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Lynch syndrome–associated ultra-hypermutated pediatric glioblastoma mimicking a constitutional mismatch repair deficiency syndrome

Pediatric glioblastoma multiforme (GBM) has a poor prognosis as a result of recurrence after treatment of surgery and radiochemotherapy. A small subset of pediatric GBMs presenting with an ultra-high tumor mutational burden (TMB) may be sensitive to immune checkpoint inhibition. Here we report a 16-...

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Detalles Bibliográficos
Autores principales: Yang, Chen, Austin, Frances, Richard, Hope, Idowu, Michael, Williamson, Vernell, Sabato, Fernanda, Ferreira-Gonzalez, Andrea, Turner, Scott A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Cold Spring Harbor Laboratory Press 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6824252/
https://www.ncbi.nlm.nih.gov/pubmed/31604779
http://dx.doi.org/10.1101/mcs.a003863
Descripción
Sumario:Pediatric glioblastoma multiforme (GBM) has a poor prognosis as a result of recurrence after treatment of surgery and radiochemotherapy. A small subset of pediatric GBMs presenting with an ultra-high tumor mutational burden (TMB) may be sensitive to immune checkpoint inhibition. Here we report a 16-yr-old male with an ultra-hypermutated GBM. After incomplete surgical resection, molecular analysis of the tumor identified unusually high numbers of mutations and intratumor heterogeneity by a hotspot next-generation sequencing (NGS) panel. Further comprehensive molecular profiling identified a TMB of 343 mutations/Mb. An ultra-hypermutation genotype in pediatric GBMs is suggestive of a constitutive mismatch repair deficiency syndrome (CMMRD), which often acquires additional somatic driver mutations in replicating DNA polymerase genes. Tumor sequencing identified two MSH6 nonsense variants, a hotspot POLE mutation and a mutational signature supportive of a germline MMR deficiency with a somatic POLE mutation. However, constitutional testing identified only one nonsense MSH6 variant consistent with a Lynch syndrome diagnosis. This case represents the first confirmed Lynch syndrome case mimicking CMMRD by manifesting as an ultra-hypermutated pediatric GBM, following somatic mutations in MSH6 and POLE. These findings permitted the patient's enrollment in an anti-PD-1 clinical trial for children with ultra-hypermutated GBM. Immunotherapy response has resulted in the patient's stable condition for over more than 1 year postdiagnosis.