Pediatric
cancers, particularly high-risk solid
tumors, urgently need effective and specific
therapies. Their outlook has not appreciably improved in decades.
Immunotherapies such as
immune checkpoint inhibitors offer much promise, but most are only approved for use in adults. Though several hundred clinical trials have tested immune-based approaches in childhood
cancers, few have been guided by
biomarkers or clinical-grade assays developed to predict patient response and, ultimately, to help select those most likely to benefit. There is extensive evidence in adults to show that immune profiling has substantial predictive value, but few studies focus on childhood
tumors, because of the relatively small disease population and restricted use of immune-based
therapies. For instance, only one published study has retrospectively examined the immune profiles of pediatric
brain tumors after
immunotherapy. Furthermore, application and integration of advanced multiplex techniques has been extremely limited. Here, we review the current status of immune profiling of pediatric solid
tumors, with emphasis on
tumor types that represent enormous unmet clinical need, primarily in the context of
immune checkpoint inhibitor therapy. Translating optimized and informative immune profiling into standard practice and access to personalized combination
therapy will be critical if childhood
cancers are to be treated effectively and affordably.