Genomic Analysis of Posterior Fossa Meningioma Demonstrates Frequent AKT1 E17K Mutations in Foramen Magnum Meningiomas.

Objective Posterior fossa meningiomas are surgically challenging tumors that are associated with high morbidity and mortality. We sought to investigate the anatomical distribution of clinically actionable mutations in posterior fossa meningioma to facilitate identifying patients amenable for systemic targeted therapy trials. Methods Targeted sequencing of clinically targetable AKT1 , SMO , and PIK3CA mutations was performed in 61 posterior fossa meningioma using Illumina NextSeq 500 to a target depth of >500 × . Samples were further interrogated for 53 cancer-relevant RNA fusions by the Archer FusionPlex panel to detect gene rearrangements. Results AKT 1 ( E17K ) mutations were detected in five cases (8.2%), four in the foramen magnum and one in the cerebellopontine angle. In contrast, none of the posterior fossa tumors harbored an SMO ( L412F ) or a PIK3CA ( E545K ) mutation. Notably, the majority of foramen magnum meningiomas (4/7, 57%) harbored an AKT1 mutation. In addition, common clinically targetable gene fusions were not detected in any of the cases. Conclusion A large subset of foramen magnum meningiomas harbor AKT1 E17K mutations and are therefore potentially amenable to targeted medical therapy. Genotyping of foramen magnum meningiomas may enable more therapeutic alternatives and guide their treatment decision process.

The Dual PI3K/mTOR Pathway Inhibitor GDC-0084 Achieves Antitumor Activity in PIK3CA-Mutant Breast Cancer Brain Metastases.

PURPOSE: Previous studies have shown that the PI3K/Akt/mTOR pathway is activated in up to 70% of breast cancer brain metastases, but there are no approved agents for affected patients. GDC-0084 is a brain penetrant, dual PI3K/mTOR inhibitor that has shown promising activity in a preclinical model of glioblastoma. The aim of this study was to analyze the efficacy of PI3K/mTOR blockade in breast cancer brain metastases models.Experimental Design: The efficacy of GDC-0084 was evaluated in PIK3CA-mutant and PIK3CA wild-type breast cancer cell lines and the isogenic pairs of PIK3CA wild-type and mutant (H1047R/+) MCF10A cells in vitro. In vitro studies included cell viability and apoptosis assays, cell-cycle analysis, and Western blots. In vivo, the effect of GDC-0084 was investigated in breast cancer brain metastasis xenograft mouse models and assessed by bioluminescent imaging and IHC. RESULTS: In vitro, GDC-0084 considerably decreased cell viability, induced apoptosis, and inhibited phosphorylation of Akt and p70 S6 kinase in a dose-dependent manner in PIK3CA-mutant breast cancer brain metastatic cell lines. In contrast, GDC-0084 led only to growth inhibition in PIK3CA wild-type cell lines in vitro. In vivo, treatment with GDC-0084 markedly inhibited the growth of PIK3CA-mutant, with accompanying signaling changes, and not PIK3CA wild-type brain tumors. CONCLUSIONS: The results of this study suggest that the brain-penetrant PI3K/mTOR targeting GDC-0084 is a promising treatment option for breast cancer brain metastases with dysregulated PI3K/mTOR signaling pathway conferred by activating PIK3CA mutations. A national clinical trial is planned to further investigate the role of this compound in patients with brain metastases.

A Clinical Rule for Preoperative Prediction of BRAF Mutation Status in Craniopharyngiomas.

BACKGROUND: Papillary craniopharyngiomas are characterized by BRAFV600E mutations. Targeted therapy can elicit a dramatic radiographic regression of these tumors. Therefore, prediction of BRAF mutation status before definitive surgery could enable neoadjuvant treatment strategies. OBJECTIVE: To establish preoperative prediction criteria to identify patients with a BRAF mutant craniopharyngioma. METHODS: Sixty-four patients with craniopharyngioma were included in this study. We determined BRAF mutation status by targeted sequencing. After scoring interobserver variability between presurgical clinical data and radiographic features, we established a diagnostic rule for BRAF mutation in our discovery cohort. We then validated the rule in an independent cohort. RESULTS: The BRAFV600E mutation was detected in 12 of 42 patients in the discovery cohort. There were no patients under age 18 with BRAF mutation. Calcification was rare in tumors with BRAF mutation (P < .001), and 92% of them were supradiaphragmatic in location. Combining these 3 features-older than 18 years, absence of calcification, and supradiaphragmatic tumor location-we established a rule for predicting BRAF mutation. In cases where all 3 criteria were fulfilled, the sensitivity and specificity for the presence of BRAF mutation were 83% and 93%, respectively. In the validation cohort (n = 22), the sensitivity was 100% and specificity was 89%. CONCLUSION: We propose predictive criteria for a BRAF mutation in craniopharyngioma using preoperative clinical and radiographic data. This rule may be useful in identifying patients who could potentially benefit from neoadjuvant BRAFV600E-targeted systemic therapies.

DMD genomic deletions characterize a subset of progressive/higher-grade meningiomas with poor outcome.

Progressive meningiomas that have failed surgery and radiation have a poor prognosis and no standard therapy. While meningiomas are more common in females overall, progressive meningiomas are enriched in males. We performed a comprehensive molecular characterization of 169 meningiomas from 53 patients with progressive/high-grade tumors, including matched primary and recurrent samples. Exome sequencing in an initial cohort (n = 24) detected frequent alterations in genes residing on the X chromosome, with somatic intragenic deletions of the dystrophin-encoding and muscular dystrophy-associated DMD gene as the most common alteration (n = 5, 20.8%), along with alterations of other known X-linked cancer-related genes KDM6A (n =2, 8.3%), DDX3X, RBM10 and STAG2 (n = 1, 4.1% each). DMD inactivation (by genomic deletion or loss of protein expression) was ultimately detected in 17/53 progressive meningioma patients (32%). Importantly, patients with tumors harboring DMD inactivation had a shorter overall survival (OS) than their wild-type counterparts [5.1 years (95% CI 1.3-9.0) vs. median not reached (95% CI 2.9-not reached, p = 0.006)]. Given the known poor prognostic association of TERT alterations in these tumors, we also assessed for these events, and found seven patients with TERT promoter mutations and three with TERT rearrangements in this cohort (n = 10, 18.8%), including a recurrent novel RETREG1-TERT rearrangement that was present in two patients. In a multivariate model, DMD inactivation (p = 0.033, HR = 2.6, 95% CI 1.0-6.6) and TERT alterations (p = 0.005, HR = 3.8, 95% CI 1.5-9.9) were mutually independent in predicting unfavorable outcomes. Thus, DMD alterations identify a subset of progressive/high-grade meningiomas with worse outcomes.

Secreted factors from equine mesenchymal stromal cells diminish the effects of TGF-ß1 on equine dermal fibroblasts and alter the phenotype of dermal fibroblasts isolated from cutaneous fibroproliferative wounds.

The prevalence of cutaneous fibroproliferative disorders (CFPDs) is high and almost exclusively occurs in humans (keloids and hypertrophic scars) and horses (exuberant granulation tissue), making the horse a valuable translational model for studies on prevention and treatment of human CFPDs. CFPDs arise as a result of dysregulated wound healing characterized by persistently high levels of cytokines, such as transforming growth factor beta 1 (TGF-ß1), that contribute to excessive extracellular matrix deposition, and the physical disorganization of dermal fibroblasts (DF). The mesenchymal stromal cell (MSC) secretome, consisting of all factors secreted by MSC, has been shown to promote normal wound healing in both humans and horses, but its potential to treat CFPDs remains largely unexplored. Therefore, the objective of this study was to examine the effects of the equine MSC secretome on equine DF influenced by cytokines that contribute to the development of CFPDs. First, primary equine DF were treated with TGF-ß1 in vitro in the presence or absence of MSC secreted products. We found that MSC secreted products could block TGF-ß1-induced changes in DF morphology, proliferation rate, gene expression, and contractile-capacity. We then isolated primary DF from equine exuberant granulation tissue, to evaluate the potential of the MSC secretome to alter the phenotype of cells derived from a complex CFPD environment. These results showed that MSC secreted factors did not change proliferation or migration of these cells, but did lead to changes in expression of genes and proteins involved in extracellular matrix remodeling and did affect contractile capacity. These results warrant future studies designed to evaluate the potential of the MSC secretome to minimize the pathologies associated with CFPD in vivo.