What is the SIOPEN High‑Risk Neuroblastoma 2 (HR‑NBL2) Trial? 

The SIOPEN High‑Risk Neuroblastoma 2 (HR‑NBL2) trial is a large international research study looking at how to improve frontline treatment for children with high‑risk neuroblastoma. It is run by SIOPEN (the European neuroblastoma research network) and involves expert teams across Europe, including the UK. 

The trial aims to understand whether certain changes to standard treatment could improve outcomes or reduce side effects. All treatments being studied are already used in hospitals; the trial is testing how best to use them. 

What parts of treatment does the trial look at? 

HR‑NBL2 has three treatment arms, each studying a different stage of standard high‑risk neuroblastoma treatment. A child may take part in one, two, or all three parts depending on their treatment pathway. 

1. Induction chemotherapy

This part of the study compares two different induction chemotherapy regimens to see which is more effective at shrinking the cancer at the start of treatment. The two different regimens are: 

• RAPID COJEC 

• GPOH 

2. High‑dose chemotherapy and stem cell rescue (transplant) 

This part compares: 

• one high‑dose chemotherapy and stem‑cell rescue with 

• two high‑dose chemotherapy and stem‑cell rescues 

Researchers want to understand whether giving two high‑dose treatments offers any additional benefit compared to one. 

3. Radiotherapy (post‑consolidation) 

This part compares: 

• a standard radiotherapy dose, with 

• a slightly higher radiotherapy dose delivered to any remaining cancer sites 

The aim is to see whether a higher dose improves tumour control without causing additional long‑term side effects. 

Does taking part mean my child gets less treatment? 

No. All children taking part receive full, standard high‑risk treatment. The trial is testing small but important differences in how treatments are given, not reducing the amount of treatment. 

Every treatment option being studied is already used safely in neuroblastoma treatment across Europe. 

How are treatment options chosen in the trial? 

If you choose to enrol your child, they will be randomly assigned to one of the treatment options being studied in each part of the trial. Randomisation is how researchers make sure results are fair and reliable. 

You can choose to leave the trial at any time. If you decide to withdraw, your child will continue to receive the best standard of care. 

Read more about withdrawing your child from a clinical trial. 

How will we know if the trial is right for our child? 

Your child’s medical team will explain: 

• why the trial is being offered 

• which part(s) of the trial apply to your child 

• what each treatment option involves 

• potential risks and benefits 

• alternative treatments outside the trial 

You will have the chance to ask questions and take time to decide whether joining the trial feels right for your family.