Multi-institution analysis of tumor mutational burden and outcomes in
pediatric CNS tumor patients
Abstract
Background: Pediatric CNS tumors are the leading cause of
pediatric cancer mortality. Research addressing genomic biomarkers and
clinical outcomes is needed to inform therapeutic decision making.
Methods: We conducted a retrospective analysis of pediatric
patients (age <21) diagnosed with a primary CNS tumor at four
upstate New York hospitals from 2008 to 2021. Clinical and
histopathologic data were identified from each patient, including
genomic analysis of somatic mutations and tumor mutation burden (TMB)
where available. These variables were each compared with overall
survival using cox-regression analyses. Multivariable analysis was
conducted to identify patient characteristics that may independently
predict survival. Results: We identified 119 patients. Common
tumor types included low-grade glioma (N=51), high-grade glioma (N=29),
and medulloblastoma (N=11). Common driver-mutations included TP53
inactivation (N=16), BRAF-KIAA1549 fusion (N=16), FGFR1
amplification (N=12), BRAF V600E mutation (N=12), NF1 loss
(N=12), and H3F3A K28M mutation (N=6). Median TMB was 1
mutation/megabase (mut/Mb, range=0-132). Overall survival was 79.9%.
Variables associated with poorer survival on univariable analysis were
higher TMB (p=0.002, HR 4.97), high grade tumors (p=0.009, HR 84.3), and
high-grade glioma histology (p=0.021, HR 3.14). Multivariable analyses
further identified TMB (p=0.011, HR 4.46) and high-grade histology
(p=0.015, HR 5.28) as independently predictive of worse survival. Tumor
progression was more common in high TMB (N=15, 44%) than in low TMB
tumors (N=19, 35%). Conclusions: High TMB is correlated with
higher rates of progression and death as compared to low TMB tumors.
These findings may help identify patients who may benefit from
alternative treatments, such as immunotherapies.