Evaluation of Image-Defined Risk Factor (IDRF) Assessment in Patients With Intermediate-risk Neuroblastoma: A Report From the Children's Oncology Group Study ANBL0531.

BACKGROUND: The International Neuroblastoma Risk Group (INRG) classifier utilizes a staging system based on pretreatment imaging criteria in which image-defined risk factors (IDRFs) are used to evaluate the extent of locoregional disease. Children's Oncology Group (COG) study ANBL0531 prospectively examined institutional determination of IDRF status and compared that to a standardized central review. METHODS: Between 9/2009-6/2011, patients with intermediate-risk neuroblastoma were enrolled on ANBL0531 and had IDRF assessment at treating institutions. Paired COG pediatric surgeons and radiologists performed blinded central review of diagnostic imaging for the presence or absence of IDRFs. Second blinded review was performed in cases of discordance. Comparison of local and central review was performed using the Kappa coefficient to determine concordance in IDRF assessment. RESULTS: 211 patients enrolled in ANBL0531 underwent IDRF assessment; 3 patients were excluded due to poor image quality. Central reviewer pairs agreed on the presence or absence of any IDRF in 170/208 (81.7%; κ = 0.48) cases. Thirteen (6.3%) cases could not be adjudicated after second blinded review. Radiologists were more likely to identify IRDFs as present than surgeons (p < 0.001). Local and central reviewers agreed on the presence or absence of any IDRF in only108/208 (51.9%; κ = 0.06) cases. CONCLUSIONS: Among experienced pediatric surgeons and radiologists participating in central review, concordance was moderate, with agreement in 81.7% of cases. On comparison of local and central assessment of IDRFs, concordance was poor. These data indicate that greater standardization, education, technology, and training are needed to improve the assessment of IDRFs in children with neuroblastoma. LEVEL OF EVIDENCE: Treatment Study, Level III.

STRIvE-02: A First-in-Human Phase I Study of Systemically Administered B7-H3 Chimeric Antigen Receptor T Cells for Patients With Relapsed/Refractory Solid Tumors.

PURPOSE: B7-H3 is an immunoregulatory protein overexpressed by many pediatric solid tumors with limited expression on critical organs, making it an attractive immunotherapy target. We present a first-in-human phase I clinical trial systemically administered B7-H3 chimeric antigen receptor (CAR) T cells for young patients with relapsed or refractory solid tumors. PATIENTS AND METHODS: Patients were enrolled onto a phase I trial to examine the safety of B7-H3-specific CARs at various dose levels (DLs) using a standard 3 + 3 dose escalation design. RESULTS: Sixteen patients (range, 11-24 years; median, 18.5 years) were enrolled, and nine were treated at DL1 (0.5 × 106 CAR T cells/kg; n = 3) or DL2 (1 × 106 CAR T cells/kg; n = 6). There were no first infusion dose-limiting toxicities. Maximum first-infusion circulating CAR T cells detected in the peripheral blood were 4.98 cells/µL (range, 0-4.98 cells/µL) with detection of CAR T cells colocalizing with tumor cells at the site of metastatic disease in one patient. Patients were eligible for subsequent infusions. An objective partial response by PERCIST criteria was observed 28 days after a second CAR T cell infusion in a patient who did not have an objective response after the first infusion. The second infusion demonstrated marked enhancement of CAR T cell expansion to 1,590 cells/µL and was accompanied by cytokine release syndrome and dose-limiting transaminitis. Detailed peripheral blood cytokine profiling revealed elevated IL-21 levels preinfusion 2 compared with infusion 1. CONCLUSION: B7-H3 CAR T cells are tolerable and demonstrate limited antitumor activity without acute on-target, off-tumor toxicity. High levels of CAR T cell expansion may be necessary to achieve objective responses, but undefined host and tumor microenvironment factors appear to be critical (ClinicalTrials.gov identifier: NCT04483778).

Locoregional CAR T Cells for the Treatment of CNS Tumors in Children: Investigational Drug Service Pharmacy Activities.

BACKGROUND: A major obstacle in translating the therapeutic potential of chimeric antigen receptor (CAR) T cells to children with central nervous system (CNS) tumors is the blood-brain barrier. To overcome this limitation, preclinical and clinical studies have supported the use of repeated, locoregional intracranial CAR T-cell delivery. However, there is limited literature available describing the process for the involvement of an investigational drug service (IDS) pharmacy, particularly in the setting of a children's hospital with outpatient dosing for CNS tumors. OBJECTIVES: To describe Seattle Children's Hospital's experience in clinically producing CAR T cells and the implementation of IDS pharmacy practices used to deliver more than 300 intracranial CAR T-cell doses to children, as well as to share how we refined the processing techniques from CAR T-cell generation to the thawing of fractionated doses for intracranial delivery. METHODS: Autologous CD4+ and CD8+ T cells were collected and transduced to express HER2, EGFR, or B7-H3-specific CAR T cells. Cryopreserved CAR T cells were thawed by the IDS pharmacy before intracranial delivery to patients with recurrent/refractory CNS tumors or with diffuse intrinsic pontine glioma/diffuse midline glioma. RESULTS: The use of a thaw-and-dilute procedure for cryopreserved individual CAR T-cell doses provides reliable viability and is more efficient than typical thaw-and-wash protocols. Cell viability with the thaw-and-dilute protocol was approximately 75% and was always within 10% of the viability assessed at cryopreservation. Cell viability was preserved through 6 hours after thawing, which exceeded the 1-hour time frame from thawing to infusion. CONCLUSION: As the field of adoptive immunotherapy grows and continues to bring hope to patients with fatal CNS malignancies, it is critical to focus on improving the preparatory steps for CAR T-cell delivery.

CAR T cell therapy for pediatric central nervous system tumors: a review of the literature and current North American trials.

Central nervous system (CNS) tumors are the leading cause of cancer-related death in children. Typical therapy for CNS tumors in children involves a combination of surgery, radiation, and chemotherapy. While upfront therapy is effective for many high-grade tumors, therapy at the time of relapse remains limited. Furthermore, for diffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG), there are currently no curative therapies. Chimeric antigen receptor T (CAR T) cell therapy is a promising novel treatment avenue for these tumors. Here, we review the preclinical evidence for CAR T cell use in pediatric brain tumors, the preliminary clinical experience of CNS CAR T cell trials, toxicity associated with systemic and locoregional CAR T cell therapy for CNS tumors, challenges in disease response evaluation with CAR T cell therapy, and the knowledge gained from correlative biologic studies from these trials in the pediatric and young adult population.

Feasibility and Favorable Responses Following Investigational CAR T-Cell Therapy for Relapsed and Refractory Infant ALL.

Infants with B-cell acute lymphoblastic leukemia (B-ALL) continue to have significantly worse outcomes compared to older children with B-ALL, and those with relapsed or refractory (R/R) infant ALL have especially dismal outcomes with conventional treatment. CD19-targeting chimeric antigen receptor (CAR) T-cell therapy has demonstrated remarkable success in the treatment of R/R childhood B-ALL, though the majority of reports have been in non-infant patients. Barriers to the successful implementation of CAR T-cell therapy in infant B-ALL include challenges related to apheresis, product manufacturing and disease-specific considerations such as lineage switch. We describe our experience utilizing two experimental CD19-CAR T-cell products, SCRI-CAR19 or SCRI-CAR19x22, for 19 patients with R/R infant B-ALL enrolled on three clinical trials. CAR T-cell products were successfully manufactured in 18/19 (94.7%) patients, with a median age of 22.5 months at enrollment (range, 14.5-40.1 months). Sixteen of 17 (94.1%) treated patients achieved a complete remission without detectable minimal residual disease. The 1-year leukemia free survival was 75% and 1-year overall survival was 76.5%, with a median follow up time of 35.8 months (range, 1.7-83.6 months). Cytokine release syndrome (CRS) occurred in 14/17 (82.4%) patients, with only 1 patient experiencing Grade 3 CRS. Neurotoxicity occurred in 2/17 (11.8%) patients with all events ≤ Grade 2. With the successful early clinical experience of CAR T-cell therapy in this population, more systematic evaluation specific to infant ALL is warranted.

Neuroblastoma, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology.

Neuroblastoma is the most common extracranial solid tumor diagnosed in children. This inaugural version of the NCCN Guidelines for Neuroblastoma provides recommendations for the diagnosis, risk classification, and treatment of neuroblastoma. The information in these guidelines was developed by the NCCN Neuroblastoma Panel, a multidisciplinary group of representatives with expertise in neuroblastoma, consisting of pediatric oncologists, radiologists, pathologists, surgeons, and radiation oncologists from NCCN Member Institutions. The evidence-based and consensus recommendations contained in the NCCN Guidelines are intended to guide clinicians in selecting the most appropriate treatments for their patients with this clinically heterogeneous disease.

Pharmacogenomic associations of cyclophosphamide pharmacokinetic candidate genes with 4hydroxycyclophosphamide formation in children with Cancer.

PURPOSE: 4-hydroxycyclophosphamide (4HCY) is the principal precursor to the cytotoxic metabolite of cyclophosphamide (CY), which is often used as first-line treatment of children with cancer. There is conflicting data regarding the relationship between CY efficacy, toxicity, and pharmacokinetics with the genes encoding proteins involved in 4HCY pharmacokinetics, specifically its formation and elimination. METHODS: We evaluated germline pharmacogenetics in children with various malignancies receiving their first CY dose. Using linear regression, we analyzed the associations between two pharmacokinetic outcomes - how fast a child cleared CY (i.e., CY clearance) and the ratio of the 4HCY/CY exposure, specifically area under the plasma concentration-time curve (AUC), and 372 single nucleotide polymorphisms (SNP) in 14 drug-metabolizing transporters or enzymes involved in 4HCY formation or elimination. RESULTS: Age was associated with the ratio of 4HCY/CY AUC (P = 0.004); Chemotherapy regimen was associated with CY clearance (P = 0.003). No SNPs were associated with CY clearance or the ratio of 4HCY/CY AUC after controlling for a false discovery rate. CONCLUSION: Age and chemotherapy regimen, but not germline pharmacogenomics, were associated with CY clearance or the ratio of 4HCY/CY AUC. Other methods, such as metabolomics or lipidomics, should be explored.

Perspectives of pediatric oncologists on referral for CAR-T therapy: a mixed methods pilot study.

BACKGROUND: Receipt of chimeric antigen receptor T-cell (CAR-T) therapy at an institution different from the primary oncologist's institution is a complex, multistep process. Referral by oncologists plays an important role in the process but may be susceptible to bias. METHODS: Oncologists who previously referred patients for CAR-T therapy at 5 pediatric hospitals were sent surveys by email exploring their CAR-T referral practices. Descriptive statistics were generated, and multivariate analyses examined associations among oncologist characteristics, familiarity with CAR-T therapy, and referral practices. We conducted semistructured interviews with a subset of participants and used thematic analysis to code transcripts. RESULTS: Sixty-eight oncologists completed the survey; 77% expressed being "very familiar" with CAR-T therapy. Hispanic oncologists and oncologists at institutions with 50 or fewer new diagnoses per year were more likely to identify as less familiar with CAR-T therapy (odds ratio [OR] = 64.3, 95% confidence interval [CI] = 2.45 to 10 452.50, P = .04 and OR = 24.5, 95% CI = 3.3 to 317.3, P = .005, respectively). In total, 38% of respondents considered nonclinical features (compliance, social support, resources, insurance, language, education, and race or ethnicity) influential in referral decisions. Oncologists who were Hispanic and oncologists who had been practicing for 20 or more years were more likely to consider these features significantly influential (OR = 14.52, 95% CI = 1.49 to 358.66, P = .04 and OR = 6.76, 95% CI = 1.18 to 50.5, P = .04). Nine oncologists completed in-depth interviews; common themes included barriers and concerns regarding CAR-T therapy referral, the value of an established relationship with a CAR-T therapy center, and poor communication after CAR-T therapy. CONCLUSIONS: Nearly 40% of oncologists consider nonclinical features significantly influential when deciding to refer patients for CAR-T therapy, raising concern for bias in the referral process. Establishing formal partnerships with CAR-T therapy centers may help address physician barriers in referral.

A subset of image-defined risk factors predict completeness of resection in children with high-risk neuroblastoma: An international multicenter study.

BACKGROUND: Image-defined risk factors (IDRFs) were promulgated for predicting the feasibility and safety of complete primary tumor resection in children with neuroblastoma (NB). There is limited understanding of the impact of individual IDRFs on resectability of the primary tumor or patient outcomes. A multicenter database of patients with high-risk NB was interrogated to answer this question. DESIGN/METHODS: Patients with high-risk NB (age <20 years) were eligible if cross-sectional imaging was performed at least twice prior to resection. IDRFs and primary tumor measurements were recorded for each imaging study. Extent of resection was determined from operative reports. RESULTS: There were 211 of 229 patients with IDRFs at diagnosis, and 171 patients with IDRFs present pre-surgery. A ≥90% resection was significantly more likely in the absence of tumor invading or encasing the porta hepatis, hepatoduodenal ligament, superior mesenteric artery (SMA), renal pedicles, abdominal aorta/inferior vena cava (IVC), iliac vessels, and/or diaphragm at diagnosis or an overlapping subset of IDRFs (except diaphragm) at pre-surgery. There were no significant differences in event-free survival (EFS) and overall survival (OS) when patients were stratified by the presence versus absence of any IDRF either at diagnosis or pre-surgery. CONCLUSION: Two distinct but overlapping subsets of IDRFs present either at diagnosis or after induction chemotherapy significantly influence the probability of a complete resection in children with high-risk NB. The presence of IDRFs was not associated with significant differences in OS or EFS in this cohort.

Long-term follow-up of patients with intermediate-risk neuroblastoma treated with response- and biology-based therapy: A report from the Children's Oncology Group study ANBL0531.

BACKGROUND: We previously reported excellent three-year overall survival (OS) for patients with newly diagnosed intermediate-risk neuroblastoma treated with a biology- and response-based algorithm on the Children's Oncology Group study ANBL0531. We now present the long-term follow-up results. METHODS: All patients who met the age, stage, and tumor biology criteria for intermediate-risk neuroblastoma were eligible. Treatment was based on prognostic biomarkers and overall response. Event-free survival (EFS) and OS were estimated by the Kaplan-Meier method. RESULTS: The 10-year EFS and OS for the entire study cohort (n = 404) were 82.0% (95% confidence interval (CI), 77.2%-86.9%) and 94.7% (95% CI, 91.8%-97.5%), respectively. International Neuroblastoma Staging System stage 4 patients (n = 133) had inferior OS compared with non-stage 4 patients (n = 271; 10-year OS: 90.8% [95% CI, 84.5%-97.0%] vs 96.6% [95% CI, 93.9%-99.4%], p = .02). Infants with stage 4 tumors with ≥1 unfavorable biological feature (n = 47) had inferior EFS compared with those with favorable biology (n = 61; 10-year EFS: 66.8% [95% CI, 50.4%-83.3%] vs 86.9% [95% CI, 76.0%-97.8%], p = .02); OS did not differ (10-year OS: 84.4% [95% CI, 71.8%-97.0%] vs 95.0% [95% CI, 87.7%-100.0%], p = .08). Inferior EFS but not OS was observed among patients with tumors with (n = 26) versus without (n = 314) 11q loss of heterozygosity (10-year EFS: 68.4% [95% CI, 44.5%-92.2%] vs 83.9% [95% CI, 78.7%-89.2%], p = .03; 10-year OS: 88.0% [95% CI, 72.0%-100.0%] vs 95.7% [95% CI, 92.8%-98.6%], p = .09). CONCLUSIONS: The ANBL0531 trial treatment algorithm resulted in excellent long-term survival. More effective treatments are needed for subsets of patients with unfavorable biology tumors.

Development of a Safety Surveillance Plan for the Academic Medicine Sponsor Performing First-in-Human Cellular Therapy Clinical Trials: A Report from the Consortium for Pediatric Cellular Immunotherapy.

Pharmacovigilance (PV), also known as drug safety, is the science of risk management involving the detection, assessment, understanding, and prevention of adverse effects related to a medication. This discipline has traditionally focused on the postmarketing period, with less attention to early-phase clinical trials. However, during the immunotherapy and cellular therapy investigational stage, regulatory agencies are increasingly emphasizing the need to identify and characterize safety signals earlier in clinical development as part of a comprehensive safety surveillance plan. Compliance with PV and safety regulations are further heightened as cell and gene therapy (CGT) trials grow in complexity and scope owing to ever-changing and increasingly rigorous regulatory mandates. Based on this changing landscape, a critical aspect of early-phase trials of cellular products where significant safety events are anticipated is to ensure that every effort is made to protect clinical trial participants by maximizing attention to the risk-versus-benefit profile. This includes the development of robust plans for safety surveillance that provide a continual assessment of safety signals to enable safety reporting to regulatory bodies and the Food and Drug Administration, a regular analysis of aggregate safety data, and a plan to communicate safety findings. This report focuses on PV in early-phase clinical trials of first-in-human investigational products sponsored by academic centers in which the availability of PV resources and subject matter experts is limited. To more fully understand the challenges of CGT PV oversight within pediatric academic medical centers conducting early-phase clinical trials, a working group from institutions participating in the Consortium for Pediatric Cellular Immunotherapy composed of faculty and regulatory professionals was convened to compare experiences, identify best practices, and review published literature to identify commonalities and opportunities for alignment. Here we present guidelines on PV planning in early-phase CGT clinical trials occurring in academic medical centers and offer strategies to mitigate risk to trial participants. Standards to address regulatory requirements and governance for safety signal identification and risk assessment are discussed.

Phase 1 study of high-dose DFMO, celecoxib, cyclophosphamide and topotecan for patients with relapsed neuroblastoma: a New Approaches to Neuroblastoma Therapy trial.

BACKGROUND: MYC genes regulate ornithine decarboxylase (Odc) to increase intratumoral polyamines. We conducted a Phase I trial [NCT02030964] to determine the maximum tolerated dose (MTD) of DFMO, an Odc inhibitor, with celecoxib, cyclophosphamide and topotecan. METHODS: Patients 2-30 years of age with relapsed/refractory high-risk neuroblastoma received oral DFMO at doses up to 9000 mg/m2/day, with celecoxib (500 mg/m2 daily), cyclophosphamide (250 mg/m2/day) and topotecan (0.75 mg/m2/day) IV for 5 days, for up to one year with G-CSF support. RESULTS: Twenty-four patients (median age, 6.8 years) received 136 courses. Slow platelet recovery with 21-day courses (dose-levels 1 and 2) led to subsequent dose-levels using 28-day courses (dose-levels 2a-4a). There were three course-1 dose-limiting toxicities (DLTs; hematologic; anorexia; transaminases), and 23 serious adverse events (78% fever-related). Five patients (21%) completed 1-year of therapy. Nine stopped for PD, 2 for DLT, 8 by choice. Best overall response included two PR and four MR. Median time-to-progression was 19.8 months, and 3 patients remained progression-free at >4 years without receiving additional therapy. The MTD of DFMO with this regimen was 6750 mg/m2/day. CONCLUSION: High-dose DFMO is tolerable when added to chemotherapy in heavily pre-treated patients. A randomized Phase 2 trial of DFMO added to chemoimmunotherapy is ongoing [NCT03794349].

Factors influencing parents' choice of palliative treatment goals for children with relapsed or refractory neuroblastoma: A multi-site longitudinal survey study.

BACKGROUND: Many parents of children with advanced cancer report curative goals and continue intensive therapies that can compound symptoms and suffering. Factors that influence parents to choose palliation as the primary treatment goal are not well understood. The objective of this study was to examine experiences impacting parents' report of palliative goals adjusted for time. The authors hypothesized that awareness of poor prognosis, recall of oncologists' prognostic disclosure, intensive treatments, and burdensome symptoms and suffering would influence palliative goal-setting. METHODS: The authors collected prospective, longitudinal surveys from parents of children with relapsed/refractory neuroblastoma at nine pediatric cancer centers across the United States, beginning at relapse and continuing every 3 months for 18 months or until death. Hypothesized covariates were examined for possible associations with parental report of palliative goals. Generalized linear mixed models were used to evaluate factors associated with parents' report of palliative goals at different time points. RESULTS: A total of 96 parents completed surveys. Parents were more likely to report a primary goal of palliation when they recalled communication about prognosis by their child's oncologist (odds ratio [OR], 52.48; p = .010). Treatment intensity and previous ineffective therapeutic regimens were not associated with parents' report of palliative goals adjusted for time. A parent who reported new suffering for their child was less likely to report palliative goals (OR, 0.13; p = .008). CONCLUSIONS: Parents of children with poor prognosis cancer may not report palliative goals spontaneously in the setting of treatment-related suffering. Prognostic communication, however, does influence palliative goal-setting. Evidence-based interventions are needed to encourage timely, person-centered prognostic disclosure in the setting of advanced pediatric cancer. PLAIN LANGUAGE SUMMARY: Many parents of children with poor-prognosis cancer continue to pursue curative treatments that may worsen symptoms and suffering. Little is known about which factors influence parents to choose palliative care as their child's main treatment goal. To explore this question, we asked parents of children with advanced neuroblastoma across the United States to complete multiple surveys over time. We found that the intensity of treatment, number of treatments, and suffering from treatment did not influence parents to choose palliative goals. However, when parents remembered their child's oncologist talking about prognosis, they were more likely to choose palliative goals of care.

Norepinephrine transporter and vesicular monoamine transporter 2 tumor expression as a predictor of response to 131 I-MIBG in patients with relapsed/refractory neuroblastoma.

BACKGROUND: Prior studies suggest that norepinephrine transporter (NET) and vesicular monoamine transporter 2 (VMAT2) mediate meta-iodobenzylguanidine (MIBG) uptake and retention in neuroblastoma tumors. We evaluated the relationship between NET and VMAT2 tumor expression and clinical response to 131 I-MIBG therapy in patients with neuroblastoma. METHODS: Immunohistochemistry (IHC) was used to evaluate NET and VMAT2 protein expression levels on archival tumor samples (obtained at diagnosis or relapse) from patients with relapsed or refractory neuroblastoma treated with 131 I-MIBG. A composite protein expression H-score was determined by multiplying a semi-quantitative intensity value (0-3+) by the percentage of tumor cells expressing the protein. RESULTS: Tumor samples and clinical data were available for 106 patients, of whom 28.3% had partial response (PR) or higher. NET H-score was not significantly associated with response (≥PR), though the percentage of tumor cells expressing NET was lower among responders (median 80% for ≥PR vs. 90% for

Topotecan clearance based on a single sample and a population pharmacokinetic model: Application to a pediatric high-risk neuroblastoma clinical trial.

BACKGROUND: Topotecan, an antitumor drug with systemic exposure (SE)-dependent activity against many pediatric tumors has wide interpatient pharmacokinetic variability, making it challenging to attain the desired topotecan SE. The study objectives were to update our topotecan population pharmacokinetic model, to evaluate the feasibility of determining individual topotecan clearance using a single blood sample, and to apply this approach to topotecan data from a neuroblastoma trial to explore exposure-response relationships. PROCEDURE: Our previous population pharmacokinetic and covariate model was updated using data from 13 clinical pediatric studies. A simulation-based Bayesian analysis was performed to determine if a single blood sample could be sufficient to estimate individual topotecan clearance. Following the Bayesian approach, single pharmacokinetic samples collected from a Children's Oncology Group Phase III clinical trial (ANBL0532; NCT0056767) were analyzed to estimate individual topotecan SE. Associations between topotecan SE and toxicity or early response were then evaluated. RESULTS: The updated population model included the impact of patient body surface area (BSA), age, and renal function on topotecan clearance. The Bayesian analysis with the updated model and single plasma samples showed that individual topotecan clearance values were estimated with good precision (mean absolute prediction error ≤16.2%) and low bias (mean prediction error ≤7.2%). Using the same approach, topotecan SE was derived in patients from ANBL0532. The exposure-response analysis showed an increased early response after concomitant cyclophosphamide and topotecan up to a topotecan SE of 45 h ng/mL. CONCLUSIONS: A simple single-sample approach during topotecan therapy could guide dosing for patients, resulting in more patients reaching target attainment.

The Plasma Membrane Monoamine Transporter is Highly Expressed in Neuroblastoma and Functions as an mIBG Transporter.

Neuroblastoma (NB) is a pediatric cancer with low survival rates in high-risk patients. 131I-mIBG has emerged as a promising therapy for high-risk NB and kills tumor cells by radiation. Consequently, 131I-mIBG tumor uptake and retention are major determinants for its therapeutic efficacy. mIBG enters NB cells through the norepinephrine transporter (NET), and accumulates in mitochondria through unknown mechanisms. Here we evaluated the expression of monoamine and organic cation transporters in high-risk NB tumors and explored their relationship with MYCN amplification and patient survival. We found that NB mainly expresses NET, the plasma membrane monoamine transporter (PMAT), and the vesicular membrane monoamine transporter 1/2 (VMAT1/2), and that the expression of these transporters is significantly reduced in MYCN-amplified tumor samples. PMAT expression is the highest and correlates with overall survival in high-risk NB patients without MYCN amplification. Immunostaining showed that PMAT resides intracellularly in NB cells and co-localizes with mitochondria. Using cells expressing PMAT, mIBG was identified as a PMAT substrate. In mitochondria isolated from NB cell lines, mIBG uptake was reduced by ∼50% by a PMAT inhibitor. Together, our data suggest that PMAT is a previously unrecognized transporter highly expressed in NB and could impact intracellular transport and therapeutic response to 131I-mIBG. SIGNIFICANCE STATEMENT: This study identified that plasma membrane monoamine transporter (PMAT) is a novel transporter highly expressed in neuroblastoma and its expression level is associated with overall survival rate in high-risk patients without MYCN amplification. PMAT is expressed intracellularly in neuroblastoma cells, transports meta-iodobenzylguanidine (mIBG) and thus could impact tumor retention and response to 131I-mIBG therapy. These findings have important clinical implications as PMAT could represent a novel molecular marker to help inform disease prognosis and predict response to 131I-mIBG therapy.

Children's Oncology Group's 2023 blueprint for research: Neuroblastoma.

Neuroblastoma is the most common extra-cranial solid tumor in children and is known for its clinical heterogeneity. A greater understanding of the biology of this disease has led to both improved risk stratification and new approaches to therapy. Outcomes for children with low and intermediate risk disease are excellent overall, and efforts to decrease therapy for such patients have been largely successful. Although survival has improved over time for patients with high-risk disease and treatments evaluated in the relapse setting are now being moved into earlier phases of treatment, much work remains to improve survival and decrease therapy-related toxicities. Studies of highly annotated biobanked samples continue to lead to important insights regarding neuroblastoma biology. Such studies, along with correlative biology studies incorporated into therapeutic trials, are expected to continue to provide insights that lead to new and more effective therapies. A focus on translational science is accompanied by an emphasis on new agent development, optimized risk stratification, and international collaboration to address questions relevant to molecularly defined subsets of patients. In addition, the COG Neuroblastoma Committee is committed to addressing the patient/family experience, mitigating late effects of therapy, and studying social determinants of health in patients with neuroblastoma.

Impact of diagnostic and end-of-induction Curie scores with tandem high-dose chemotherapy and autologous transplants for metastatic high-risk neuroblastoma: A report from the Children's Oncology Group.

BACKGROUND: Diagnostic mIBG (meta-iodobenzylguanidine) scans are an integral component of response assessment in children with high-risk neuroblastoma. The role of end-of-induction (EOI) Curie scores (CS) was previously described in patients undergoing a single course of high-dose chemotherapy (HDC) and autologous hematopoietic cell transplant (AHCT) as consolidation therapy. OBJECTIVE: We now examine the prognostic significance of CS in patients randomized to tandem HDC and AHCT on the Children's Oncology Group (COG) trial ANBL0532. STUDY DESIGN: A retrospective analysis of mIBG scans obtained from patients enrolled in COG ANBL0532 was performed. Evaluable patients had mIBG-avid, International Neuroblastoma Staging System (INSS) stage 4 disease, did not progress during induction therapy, consented to consolidation randomization, and received either single or tandem HDC (n = 80). Optimal CS cut points maximized the outcome difference (≤CS vs. >CS cut-off) according to the Youden index. RESULTS: For recipients of tandem HDC, the optimal cut point at diagnosis was CS = 12, with superior event-free survival (EFS) from study enrollment for patients with CS ≤ 12 (3-year EFS 74.2% ± 7.9%) versus CS > 12 (59.2% ± 7.1%) (p = .002). At EOI, the optimal cut point was CS = 0, with superior EOI EFS for patients with CS = 0 (72.9% ± 6.4%) versus CS > 0 (46.5% ± 9.1%) (p = .002). CONCLUSION: In the setting of tandem transplantation for children with high-risk neuroblastoma, CS at diagnosis and EOI may identify a more favorable patient group. Patients treated with tandem HDC who exhibited a CS ≤ 12 at diagnosis or CS = 0 at EOI had superior EFS compared to those with CS above these cut points.

Cellular Therapy for Children with Central Nervous System Tumors: Mining and Mapping the Correlative Data.

PURPOSE OF REVIEW: Correlative studies should leverage clinical trial frameworks to conduct biospecimen analyses that provide insight into the bioactivity of the intervention and facilitate iteration toward future trials that further improve patient outcomes. In pediatric cellular immunotherapy trials, correlative studies enable deeper understanding of T cell mobilization, durability of immune activation, patterns of toxicity, and early detection of treatment response. Here, we review the correlative science in adoptive cell therapy (ACT) for childhood central nervous system (CNS) tumors, with a focus on existing chimeric antigen receptor (CAR) and T cell receptor (TCR)-expressing T cell therapies. RECENT FINDINGS: We highlight long-standing and more recently understood challenges for effective alignment of correlative data and offer practical considerations for current and future approaches to multi-omic analysis of serial tumor, serum, and cerebrospinal fluid (CSF) biospecimens. We highlight the preliminary success in collecting serial cytokine and proteomics from patients with CNS tumors on ACT clinical trials.

Circulating tumor DNA reveals mechanisms of lorlatinib resistance in patients with relapsed/refractory ALK-driven neuroblastoma.

Activating point mutations in Anaplastic Lymphoma Kinase (ALK) have positioned ALK as the only mutated oncogene tractable for targeted therapy in neuroblastoma. Cells with these mutations respond to lorlatinib in pre-clinical studies, providing the rationale for a first-in-child Phase 1 trial (NCT03107988) in patients with ALK-driven neuroblastoma. To track evolutionary dynamics and heterogeneity of tumors, and to detect early emergence of lorlatinib resistance, we collected serial circulating tumor DNA samples from patients enrolled on this trial. Here we report the discovery of off-target resistance mutations in 11 patients (27%), predominantly in the RAS-MAPK pathway. We also identify newly acquired secondary compound ALK mutations in 6 (15%) patients, all acquired at disease progression. Functional cellular and biochemical assays and computational studies elucidate lorlatinib resistance mechanisms. Our results establish the clinical utility of serial circulating tumor DNA sampling to track response and progression and to discover acquired resistance mechanisms that can be leveraged to develop therapeutic strategies to overcome lorlatinib resistance.