Clinical and mutational profiles of adult medulloblastoma groups

Acta Neuropathol Commun. 2020 Nov 10;8(1):191. doi: 10.1186/s40478-020-01066-6.

Abstract

Adult medulloblastomas are clinically and molecularly understudied due to their rarity. We performed molecular grouping, targeted sequencing, and TERT promoter Sanger sequencing on a cohort of 99 adult medulloblastomas. SHH made up 50% of the cohort, whereas Group 3 (13%) was present in comparable proportion to WNT (19%) and Group 4 (18%). In contrast to paediatric medulloblastomas, molecular groups had no prognostic impact in our adult cohort (p = 0.877). Most frequently mutated genes were TERT (including promoter mutations, mutated in 36% cases), chromatin modifiers KMT2D (31%) and KMT2C (30%), TCF4 (31%), PTCH1 (27%) and DDX3X (24%). Adult WNT patients showed enrichment of TP53 mutations (6/15 WNT cases), and 3/6 TP53-mutant WNT tumours were of large cell/anaplastic histology. Adult SHH medulloblastomas had frequent upstream pathway alterations (PTCH1 and SMO mutations) and few downstream alterations (SUFU mutations, MYCN amplifications). TERT promoter mutations were found in 72% of adult SHH patients, and were restricted to this group. Adult Group 3 tumours lacked hallmark MYC amplifications, but had recurrent mutations in KBTBD4 and NOTCH1. Adult Group 4 tumours harboured recurrent mutations in TCF4 and chromatin modifier genes. Overall, amplifications of MYC and MYCN were rare (3%). Since molecular groups were not prognostic, alternative prognostic markers are needed for adult medulloblastoma. KMT2C mutations were frequently found across molecular groups and were associated with poor survival (p = 0.002). Multivariate analysis identified histological type (p = 0.026), metastasis (p = 0.031) and KMT2C mutational status (p = 0.046) as independent prognosticators in our cohort. In summary, we identified distinct clinical and mutational characteristics of adult medulloblastomas that will inform their risk stratification and treatment.

Keywords: Adult medulloblastoma; KMT2C; MYC; Molecular group; TP53; Targeted sequencing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Cerebellar Neoplasms / classification
  • Cerebellar Neoplasms / genetics*
  • Cerebellar Neoplasms / mortality
  • DNA-Binding Proteins / genetics
  • Female
  • Humans
  • Male
  • Medulloblastoma / classification
  • Medulloblastoma / genetics*
  • Medulloblastoma / mortality
  • Middle Aged
  • Mutation
  • Neoplasm Proteins / genetics
  • Patched-1 Receptor / genetics
  • Prognosis
  • Proportional Hazards Models
  • Survival Rate
  • Telomerase / genetics
  • Transcription Factor 4 / genetics
  • Wnt Signaling Pathway / genetics
  • Young Adult

Substances

  • DNA-Binding Proteins
  • KMT2C protein, human
  • KMT2D protein, human
  • Neoplasm Proteins
  • PTCH1 protein, human
  • Patched-1 Receptor
  • TCF4 protein, human
  • Transcription Factor 4
  • TERT protein, human
  • Telomerase