Abstract
Exciting therapeutic targets are emerging from CRISPR-based screens
of high mutational burden adult cancers. A key question, however, is
whether functional genomic approaches will yield new targets in
pediatric cancers, known for remarkably few mutations which often
encode proteins considered challenging drug targets. To address
this, we created a first-generation Pediatric Cancer Dependency Map
representing 13 pediatric solid and brain tumor types. Eighty-two
pediatric cancer cell lines were subjected to genome-scale
CRISPR-Cas9 loss-of-function screening to identify genes required
for cell survival. In contrast to the finding that pediatric cancers
harbor fewer somatic mutations, we found a similar complexity of
genetic dependencies in pediatric cancer cell lines compared to
adult models. Findings from the Pediatric Cancer Dependency Map
provide pre-clinical support for ongoing precision medicine clinical
trials. The vulnerabilities seen in pediatric cancers were often
distinct from adult, indicating that repurposing adult oncology
drugs will be insufficient to address childhood cancers.
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Selective dependencies in pediatric and adult solid tumor lines
Selective dependency genes demonstrate subsets that are more
common in pediatric compared to adult cancer cell lines. Each row
on the y-axis represents one of the selective dependencies
(removing common essential and non-essential genes) ordered across
the three subpanels by rate of dependency seen in adult cancer
cell lines. The left subpanel shows the rate at which adult cell
lines are dependent and the center subpanel shows the rate at
which pediatric cell lines are dependent. The right subpanel
demonstrates the difference in rate of dependency in pediatric
versus adult cell lines with dependencies seen at greater
frequency in pediatric cell lines colored red and those seen more
frequently in adult cell lines as black. The bars in the center
and right panels are colored by the contribution of each tumor
type.
When a single gene is selected from the plot or search box, the
frequency of dependency on that gene is depicted in pediatric and
adult solid tumor types with at least 3 cell lines screened per
type in polar bar graphs. The heights of the bars correspond to
the fraction of cell lines of a particular tumor type that are
dependent on the gene.