Targeting refractory/recurrent neuroblastoma and osteosarcoma with anti-CD3×anti-GD2 bispecific antibody armed T cells.

BACKGROUND: The survival benefit observed in children with neuroblastoma (NB) and minimal residual disease who received treatment with anti-GD2 monoclonal antibodies prompted our investigation into the safety and potential clinical benefits of anti-CD3×anti-GD2 bispecific antibody (GD2Bi) armed T cells (GD2BATs). Preclinical studies demonstrated the high cytotoxicity of GD2BATs against GD2+cell lines, leading to the initiation of a phase I/II study in recurrent/refractory patients. METHODS: The 3+3 dose escalation phase I study (NCT02173093) encompassed nine evaluable patients with NB (n=5), osteosarcoma (n=3), and desmoplastic small round cell tumors (n=1). Patients received twice-weekly infusions of GD2BATs at 40, 80, or 160×106 GD2BATs/kg/infusion complemented by daily interleukin-2 (300,000 IU/m2) and twice-weekly granulocyte macrophage colony-stimulating factor (250 µg/m2). The phase II segment focused on patients with NB at the dose 3 level of 160×106 GD2BATs/kg/infusion. RESULTS: Of the 12 patients enrolled, 9 completed therapy in phase I with no dose-limiting toxicities. Mild and manageable cytokine release syndrome occurred in all patients, presenting as grade 2-3 fevers/chills, headaches, and occasional hypotension up to 72 hours after GD2BAT infusions. GD2-antibody-associated pain was minimal. Median overall survival (OS) for phase I and the limited phase II was 18.0 and 31.2 months, respectively, with a combined OS of 21.1 months. A phase I NB patient had a complete bone marrow response with overall stable disease. In phase II, 10 of 12 patients were evaluable: 1 achieved partial response, and 3 showed clinical benefit with prolonged stable disease. Over 50% of evaluable patients exhibited augmented immune responses to GD2+targets post-GD2BATs, as indicated by interferon-gamma (IFN-γ) EliSpots, Th1 cytokines, and/or chemokines. CONCLUSIONS: This study demonstrated the safety of GD2BATs up to 160×106 cells/kg/infusion. Coupled with evidence of post-treatment endogenous immune responses, our findings support further investigation of GD2BATs in larger phase II clinical trials.

Intraoperative Radiation Therapy for Relapsed or Refractory High-Risk Neuroblastoma: A 27-Year Experience.

PURPOSE: To evaluate outcomes after intraoperative radiation therapy (IORT) in high-risk neuroblastoma (NB), including local control, overall survival, and toxicity. METHODS AND MATERIALS: This was a single institution retrospective study of 92 pediatric patients with NB treated with IORT from 1995 to 2022. Each IORT application was considered a separate event for a total of 110 sites treated. Local failure was calculated using the cumulative incidence function and survival by Kaplan-Meier method from the day of surgery. RESULTS: All patients had high-risk relapsed or treatment refractory disease. Median age was 6 years (range, 2-34 years). Median follow-up for all patients and surviving patients was 16 months and 4 years, respectively. All patients previously received chemotherapy, 93% had prior external beam radiation therapy to the site of IORT (median dose, 21.6 Gy; range, 10-36 Gy), and 94% had a prior surgery for tumor resection. The median IORT dose was 12 Gy (range, 8-18 Gy) and median area treated was 18 cm2 (range, 2.5-60 cm2). The cumulative incidence of local failure was 23% at 2 years and 29% at 5 years. The overall survival (OS) was 44% at 2 years and 29% at 5 years. Local failure after IORT was associated with worse OS (hazard ratio, 1.74; 95% CI, 1.07-2.84; P = .0267). Toxicity from IORT was rare, with postoperative complications likely related to IORT seen in 7 (8%) patients. CONCLUSIONS: Our study represents the largest, most recent analysis of the efficacy and safety of IORT in patients with relapsed or refractory NB. Less than one-third of patients failed locally at 5 years, and achieving local control affected overall survival. Minimal toxicities directly related to IORT were observed. Overall, IORT is an effective and safe technique to achieve local control in high-risk relapsed or refractory neuroblastoma.

GM-CSF, G-CSF or no cytokine therapy with anti-GD2 immunotherapy for high-risk neuroblastoma.

Colony-stimulating factors have been shown to improve anti-disialoganglioside 2 (anti-GD2) monoclonal antibody response in high-risk neuroblastoma by enhancing antibody-dependent cell-mediated cytotoxicity (ADCC). A substantial amount of research has focused on recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) as an adjuvant to anti-GD2 monoclonal antibodies. There may be a disparity in care among patients as access to GM-CSF therapy and anti-GD2 monoclonal antibodies is not uniform. Only select countries have approved these agents for use, and even with regulatory approvals, access to these agents can be complex and cost prohibitive. This comprehensive review summarizes clinical data regarding efficacy and safety of GM-CSF, recombinant human granulocyte colony-stimulating factor (G-CSF) or no cytokine in combination with anti-GD2 monoclonal antibodies (ie, dinutuximab, dinutuximab beta or naxitamab) for immunotherapy of patients with high-risk neuroblastoma. A substantial body of clinical data support the immunotherapy combination of anti-GD2 monoclonal antibodies and GM-CSF. In contrast, clinical data supporting the use of G-CSF are limited. No formal comparison between GM-CSF, G-CSF and no cytokine has been identified. The treatment of high-risk neuroblastoma with anti-GD2 therapy plus GM-CSF is well established. Suboptimal efficacy outcomes with G-CSF raise concerns about its suitability as an alternative to GM-CSF as an adjuvant in immunotherapy for patients with high-risk neuroblastoma. While programs exist to facilitate obtaining GM-CSF and anti-GD2 monoclonal antibodies in regions where they are not commercially available, continued work is needed to ensure equitable therapeutic options are available globally.

Targeting GD2-positive Refractory/Resistant Neuroblastoma and Osteosarcoma with Anti- CD3 x Anti-GD2 Bispecific Antibody Armed T cells.

Background: Since treatment of neuroblastoma (NB) with anti-GD2 monoclonal antibodies provides a survival benefit in children with minimal residual disease and our preclinical study shows that anti-CD3 x anti-GD2 bispecific antibody (GD2Bi) armed T cells (GD2BATs) were highly cytotoxic to GD2+ cell lines, we conducted a phase I/II study in recurrent/refractory patients to establish safety and explore the clinical benefit of GD2BATs. Methods: The 3+3 dose escalation study (NCT02173093) phase I involved 9 evaluable patients with NB (n=5), osteosarcoma (OST) (n=3), and desmoplastic small round cell tumors (DSRCT) (n=1) with twice weekly infusions of GD2BATs at 40, 80, or 160 x 106 GD2BATs/kg/infusion with daily interleukin 2 (300,000 IU/m2) and twice weekly granulocyte-macrophage colony stimulating factor (250 µg/m2). Phase II portion of the trial was conducted in patients with NB at the dose 3 level of 160 x 106 GD2BATs/kg/infusion but failed to enroll the planned number of patients. Results: Nine of 12 patients in the phase I completed therapy. There were no dose limiting toxicities (DLTs). All patients developed mild and manageable cytokine release syndrome (CRS) with grade 2-3 fevers/chills, headaches, and occasional hypotension up to 72 hours after GD2BAT infusions. GD2-antibody associated pain was not significant in this study. The median OS for patients in the Phase I and limited Phase II was 18.0 and 31.2 months, respectively, whereas the combined OS was 21.1 months. There was a complete bone marrow response with overall stable disease in one of the phase I patients with NB. Ten of 12 phase II patients were evaluable for response: 1 had partial response. Three additional patients were deemed to have clinical benefit with prolonged stable disease. More than 50% of evaluable patients showed augmented immune responses to GD2+ targets after GD2BATs as measured by interferon-gamma (IFN-γ) EliSpots, Th1 cytokines, and/or chemokines. Conclusions: Our study demonstrated safety of up to 160 x 106 cells/kg/infusion of GD2BATs. Combined with evidence for the development of post treatment endogenous immune responses, this data supports further investigation of GD2 BATs in larger Phase II clinical trials.

Stage 4N neuroblastoma before and during the era of anti-GD2 immunotherapy.

Patients with stage 4N neuroblastoma (distant metastases limited to lymph nodes) stand out as virtually the only survivors of high-risk neuroblastoma (HR-NB) before myeloablative therapy (MAT) and immunotherapy with anti-GD2 monoclonal antibodies (mAbs) became standard. Because no report presents more recent results with 4N, we analyzed our large 4N experience. All 51 pediatric 4N patients (<18 years old) diagnosed 1985 to 2021 were reviewed. HR-NB included MYCN-nonamplified 4N diagnosed at age ≥18 months and MYCN-amplified 4N. Among 34 MYCN-nonamplified high-risk patients, 20 are relapse-free 1.5+ to 37.5+ (median 12.5+) years post-diagnosis, including 13 without prior MAT and 5 treated with little (1 cycle; n = 2) or no mAb (n = 3), while 14 patients (7 post-MAT, 8 post-mAbs) relapsed (all soft tissue). Of 15 MYCN-amplified 4N patients, 7 are relapse-free 2.1+ to 26.4+ (median 11.6+) years from the start of chemotherapy (all received mAbs; 3 underwent MAT) and 4 are in second remission 4.2+ to 21.8+ years postrelapse (all soft tissue). Statistical analyses showed no significant association of survival with either MAT or mAbs for MYCN-nonamplified HR-NB; small numbers prevented these analyses for MYCN-amplified patients. The two patients with intermediate-risk 4N (14-months-old) are relapse-free 7+ years postresection of primary tumors; distant disease spontaneously regressed. The natural history of 4N is marked by NB confined to soft tissue without early relapse in bones or bone marrow, where mAbs have proven efficacy. These findings plus curability without MAT, as seen elsewhere and at our center, support consideration of treatment reduction for MYCN-nonamplified 4N.

Anaplastic Lymphoma Kinase Inhibitors for Therapy of Neuroblastoma in Adults.

PURPOSE: Adult-onset neuroblastoma (AON) differs significantly in biology and clinical behavior from childhood-onset disease. AON poses therapeutic challenges since tolerance of intensive multimodality therapies that are standard of care for pediatric neuroblastoma (NB) is poor. AON is enriched for somatic mutations including anaplastic lymphoma kinase (ALK), deemed to be an oncogenic driver in NB. ALK inhibitors (ALKis), therefore, have the potential to be of therapeutic benefit. The purpose of this study is to report on their use in AON. METHODS: A single-center retrospective review of adults with NB receiving ALKi (2012-2022) was performed. Response was evaluated using International Neuroblastoma Response Criteria. RESULTS: Fifteen patients with ALK-mutated AON were treated with US Food and Drug Administration-approved ALKi starting at a median age of 34 (16-71) years. Initial ALKi was lorlatinib, crizotinib, and alectinib in seven, five, and three patients respectively; seven received multiple ALKis due to progressive disease/intolerability of one agent. All patients experienced ≥grade 2 adverse events (AEs): crizotinib and alectinib were associated primarily with gastrointestinal AEs, lorlatinib with neurologic AEs, weight gain, and hyperlipidemia resulting in dose reduction or discontinuation of ALKi in several patients. No responses were observed with crizotinib (n = 5 patients), ceritinib, alectinib, or brigatinib (n = 1 each). Of the 13 patients receiving lorlatinib, four, five, and four patients had a complete or partial response (major response rate 69%), and stable disease, respectively. Responses were noted in all disease compartments; complete metabolic response was seen in two L2 patients. Ten of 13 patients remain progression-free at a median of 19 (6-50) months on lorlatinib. Three (two receiving dose-reduced therapy) had progressive disease. Median survival from start of first ALKi was 43 ± 26 months. CONCLUSION: ALKis, particularly lorlatinib, are effective treatment options for AON. However, AEs necessitating dose reduction are common.

Clonal evolution during metastatic spread in high-risk neuroblastoma.

Patients with high-risk neuroblastoma generally present with widely metastatic disease and often relapse despite intensive therapy. As most studies to date focused on diagnosis-relapse pairs, our understanding of the genetic and clonal dynamics of metastatic spread and disease progression remain limited. Here, using genomic profiling of 470 sequential and spatially separated samples from 283 patients, we characterize subtype-specific genetic evolutionary trajectories from diagnosis through progression and end-stage metastatic disease. Clonal tracing timed disease initiation to embryogenesis. Continuous acquisition of structural variants at disease-defining loci (MYCN, TERT, MDM2-CDK4) followed by convergent evolution of mutations targeting shared pathways emerged as the predominant feature of progression. At diagnosis metastatic clones were already established at distant sites where they could stay dormant, only to cause relapses years later and spread via metastasis-to-metastasis and polyclonal seeding after therapy.

Ganglioneuroblastoma intermixed: Clinicopathological implications of diagnosis at presentation and genomic correlations.

BACKGROUND: Ganglioneuroblastoma intermixed (GNBI) is classified as "favorable" histology by International Neuroblastoma Pathology Classification system. However, the International Neuroblastoma Risk Group (INRG) stratifies patients using wider clinicopathological and cytogenetic/molecular parameters. While the diagnosis of GNBI is typically made on resected tumor, it may sometimes be rendered on initial biopsy. We studied GNBI noted at diagnosis to evaluate its correlation with INRG staging and other clinicopathological and molecular features. METHODS: In this retrospective study, clinical, radiological, pathological, cytogenetic, and molecular information from patients with GNBI at diagnosis seen between 1995 and 2021 was analyzed. INRG staging was performed. RESULTS: Of the 15,827 neuroblastoma specimens, GNBI was noted in 237 patients. Of these, 53 had the initial pathological diagnosis of GNBI; median follow-up 3.5 (range: 0.2-14) years. Disease was locoregional in 41 (77%, 16 stage L1 and 25 L2); none relapsed. Twelve (23%) had metastatic disease at presentation; six (50%) relapsed, and two died of disease. MYCN was amplified in two metastatic tumors. Six of 31 (19%) tumors tested had recurrent cytogenetic abnormalities and nonrecurrent somatic gene mutations in 10/23 (43%). The presence of any adverse molecular/cytogenetic findings was associated with metastatic disease (p < .05). For patients with localized GNBI undergoing both biopsy and resection, GNBI was diagnosed in both in 17/19 (90%). CONCLUSIONS: Localized GNBI at diagnosis has excellent long-term clinical outcome even without cytotoxic therapy. For localized GNBI, a biopsy sample is adequate to make the diagnosis. When associated with metastasis at diagnosis, prognosis is poorer, possibly due to associated adverse biological features.

Radioimmunoscintigraphy and Pretreatment Dosimetry of 131I-Omburtamab for Planning Treatment of Leptomeningeal Disease.

Radiolabeled antibody treatment with 131I-omburtamab, administered intraventricularly into the cerebrospinal fluid (CSF) space, can deliver therapeutic absorbed doses to sites of leptomeningeal disease. Assessment of distribution and radiation dosimetry is a key element in optimizing such treatments. Using a theranostic approach, we performed pretreatment 131I-omburtamab imaging and dosimetric analysis in patients before therapy. Methods: Whole-body planar images were acquired 3 ± 1, 23 ± 2, and 47 ± 2 h after intracranioventricular administration of 75 ± 5 MBq of 131I-omburtamab via an Ommaya reservoir. Multiple blood samples were also obtained for kinetic analysis. Separate regions of interest (ROIs) were manually drawn to include the lateral ventricles, entire spinal canal CSF space, and over the whole body. Count data in the ROIs were corrected for background and physical decay, converted to activity, and subsequently fitted to an exponential clearance function. The radiation absorbed dose was estimated to the CSF, separately to the spinal column and ventricles, and to the whole body and blood. Biodistribution of the injected radiolabeled antibody was assessed for all patients. Results: Ninety-five patients were included in the analysis. Biodistribution showed prompt localization in the ventricles and spinal CSF space with low systemic distribution, noted primarily as hepatic, renal, and bladder activity after the first day. Using ROI analysis, the effective half-lives were 13 ± 11 h (range, 5-75 h) for CSF in the spinal column, 8 ± 3 h (range, 3-17 h) for ventricles, and 41 ± 11 (range, 23-81 h) for the whole body. Mean absorbed doses were 0.63 ± 0.38 cGy/MBq (range, 0.24-2.25 cGy/MBq) for CSF in the spinal column, 1.03 ± 0.69 cGy/MBq (range, 0.27-5.15 cGy/MBq) for the ventricular CSF, and 0.45 ± 0.32 mGy/MBq (range, 0.05-1.43 mGy/MBq) for the whole body. Conclusion: Pretherapeutic imaging with 131I-omburtamab allows assessment of biodistribution and dosimetry before the administration of therapeutic activity. Absorbed doses to the CSF compartments and whole body derived from the widely applicable serial 131I-omburtamab planar images had acceptable agreement with previously reported data determined from serial 124I-omburtamab PET scans.

Effect of Oral ß-Glucan on Antibody Response to Ganglioside Vaccine in Patients With High-Risk Neuroblastoma: A Phase 2 Randomized Clinical Trial.

Importance: Among patients with high-risk relapsed metastatic neuroblastoma, oral ß-glucan adjuvant during GD2/GD3 ganglioside vaccine boost has stimulated IgG antibody response, which was associated with improved survival; however, the effectiveness of oral ß-glucan during the vaccine priming phase remains unproven. Objective: To isolate the adjuvant effect of oral ß-glucan on antibody response to GD2/GD3 ganglioside vaccine in patients with high-risk neuroblastoma. Design, Setting, and Participants: In this phase 2 randomized clinical trial, enrolled patients with high-risk neuroblastoma were randomized to 2 groups to receive the GD2/GD3 vaccine at a large cancer center in a major metropolitan area from October 2018 to September 2020. Data were analyzed from October 7, 2021, to February 28, 2022. Interventions: Eligible patients receiving GD2/GD3 vaccine were randomly assigned to group 1 (n = 54) to receive no ß-glucan or group 2 (n = 53) to receive an oral ß-glucan regimen during the first 5 weeks of vaccine priming. From week 6 onwards, all 107 patients received oral ß-glucan during vaccine boost for 1 year or until disease progression. Main Outcomes and Measures: Primary end point was comparison of anti-GD2 IgG1 response before vaccine injection 6 (week 32) in group 1 vs group 2. Seroconversion rate and the association of antibody titer with ß-glucan receptor dectin-1 single nucleotide polymorphism (SNP) rs3901533 were also assessed. Results: In all, 107 patients with high-risk neuroblastoma were randomized to the 2 groups: 54 patients (median [range] age, 5.2 [1.0-17.3] years; 28 [52%] male and 26 [48%] female) in group 1; and 53 patients (median [range] age, 6.2 [1.9-18.4] years; 25 [47%] male and 28 [53%] female) in group 2; both groups were also comparable in their first remission status at study entry (70% vs 70%). Adding oral ß-glucan during the first 5 weeks of vaccine priming elicited a higher anti-GD2 IgG1 antibody response in group 2 (1.80; 90% CI, 0.12-3.39; P = .08; planned type I error, 0.10). Anti-GD2 IgG1 titer of 230 ng/mL or greater by week 8 was associated with statistically favorable PFS. Antibody titer correlated significantly with dectin-1 SNP. The genotype frequency, seroconversion rates, and vaccine-related toxic effects were similar in the 2 groups. Conclusions and Relevance: This phase 2 randomized clinical trial found that adding oral ß-glucan during vaccine priming increased anti-GD2 IgG1 titer among genetic responders without added toxic effects. Because responder dectin-1 SNP was identical in the 2 randomized groups, no difference was detected in seroconversion rates. Alternative or additional adjuvants may be needed to enhance seroconversion. Trial Registration: ClinicalTrials.gov Identifier: NCT00911560.

Clinical outcomes of pediatric patients receiving multimodality treatment of second central nervous system relapse of neuroblastoma.

BACKGROUND: In high-risk neuroblastoma, multimodality therapy including craniospinal irradiation (CSI) is effective for central nervous system (CNS) relapse. Management of post-CSI CNS relapse is not clearly defined. PROCEDURE: Pediatric patients with neuroblastoma treated with CSI between 2000 and 2019 were identified. Treatment of initial CNS disease (e.g., CSI, intraventricular compartmental radioimmunotherapy [cRIT] with 131 I-monoclonal antibodies targeting GD2 or B7H3) and management of post-CSI CNS relapse ("second CNS relapse") were characterized. Cox proportional hazards models to evaluate factors associated with third CNS relapse and overall survival (OS) were used. RESULTS: Of 128 patients (65% male, median age 4 years), 19 (15%) received CSI with protons and 115 (90%) had a boost. Most (103, 81%) received cRIT, associated with improved OS (hazard ratio [HR] 0.3, 95% confidence interval [CI]: 0.1-0.5, p < .001). Forty (31%) developed a second CNS relapse, associated with worse OS (1-year OS 32.5%, 95% CI: 19-47; HR 3.8; 95% CI: 2.4-6.0, p < .001), and more likely if the leptomeninges were initially involved (HR 2.5, 95% CI: 1.3-4.9, p = .006). Median time to second CNS relapse was 6.8 months and 51% occurred outside the CSI boost field. Twenty-five (63%) patients underwent reirradiation, most peri-operatively (18, 45%) with focal hypofractionation. Eight (20%) patients with second CNS relapse received cRIT, associated with improved OS (HR 0.1; 95% CI: 0.1-0.4, p < .001). CONCLUSIONS: CNS relapse after CSI for neuroblastoma portends a poor prognosis. Surgery with hypofractionated radiotherapy was the most common treatment. Acknowledging the potential for selection bias, receipt of cRIT both at first and second CNS relapse was associated with improved survival. This finding necessitates further investigation.

Immunotherapy with anti-GD2 monoclonal antibody in infants with high-risk neuroblastoma.

Anti-GD2 monoclonal antibodies (mAb) improve the prognosis of high-risk neuroblastoma (HR-NB). Worldwide experience almost exclusively involves toddlers and older patients treated after multimodality or second-line therapies, that is, many months postdiagnosis. In contrast, at our center, infants received anti-GD2 mAbs because this immunotherapy started during or immediately after induction chemotherapy. We now report on the feasibility, safety, and long-term survival in this vulnerable age group. Thirty-three HR-NB patients were <19 months old when started on 3F8 (murine mAb; n = 21) or naxitamab (humanized-3F8; n = 12), with 30″ to 90″ intravenous infusions. Patients received analgesics and antihistamines. Common toxicities (pain, urticaria, cough) were manageable, allowing outpatient treatment. Capillary leak, posterior reversible encephalopathy syndrome, and mAb-related long-term toxicities did not occur. Two 3F8 cycles were aborted due to bradycardia (a preexisting condition) and asthmatic symptoms, respectively. One patient received ½ dose of Day 1 naxitamab because of hypotension; full doses were subsequently administered. Post-mAb treatments included chemotherapy, radiotherapy, and anti-NB vaccine. Among 3F8 patients, 17/21 are in complete remission off all treatment at 5.6+ to 24.1+ (median 13.4+) years from diagnosis. Among naxitamab patients, 10/12 remain relapse-free post-mAb at 1.7+ to 4.3+ (median 3.1+) years from diagnosis. Toxicity was similar with short outpatient infusions and matched that observed with these and other anti-GD2 mAbs in older patients. These findings were reassuring given that naxitamab is dosed >2.5× higher (~270 mg/m2 /cycle) than 3F8, dinutuximab, and dinutuximab beta (70-100 mg/m2 /cycle). HR-NB in infants proved to be highly curable.

Phase 1 study of intraventricular 131I-omburtamab targeting B7H3 (CD276)-expressing CNS malignancies.

BACKGROUND: The prognosis for metastatic and recurrent tumors of the central nervous system (CNS) remains dismal, and the need for newer therapeutic targets and modalities is critical. The cell surface glycoprotein B7H3 is expressed on a range of solid tumors with a restricted expression on normal tissues. We hypothesized that compartmental radioimmunotherapy (cRIT) with the anti-B7H3 murine monoclonal antibody omburtamab injected intraventricularly could safely target CNS malignancies. PATIENTS AND METHODS: We conducted a phase I trial of intraventricular 131I-omburtamab using a standard 3 + 3 design. Eligibility criteria included adequate cerebrospinal fluid (CSF) flow, no major organ toxicity, and for patients > dose level 6, availability of autologous stem cells. Patients initially received 74 MBq radioiodinated omburtamab to evaluate dosimetry and biodistribution followed by therapeutic 131I-omburtamab dose-escalated from 370 to 2960 MBq. Patients were monitored clinically and biochemically for toxicity graded using CTCAEv 3.0. Dosimetry was evaluated using serial CSF and blood sampling, and serial PET or gamma-camera scans. Patients could receive a second cycle in the absence of grade 3/4 non-hematologic toxicity or progressive disease. RESULTS: Thirty-eight patients received 100 radioiodinated omburtamab injections. Diagnoses included metastatic neuroblastoma (n = 16) and other B7H3-expressing solid tumors (n = 22). Thirty-five patients received at least 1 cycle of treatment with both dosimetry and therapy doses. Acute toxicities included < grade 4 self-limited headache, vomiting or fever, and biochemical abnormalities. Grade 3/4 thrombocytopenia was the most common hematologic toxicity. Recommended phase 2 dose was 1850 MBq/injection. The median radiation dose to the CSF and blood by sampling was 1.01 and 0.04 mGy/MBq, respectively, showing a consistently high therapeutic advantage for CSF. Major organ exposure was well below maximum tolerated levels. In patients developing antidrug antibodies, blood clearance, and therefore therapeutic index, was significantly increased. In patients receiving cRIT for neuroblastoma, survival was markedly increased (median PFS 7.5 years) compared to historical data. CONCLUSIONS: cRIT with 131I-omburtamab is safe, has favorable dosimetry and may have a therapeutic benefit as adjuvant therapy for B7-H3-expressing leptomeningeal metastases. TRIAL REGISTRATION: clinicaltrials.gov NCT00089245, August 5, 2004.

Bone Marrow Surveillance of Pediatric Cancer Survivors Identifies Clones that Predict Therapy-Related Leukemia.

PURPOSE: Therapy-related myelodysplastic syndrome and acute leukemias (t-MDS/AL) are a major cause of nonrelapse mortality among pediatric cancer survivors. Although the presence of clonal hematopoiesis (CH) in adult patients at cancer diagnosis has been implicated in t-MDS/AL, there is limited published literature describing t-MDS/AL development in children. EXPERIMENTAL DESIGN: We performed molecular characterization of 199 serial bone marrow samples from 52 patients treated for high-risk neuroblastoma, including 17 with t-MDS/AL (transformation), 14 with transient cytogenetic abnormalities (transient), and 21 without t-MDS/AL or cytogenetic alterations (neuroblastoma-treated control). We also evaluated for CH in a cohort of 657 pediatric patients with solid tumor. RESULTS: We detected at least one disease-defining alteration in all cases at t-MDS/AL diagnosis, most commonly TP53 mutations and KMT2A rearrangements, including involving two novel partner genes (PRDM10 and DDX6). Backtracking studies identified at least one t-MDS/AL-associated mutation in 13 of 17 patients at a median of 15 months before t-MDS/AL diagnosis (range, 1.3-32.4). In comparison, acquired mutations were infrequent in the transient and control groups (4/14 and 1/21, respectively). The relative risk for development of t-MDS/AL in the presence of an oncogenic mutation was 8.8 for transformation patients compared with transient. Unlike CH in adult oncology patients, TP53 mutations were only detectable after initiation of cancer therapy. Last, only 1% of pediatric patients with solid tumor evaluated had CH involving myeloid genes. CONCLUSIONS: These findings demonstrate the clinical relevance of identifying molecular abnormalities in predicting development of t-MDS/AL and should guide the formation of intervention protocols to prevent this complication in high-risk pediatric patients.

F-18 meta-fluorobenzylguanidine PET imaging of myocardial sympathetic innervation.

BACKGROUND: I-123 meta-iodobenzylguanidine (MIBG) imaging has long been employed to noninvasively assess the integrity of human norepinephrine transporter-1 and, hence, myocardial sympathetic innervation. Positron-emitting F-18 meta-fluorobenzylguanidine (MFBG) has recently been developed for potentially superior quantitative characterization. We assessed the feasibility of MFBG imaging of myocardial sympathetic innervation. METHODS: 16 patients were imaged with MFBG PET (30-minute dynamic imaging of chest, followed by 3 whole-body acquisitions between 30 minutes and 4-hour post-injection). Blood kinetics were assessed from multiple samples. Pharmacokinetic modeling with reversible 1- and 2-compartment models was performed. Kinetic rate constants were re-calculated from truncated datasets. All patients underwent concurrent MIBG SPECT. RESULTS: MFBG myocardial uptake was rapid and sustained; the mean standardized uptake value (SUV (mean ± standard deviation)) was 5.1 ± 2.2 and 3.4 ± 1.9 at 1 hour and 3-4-hour post-injection, respectively. The mean K1 and distribution volume (VT) were 1.1 ± 0.6 mL/min/g and 34 ± 22 mL/cm3, respectively. Both were reproducible when re-calculated from truncated 1-hour datasets (Intraclass Correlation Coefficient of 0.99 and 0.91, respectively). Spearman's ϱ = 0.86 between MFBG SUV and VT and 0.80 between MFBG PET-derived VT and MIBG SPECT-derived heart-to-mediastinum activity concentration ratio. CONCLUSION: MFBG is a promising PET radiotracer for the assessment of myocardial sympathetic innervation.

Biodistribution and Radiation Dosimetry of Intraperitoneally Administered 124I-Omburtamab in Patients with Desmoplastic Small Round Cell Tumors.

The aim of this study was to assess the pharmacokinetics, biodistribution, and radiation dosimetry of 124I-omburtamab administered intraperitoneally in patients with desmoplastic small round cell tumor. Methods: Eligible patients diagnosed with desmoplastic small round cell tumor with peritoneal involvement were enrolled in a phase I trial of intraperitoneal radioimmunotherapy with 131I-omburtamab. After thyroid blockade and before radioimmunotherapy, patients received approximately 74 MBq of 124I-omburtamab intraperitoneally. Five serial PET/CT scans were obtained up to 144 h after injection. Multiple blood samples were obtained up to 120 h after injection. Organ-absorbed doses were calculated with OLINDA/EXM. Results: Thirty-one patients were studied. Blood pharmacokinetics exhibited a biphasic pattern consisting of an initial rising phase with a median half-time (±SD) of 23 ± 15 h and a subsequent falling phase with a median half-time of 56 ± 34 h. Peritoneal distribution was heterogeneous and diffuse in most patients. Self-dose to the peritoneal cavity was 0.58 ± 0.19 mGy/MBq. Systemic distribution and activity in major organs were low. The median absorbed doses were 0.72 ± 0.23 mGy/MBq for liver, 0.48 ± 0.17 mGy/MBq for spleen, and 0.57 ± 0.12 mGy/MBq for kidneys. The mean effective dose was 0.31 ± 0.10 mSv/MBq. Whole-body and peritoneal cavity biologic half-times were 45 ± 9 and 24 ± 5 h, respectively. Conclusion: PET/CT imaging with intraperitoneally administered 124I-omburtamab enables assessment of intraperitoneal distribution and estimation of absorbed dose to peritoneal space and normal organs before therapy.

Skeletal muscle metastases in neuroblastoma share common progenitors with primary tumor and biologically resemble stage MS disease.

Introduction: While subcutaneous metastases are often observed with stage MS neuroblastoma, an entity that usually resolves spontaneously, skeletal muscle metastases (SMM) have been rarely described. The purpose of this retrospective study was to investigate the significance of SMM in neuroblastoma. Patients and methods: Seventeen patients with neuroblastoma SMM were diagnosed at a median age of 4.3 (0.1-15.6) months. All had SMM at diagnosis and metastases at other sites. Fifteen (88%) had ≥ 2 SMM in disparate muscle groups. One, 14, and 2 patients had low, intermediate, and high-risk disease respectively. Fifteen tumors had favorable histology without MYCN amplification, and 2 were MYCN-amplified. Most SMM (80%; n=12/15 evaluated) were MIBG-avid. Results: Only 1 patient (with MYCN-non-amplified neuroblastoma) had disease progression. All survive at median follow-up of 47.9 (16.9-318.9) months post-diagnosis. Biological markers (histology, chromosomal and genetic aberrations) were not prognostic. Whole genome sequencing of 3 matched primary and SMM lesions suggested that both primary and metastatic tumors arose from the same progenitor. SMM completely resolved in 10 patients by 12 months post-diagnosis. Of 4 patients managed with watchful observation alone without any cytotoxic therapy, 3 maintain complete remission with SMM resolving by 5, 13, and 21 months post-diagnosis respectively. Conclusions: Children with neuroblastoma SMM have an excellent prognosis, with a clinical course suggestive of stage MS disease. Based on these results, the initial management of infants with non-MYCN-amplified NB with SMM could be watchful observation, which could eliminate or reduce exposure to genotoxic therapy.

Phase I Trial of Oral Yeast-Derived ß-Glucan to Enhance Anti-GD2 Immunotherapy of Resistant High-Risk Neuroblastoma.

Beta glucans, complex polysaccharides, prime leukocyte dectin-1 and CR3-receptors and enhance anti-tumor cytotoxicity of complement-activating monoclonal antibodies. We conducted a phase I study (clinicaltrials.gov NCT00492167) to determine the safety of the combination of yeast-derived beta glucan (BG) and anti-GD2 murine monoclonal antibody 3F8 in patients with relapsed or refractory high-risk neuroblastoma. Patients received intravenous 3F8 (fixed dose of 10 mg/m2/day × 10 days) and oral BG (dose-escalated from 10-200 mg/kg/day × 17 days in cohorts of 3-6 patients each). Forty-four patients completed 141 cycles. One patient developed DLT: transient self-limiting hepatic transaminase elevation 5 days after starting BG (120 mg/kg/day). Overall, 1, 3, 12 and 24 evaluable patients had complete response, partial response, stable and progressive disease, respectively, at the end of treatment. Positive human anti-mouse antibody response and dectin-1 rs3901533 polymorphism were associated with better overall survival. BG dose level and serum BG levels did not correlate with response. Progression-free and overall survival at 2 years were 28% and 61%, respectively. BG lacked major toxicity. Treatment with 3F8 plus BG was associated with anti-neuroblastoma responses in patients with resistant disease. Although the maximal tolerated dose for yeast BG was not reached, considering the large volume of oral BG, we recommended 40 mg/kg/day as the phase II dose.

Differential Impact of ALK Mutations in Neuroblastoma.

PURPOSE: The tyrosine kinase receptor anaplastic lymphoma kinase (ALK) can be abnormally activated in neuroblastoma, and somatic ALK mutations occur in 6%-10% of patients. The differential clinical impact of these mutations has not been clearly elucidated. METHODS: Data on patients with neuroblastoma harboring ALK mutations were retrospectively analyzed. ALK sequencing was performed by whole-genome sequencing, hybrid-based capture of targeted exomes, or hotspot ALK mutation profiling. The differential impact of ALK mutation site on clinical characteristics, response to treatment, and survival was analyzed. In a subgroup of patients with locoregional neuroblastoma diagnosed after 2014, the impact of all ALK mutations was compared with wild-type ALK. RESULTS: Of 641 patients with neuroblastoma with ALK status analyzed on at least one tumor sample, 103 (16%) had tumors harboring ALK mutations. Mutations existed across all ages (birth to 67.8 years), stages (30% locoregional and 70% metastatic), and risk groups (20%, 11%, and 69% with low-, intermediate-, and high-risk disease, respectively). Mutation sites included F1174 (51%), R1275 (29%), R1245 (10%), and others (10%). Mutation site was not prognostic for progression-free survival or overall survival in the entire cohort, high-risk subgroup, or locoregional subgroup. Locoregional tumors with any ALK mutation were generally invasive: L2 by International Neuroblastoma Research Group staging in 30/31 patients with a 2-year progression-free survival (59%, 95% CI, 37.4 to 80.5) that was inferior to historical controls. This observation was corroborated in the post-2014 subgroup in which gross total resection was less likely for ALK-mutated tumors. CONCLUSION: Somatic ALK mutations are present across all stages and risk groups of neuroblastoma. No specific mutation carries differential prognostic significance. Locoregional neuroblastoma has an invasive phenotype when harboring somatic ALK mutations in this population.

Prospective pan-cancer germline testing using MSK-IMPACT informs clinical translation in 751 patients with pediatric solid tumors.

The spectrum of germline predisposition in pediatric cancer continues to be realized. Here we report 751 solid tumor patients who underwent prospective matched tumor-normal DNA sequencing and downstream clinical use (clinicaltrials.gov NCT01775072). Germline pathogenic and likely pathogenic (P/LP) variants were reported. One or more P/LP variants were found in 18% (138/751) of individuals when including variants in low, moderate, and high penetrance dominant or recessive genes, or 13% (99/751) in moderate and high penetrance dominant genes. 34% of high or moderate penetrance variants were unexpected based on the patient's diagnosis and previous history. 76% of patients with positive results completed a clinical genetics visit, and 21% had at least one relative undergo cascade testing as a result of this testing. Clinical actionability additionally included screening, risk reduction in relatives, reproductive use, and use of targeted therapies. Germline testing should be considered for all children with cancer.