Background Naxitamab is a humanized anti‐disialoganglioside (GD2) monoclonal antibody approved for treatment of bone/bone marrow refractory high‐risk neuroblastoma (HR‐NB). Compassionate use (CU) expanded access program at Hospital Sant Joan de Deu permitted treatment of patients in complete remission (CR). We here report the survival, toxicity, and relapse pattern of patients in first or second CR treated with naxitamab and sargramostim (GM‐CSF). Procedure Seventy‐three consecutive patients with HR‐NB (stage M at age >18 months or MYCN‐amplified stages L1/L2 at any age) were treated in first or second CR. Treatment comprised five cycles of subcutaneous (SC) GM‐CSF for 5 days at 250 μg/m2/day (days −4 to 0), followed by naxitamab + SC GM‐CSF for 5 days at 500 μg/m2/day (days 1–5). Naxitamab was infused over 30 minutes at 3 mg/kg/day, days 1, 3, and 5, outpatient. Results Fifty‐five patients were in first CR and 18 in second CR. Seventeen patients had MYCN‐amplified NB and 11 detectable minimal residual disease in the bone marrow. Fifty‐eight (79.5%) patients completed therapy. Four (5%) experienced grade 4 toxicities and 10 (14%) early relapse. Three‐year event‐free survival (EFS) 58.4%, 95% CI = (43.5%, 78.4%) and overall survival (OS) 82.4%, 95% CI = (66.8%, 100%). First CR patients 3‐year EFS 74.3%, 95% CI = (62.7%, 88.1%), and OS 91.6%, 95% CI = (82.4%, 100%). EFS is significantly different between first and second CR (p = .0029). The pattern of relapse is predominantly (75%) of an isolated organ, mainly bone (54%). Univariate Cox models show prior history of relapse as the only statistically significant predictor of EFS but not OS. Conclusions Consolidation with naxitamab and GM‐CSF resulted in excellent survival rates for HR‐NB patients in CR.

Background: Treatment of HR-NB comprise induction, consolidation with autologous stem cell transplant (ASCT) followed by anti-GD2 immunotherapy and isotretinoin. Childrens Oncology Group and SIOPEN studies used dinutuximab and cytokines to treat patients in complete remission or refractory Bone/Bone marrow (B/BM) disease after ASCT. Methods: HR-NB patients referred to Hospital Sant Joan de Déu for anti-GD2 immunotherapy were eligible for two consecutive studies (dinutuximab for EudraCT 2013–004864–69 and naxitamab for 017–001829–40) and naxitamab/Sargramostim CU with or without prior ASCT. Patients enrolled in first complete remission or with primary refractory B/BM disease. We accrued a study population of two groups whose therapy, aside from ASCT, was similar. This is a retrospective analysis of their outcome calculated from study entry. Results: From December 2014–2019, 67 patients were treated with dinutuximab and cytokines (n = 21) in the Hospital Sant Joan de Déu-HRNB-Ch14.18 study or with naxitamab and Sargramostim either in the Ymabs study 201 (n = 12) or CU (n = 34). 23 patients were treated with primary refractory disease in the B/BM (11 with dinutuximab and 12 with naxitamab), and 44 in first CR (10 with dinutuximab and 34 with naxitamab). Study patients included 13 (19.4%) treated following single ASCT and 54 following conventional chemotherapy. Median follow-up for all patients is 16.2 months. Two-year rates for ASCT and non-ASCT patients were, respectively, EFS 64.1% vs. 54.2% ( p = 0.28), and OS 66.7% vs. 84.1% ( p = 0.81). For the 44 pts in first CR, 2-years rates for ASCT and non-ASCT patients were, respectively, EFS 65.5% vs. 58.7% ( p = 0.48), and OS 71.4% vs. 85.4% ( p = 0.63). Conclusions: In this retrospective, single center study, ASCT did not provide survival benefit when anti-GD2 immunotherapy was used after induction chemotherapy.

Immunotherapy with the anti-GD2 monoclonal antibody ch14.18, or dinutuximab, represents an important therapeutic advance in the treatment of pediatric high-risk neuroblastoma and is now considered part of standard of care in this patient population. To date, transverse myelitis as a result of dinutuximab therapy has not been reported in clinical trials or in the published literature. We describe three patients with clinical symptoms of transverse myelitis, confirmed via magnetic resonance imaging, shortly following initiation of dinutuximab. All patients were discontinued from dinutuximab treatment and received urgent treatment, with rapid improvement in symptoms and resultant functional recovery. K E Y W O R D Santi-GD2 monoclonal antibody, dinutuximab, neuroblastoma, transverse myelitis, Unituxin

Introduction Data regarding real-world impact on cancer clinical research during COVID-19 are scarce. We analysed the impact of the COVID-19 pandemic on the conduct of paediatric cancer phase I-II trials in Europe through the experience of the Innovative Therapies for Children with Cancer (ITCC). Methods A survey was sent to all ITCC-accredited Early-Phase Clinical Trial Hospitals including questions about impact on staff activities, recruitment, patient care, supply of investigational products and legal aspects, between 1/March and 30/April/2020. Results Thirty-one out of 53 hospitals from 12 countries participated. Challenges reported included staff constraints (30% drop), reduction in planned monitoring activity (67% drop of site initiation visits and 64% of monitoring visits) and patient recruitment (61% drop compared to 2019). The percentage of phase I, phase II trials and molecular platforms closing to recruitment in at least one site was 48.5%, 61.3% and 64.3%, respectively. Additionally, 26% of sites had restrictions on performing trial assessments due to local contingency plans. Almost half of the units suffered impact upon pending contracts. Most hospitals (65%) are planning on improving organizational and structural changes. Conclusion The study reveals a profound disruption of paediatric cancer early phase clinical research due to the COVID-19 pandemic across Europe. Reported difficulties affected both patient care and monitoring activity. Efforts should be made to reallocate resources to avoid lost opportunities for patients and to allow the continued advancement of oncology research. Identified adaptations to clinical trial procedures may be integrated to increase preparedness of clinical research to futures crises.

Background:First Spanish trial of Ewing sarcoma (ES) including adults and children with the aim to test the efficacy of Gemcitabine and Docetaxel (G/D) in newly diagnosed high-risk (HR) patients.Methods:This was a prospective, multicentric, non-randomised, open study for patients ⩽40 years with newly diagnosed ES. HR patients (metastatic, axial-pelvic primaries or bone marrow micrometastasis) received 2 window cycles of G/D. Patients with an objective response (OR) to G/D received 12 monthly cycles of G/D after completion of mP6. The primary end point was the OR rate to the G/D window phase and the event-free survival (EFS) and overall survival (OS) for all patients. The study is registered at ClinicalTrials.gov (identifier: NCT00006734).Results:Forty-three patients were enroled, median age 17 years (range, 3–40). After a median follow-up of 43.4 months, the 5-year OS rate is 55.0% (95% CI, 41–74%) with an EFS of 50.0% (95% CI, 36–68%). The 5-year OS and EFS rates for standard risk (SR) patients was 76.0% (95% CI, 57–100%) and 71.0% (CI, 54–94%); for HR 36.0% (CI, 20–65%) and 29.0% (CI, 15–56%). Twelve of 17 (70.6%) high-risk (HR) patients showed an OR (7 PR and 5 SD) to G/D window therapy. The 5-year OS rate for patients ⩽18 years of age was 74.0% (CI, 56–97%) and 31.0% for >18 years (95% CI, 15–66%), P<0.001. Grade 4 adverse events during mP6 occurred in 28/39 of patients (72%) and did not correlate with age. Multivariate survival analyses with <18 vs ⩾18 and risk groups significant differences, P<0.00001. Using a Cox model for OS, both age and risk group were statistically significant (P=0.0011 and P=0.0065, respectively).Conclusions:Age at diagnosis is an independent prognostic factor superior to the presence of metastases with 18 years as the strongest cut-off. The mP6 regimen provided survival curves that plateau at 3 years and G/D produced significant responses in HR-ES that is worth further exploring.