High Risk Neuroblastoma Study 1.8 of SIOP-Europe (SIOPEN)

In this protocol the term high-risk neuroblastoma refers to children with either

• disseminated disease (INSS stage 4: about 40 to 50% of all neuroblastoma) over the age of one or

• INSS stage 2 and 3 disease with amplification of the MycN proto-oncogene Between 10% and 20% of children with stage 3 and occasional patients with stage 2 disease are characterized by amplification of the MycN gene in their tumours. This biological characteristic has clearly been shown to be associated with a greater risk of relapse and death from disease progression. These patients may benefit from very aggressive treatment and, based on this hypothesis, they are included in this protocol. Infants (< 12 months at diagnosis) with MYCN amplified tumors are included.

Children with this type of presentation and age represent the largest neuroblastoma subgroup. Their prognosis remains poor in most cases and our ability to predict the clinical course and the outcome of the individual patient is modest.

Primary objectives:

R0 randomization: R0 was opened with the study activation in February 2002 and closed in November 2005. The randomized use of G-CSF during COJEC induction resulted in the recommendation of the prophylactic use of G-CSF to prevent episodes of febrile neutropenia (Ladenstein R, Valteau-Couanet D, Brock P, et al. Randomized Trial of prophylactic granulocyte colony-stimulating factor during rapid COJEC induction in pediatric patients with high-risk neuroblastoma: the European HR-NBL1/SIOPEN study. J Clin Oncol. 2010 Jul 20;3516-24).

R1 randomization: R1 was opened with the study activation in February 2002 and closed in 10/2010 following the results showing significant superiority of myeloablative therapy (MAT) with busulfan and melphalan over continuous infusion of carboplatin, etoposide and melphalan (CEM). BuMel is now the standard MAT (Ladenstein R, Pötschger U, Pearson ADJ, et al. Busulfan and melphalan versus carboplatin, etoposide, and melphalan as high-dose chemotherapy for high-risk neuroblastoma (HR-NBL1/SIOPEN): an international, randomized, multi-arm, open-label, phase 3 trial. Lancet Oncol. 2017 Apr;500-14).

R2 randomization: R2 was activated in November 2006 (13-cis retinoic acid +/- chimeric ch14.18/CHO antibody), modified in July 2009 and suspended in August 2013. R2 randomization tested the hypothesis that immunotherapy with ch14.18/CHO and subcutaneous aldesleukin (IL-2, Proleukin®), following MAT and autologous stem cell transplantation, in addition to differentiation therapy with 13-cis retinoic acid, will improve 3-year EFS in patients with high-risk neuroblastoma (ASCO 2016: Ladenstein R, et al J Clin Oncol 34, 2016 (suppl; abstr 10500)).

R3 randomization: R3 was opened in June 2011 and tests the hypothesis that modified N7 induction regimen will improve the metastatic response rates or event free survival (EFS) as compared to Rapid COJEC. As of June 8th, 2017 R3 randomization reached the target of 630 randomized patients as planned. There was no difference in event free survival rate between both regimens (Rapid COJEC and modified N7), but modified N7 had a significantly higher grade 3 and 4 toxicity profile. Therefore, Rapid COJEC is maintained as the SIOPEN standard induction treatment with G-CSF support based on the results of the R0 randomization open from 2002 top 2005 This change has been implemented in amendment 8 of the protocol.

R4 randomization: R4 was activated in April 2014. The SIOPEN long term infusion (LTI) ch14.18/CHO trial successfully lowered the toxicity profile by prolonging the infusion time of the same total ch14.18/CHO antibody dose of 100 mg/m² to 10 days of continuous infusion in relapsed /refractory patients. Hence the HRNBL1/SIOPEN study committee wished to implement this more favorable immunotherapy dosing schedule for the time till the induction question R3 was answered and the HRNBL1/SIOPEN trial may be closed. Considering the high R2 dropout rate of patients unable to receive all immunotherapy cycles in the IL-2 s.c. combination treatment arm and not observing this effect in the current SIOPEN LTI trial, it is suggested to address the IL-2sc dose in the new R4. Therefore the potential synergistic effect of sc IL-2 will be addressed again with 50% of the original s.c. IL-2 dose. The IL-2sc dose will hence be reduced to 3 x 106 IU IL-2/m2/day s.c. in the HR-NBL1/SIOPEN R4 amendment instead of 6 x 106 IU IL-2/m2/day s.c as used in the SIOPEN LTI trial. In the second week of each IT course s.c.IL-2 will be given on days 2, 4, 6, 8, 10 in parallel to the ch14.18/CHO ctn infusion and not during the first 5 days in week 2 as scheduled in the SIOPEN LTI trial. R4 randomization is closed for patients diagnosed after June 8th, 2017, the closure date of R3 randomization. For these patients the use of ch14.18/CHO antibody is recommended without scIL-2 as continuous infusion (total dose 100 mg/m² over 10 days) as standard of care outside of controlled trials without scIL-2. The ch14.18/CHO monoclonal antibody received marketing authorization by EMA in May 2017 (dinutuximab beta, Qarziba®).