BEACON-Immuno: Results of the Dinutuximab Beta (db) Randomization of the BEACON-Neuroblastoma Phase 2 Trial—a European Innovative Therapies for Children with Cancer (itcc–international Society of Paediatric Oncology Europe Neuroblastoma Group (SIOPEN) Trial.

10002 Background: The BEACON phase II trial (NCT02308527) addressed a number of questions in children with relapsed/refractory high-risk neuroblastoma (RR-HRNB). Here we report the chemo-immunotherapy randomisation, assessing if anti-GD2 (dB) demonstrates activity when added to chemotherapy. Methods: Patients aged 1-21 years with RR-HRNB with adequate organ function and performance status were randomised in a 1:2 ratio to receive chemotherapy alone or with dB, given concurrently as a 7 day continuous infusion (10 mg/m2/24hr). As the trial had a factorial design, some patients were also randomised between chemotherapy regimens (temozolomide (T) versus Temozolomide-Topotecan (TTo); this randomisation closed soon after the dB randomisation opened and all patients subsequently received TTo chemotherapy. Cross-over to dB with topotecan and cyclophosphamide was allowed for patients randomised to chemotherapy alone who experienced disease progression. The primary outcome measure was best response (complete or partial) at any point during the first 6 courses of treatment, by RECIST or International Neuroblastoma Response Criteria for patients with measurable and evaluable disease respectively. Progression free and overall survival (PFS & OS) and safety were secondary outcomes. The success criterion for proceeding to a Phase 3 trial was a one-sided p-value (1p) less than 0.23 for Objective Response Rate (ORR). Results: From Aug 2019 to Feb 2021, 65 patients were randomised to chemotherapy alone (3 T, 19 TTo) or with dB (6 dBT, 37 dBTTo). Median age was 4 years; 48 and 17 had measurable and evaluable disease respectively; 29 and 36 had refractory and relapsed disease respectively; 19 had MYCN amplification. Baseline characteristics were balanced between arms. Response was assessable in all patients. The ORR was 18% with chemotherapy alone and 35% for patients receiving chemotherapy with dB (risk ratio 1.66, 80% confidence interval (CI) 0.9 to 3.06, 1p = 0.19). 1-year PFS was 27% for chemotherapy alone, and 57% for those receiving chemotherapy +dB (HR 0.63, 95% CI 0.32 to 1.25, p = 0.19). Twelve patients in the chemotherapy only arm crossed over to receive dB at progression. OS did not differ between the arms: HR = 0.99, 95% CI 0.42 to 2.36, p = 0.99. Nine (41%) patients receiving chemotherapy alone and 13 (30%) receiving chemotherapy plus dB had grade ≥3 toxicities (CTCAE v4.0). Neurotoxicities were more common in patients receiving dB compared to chemotherapy alone (Grade 1-2: 67.4% vs 13.6%, Grade 3: 9.3 vs 0%). Other toxicities were similar with and without dB. Conclusions: The Phase 2 success criterion for ORR was met and PFS is also encouraging. The addition of dB to temozolomide-based chemotherapy shows promising activity in patients with RR-HR-NB. Clinical trial information: NCT02308527.