Introduction

The development of immune-based treatment (immunotherapy) for childhood cancer is a rapidly advancing field with impressive results already achieved in children with leukaemia.1 ,2 For cancers resistant to conventional treatments, harnessing the power and specificity of the immune system to fight cancer is one of several current avenues of research. The immune system is essential for controlling cancer progression by continual surveillance and elimination of transformed cells. This protective process is hindered by the ability of cancer cells to develop mechanisms enabling them to ‘hide’ from immune destruction (including downregulation of tumour-associated antigens and major histocompatibility complex (MHC) class I, and the creation of an immunosuppressive tumour microenvironment). The aims of cancer immunotherapy are to enhance existing antitumour immune responses (active immunotherapy), including cancer vaccines and immune checkpoint inhibitors, or to enable the immune system to specifically recognise and kill cancer cells (passive immunotherapy) (table 1).

The identification of targetable tumour antigens is fundamental to the development of successful ‘passive’ immunotherapies. Ideally, targets should be highly expressed on cancer cells with little or no expression on normal tissue …