rare, and chronic conditions affecting children, adolescents, and young adults (CAYA). This includes a need for improved access to both clinical research and to non-approved or off-label therapies, together with, ultimately, more therapies achieving regulatory approval in Canada. The single patient study (SPS), also known as an open label individual patient (OLIP) study, was introduced by Health Canada to open access to non-marketed drugs where a clinical trial is not readily available, but the drug is considered too investigational to be managed on a standard Special Access Program. SPS is designed for patients who have a serious or life-threatening condition and have exhausted available treatment options. Our report summarizes this relatively new development in the Canadian regulatory environment and highlights the opportunities and challenges as identified by regulators, pharmaceutical representatives, academic researchers, and patient/parent advocates.

Developing a partnership to improve health care delivery to children <18 years with cancer and blood disorders in the English-speaking Caribbean: lessons from the SickKids-Caribbean Initiative (SCI)

In 2013, the SickKids-Caribbean Initiative (SCI) was formalised among The Hospital for Sick Children in Toronto, Canada, the University of the West Indies, and Ministries of Health in six Caribbean countries (Barbados, The Bahamas, Jamaica, St. Lucia, St. Vincent and the Grenadines, and Trinidad and Tobago). The aim was to improve the outcomes and quality of life of children (<18 years) with cancer and blood disorders in the partner countries. Core activities included filling a human resource gap by training paediatric haematologists/oncologists and specialised registered nurses; improving capacity to diagnose and treat diverse haematology/oncology cases; developing and maintaining paediatric oncology databases; creating ongoing advocacy activities with international agencies, decision makers, and civil society; and establishing an integrated administration, management, and funding structure. We describe core program components, successes, and challenges to inform others seeking to improve health service delivery in a multidisciplinary and complex partnership.

Children's Oncology Group AALL1331: Phase III Trial of Blinatumomab in Children, Adolescents, and Young Adults With Low-Risk B-Cell ALL in First Relapse

PURPOSE

Blinatumomab, a bispecific T-cell engager immunotherapy, is efficacious in relapsed/refractory B-cell ALL (B-ALL) and has a favorable toxicity profile. One aim of the Children's Oncology Group AALL1331 study was to compare survival of patients with low-risk (LR) first relapse of B-ALL treated with chemotherapy alone or chemotherapy plus blinatumomab.

PATIENTS AND METHODS

After block 1 reinduction, patients age 1-30 years with LR first relapse of B-ALL were randomly assigned to block 2/block 3/two continuation chemotherapy cycles/maintenance (arm C) or block 2/two cycles of continuation chemotherapy intercalated with three blinatumomab blocks/maintenance (arm D). Patients with CNS leukemia received 18 Gy cranial radiation during maintenance and intensified intrathecal chemotherapy. The primary and secondary end points were disease-free survival (DFS) and overall survival (OS).

RESULTS

The 4-year DFS/OS for the 255 LR patients accrued between December 2014 and September 2019 were 61.2% ± 5.0%/90.4% ± 3.0% for blinatumomab versus 49.5% ± 5.2%/79.6% ± 4.3% for chemotherapy (P = .089/P = .11). For bone marrow (BM) ± extramedullary (EM) (BM ± EM; n = 174) relapses, 4-year DFS/OS were 72.7% ± 5.8%/97.1% ± 2.1% for blinatumomab versus 53.7% ± 6.7%/84.8% ± 4.8% for chemotherapy (P = .015/P = .020). For isolated EM (IEM; n = 81) relapses, 4-year DFS/OS were 36.6% ± 8.2%/76.5% ± 7.5% for blinatumomab versus 38.8% ± 8.0%/68.8% ± 8.6% for chemotherapy (P = .62/P = .53). Blinatumomab was well tolerated and patients had low adverse event rates.

CONCLUSION

For children, adolescents, and young adults with B-ALL in LR first relapse, there was no statistically significant difference in DFS or OS between the blinatumomab and standard chemotherapy arms overall. However, blinatumomab significantly improved DFS and OS for the two thirds of patients with BM ± EM relapse, establishing a new standard of care for this population. By contrast, similar outcomes and poor DFS for both arms were observed in the one third of patients with IEM; new treatment approaches are needed for these patients (ClinicalTrials.gov identifier: NCT02101853).

Abstract 4509: A pan-Canadian precision oncology program for children, adolescents and young adults with hard-to-cure cancer: The PRecision Oncology For Young peopLE (PROFYLE) Program

Background: Over 4,300 children, adolescents, and young adults (CAYA) are diagnosed with cancer each year in Canada, 1/3 of whom have refractory/metastatic disease or will relapse. The PRecision Oncology For Young peopLE (PROFYLE) national, collaborative program, was created to provide equitable access to molecular profiling to identify novel targeted treatment options in a clinically relevant timeframe for all CAYA with hard-to-cure cancers in Canada.

Design: Building upon 3 pre-existing regional precision oncology programs, PROFYLE now includes &gt;20 institutions and has united an interdisciplinary team of experts, leaders, research teams, end-users and advocates from across Canada. The program has 14 domain specific nodes that are unified by a shared governance structure, and has harmonized biobanking, genomics, bioinformatics and reporting procedures. PROFYLE includes genomic and transcriptomic sequencing of paired germline and cancer fresh/frozen samples, proteomic analysis, and cancer modelling. Inclusion criteria: ≤29y; treatment at a Canadian center; diagnosis of a hard-to-cure cancer. Profiling results are reviewed by multidisciplinary Molecular Tumor Boards. A report including a results/recommendations summary of actionable findings (therapeutic, diagnostic, prognostic, cancer predisposition), potential targeted therapy options including available clinical trials, clarification of diagnosis, and genetic counseling recommendations is provided to the treating oncologist.

Results: &gt;1,000 CAYA are included from all of the provinces. Cancer diagnoses: 34% sarcoma, 16% leukemia/lymphoma, 16% CNS tumor, 11% neuroblastoma, 23% other. 17% of participants had a cancer-predisposing pathogenic/likely pathogenic germline variant, 45% had ≥1 potentially actionable somatic alteration, 22.6% had a therapeutically targetable somatic alteration. The most frequent classes of therapeutic alterations were RAS/MAPK (15%), cell cycle (14%), epigenetic (13%), RTK (12%), PI3K/AKT/mTOR (11%), DNA repair (9%), immune checkpoint (8%). Of clinicians who reported the utility of results, 55% indicated the findings were useful for clinical management.

Future Directions: Collaborations with other national and international initiatives and data from this interdisciplinary, multi-institutional research program will inform the development of a framework to innovatively link research, clinical and system considerations with Canadian values relevant to multi-omic profiling and drug access for CAYA. In addition, we believe that with a comprehensive molecular view of cancer, PROFYLE will transform our understanding of underlying disease mechanisms, facilitate and improve diagnostic and prognostic indicators, and identify new therapeutic strategies and targets for CAYA patients with cancer.

Citation Format: Stephanie A. Grover, Lesleigh Abbott, Jason N. Berman, Guillaume Bourque, Jennifer A. Chan, Avram E. Denburg, Rebecca J. Deyell, Conrad V. Fernandez, Cynthia Hawkins, Jan-Willem Henning, Meredith S. Irwin, Nada Jabado, Steven J. Jones, Philipp F. Lange, Paul Moorehead, Michael F. Moran, Daniel A. Morgenstern, Sapna Oberoi, Antonia Palmer, Shahrad R. Rassekh, Donna L. Senger, Adam Shlien, Daniel Sinnett, Caron Strahlendorf, Patrick J. Sullivan, Michael D. Taylor, Suzanne Vercauteren, Anita Villani, Stephanie Villeneuve, James A. Whitlock, David Malkin, on behalf of the PROFYLE Consortium. A pan-Canadian precision oncology program for children, adolescents and young adults with hard-to-cure cancer: The PRecision Oncology For Young peopLE (PROFYLE) Program. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4509.

The clinical utility of integrative genomics in childhood cancer extends beyond targetable mutations

We conducted integrative somatic-germline analyses by deeply sequencing 864 cancer-associated genes, complete genomes and transcriptomes for 300 mostly previously treated children and adolescents/young adults with cancer of poor prognosis or with rare tumors enrolled in the SickKids Cancer Sequencing (KiCS) program. Clinically actionable variants were identified in 56% of patients. Improved diagnostic accuracy led to modified management in a subset. Therapeutically targetable variants (54% of patients) were of unanticipated timing and type, with over 20% derived from the germline. Corroborating mutational signatures (SBS3/BRCAness) in patients with germline homologous recombination defects demonstrates the potential utility of PARP inhibitors. Mutational burden was significantly elevated in 9% of patients. Sequential sampling identified changes in therapeutically targetable drivers in over one-third of patients, suggesting benefit from rebiopsy for genomic analysis at the time of relapse. Comprehensive cancer genomic profiling is useful at multiple points in the care trajectory for children and adolescents/young adults with cancer, supporting its integration into early clinical management.

Efficacy and Safety of Trametinib Monotherapy or in Combination With Dabrafenib in Pediatric BRAF V600-Mutant Low-Grade Glioma

PURPOSE

BRAF V600 mutations occur in many childhood cancers, including approximately 20% of low-grade gliomas (LGGs). Here, we describe a phase I/II study establishing pediatric dosing and pharmacokinetics of trametinib with or without dabrafenib, as well as efficacy and safety in a disease-specific cohort with BRAF V600-mutant LGG; other cohorts will be reported elsewhere.

METHODS

This is a four-part, phase I/II study (ClinicalTrials.gov identifier: NCT02124772) in patients age < 18 years with relapsed/refractory malignancies: trametinib monotherapy dose finding (part A) and disease-specific expansion (part B), and dabrafenib + trametinib dose finding (part C) and disease-specific expansion (part D). The primary objective assessed in all patients in parts A and C was to determine pediatric dosing on the basis of steady-state pharmacokinetics. Disease-specific efficacy and safety (across parts A-D) were secondary objectives.

RESULTS

Overall, 139 patients received trametinib (n = 91) or dabrafenib + trametinib (n = 48). Trametinib dose-limiting toxicities in > 1 patient (part A) included mucosal inflammation (n = 3) and hyponatremia (n = 2). There were no dose-limiting toxicities with combination therapy (part C). The recommended phase II dose of trametinib, with or without dabrafenib, was 0.032 mg/kg once daily for patients age < 6 years and 0.025 mg/kg once daily for patients age ≥ 6 years; dabrafenib dosing in the combination was as previously identified for monotherapy. In 49 patients with BRAF V600-mutant glioma (LGG, n = 47) across all four study parts, independently assessed objective response rates were 15% (95% CI, 1.9 to 45.4) for monotherapy (n = 13) and 25% (95% CI, 12.1 to 42.2) for combination (n = 36). Adverse event-related treatment discontinuations were more common with monotherapy (54% v 22%).

CONCLUSION

The trial design provided efficient evaluation of pediatric dosing, safety, and efficacy of single-agent and combination targeted therapy. Age-based and weight-based dosing of trametinib with or without dabrafenib achieved target concentrations with manageable safety and demonstrated clinical efficacy and tolerability in BRAF V600-mutant LGG.

Nelarabine, etoposide, and cyclophosphamide in relapsed pediatric T-acute lymphoblastic leukemia and T-lymphoblastic lymphoma (study T2008-002 NECTAR)

Children with relapse of T-cell acute lymphoblastic leukemia (T-ALL) or lymphoblastic lymphoma (T-LBL) have a dismal prognosis, largely due to difficulty attaining second remission. We hypothesized that adding etoposide and cyclophosphamide to the nucleoside analog nelarabine could improve response rates over single-agent nelarabine for relapsed T-ALL and T-LBL. This phase I dose-escalation trial's primary objective was to evaluate the dose and safety of nelarabine given in combination with etoposide at 100 mg/m² /day and cyclophosphamide at 330-400 mg/m² /day, each for 5 consecutive days in children with either T-ALL (13 patients) or T-LBL (10 patients). Twenty-three patients were treated at three dose levels; 21 were evaluable for dose-limiting toxicities (DLT) and response. The recommended phase II doses (RP2D) for this regimen, when given daily ×5 every 3 weeks, were nelarabine 650 mg/m² /day, etoposide 100 mg/m² /day, and cyclophosphamide 400 mg/m² /day. DLTs included peripheral motor and sensory neuropathies. An expansion cohort to evaluate responses at the RP2D was terminated early due to slow accrual. The overall best response rate was 38% (8/21), with 33% (4/12) responses in the T-ALL cohort and 44% (4/9) responses in the T-LBL cohort. These response rates are comparable to those seen with single-agent nelarabine in this setting. These data suggest that the addition of cyclophosphamide and etoposide to nelarabine does not increase the incidence of neurologic toxicities or the response rate beyond that obtained with single-agent nelarabine in children with first relapse of T-ALL and T-LBL.

Abstract 5224: The PRecision Oncology For Young peopLE (PROFYLE) Program: A national precision oncology program for children, adolescents and young adults with hard-to-cure cancer in Canada

Background: Over 4,300 children, adolescents, and young adults (CAYA) are diagnosed with cancer each year in Canada, 1/3 of whom have refractory/metastatic disease or will relapse. A national collaborative program, PRecision Oncology For Young peopLE (PROFYLE), was created with the goal to develop and implement a pipeline providing access to tumor molecular profiling to identify novel targeted treatment options in a clinically relevant timeframe for CAYA with hard-to-cure cancers.

Design: PROFYLE includes more than 20 institutions, building upon 3 pre-existing regional precision oncology programs (Personalized Oncogenomics (POG), SickKids Cancer Sequencing (KiCS), and Personalized Targeted Therapy in Refractory or Relapsed Cancer in Childhood (TRICEPS)). PROFYLE has united an interdisciplinary team of experts, leaders, research team, end-users and advocates from across Canada to form 14 domain specific nodes unified by a shared governance structure. PROFYLE includes genomic and transcriptomic sequencing of paired germline/cancer fresh/frozen samples. Inclusion criteria: ≤29y; treatment at a Canadian center; diagnosis of a hard-to-cure cancer. Profiling results are reviewed by multidisciplinary Molecular Tumor Boards. A report including a results/recommendations summary of actionable findings (therapeutic, diagnostic, prognostic, cancer predisposition), potential targeted therapy options including available clinical trials, clarification of diagnosis, and genetic counseling recommendations is provided to the treating oncologist.

Results: To date, &gt;900 CAYA are enrolled. Cancer diagnoses: 36% sarcoma, 16% leukemia/lymphoma, 16% CNS tumor, 13% neuroblastoma, 19% other. At study entry, 44% of participants had not relapsed, 40% had 1 relapse, 9% 2 relapses, 4% 3+ relapses. 17% had a cancer-predisposing pathogenic/likely pathogenic germline variant, 40% had ≥1 potentially actionable somatic alteration, 9.7% had a therapeutically targetable somatic alteration. The most frequent classes of therapeutic alterations were cell cycle (15%), RAS/MAPK (14%), epigenetic (13%), RTK (12%), PI3K/AKT/mTOR (10%), DNA repair (9%), immune checkpoint (8%). Of clinicians who reported the utility of results, 56% indicated the findings were useful for clinical management.

Future Directions: With a comprehensive molecular view of cancer, PROFYLE will transform our understanding of underlying disease mechanisms, facilitate and improve diagnostic and prognostic indicators, and identify new therapeutic strategies and targets. Data from this interdisciplinary, multi-institutional research program will inform the development of a framework to innovatively link research, clinical and system considerations with Canadian values relevant to genomic profiling and drug access for CAYA in Canada.

Citation Format: Stephanie A. Grover, Lesleigh Abbott, Jason N. Berman, Jennifer A. Chan, Avram E. Denburg, Rebecca J. Deyell, Conrad V. Fernandez, Cynthia Hawkins, Jan-Willem Henning, Meredith S. Irwin, Nada Jabado, Steven J. Jones, Philipp F. Lange, Michael F. Moran, Daniel A. Morgenstern, Antonia Palmer, Shahrad R. Rassekh, Donna L. Senger, Adam Shlien, Daniel Sinnett, Caron Strahlendorf, Patrick J. Sullivan, Michael D. Taylor, Suzanne Vercauteren, Anita Villani, James A. Whitlock, David Malkin, on behalf of the Terry Fox PROFYLE Consortium. The PRecision Oncology For Young peopLE (PROFYLE) Program: A national precision oncology program for children, adolescents and young adults with hard-to-cure cancer in Canada [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5224.

Temsirolimus combined with cyclophosphamide and etoposide for pediatric patients with relapsed/refractory acute lymphoblastic leukemia: a Therapeutic Advances in Childhood Leukemia Consortium trial (TACL 2014-001)

Phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) signaling is commonly dysregulated in acute lymphoblastic leukemia (ALL). The TACL2014-001 phase I trial of the mTOR inhibitor temsirolimus in combination with cyclophosphamide and etoposide was performed in children and adolescents with relapsed/refractory ALL. Temsirolimus was administered intravenously (IV) on days 1 and 8 with cyclophosphamide 440 mg/m2 and etoposide 100 mg/m2 IV daily on days 1-5. The starting dose of temsirolimus was 7.5 mg/m2 (DL1) with escalation to 10 mg/m2 (DL2), 15 mg/m2 (DL3), and 25 mg/m2 (DL4). PI3K/mTOR pathway inhibition was measured by phosphoflow cytometry analysis of peripheral blood specimens from treated patients. Sixteen heavily-pretreated patients were enrolled with 15 evaluable for toxicity. One dose-limiting toxicity of grade 4 pleural and pericardial effusions occurred in a patient treated at DL3. Additional dose-limiting toxicities were not seen in the DL3 expansion or DL4 cohort. Grade 3/4 non-hematologic toxicities occurring in three or more patients included febrile neutropenia, elevated alanine aminotransferase, hypokalemia, mucositis, and tumor lysis syndrome and occurred across all doses. Response and complete were observed at all dose levels with a 47% overall response rate and 27% complete response rate. Pharmacodynamic correlative studies demonstrated dose-dependent inhibition of PI3K/mTOR pathway phosphoproteins in all studied patients. Temsirolimus at doses up to 25 mg/m2 with cyclophosphamide and etoposide had an acceptable safety profile in children with relapsed/refractory ALL. Pharmacodynamic mTOR target inhibition was achieved and appeared to correlate with temsirolimus dose. Future testing of next-generation PI3K/mTOR pathway inhibitors with chemotherapy may be warranted to increase response rates in children with relapsed/refractory ALL.

ALK-positive histiocytosis: a new clinicopathologic spectrum highlighting neurologic involvement and responses to ALK inhibition

ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Allogeneic Hematopoietic Stem Cell Transplantation for Children With Acute Lymphoblastic Leukemia: Shifting Indications in the Era of Immunotherapy

Pediatric acute lymphoblastic leukemia generally carries a good prognosis, and most children will be cured and become long-term survivors. However, a portion of children will harbor high-risk features at the time of diagnosis, have a poor response to upfront therapy, or suffer relapse necessitating more intensive therapy, which may include allogeneic hematopoietic stem cell transplant (HSCT). Recent advances in risk stratification, improved detection and incorporation of minimal residual disease (MRD), and intensification of upfront treatment have changed the indications for HSCT over time. For children in first complete remission, HSCT is generally reserved for those with the highest risk of relapse. These include patients with unfavorable features/cytogenetics who also have a poor response to induction and consolidation chemotherapy, usually reflected by residual blasts after prednisone or by detectable MRD at pre-defined time points. In the relapsed setting, children with first relapse of B-cell ALL are further stratified for HSCT depending on the time and site of relapse, while all patients with T-cell ALL are generally consolidated with HSCT. Alternatives to HSCT have also emerged over the last decade including immunotherapy and chimeric antigen receptor (CAR) T-cell therapy. These novel agents may spare toxicity while attempting to achieve MRD-negative remission in the most refractory cases and serve as a bridge to HSCT. In some situations, these emerging therapies can indeed be curative for some children with relapsed or resistant disease, thus, obviating the need for HSCT. In this review, we seek to summarize the role of HSCT in the current era of immunotherapy.

Descriptive Analysis of Forces Applied by Trained Clinicians During Two-Handed Instrument-Assisted Soft Tissue Mobilization

Instrument-assisted soft tissue mobilization (IASTM) is a common intervention among clinicians. Despite the popularity, little is known about the forces applied by the clinician with the instruments during treatment. The purpose of this investigation was to examine the forces applied by trained clinicians using IASTM instruments during a simulated treatment. Eleven IASTM trained (Graston Technique, Técnica Gavilán, or RockBlades) clinicians (Physical Therapist = 2, Chiropractor = 2, Athletic Trainer = 7) participated in the study. Each clinician performed 75 two-handed strokes distributed evenly across five different IASTM instruments on a skin simulant attached to a force plate. IASTM stroke application was analyzed for peak normal forces (Fpeak) and mean normal forces (Fmean) by stroke. We observed an average Fpeak of 8.9N and Fmean of 6.0N across all clinicians and instruments. Clinicians and researchers may use the descriptive values as a reference for application of IASTM in practice and research.

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.

Abstract 636: PROFYLE: The pan-Canadian precision oncology program for children, adolescents and young adults with hard-to-treat cancer

Background: Over 4300 children, adolescents, and young adults (CAYA) are diagnosed with cancer each year in Canada, 1/3 of whom have refractory/metastatic disease or will relapse. A national collaborative program, PRecision Oncology For Young peopLE (PROFYLE), was created with the goal to develop and implement a pipeline providing access to tumor molecular profiling to identify novel targeted treatment options in a clinically relevant timeframe for CAYA with hard-to-treat cancers.

Design: PROFYLE unites 21 institutions, building upon 3 pre-existing regional pediatric precision oncology programs (Personalized Oncogenomics (POG), SickKids Cancer Sequencing (KiCS), and Personalized Targeted Therapy in Refractory or Relapsed Cancer in Childhood (TRICEPS)). PROFYLE nodes (genomics/bioinformatics, proteomics, modeling, biomarkers, data/biobanking, therapeutics, bioethics, policy, AYA) are unified by a shared governance structure. PROFYLE includes genomic and transcriptomic sequencing of paired germline/cancer fresh/frozen samples. Inclusion criteria: ≤29y; treatment at a Canadian center; diagnosis of a hard-to-treat cancer. Profiling results are reviewed by multidisciplinary Molecular Tumor Boards. A report including a results/recommendations summary of actionable findings (therapeutic, diagnostic, prognostic, cancer predisposition), potential targeted therapy options including available clinical trials, clarification of diagnosis, and genetic counseling referral is provided to the treating oncologist.

Results: To date, &gt;800 CAYA are enrolled in PROFYLE and POG, KiCS, TRICEPS. Cancer diagnoses: 35% sarcoma, 18% leukemia/lymphoma, 14% CNS tumor, 14% neuroblastoma, 19% other. At study entry, 44% of participants had not relapsed, 39% 1 relapse, 14% 2 relapses, and 3% 3+ relapses. 13% had a cancer-predisposing pathogenic/likely pathogenic germline variant, 39% had ≥1 potentially actionable somatic alteration, and 13% had a therapeutically targetable somatic alteration. The most frequent classes of alterations were RAS/MAPK, immune checkpoint, cell cycle, DNA repair, epigenetic, PI3K/AKT/mTOR, RTK. Of clinicians who reported the utility of results, 78% indicated the findings had the potential to inform a medical decision.

Future Directions: We will build on PROFYLE's success by addressing the challenge of real-time availability of target-based therapies through innovative clinical trial strategies incorporating new drugs, off-label use, drug combinations, basket and single patient study designs to enable improved access to therapies for CAYA with actionable molecular targets. We will work on policy-relevant research to facilitate implementation of precision oncology care for CAYA in Canada. We will leverage knowledge developed by PROFYLE thus far by integrating omics, modeling and biomarkers research in the trials being developed.

Citation Format: Stephanie A. Grover, Thierry Alcindor, Jason N. Berman, Jennifer A. Chan, Avram E. Denburg, Rebecca J. Deyell, David D. Eisenstat, Conrad V. Fernandez, Paul E. Grundy, Abha Gupta, Cynthia Hawkins, Meredith S. Irwin, Nada Jabado, Steven J. Jones, Michael F. Moran, Daniel A. Morgenstern, Shahrad R. Rassekh, Adam Shlien, Daniel Sinnett, Poul H. Sorensen, Patrick J. Sullivan, Michael D. Taylor, Anita Villani, James A. Whitlock, David Malkin, on behalf of the Terry Fox PROFYLE Consortium. PROFYLE: The pan-Canadian precision oncology program for children, adolescents and young adults with hard-to-treat cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 636.

Low-dose metronomic topotecan and pazopanib in children with recurrent or refractory solid tumors: A C17 Canadian phase I trial (TOPAZ)

10020

Background: Low-dose metronomic topotecan (mTP) represents a novel approach to chemotherapy delivery which, in preclinical models, may work synergistically with pazopanib (PZ) in targeting angiogenesis. This study was designed to determine the recommended phase 2 dose (RP2D) of mTP/PZ in pediatric patients with solid tumors, while describing the safety and toxicity of this regimen. Methods: A phase I dose-escalation, pharmacokinetic (PK) and pharmacodynamic (PD) study of mTP/PZ was conducted at ten sites across Canada, enrolling pediatric patients aged 2-21 years with relapsed/refractory solid tumors. Patients were treated with oral mTP and PZ suspension daily without interruption in 28-day cycles, with dose escalation in accordance with the rolling-six design. Five dose levels (0.12/125, 0.16/125, 0.22/125, 0.22/160, and 0.3/160 mg/m2/day of mTP/PZ) were evaluated. PK studies were performed on day 1 and at steady state, and PD studies included circulating angiogenic factors VEGFR1, VEGFR2, VEGF, endoglin and placental growth factor. Results: Thirty patients (pts) were enrolled, of whom 26 were evaluable for dose-limiting toxicity (DLT), with median age 12 years (3-20). The most common diagnoses included osteosarcoma (8), neuroblastoma (NB, 7), Ewing sarcoma/PNET (4), and rhabdomyosarcoma (4). The most common grade 3/4 adverse events (AEs) related to protocol therapy were neutropenia (18%), thrombocytopenia (11%), lymphocytopenia (11%), AST elevation (11%), and lipase elevation (11%). Only 2 cycle-1 DLTs were observed on study, both at the 0.3/160 mg/m2 mTP/PZ dose level (2/5 pts) comprising persistent grade 3 thrombocytopenia and grade 3 ALT elevation. No AEs experienced beyond cycle-1 required treatment discontinuation. Best response was stable disease in 10/25 pts (40%) for a median duration of 6.4 months (1.7-45.1). One patient with refractory NB achieved stable disease for 45 months and continued on mTP/PZ via compassionate access after study closure. PK and PD results are pending at this time. Conclusions: The combination of oral mTP and PZ is safe and tolerable in pediatric patients with solid tumors, with a RP2D of mTP 0.22 mg/m2/day and PZ suspension 160 mg/m2/day. Ten patients achieved stable disease for a median of 6 months. The lack of objective responses suggests that this combination is likely of limited benefit for relapsed disease, but may play a role as maintenance therapy. Clinical trial information: NCT02303028.

Effect of Postreinduction Therapy Consolidation With Blinatumomab vs Chemotherapy on Disease-Free Survival in Children, Adolescents, and Young Adults With First Relapse of B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial

IMPORTANCE

Standard chemotherapy for first relapse of B-cell acute lymphoblastic leukemia (B-ALL) in children, adolescents, and young adults is associated with high rates of severe toxicities, subsequent relapse, and death, especially for patients with early relapse (high risk) or late relapse with residual disease after reinduction chemotherapy (intermediate risk). Blinatumomab, a bispecific CD3 to CD19 T cell-engaging antibody construct, is efficacious in relapsed/refractory B-ALL and has a favorable toxicity profile.

OBJECTIVE

To determine whether substituting blinatumomab for intensive chemotherapy in consolidation therapy would improve survival in children, adolescents, and young adults with high- and intermediate-risk first relapse of B-ALL.

DESIGN, SETTING, AND PARTICIPANTS

This trial was a randomized phase 3 clinical trial conducted by the Children's Oncology Group at 155 hospitals in the US, Canada, Australia, and New Zealand with enrollment from December 2014 to September 2019 and follow-up until September 30, 2020. Eligible patients included those aged 1 to 30 years with B-ALL first relapse, excluding those with Down syndrome, Philadelphia chromosome-positive ALL, prior hematopoietic stem cell transplant, or prior blinatumomab treatment (n = 669).

INTERVENTIONS

All patients received a 4-week reinduction chemotherapy course, followed by randomized assignment to receive 2 cycles of blinatumomab (n = 105) or 2 cycles of multiagent chemotherapy (n = 103), each followed by transplant.

MAIN OUTCOME AND MEASURES

The primary end point was disease-free survival and the secondary end point was overall survival, both from the time of randomization. The threshold for statistical significance was set at a 1-sided P <.025.

RESULTS

Among 208 randomized patients (median age, 9 years; 97 [47%] females), 118 (57%) completed the randomized therapy. Randomization was terminated at the recommendation of the data and safety monitoring committee without meeting stopping rules for efficacy or futility; at that point, 80 of 131 planned events occurred. With 2.9 years of median follow-up, 2-year disease-free survival was 54.4% for the blinatumomab group vs 39.0% for the chemotherapy group (hazard ratio for disease progression or mortality, 0.70 [95% CI, 0.47-1.03]); 1-sided P = .03). Two-year overall survival was 71.3% for the blinatumomab group vs 58.4% for the chemotherapy group (hazard ratio for mortality, 0.62 [95% CI, 0.39-0.98]; 1-sided P = .02). Rates of notable serious adverse events included infection (15%), febrile neutropenia (5%), sepsis (2%), and mucositis (1%) for the blinatumomab group and infection (65%), febrile neutropenia (58%), sepsis (27%), and mucositis (28%) for the chemotherapy group.

CONCLUSIONS AND RELEVANCE

Among children, adolescents, and young adults with high- and intermediate-risk first relapse of B-ALL, postreinduction treatment with blinatumomab compared with chemotherapy, followed by transplant, did not result in a statistically significant difference in disease-free survival. However, study interpretation is limited by early termination with possible underpowering for the primary end point.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02101853.

Outcomes after late bone marrow and very early central nervous system relapse of childhood B-acute lymphoblastic leukemia: a report from the Children's Oncology Group phase III study AALL0433

Outcomes after relapse of childhood B-acute lymphoblastic leukemia (B-ALL) are poor, and optimal therapy is unclear. The children’s Oncology Group study AALL0433 evaluated a new platform for relapsed ALL. Between March 2007 and October 2013 AALL0433 enrolled 275 participants with late bone marrow or very early isolated central nervous system (iCNS) relapse of childhood B-ALL. Patients were randomized to receive standard versus intensive vincristine dosing; this randomization was closed due to excess peripheral neuropathy in 2010. Patients with matched sibling donors received allogeneic hematopoietic cell transplantation (HCT) after the first three blocks of therapy. The prognostic value of minimal residual disease (MRD) was also evaluated in this study. The 3-year event free and overall survival (EFS/OS) for the 271 eligible patients were 63.6±3.0% and 72.3±2.8% respectively. MRD at the end of Induction-1 was highly predictive of outcome, with 3-year EFS/OS of 84.9±4.0% and 93.8±2.7% for patients with MRD <0.1%, versus 53.7±7.8% and 60.6± 7.8% for patients with MRD ≥0.1% (P<0.0001). Patients who received HCT versus chemotherapy alone had an improved 3-year disease-free survival (77.5±6.2% vs. 66.9 + 4.5%, P=0.03) but not OS (81.5±5.8% for HCT vs. 85.8±3.4% for chemotherapy, P=0.46). Patients with early iCNS relapse fared poorly, with a 3-year EFS/OS of 41.4±9.2% and 51.7±9.3%, respectively. Infectious toxicities of the chemotherapy platform were significant. The AALL0433 chemotherapy platform is efficacious for late bone marrow relapse of B-ALL, but with significant toxicities. The MRD threshold of 0.1% at the end of Induction-1 was highly predictive of the outcome. The optimal role for HCT for this patient population remains uncertain. This trial is registered at clinicaltrials.gov (NCT# 00381680).

LGG-49. SAFETY AND EFFICACY OF TRAMETINIB (T) MONOTHERAPY AND DABRAFENIB + TRAMETINIB (D+T) COMBINATION THERAPY IN PEDIATRIC PATIENTS WITH BRAF V600-MUTANT LOW-GRADE GLIOMA (LGG)

BACKGROUND

Children with BRAF V600-mutant LGG have suboptimal response to standard chemotherapy. Previously, D (BRAF V600 inhibitor) monotherapy has demonstrated clinical benefit in this population. We report interim analysis results of pediatric patients with recurrent/refractory BRAF V600-mutant LGG treated with either T (MEK1/2 inhibitor) monotherapy or D+T combination therapy.

METHODS

This is a 4-part, open-label, multicenter, phase I/II study (NCT02124772) in pediatric patients (<18 y) with refractory/recurrent tumors. The dose-finding phase, including dose confirmation stratified by age, was followed by disease-specific cohorts at recommended dose levels. Efficacy was determined by both investigator and independent review using RANO criteria. Adverse events (AEs) were assessed per NCI-CTCAE v4.03.

RESULTS

Of 49 pediatric patients with BRAF V600-mutant LGG (T, n=13; D+T, n=36) enrolled, pooled efficacy data was available for both treatments while safety data was available for 30 patients (T, n=10; D+T, n=20). Most patients (n=8/10) receiving T monotherapy withdrew/discontinued the treatment in contrast to 3/20 in the D+T group. Pyrexia occurred in 50% of patients (n=5/10) in the monotherapy group and was a frequent AE in the combination group (75%; n=15/20). Objective response rate per independent review was 15% (95% CI, 2%–45%) with T monotherapy and 25% (95% CI, 12%–42%) with D+T combination therapy. Seven patients (54%) on monotherapy and 33 patients (92%) on combination therapy had stable disease or better.

CONCLUSION

In pediatric patients with previously treated BRAF V600-mutant LGG, T monotherapy and D+T combination therapy demonstrated clinical activity, with pyrexia being a common AE.

Efficacy and Safety of Dabrafenib in Pediatric Patients with BRAF V600 Mutation-Positive Relapsed or Refractory Low-Grade Glioma: Results from a Phase I/IIa Study

PURPOSE

Pediatric low-grade glioma (pLGG) is the most prevalent childhood brain tumor. Patients with BRAF V600 mutation-positive pLGG may benefit from treatment with dabrafenib. Part 2 of a phase I/IIa study, open-label study (NCT01677741) explores the activity and safety of dabrafenib treatment in these patients.

PATIENTS AND METHODS

Patients ages 1 to <18 years who had BRAF V600-mutant solid tumors (≥1 evaluable lesion) with recurrent, refractory, or progressive disease after ≥1 standard therapy were treated with oral dabrafenib 3.0 to 5.25 mg/kg/day (part 1) or at the recommended phase II dose (RP2D; part 2). Primary objectives were to determine the RP2D (part 1, results presented in a companion paper) and assess clinical activity (part 2). Here, we report the clinical activity, including objective response rates (ORRs) using Response Assessment in Neuro-Oncology criteria and safety across parts 1 and 2.

RESULTS

Overall, 32 patients with pLGG were enrolled (part 1, n = 15; part 2, n = 17). Minimum follow-up was 26.2 months. Among all patients, the ORR was 44% [95% confidence interval (CI), 26-62] by independent review. The 1-year progression-free survival rate was 85% (95% CI, 64-94). Treatment-related adverse events (AE) were reported in 29 patients (91%); the most common was fatigue (34%). Grade 3/4 treatment-related AEs were reported in 9 patients (28%).

CONCLUSIONS

Dabrafenib demonstrated meaningful clinical activity and acceptable tolerability in patients with BRAF V600-mutant pLGG.

Abstract 5413: Terry Fox PRecision Oncology For Young peopLE (PROFYLE): A Canadian precision medicine program for children, adolescents and young adults with hard-to-treat cancer

Introduction: Over 4300 children, adolescents, and young adults (CAYA) are diagnosed with cancer each year in Canada, 1/3 of whom will have refractory or metastatic disease or will relapse with a very poor prognosis. Most CAYA cancer survivors suffer significant late effects that impose an enormous burden to them, their family and the health care system. To address this urgent medical and socioeconomic need, a pan-Canadian collaborative program, PRecision Oncology For Young peopLE (PROFYLE), was created with the objective to develop and implement the first Canadian precision oncology pipeline providing access to tumour molecular profiling with the aim of identifying novel targeted therapeutic options in a clinically relevant timeframe for CAYA with hard-to-treat cancer.

Design: Prior to PROFYLE, 3 programs (Personalized Oncogenomics Project (POG), SickKids Cancer Sequencing Program (KiCS), and Personalized Targeted Therapy in Refractory or Relapsed Cancer in Childhood (TRICEPS)) constituted the bulk of childhood precision oncology efforts in Canada. PROFYLE was designed to unite and build upon them, and consists of interconnected nodes including: genomics/bioinformatics, proteomics, cancer modeling, biomarkers, biobanking/data repositories, therapeutics/clinical trial design and biomedical ethics; unified by a shared governance structure. There are 16+ institutions in the PROFYLE consortium. The PROFYLE profiling strategy consists of initial reporting from a &gt;800 cancer gene panel, followed by whole genome (paired germline/cancer samples) and whole transcriptome analyses. Eligibility criteria: ≤29y; treatment at a Canadian oncology center; diagnosis with a hard-to-treat cancer. Profiling results are reviewed by multidisciplinary Molecular Tumour Boards. A patient-specific molecular research report including summary of results and recommendations (actionable finding, potential targeted therapies, any open clinical trials which the patient may be eligible for, change of diagnosis, and/or referral for genetic counselling) is provided to the treating oncologist.

Results: To date, 644 patients have taken part in PROFYLE (n=338) and POG, KiCS, TRICEPS. For the first 100 participants, cancer diagnoses include 43 sarcomas, 23 CNS tumors, 10 leukemia and lymphomas, 10 neuroblastoma and 14 other rare cancers. At study entry, 48% had not yet relapsed, 40% 1 relapse, 10% 2 relapses, and 2% 3+ relapses. 13 had a cancer-predisposing germline mutation and 82 had at least one potentially actionable somatic alteration. The most commonly mutated genes/pathways included TP53, CDNK2A/B, FGFR, MYC, and FLT1/3/4. 82% had results/recommendations from the MTB that informed a medical decision to alter diagnosis, prognosis, or treatment of their disease. In 71%, management recommendations were provided. Analyses of the complete dataset will be presented at the meeting.

Conclusion: The goal of developing a national precision oncology pipeline has been realized through the establishment of the PROFYLE initiative. PROFYLE continues to grow through increased recruitment, additional institutions, contribution of new knowledge to the field of precision oncology, improving access to clinical trials for CAYA patients, and advocacy and partnerships on local, national and international scales.

Citation Format: Stephanie A. Grover, Jason N. Berman, Jennifer A. Chan, Rebecca J. Deyell, David D. Eisenstat, Conrad V. Fernandez, Paul E. Grundy, Cynthia Hawkins, Meredith S. Irwin, Nada Jabado, Steven J. Jones, Michael Moran, Shahrad R. Rassekh, Adam Shlien, Daniel Sinnett, Poul H. Sorensen, Patrick J. Sullivan, Michael D. Taylor, Anita Villani, James A. Whitlock, David Malkin, on behalf of the Terry Fox PROFYLE Consortium. Terry Fox PRecision Oncology For Young peopLE (PROFYLE): A Canadian precision medicine program for children, adolescents and young adults with hard-to-treat cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5413.

Dabrafenib + trametinib combination therapy in pediatric patients with BRAF V600-mutant low-grade glioma: Safety and efficacy results

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Background: Low-grade gliomas (LGGs) are the most common brain tumors among children. Pediatric LGGs are often not surgically resectable and tend to demonstrate relapsed/remitting courses with current standard chemotherapy regimens. Moreover, radiation is often avoided due to its associated neurocognitive and endocrinologic sequelae. However, in pediatric patients (pts) with BRAF V600-mutant LGG, dabrafenib monotherapy has demonstrated meaningful clinical activity and acceptable tolerability (Hargrave et al, Clin Cancer Res. 2019; NCT01677741). Here we report the efficacy and safety of dabrafenib + trametinib (D+T) combination therapy in pediatric pts with previously treated BRAF V600-mutant LGG. Methods: This is a 4-part, open-label, multicenter, phase I/II study (NCT02124772). The limited dose-escalation (ESC) portion evaluated the D+T combination in pediatric pts ( < 18 y) with recurrent/refractory BRAF V600-mutated solid tumors that were naive to MAPK pathway–targeted therapy. This was followed by a tumor cohort expansion (EXP), and the D+T combination was evaluated in BRAF V600-mutant LGG pts at recommended dose levels. Efficacy was determined by both investigator and independent review using the RANO criteria (for gliomas). Adverse events (AEs) were assessed per NCI-CTCAE v4.03. Results: Overall, 36 pediatric pts with LGG received D+T combination therapy (ESC, n = 16; EXP, n = 20); pooled efficacy data were available for both ESC and EXP, while LGG-specific safety data were available for EXP. At interim analysis (Aug 2019), 17 of the 20 pts in EXP remained on protocol therapy. Three pts withdrew/discontinued treatment because of AEs. Skin toxicity (95%) and pyrexia (75%) were the frequent AEs reported. No on-treatment deaths were reported. Across both ESC and EXP, the objective response rate (ORR) was 25% (95% CI, 12%–42%) per independent review (1 complete response [CR], 8 partial response [PR], 24 stable disease [SD], 2 progressive disease [PD], 1 unknown [UNK]) and 50% (95% CI, 33%–67%) per investigator review (2 CR, 16 PR, 17 SD, 1 UNK). However, ORR + SD was similar, with 92% and 97% of pts having SD or better per independent and investigator review, respectively. Conclusions: In pediatric pts with pretreated BRAF V600-mutant LGG, D+T combination therapy demonstrated clinical activity, with 92% of pts having SD or better by independent review using the RANO criteria. Pyrexia and skin toxicity were the common AEs; majority of these were low-grade and manageable. Clinical trial information: NCT02124772.

Temsirolimus combined with etoposide and cyclophosphamide for relapsed/refractory acute lymphoblastic leukemia: Therapeutic advances in Childhood Leukemia Consortium (TACL 2014-001) trial

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Background: PI3K/mTOR signaling, a critical pathway in cell proliferation, metabolism, and apoptosis, is often dysregulated in acute lymphoblastic leukemia (ALL). A phase 1 trial of the mTOR inhibitor temsirolimus combined with etoposide and cyclophosphamide was performed in children with relapsed/refractory (r/r) ALL. Methods: Temsirolimus was administered intravenously (IV) on days 1 and 8 with cyclophosphamide 440 mg/m2 and etoposide 100 mg/m2 IV daily days 1-5. The starting dose level (DL) of temsirolimus was 7.5 mg/m2 (DL1) with escalation to 10 mg/m2 (DL2), 15 mg/m2 (DL3), and 25 mg/m2 (DL4). MRD was performed centrally. PI3K pathway inhibition was measured by phosphoflow cytometry (PFC) analysis of peripheral blood (PB) from treated patients (pts). Results: Sixteen heavily pretreated r/r ALL pts ages 2-19 years with marrow blasts > 25% were enrolled; 15 were evaluable [10 B-ALL/5 T-ALL]. One dose-limiting toxicity (DLT) of grade (Gr) 4 pleural and pericardial effusions with pneumonitis/lung infection leading to Gr 5 cardiorespiratory arrest occurred in a pt treated at DL3. No further DLTs were seen in the DL3 expansion and DL4 cohorts. Gr 3/4 non-hematologic toxicities occurring in ≥ 3 pts included febrile neutropenia, elevated ALT, hypokalemia, mucositis, and tumor lysis syndrome and were independent of dose. Of 15 evaluable pts, 4 (27%; 2 B-ALL/2 T-ALL) had a complete response (CR) after cycle 1, comprised of 1 pt at each DL. Three had MRD < 0.01%. Three pts (20%; 2 B-ALL/1 T-ALL) had partial response (PR). Overall response rate (CR+PR = ORR) was 47%. Pharmacodynamic PFC studies compared phosphoprotein levels pre (day 0) and post treatment (days 3-5) in 9 consenting pts with available PB. All tested pts showed basal activation of PI3K pathway signaling. Dose-dependent inhibition of mTOR targets phosphorylated (p) S6 and/or p4EBP1 was observed in 9/9 and 6/9 pts, respectively, following temsirolimus and chemotherapy treatment. Various patterns of compensatory upregulation of pPI3K, pmTOR, pAkt, and/or pERK was observed. Conclusions: Temsirolimus at 25 mg/m2 combined with salvage etoposide and cyclophosphamide has an acceptable safety profile in high-risk pediatric patients with r/r ALL. Responses were observed at all DLs. mTOR target inhibition was achieved and appeared to correlate with dose level. Future testing of other PI3K/mTOR pathway inhibitors in combination with chemotherapy may be warranted with a goal of further increasing response in r/r ALL. Clinical trial information: NCT01614197.

Clinical decisions following implementation of asparaginase activity monitoring in pediatric patients with acute lymphoblastic leukemia: Experience from a single-center study

We undertook this retrospective study to describe decisions made following asparaginase activity monitoring implementation at our center. Clinically apparent reactions (CARs) and asparaginase activity monitoring costs were described. Patients with acute lymphoblastic leukemia, aged <18 years who received asparaginase between April 2016 and September 2017, were included. Decisions made following receipt of asparaginase activity results were categorized as continuation, modification, premedication, or discontinuation. We included 129 patients (median age: 5.33 years) receiving 565 asparaginase doses. CARs were observed following 25 asparaginase doses (19/361 [5.3%] pegaspargase). A total of 224 asparaginase activity levels were ordered in 88 patients. Following receipt of 190 asparaginase activity results, asparaginase therapy was continued, modified, or premedicated in 188 (98.9%), 1 (0.005%), and 1 (0.005%) cases, respectively. Inadequate asparaginase activity was observed in three patients receiving Erwinia asparaginase. Asparaginase activity monitoring allowed patients with pegaspargase-associated CAR and adequate activity to continue therapy unchanged and was cost neutral.

A Phase I and Pharmacokinetic Study of Oral Dabrafenib in Children and Adolescent Patients with Recurrent or Refractory BRAF V600 Mutation-Positive Solid Tumors

PURPOSE

The 2-part, phase I/IIa, open-label study (NCT01677741) sought to determine the safety, tolerability, pharmacokinetics, and preliminary activity of dabrafenib in pediatric patients with advanced BRAF V600-mutated cancers.

PATIENTS AND METHODS

This phase I dose-finding part treated patients ages 1 to <18 years with BRAF V600 mutation-positive tumors with oral dabrafenib 3 to 5.25 mg/kg/day to determine the RP2D based on safety and drug exposure target.

RESULTS

Between May 2013 and November 2014, 27 patients [12 male; median age, 9 years (range, 1-17 years)] with BRAF V600-mutant solid tumors recurrent/refractory to treatment (low- or high-grade glioma, Langerhans cell histiocytosis, neuroblastoma, or thyroid cancer) were enrolled. The median treatment duration was 75.6 weeks (range, 5.6-148.7 weeks), with 63% treated for >52 weeks and 52% undergoing treatment at data cutoff date. The most common grade 3/4 adverse events suspected to be related to study drug were maculopapular rash and arthralgia (2 patients each). No dose-limiting toxicities were observed. Pharmacokinetic analyses showed a dose-dependent increase in AUC0-12 and achievement of adult exposure levels at the recommended phase II doses of 5.25 mg/kg/day (age <12 years) and 4.5 mg/kg/day (age ≥12 years) divided into 2 equal doses daily, not exceeding 300 mg daily.

CONCLUSIONS

In this first clinical trial in pediatric patients with pretreated BRAF V600-mutant tumors, dabrafenib was well tolerated while achieving target exposure levels; the average treatment duration was >1 year with many patients still on treatment. The phase II component is also closed and will be reported separately.

Atypical juvenile histiocytosis with novel KIF5B-ALK gene fusion mimicking subglottic hemangioma

Juvenile Xanthograuloma (JXG) is part of a diverse set of rare histiocytic disorders marked by infiltration of tissues with neoplastic myelomonocytic-derived cells. Molecular analysis has yielded new insights into the classification and management of histiocytic diseases. A three-year-old presented with atypical croup due to a localized subglottic histiocytic lesion mimicking subglottic hemangioma. The lesion was removed via tracheofissure. Pathology revealed a JXG-like histopathology with a rare KIF5B-ALK fusion gene. This is the first isolated ALK-positive lesion to be reported in this location. The discovery of the new ALK-positive subclass of histiocytosis has opened the door for targeted monoclonal ALK inhibition.

Bortezomib reinduction chemotherapy in high-risk ALL in first relapse: a report from the Children's Oncology Group

While survival in paediatric acute lymphoblastic leukaemia (ALL) is excellent, survival following relapse is poor. Previous studies suggest proteasome inhibition with chemotherapy improves relapse ALL response rates. This phase 2 Children's Oncology Group study tested the hypothesis that adding the proteasome inhibitor bortezomib to chemotherapy increases complete response rates (CR2). Evaluable patients (n = 135, 103 B-ALL, 22 T-ALL, 10 T-lymphoblastic lymphoma) were treated with reinduction chemotherapy plus bortezomib. Overall CR2 rates were 68 ± 5% for precursor B-ALL patients (<21 years of age), 63 ± 7% for very early relapse (<18 months from diagnosis) and 72 ± 6% for early relapse (18-36 months from diagnosis). Relapsed T-ALL patients had an encouraging CR2 rate of 68 ± 10%. End of induction minimal residual disease (MRD) significantly predicted survival. MRD negative (MRDneg; MRD <0·01%) rates increased from 29% (post-cycle 1) to 64% following cycle 3. Very early relapse, end-of-induction MRDneg precursor B-ALL patients had 70 ± 14% 3-year event-free (EFS) and overall survival (OS) rates, vs. 3-year EFS/OS of 0-3% (P = 0·0001) for MRDpos (MRD ≥0·01) patients. Early relapse patients had similar outcomes (MRDneg 3-year EFS/OS 58-65% vs. MRDpos 10-19%, EFS P = 0·0014). These data suggest that adding bortezomib to chemotherapy in certain ALL subgroups, such as T-cell ALL, is worthy of further investigation. This study is registered at http://www.clinical.trials.gov as NCT00873093.

Phase 1 study of the anti-CD22 immunotoxin moxetumomab pasudotox for childhood acute lymphoblastic leukemia

Novel therapies are needed to overcome chemotherapy resistance for children with relapsed/refractory acute lymphoblastic leukemia (ALL). Moxetumomab pasudotox is a recombinant anti-CD22 immunotoxin. A multicenter phase 1 study was conducted to determine the maximum-tolerated cumulative dose (MTCD) and evaluate safety, activity, pharmacokinetics, and immunogenicity of moxetumomab pasudotox in children, adolescents, and young adults with ALL (N = 55). Moxetumomab pasudotox was administered as a 30-minute IV infusion at doses of 5 to 50 µg/kg every other day for 6 (cohorts A and B) or 10 (cohort C) doses in 21-day cycles. Cohorts B and C received dexamethasone prophylaxis against capillary leak syndrome (CLS). The most common treatment-related adverse events were reversible weight gain, hepatic transaminase elevation, and hypoalbuminemia. Dose-limiting CLS occurred in 2 of 4 patients receiving 30 µg/kg of moxetumomab pasudotox every other day for 6 doses. Incorporation of dexamethasone prevented further dose-limiting CLS. Six of 14 patients receiving 50 µg/kg of moxetumomab pasudotox for 10 doses developed hemolytic uremic syndrome (HUS), thrombotic microangiopathy (TMA), or HUS-like events, exceeding the MTCD. Treatment expansion at 40 µg/kg for 10 doses (n = 11) exceeded the MTCD because of 2 HUS/TMA/HUS-like events. Dose level 6B (ie, 50 µg/kg × 6 doses) was the MTCD, selected as the recommended phase 2 dose. Among 47 evaluable patients, an objective response rate of 32% was observed, including 11 (23%) composite complete responses, 5 of which were minimal residual disease negative by flow cytometry. Moxetumomab pasudotox showed a manageable safety profile and evidence of activity in relapsed or refractory childhood ALL. This trial was registered at www.clinicaltrials.gov as #NCT00659425.

A phase 1 trial of temsirolimus and intensive re-induction chemotherapy for 2nd or greater relapse of acute lymphoblastic leukaemia: a Children's Oncology Group study (ADVL1114)

The phosphatidylinositol 3-kinase (PI3K)/mammalian (or mechanistic) target of rapamycin (mTOR) signalling pathway is commonly dysregulated in acute lymphoblastic leukaemia (ALL). A phase 1 trial of the mTOR inhibitor temsirolimus in combination with UKALL R3 re-induction chemotherapy was conducted in children and adolescents with second or greater relapse of ALL. The initial temsirolimus dose level (DL1) was 10 mg/m² weekly × 3 doses. Subsequent patient cohorts received temsirolimus 7·5 mg/m² weekly × 3 doses (DL0) or, secondary to toxicity, 7·5 mg/m² weekly × 2 doses (DL-1). Sixteen patients were enrolled, 15 were evaluable for toxicity. Dose-limiting toxicity (DLT) occurred at all three dose levels and included hypertriglyceridaemia, mucositis, ulceration, hypertension with reversible posterior leucoencephalopathy, elevated gamma-glutamyltransferase or alkaline phosphatase and sepsis. The addition of temsirolimus to UKALL R3 re-induction therapy resulted in excessive toxicity and was not tolerable in children with relapsed ALL. However, this regimen induced remission in seven of fifteen patients. Three patients had minimal residual disease levels <0·01%. Inhibition of PI3K signalling was detected in patients treated at all dose levels of temsirolimus, but inhibition at an early time point did not appear to correlate with clinical responses at the end of re-induction therapy.

Consensus expert recommendations for identification and management of asparaginase hypersensitivity and silent inactivation

L-asparaginase is an integral component of therapy for acute lymphoblastic leukemia. However, asparaginase-related complications, including the development of hypersensitivity reactions, can limit its use in individual patients. Of considerable concern in the setting of clinical allergy is the development of neutralizing antibodies and associated asparaginase inactivity. Also problematic in the use of asparaginase is the potential for the development of silent inactivation, with the formation of neutralizing antibodies and reduced asparaginase activity in the absence of a clinically evident allergic reaction. Here we present guidelines for the identification and management of clinical hypersensitivity and silent inactivation with Escherichia coli- and Erwinia chrysanthemi- derived asparaginase preparations. These guidelines were developed by a consensus panel of experts following a review of the available published data. We provide a consensus of expert opinions on the role of serum asparaginase level assessment, indications for switching asparaginase preparation, and monitoring after change in asparaginase preparation.

Phase I/Phase II Study of Blinatumomab in Pediatric Patients With Relapsed/Refractory Acute Lymphoblastic Leukemia

Purpose Blinatumomab is a bispecific T-cell engager antibody construct targeting CD19 on B-cell lymphoblasts. We evaluated the safety, pharmacokinetics, recommended dosage, and potential for efficacy of blinatumomab in children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Methods This open-label study enrolled children < 18 years old with relapsed/refractory BCP-ALL in a phase I dosage-escalation part and a phase II part, using 6-week treatment cycles. Primary end points were maximum-tolerated dosage (phase I) and complete remission rate within the first two cycles (phase II). Results We treated 49 patients in phase I and 44 patients in phase II. Four patients had dose-limiting toxicities in cycle 1 (phase I). Three experienced grade 4 cytokine-release syndrome (one attributed to grade 5 cardiac failure); one had fatal respiratory failure. The maximum-tolerated dosage was 15 µg/m²/d. Blinatumomab pharmacokinetics was linear across dosage levels and consistent among age groups. On the basis of the phase I data, the recommended blinatumomab dosage for children with relapsed/refractory ALL was 5 µg/m²/d for the first 7 days, followed by 15 µg/m²/d thereafter. Among the 70 patients who received the recommended dosage, 27 (39%; 95% CI, 27% to 51%) achieved complete remission within the first two cycles, 14 (52%) of whom achieved complete minimal residual disease response. The most frequent grade ≥ 3 adverse events were anemia (36%), thrombocytopenia (21%), and hypokalemia (17%). Three patients (4%) and one patient (1%) had cytokine-release syndrome of grade 3 and 4, respectively. Two patients (3%) interrupted treatment after grade 2 seizures. Conclusion This trial, which to the best of our knowledge was the first such trial in pediatrics, demonstrated antileukemic activity of single-agent blinatumomab with complete minimal residual disease response in children with relapsed/refractory BCP-ALL. Blinatumomab may represent an important new treatment option in this setting, requiring further investigation in curative indications.

Proteasome subunit expression analysis and chemosensitivity in relapsed paediatric acute leukaemia patients receiving bortezomib-containing chemotherapy

Background

Drug combinations of the proteasome inhibitor bortezomib with cytotoxic chemotherapy are currently evaluated in phase 2 and 3 trials for the treatment of paediatric acute myeloid leukaemia (AML) and acute lymphocytic leukaemia (ALL).

Methods

We investigated whether expression ratios of immunoproteasome to constitutive proteasome in leukaemic cells correlated with response to bortezomib-containing re-induction chemotherapy in patients with relapsed and refractory acute leukaemia, enrolled in two Children’s Oncology Group phase 2 trials of bortezomib for ALL (COG-AALL07P1) and AML (COG-AAML07P1). Expression of proteasome subunits was examined in 72 patient samples (ALL n = 60, AML n = 12) obtained before start of therapy. Statistical significance between groups was determined by Mann-Whitney U test.

Results

Ratios of immunoproteasome to constitutive proteasome subunit expression were significantly higher in pre-B ALL cells than in AML cells for both β5i/β5 and β1i/β1 subunits (p = 0.004 and p < 0.001). These ratios correlated with therapy response in AML patients; β1i/β1 ratios were significantly higher (p = 0.028) between patients who did (n = 4) and did not reach complete remission (CR) (n = 8), although for β5i/β5 ratios, this did not reach significance. For ALL patients, the subunit ratios were also higher for patients who showed a good early response to therapy but this relation was not statistically significant. Overall, for this study, the patients were treated with combination therapy, so response was not only attributed to proteasome inhibition. Moreover, the leukaemic blast cells were not purified for these samples.

Conclusions

These first ex vivo results encourage further studies into relative proteasome subunit expression to improve proteasome inhibition-containing therapy and as a potential indicator of bortezomib response in acute leukaemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0312-z) contains supplementary material, which is available to authorized users.

Protocol: Evaluating the impact of a nation-wide train-the-trainer educational initiative to enhance the quality of palliative care for children with cancer

BACKGROUND

There are identified gaps in the care provided to children with cancer based on the self-identified lack of education for health care professionals in pediatric palliative care and in the perceptions of bereaved parents who describe suboptimal care. In order to address these gaps, we will implement and evaluate a national roll-out of Education in Palliative and End-of-Life Care for Pediatrics (EPEC®-Pediatrics), using a 'Train-the-Trainer' model.

METHODS/DESIGN

In this study we are using a pre- post-test design and an integrated knowledge translation approach to assess the impact of the educational roll-out in four areas: 1) self-assessed knowledge of health professionals; 2) knowledge dissemination outcomes; 3) practice change outcomes; and 4) quality of palliative care. The quality of palliative care will be assessed using data from three sources: a) parent and child surveys about symptoms, quality of life and care provided; b) health record reviews of deceased patients; and c) bereaved parent surveys about end-of-life and bereavement care. After being trained in EPEC®-Pediatrics, 'Master Facilitators' will train 'Regional Teams' affiliated with 16 pediatric oncology programs in Canada. Each team will consist of three to five health professionals representing oncology, palliative care, and the community. Each team member will complete online modules and attend one of two face-to-face conferences, where they will receive training and materials to teach the EPEC®-Pediatrics curriculum to 'End-Users' in their region. Regional Teams will also choose a Tailored Implementation of Practice Standards (TIPS) Kit to guide implementation of a quality improvement project in their region; support will be provided via quarterly meetings with Co-Leads and via a listserv and webinars with other teams.

DISCUSSION

Through this study we aim to raise the level of pediatric palliative care education amongst health care professionals in Canada. Our study will be a significant step forward in evaluation of the impact of EPEC®-Pediatrics both on dissemination outcomes and on care quality at a national level. Based on the anticipated success of our project we hope to expand the EPEC®-Pediatrics roll-out to health professionals who care for children with non-oncological life-threatening conditions.

Re-induction chemoimmunotherapy with epratuzumab in relapsed acute lymphoblastic leukemia (ALL): Phase II results from Children's Oncology Group (COG) study ADVL04P2

BACKGROUND

Given the success of immunotherapeutic approaches in hematologic malignancies, the COG designed a phase I/II study to determine whether the addition of epratuzumab (anti-CD22) to an established chemotherapy platform improves rates of second remission (CR2) in pediatric patients with B-lymphoblastic leukemia (B-ALL) and early bone marrow relapse.

PROCEDURE

Therapy consisted of three established blocks of re-induction chemotherapy. Epratuzumab (360 mg/m(2)/dose) was combined with chemotherapy on weekly × 4 (B1) and twice weekly × 4 [eight doses] (B2) schedules during the first re-induction block. Remission rates and minimal residual disease (MRD) status were compared to historical rates observed with the identical chemotherapy platform alone.

RESULTS

CR2 was achieved in 65 and 66%, of the evaluable B1 (n = 54) and B2 patients (n = 60), respectively; unchanged from that observed historically without epratuzumab. Rates of MRD negativity (<0.01%) were 31% in B1 (P = 0.4128) and 39% in B2 patients (P = 0.1731), compared to 25% in historical controls. The addition of epratuzumab was well tolerated, with a similar toxicity profile to that observed with the re-induction chemotherapy platform regimen alone.

CONCLUSIONS

Epratuzumab was well tolerated in combination with re-induction chemotherapy. While CR2 rates were not improved compared to historical controls treated with chemotherapy alone, there was a non-significant trend towards improvement in MRD response with the addition of epratuzumab (twice weekly for eight doses) to re-induction chemotherapy.

Abstract LB-169: Ratios of immunoproteasome over constitutive proteasome expression are an indicator for sensitivity to bortezomib-containing reinduction chemotherapy in pediatric relapsed ALL and AML

Purpose

Despite the encouraging results of bortezomib (BTZ) in hematologic malignancies to date, resistance to BTZ may be a limiting factor to its efficacy. Hence, parameters that may identify responsiveness to BTZ-containing therapy will be of clinical interest. Recently, we reported that higher ratios of immunoproteasome over constitutive proteasome protein expression in pediatric ALL and AML leukemia cells at diagnosis were an accountable factor for ex vivo sensitivity to proteasome inhibitors (Niewerth et al, Haematologica 2013). Here we explored whether this parameter was associated with response to BTZ in first relapsed and refractory pediatric acute leukemia patients treated in phase II clinical trials of BTZ combined with re-induction chemotherapy for pediatric ALL (COG-AALL07P1) and pediatric AML (COG-AAML07P1).

Methods

Protein expression levels of constitutive- β5 and β1, and immunoproteasome subunits β5i and β1i were determined by Western blot analysis in 61 acute leukemia patient samples (ALL n=47, AML n=14) obtained before BTZ-containing reinduction therapy. In addition, β5 and β5i proteasome catalytic activities were measured in 14 ALL and 13 AML samples prior to treatment. Lastly, NF-ĸB activity was determined by p65 ELISA in nuclear extracts of PBMCs before and 24h after BTZ treatment.

Results

In pre-treatment samples, expression ratios of both β5i/β5 and β1i/β1 were significantly higher in ALL cells than in AML cells (P=0.049 and P=0.002, respectively). Ratios of both β5i/β5 and β1i/β1 were significantly higher in patients that reached complete remission (CR; n=39) compared to patients that did not reach CR (n=22) (P=0.009 for β5i/β5, P=0.025 for β1i/β1). Moreover, increased ratios of β5i/β5 catalytic activity were observed in pre-treatment ALL+AML samples that reached CR compared to those that did not reach CR (P=0.078). Proteasome activity ratios correlated significantly with proteasome expression ratios (R=0.55 P=0.005). Notably, NF-ĸB activity was similar in both groups and was suppressed after BTZ treatment, being most pronounced in the pre-B ALL patients that achieved CR (average decrease: 47% p=0.05).

Conclusion

These results suggest that a higher ratio of immuno/constitutive proteasome in pretreatment ALL and AML cells is an accountable factor for the clinical response to BTZ. These results warrant further investigation to establish a biomarker that can be used for selecting relapsed pediatric acute leukemia patients eligible for BTZ-containing reinduction treatment.

This study was sponsored by KiKa (Children Cancer-free-GJLK), Millennium pharmaceuticals (TMH), and NIH-K23-CA113775 (TMH)

Citation Format: Denise Niewerth, Gertjan J.L. Kaspers, Gerrit Jansen, Johan van Meerloo, Sonja Zweegman, Gaye Jenkins, James A. Whitlock, Stephen P. Hunger, Xiaomin Lu, Jacqueline Cloos, Terzah M. Horton. Ratios of immunoproteasome over constitutive proteasome expression are an indicator for sensitivity to bortezomib-containing reinduction chemotherapy in pediatric relapsed ALL and AML. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-169. doi:10.1158/1538-7445.AM2014-LB-169

Abstract CT230: Pediatric phase 1 trial of moxetumomab pasudotox: Activity in chemotherapy refractory acute lymphoblastic leukemia (ALL)

Background: Novel therapies are needed to overcome chemotherapy resistance and reduce toxicities of treatment for childhood ALL. CD22 is an antigen expressed on B-lineage ALL blasts. Moxetumomab pasudotox (MP) is a recombinant immunoconjugate composed of an anti-CD22 immunoglobulin variable domain genetically fused to a truncated form of Pseudomonas exotoxin.

Methods: This is a multicenter, open-label, phase 1, dose-escalation study of MP in pediatric patients (pts) with relapsed/refractory ALL and NHL with CD22 expression. MP is administered as a 30-min IV infusion at doses 5-50 µg/kg every other day for 6-10 doses every 21 days. Cohort A (n=7) consisted of an accelerated dose-escalation phase followed by standard 3+3 dose-escalation. To reduce the incidence of capillary leak syndrome (CLS), subsequent cohorts (B, n=23; C, n=14) received dexamethasone (2.5 mg/m2 every 12 hours) around the first 6 doses of MP in cycle 1. In Cohort C, doses were increased to 10/cycle and an expansion phase at 50 µg/kg was added.

Results: 44 pts with ALL 1-23 years of age have been treated. 35/44 had treatment-refractory disease; 20/44 had relapsed after stem cell transplant (SCT). Pts received a median of 1 treatment cycle (range 1-4). The majority (55%) of treatment-related adverse events (AEs) were mild and reversible. The most common treatment-related AEs were increased AST and ALT and weight gain. There were 2 treatment-related deaths and 7 pts discontinued therapy due to a treatment-related AE. Four DLTs included CLS in 2/7 pts in Cohort A (30 µg/kg; 1 reported as pleural effusion); hypercalcemia in 1 pt treated at 40 µg/kg (Cohort B) who died of a cardiac arrhythmia during attempted venous catheter placement; and grade 4 hemolytic uremic syndrome (HUS) in 1 pt at 50 µg/kg (Cohort B). HUS was noted in 6 pts, 5 treated at the 50 µg/kg dose. Two events were grade 4 with remaining cases ≤grade 2. All but 1 patient recovered from HUS. Based on HUS, the 50 µg/kg dose was determined to exceed the maximum tolerated dose and accrual at a lower dose is ongoing. Of the 37 (84%) pts evaluable for response, objective responses were achieved in 11 (30%), including 9 (24%) complete responses (CR). Per investigator report, 4/9 CRs were minimal residual disease negative, and 3 of these pts underwent a second SCT. Hematological activity (≥50% reduction in blasts and/or improvement in neutrophil and/or platelet counts) was observed in 11 (30%) pts. Anti-drug neutralizing antibodies (≥50% neutralization) developed in 7/44 (16%) pts.

Conclusions: MP is active in pediatric pts with relapsed/refractory ALL. The observed antileukemic activity and safety profile warrant further investigation; phase 2 trials are in development. Study sponsored by MedImmune, and supported in part by the Intramural Research Program of the NIH, NCI, CCR. ClinicalTrials.gov NCT00659425.

Citation Format: Alan S. Wayne, Nirali N. Shah, Deepa Bhojwani, Lewis B. Silverman, James A. Whitlock, Maryalice Stetler-Stevenson, Robert J. Kreitman, Trishna Goswami, Ramy Ibrahim, Ira Pastan. Pediatric phase 1 trial of moxetumomab pasudotox: Activity in chemotherapy refractory acute lymphoblastic leukemia (ALL). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT230. doi:10.1158/1538-7445.AM2014-CT230

Targetable kinase-activating lesions in Ph-like acute lymphoblastic leukemia

BACKGROUND

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is characterized by a gene-expression profile similar to that of BCR-ABL1-positive ALL, alterations of lymphoid transcription factor genes, and a poor outcome. The frequency and spectrum of genetic alterations in Ph-like ALL and its responsiveness to tyrosine kinase inhibition are undefined, especially in adolescents and adults.

METHODS

We performed genomic profiling of 1725 patients with precursor B-cell ALL and detailed genomic analysis of 154 patients with Ph-like ALL. We examined the functional effects of fusion proteins and the efficacy of tyrosine kinase inhibitors in mouse pre-B cells and xenografts of human Ph-like ALL.

RESULTS

Ph-like ALL increased in frequency from 10% among children with standard-risk ALL to 27% among young adults with ALL and was associated with a poor outcome. Kinase-activating alterations were identified in 91% of patients with Ph-like ALL; rearrangements involving ABL1, ABL2, CRLF2, CSF1R, EPOR, JAK2, NTRK3, PDGFRB, PTK2B, TSLP, or TYK2 and sequence mutations involving FLT3, IL7R, or SH2B3 were most common. Expression of ABL1, ABL2, CSF1R, JAK2, and PDGFRB fusions resulted in cytokine-independent proliferation and activation of phosphorylated STAT5. Cell lines and human leukemic cells expressing ABL1, ABL2, CSF1R, and PDGFRB fusions were sensitive in vitro to dasatinib, EPOR and JAK2 rearrangements were sensitive to ruxolitinib, and the ETV6-NTRK3 fusion was sensitive to crizotinib.

CONCLUSIONS

Ph-like ALL was found to be characterized by a range of genomic alterations that activate a limited number of signaling pathways, all of which may be amenable to inhibition with approved tyrosine kinase inhibitors. Trials identifying Ph-like ALL are needed to assess whether adding tyrosine kinase inhibitors to current therapy will improve the survival of patients with this type of leukemia. (Funded by the American Lebanese Syrian Associated Charities and others.).

Updates on histiocytic disorders

Histiocytic disorders are rare entities that are becoming more recognized as our understanding of the molecular pathogenesis lead to novel diagnostic tests and targeted drug development. A symposium held at the American Society of Pediatric Hematology/Oncology (ASPHO) 2013 Annual Meeting discussed new insights into histiocytic disorders. This review highlights the symposium presentations, divided into three sections encompassing Langerhans cell histiocytosis (LCH), hemophagocytic lymphohistiocytosis (HLH) and Rosai Dorfman disease (RDD) including subsections on pathogenesis, clinical diagnostic criteria and novel insights into treatment. Details of other histiocytic disorders as well as the standard treatment guidelines have been published elsewhere and are beyond the scope of this discussion [Haupt et al. (2013). Pediatr Blood Cancer 60:175-184; Henter et al. (2007). Pediatr Blood Cancer 48:124-131].

AAML0523: a report from the Children's Oncology Group on the efficacy of clofarabine in combination with cytarabine in pediatric patients with recurrent acute myeloid leukemia

BACKGROUND

The discovery of new, effective non-anthracycline-based reinduction regimens for children with recurrent acute myeloid leukemia (AML) is critical. In this phase 1/2 study, the tolerability and overall response rate of clofarabine in combination with cytarabine was investigated in children with recurrent/refractory AML.

METHODS

AAML0523 enrolled 49 children with AML in first recurrence or who were refractory to induction therapy. The study consisted of a dose-finding phase (9 patients) and an efficacy phase (40 patients). Two children received clofarabine at a dose of 40 mg/m(2)/day and 47 children at a dose of 52 mg/m(2)/day.

RESULTS

Toxicities typical for intensive chemotherapy regimens were observed at all doses of clofarabine. The recommended pediatric phase 2 dose of clofarabine in combination with cytarabine was 52 mg/m(2)/day for 5 days. Of 48 evaluable patients, the overall response rate (complete remission plus complete remission with partial platelet recovery) was 48%. Four patients met conventional criteria for complete remission with incomplete count recovery. Twenty-one of 23 responders subsequently underwent hematopoietic stem cell transplantation. The overall survival rate at 3 years was 46% for responders compared with 16% for nonresponders (P < .001). Patients found to have no minimal residual disease at the end of the first cycle by flow cytometric analysis had superior overall survival after 1 year (100% vs 38%; P = .01).

CONCLUSIONS

The combination of clofarabine and cytarabine yielded an acceptable response rate without excess toxicity in children with recurrent AML. The nearly 50% survival rate reported in responders is highly encouraging in these high-risk patients and suggests that this combination is an effective bridge to hematopoietic stem cell transplantation.

Phase I/II trial of clofarabine and cytarabine in children with relapsed/refractory acute lymphoblastic leukemia (AAML0523): a report from the Children's Oncology Group

BACKGROUND

The discovery of effective re-induction regimens for children with more than one relapse of acute lymphoblastic leukemia (ALL) remains elusive. The novel nucleoside analog clofarabine exhibits modest single agent efficacy in relapsed ALL, though optimal combinations of this agent with other active chemotherapy drugs have not yet been defined. Herein we report the response rates of relapsed ALL patients treated on Children's Oncology Group study AAML0523, a Phase I/II study of the combination of clofarabine and cytarabine.

PROCEDURE

AAML0523 enrolled 21 children with ALL in second or third relapse, or those refractory to re-induction therapy. The study consisted of two phases: a dose finding phase and an efficacy phase. The dose finding portion consisted of a single dose escalation/de-escalation of clofarabine for 5 days in combination with a fixed dose of cytarabine (1 g/m(2)/day for 5 days). Eight patients received clofarabine at 40 mg/m(2)/day and 13 patients at 52 mg/m(2)/day.

RESULTS

Toxicities observed at all doses of clofarabine were typical of intensive chemotherapy regimens for leukemia, with infection being the most common. We did not observe significant hepatotoxicity as reported in other clofarabine combination regimens. The recommended pediatric Phase II dose of clofarabine in combination with cytarabine for the efficacy portion of AAML0523 was 52 mg/m(2). Of 21 patients with ALL, 3 (14%) achieved a complete response (CR). Based on the two-stage design definition of first-stage inactivity, the therapy was deemed ineffective.

CONCLUSION

The combination of clofarabine and cytarabine in relapsed/refractory childhood ALL does not warrant further clinical investigation.

Children's Oncology Group's 2013 blueprint for research: acute lymphoblastic leukemia

Approximately 90% of the 2,000 children, adolescents, and young adults enrolled each year in Children's Oncology Group acute lymphoblastic leukemia (ALL) trials will be cured. However, high-risk subsets with significantly inferior survival remain, including infants, newly diagnosed patients with age ≥10 years, white blood count ≥50,000/µl, poor early response or T-cell ALL, and relapsed ALL patients. Effective strategies to improve survival include better risk stratification, optimizing standard chemotherapy and combining targeted therapies with cytotoxic chemotherapy, the latter of which is dependent upon identification of key driver mutations present in ALL.

Body mass index and blood pressure changes over the course of treatment of pediatric acute lymphoblastic leukemia

BACKGROUND

Obesity and hypertension are reported among survivors of pediatric acute lymphoblastic leukemia (ALL). However, little is known about the trajectory of body mass index (BMI) and blood pressure over the course of ALL therapy.

PROCEDURE

In a retrospective cohort of 183 pediatric ALL patients diagnosed from 2000 to 2008, prevalence, severity, and risk factors for obesity and hypertension were assessed during treatment.

RESULTS

At diagnosis, 36% of patients were overweight and 19% were obese. Median BMI increased during induction therapy with a return to baseline soon after, but increased again over the first 22 months of maintenance therapy. At the end of therapy, 49% were overweight and 21% were obese. Increased BMI z-score at diagnosis was associated with increased z-score during maintenance (P < 0.001). Elevated parental BMI was associated with elevated BMI at diagnosis. Median BMI z-score increased over the first 22 months of maintenance (P < 0.001). Patients with high risk disease had lower BMI z-scores regardless of cranial radiotherapy exposure (P < 0.001). Pre-hypertension was prevalent over the course of therapy (31.1% with systolic pre-hypertension and 18.6% with diastolic pre-hypertension). Hypertension was also highly prevalent with 41.5% meeting systolic criteria and 24.0% meeting diastolic criteria.

CONCLUSIONS

During ALL therapy, patients are at risk for early development of elevated BMI and blood pressure, which places them at potentially increased risk for future adverse health conditions. Future studies are needed to develop strategies to mitigate these risks, such as potential reduction of corticosteroid pulses or a family-based diet and exercise intervention during maintenance therapy.

Cytotoxicity, drug combinability, and biological correlates of ABT-737 against acute lymphoblastic leukemia cells with MLL rearrangement

BACKGROUND

ABT-737 is a BH3 mimetic small-molecule inhibitor that binds with high affinity to Bcl-2 to induce apoptosis in malignant cells and has shown promise as an effective anti-leukemic agent in pediatric preclinical tests. This study focuses on the effects of ABT-737 on leukemia cells with MLL rearrangement and identifies some of the biological correlates of its activity.

PROCEDURE

Cells were cultured in the presence of increasing concentrations of ABT-737 alone or in combination with other agents. After 4 days in culture, cell growth inhibition was measured by Alamar blue assay. The expression and activation of potential intracellular targets of ABT-737 activity were determined by Western blot analysis.

RESULTS

Significant Bcl-2 expression was detected in all infant leukemia cells investigated. ABT-737 induced cell death in all cell lines studied although the IC(50) values differed somewhat between cell lines. Western blot analysis identified the effects of ABT-737 on survival and apoptosis-regulatory proteins PARP, caspase-8, and cytochrome-c. Drug combination studies indicated synergy with distinct anti-neoplastic agents, including the multi-tyrosine kinase inhibitor sunitinib. This effective drug synergy appears to be mediated by the combined inhibition of Bcl-2 and intracellular signaling pathways.

CONCLUSIONS

We describe the in vitro studies to demonstrate the activity and drug combinability of ABT-737 against MLL rearranged leukemia cells. In addition, identification of the molecular changes that occur in the presence of ABT-737 provides information regarding effective target validation and target modulation analyses in future clinical trials.

Toxicity assessment of molecularly targeted drugs incorporated into multiagent chemotherapy regimens for pediatric acute lymphocytic leukemia (ALL): review from an international consensus conference

One of the challenges of incorporating molecularly targeted drugs into multi-agent chemotherapy (backbone) regimens is defining dose-limiting toxicities (DLTs) of the targeted agent against the background of toxicities of the backbone regimen. An international panel of 22 pediatric acute lymphocytic leukemia (ALL) experts addressed this issue (www.ALLNA.org). Two major questions surrounding DLT assessment were explored: (1) how toxicities can be best defined, assessed, and attributed; and (2) how effective dosing of new agents incorporated into multi-agent ALL clinical trials can be safely established in the face of disease- and therapy-related systemic toxicities. The consensus DLT definition incorporates tolerance of resolving Grade 3 and some resolving Grade 4 toxicities with stringent safety monitoring. This functional DLT definition is being tested in two Children's Oncology Group (COG) ALL clinical trials.

Working memory in survivors of childhood acute lymphocytic leukemia: functional neuroimaging analyses

BACKGROUND

Research on the physical and psychological late effects of treatment of childhood cancer has led to the identification of significant long-term neurocognitive deficits experienced by some survivors, particularly in the areas of memory and executive functioning. Despite indications of deficits based on cognitive assessment, the identification of specific mechanisms of neurocognitive deficits using neuroimaging techniques has yet to be adequately considered.

PROCEDURE

This study used functional neuroimaging techniques to examine working memory and executive functioning deficits of survivors of childhood acute lymphocytic leukemia (ALL), as compared to age- and gender-matched healthy controls.

RESULTS

There was a trend for ALL survivors to perform more poorly on a working memory task in terms of overall accuracy. Additionally, survivors displayed significantly greater activation in areas underlying working memory (dorsolateral and ventrolateral prefrontal cortex) and error monitoring (dorsal and ventral anterior cingulate cortex).

CONCLUSIONS

These results support the theory of compensatory activation in necessary brain regions in order to complete tasks in pediatric ALL survivors, similar to that observed in multiple sclerosis patients. Concurrent examination of testing and brain imaging enables the connection of behavioral observations with underlying neurological characteristics of deficits in survivors and may help provide insight into mechanisms through which deficits appear.

High-dose cyclophosphamide treatment for refractory severe aplastic anemia in children

OBJECTIVE

To determine if high-dose cyclophosphamide is an effective therapy for children with refractory severe aplastic anemia (SAA).

BACKGROUND

SAA is an illness characterized by the depletion of hematopoietic precursors associated with life-threatening complications. Hematopoietic stem cell transplant (HSCT) is the treatment of choice if a human leukocyte antigen (HLA)-related donor is available. Immunosuppression with anti-thymocyte globulin (ATG) and cyclosporine A (CSA) is an option for patients who are not HSCT candidates. Unrelated donor HSCT has been used with limited success. High-dose cyclophosphamide has been used successfully in the treatment of adults with SAA, but experience in children is limited.

PROCEDURE

Five pediatric patients who had failed previous immunosuppressive therapy for SAA were treated with high-dose cyclophosphamide (45 mg/kg/day x 4 days).

RESULTS

After 12 months of treatment, two of five patients experienced a complete response with high-dose cyclophosphamide therapy. The two complete responders achieved red cell recovery with a hematocrit of >36% at days 212 and 112 and platelet recovery with a platelet count of >100 x 10(9)/L at days 126 and 324. Of the remaining patients, one patient failed to respond, and two patients expired from infectious complications.

CONCLUSIONS

High-dose cyclophosphamide can lead to complete responses in children with SAA who have failed to respond to traditional immunosuppressive therapy.

Autologous stem cell transplant in a patient with Down syndrome and relapsed Hodgkin lymphoma

Children with Down syndrome (DS) are at increased risk for the development of acute leukemia but they rarely develop other hematologic malignancies or solid tumors. Despite aggressive supportive care, DS patients have increased risk of treatment related morbidity and mortality compared to other children. There are few reported cases of Hodgkin disease in children with DS, and no reported cases of successful therapy for patients with relapsed disease. We report on a child with DS and relapsed Hodgkin disease who was successfully treated with high-dose chemotherapy and autologous stem cell transplant.