IDH-wild type glioblastomas featuring at least 30% giant cells are characterized by frequent RB1 and NF1 alterations and hypermutation.

Giant cell glioblastoma (GC-GBM) is a rare variant of IDH-wt GBM histologically characterized by the presence of numerous multinucleated giant cells and molecularly considered a hybrid between IDH-wt and IDH-mutant GBM. The lack of an objective definition, specifying the percentage of giant cells required for this diagnosis, may account for the absence of a definite molecular profile of this variant. This study aimed to clarify the molecular landscape of GC-GBM, exploring the mutations and copy number variations of 458 cancer-related genes, tumor mutational burden (TMB), and microsatellite instability (MSI) in 39 GBMs dichotomized into having 30-49% (15 cases) or ≥ 50% (24 cases) GCs. The type and prevalence of the genetic alterations in this series was not associated with the GCs content (< 50% or ≥ 50%). Most cases (82% and 51.2%) had impairment in TP53/MDM2 and PTEN/PI3K pathways, but a high proportion also featured TERT promoter mutations (61.5%) and RB1 (25.6%) or NF1 (25.6%) alterations. EGFR amplification was detected in 18% cases in association with a shorter overall survival (P = 0.004). Sixteen (41%) cases had a TMB > 10 mut/Mb, including two (5%) that harbored MSI and one with a POLE mutation. The frequency of RB1 and NF1 alterations and TMB counts were significantly higher compared to 567 IDH wild type (P < 0.0001; P = 0.0003; P < 0.0001) and 26 IDH-mutant (P < 0.0001; P = 0.0227; P < 0.0001) GBMs in the TCGA PanCancer Atlas cohort. These findings demonstrate that the molecular landscape of GBMs with at least 30% giant cells is dominated by the impairment of TP53/MDM2 and PTEN/PI3K pathways, and additionally characterized by frequent RB1 alterations and hypermutation and by EGFR amplification in more aggressive cases. The high frequency of hypermutated cases suggests that GC-GBMs might be candidates for immune check-point inhibitors clinical trials.

Genomic characterization of hepatoid tumors: context matters.

Hepatoid tumors (HT) are rare neoplasms morphologically resembling hepatocellular carcinoma, which arise in several organs other than the liver. A comprehensive molecular profile of this group of neoplasms is still lacking. Genomic characterization of 19 HTs from different organs (three colon HTs, four esophagogastric HTs, four biliary HTs, six genitourinary HTs, two lung HTs) was performed using a multigene next-generation sequencing panel. NGS unraveled a composite molecular profile of HT. Their genetic alterations were clearly clustered by tumor site: (i) colorectal HT displayed microsatellite instability, high tumor mutational burden, mutations in ARID1A/B genes and NCOA4-RET gene fusion (2/3 cases); (ii) gastric HT had TP53 mutations (2/4); (iii) biliary HT displayed loss of CDKN2A (3/4) and loss of chromosome 18 (2/4); (iv) genital HT showed gain of chromosome 12 (3/6); (v) lung HT had STK11 somatic mutations (2/2). The only commonly mutated gene occurring in HT of different sites was TP53 (8/19 cases: colon 2, esophagogastric 2, biliary 2, genital 1, lungs 1). This study shows that most genetic alterations of HT were clustered by site, indicating that context matters. The novel potential targets for HT precision oncology are also clustered based on the anatomic origin. This study shed light on the biology of these rare cancers and may have important consequences for treatment decisions and clinical trial selection for HT patients.

Assessment of bile and serum mucin5AC in cholangiocarcinoma: diagnostic performance and biologic significance.

BACKGROUND: Recent studies have showed the efficacy of mucin5AC (MUC5AC) as a diagnostic and prognostic serum biomarker in biliary tract tumors. The aim of the present investigation was to improve the current knowledge on the biologic relevance of MUC5AC in malignant and benign biliary disorders by comparing its diagnostic performance in both bile and serum samples of patients with cholangiocarcinoma (CCA) or benign biliary disorders. METHODS: A quantitative determination of MUC5AC by enzyme-linked immunosorbent assay was performed in bile and serum specimens from 26 patients with extrahepatic CCA and 20 subjects with benign biliary disorders (10 with biliary stones and 10 with cholangitis). Verification analysis was made by immunoblot. RESULTS: MUC5AC of serum and biliary origin contributed to different extent to total levels of MUC5AC in the different groups of patients. In particular, the transition toward a greater degree of injury of bile duct epithelium was accompanied by a greater amount of MUC5AC in serum than in bile. The diagnostic performance of MUC5AC expressed as serum/bile ratio showed excellent diagnostic performance for differentiating CCA from cholangitis (area under the curve [AUC], 0.94; 95% CI, 0.86-1.00; P < .0001), CCA from biliary stones (AUC, 0.99; 95% CI, 0.98-1.00; P < .0001), as well as cholangitis from biliary stones (AUC, 0.93; 95% CI, 0.82-1.00; P = .001). CONCLUSION: These findings provide new insight into the biologic importance of MUC5AC in biliary disorders and suggest that combined assessment of MUC5AC in bile and serum with expression of data in terms of serum to bile ratio may improve the diagnostic performance of MUC5AC quantification in serum alone.