MAPK pathway alteration may be a new integrated diagnosis term.

Abstract

e14022 Background: The 2016 CNS WHO classification is the first to include molecular factors to classify in glioma. We are in the age of glioma subgroups, in which the category depended on the histological and molecular composition, providing more clinical behavior, prognosis, and therapeutic targets hints. The most well-known molecular modifications are IDH1/2 mutation, ATRX variant, TP53 variant, BRAF mutation or fusion, 1p/19q co-deletions. However, there is a diagnostic term“NOS” in the 2016 CNS WHO classification，which indicates that a tumor could not be placed into a more specific WHO category. Here, our analysis of the MAPK pathway may suggest a new subtype. Methods: Targeted next-generation DNA sequence of the 131-genes panel was performed on gliomas in 119 patients. We measured the somatic variations in the MAPK pathway after filtering known driver mutations. The analysis of genomic alterations was performed using a two-sided Fisher exact test. Results: 90/119（75.6%）were excluded due to known driver mutations. 29/119(24.4%) were classified in NOS with a typical “single MAPK pathway alteration” and different histological characteristics and WHO grade. The median age at diagnosis was 35 years (4-79) in our gliomas. The most frequent mutations were NF1(10/29), FGFR1(7/29), KRAS (6/29), BRAF (3/29), PTPN11(2/29), although there are other gene mutations like FGFR2, FGFR3, AKT1, MAP2K1. According to cIMPACT-NOW update 4, our pediatric gliomas ( < 30 years, n = 14) could be identified as “diffuse glioma, other MAPK pathway alteration.” Our adult gliomas have a higher frequency of NF1 mutations（8/15 vs. 2/14, p = 0.05), a lower KRAS (1/15 vs. 5/14) and FGFR1 (2/15 vs. 5/14) mutations than children. Conclusions: Our result suggests that MAPK pathway alteration may be a new integrated diagnosis term in all ages of glioma. Moreover, KRAS and FGFR1 may be associated with pediatric gliomas. NF1 is more common in adult gliomas.