TMOD-18. DIRECT IN VIVO CRISPR SCREEN IDENTIFIES COOPERATING TUMOR SUPPRESSORS THAT DRIVE PROGRESSION OF IDH1-MUTANT LOW-GRADE GLIOMA TO AGGRESSIVE GLIOBLASTOMA

Low-grade glioma (LGG) are generally slowly growing brain cancers, that frequently undergo malignant progression to aggressive, secondary glioblastoma with a dismal prognosis. By combining genetically engineered Idh1-mutant mice with in vivo CRISPR gene editing we generated a mouse model faithfully recapitulating the founder mutations of LGG. Clonal activation of the neomorphic Idh1 R132H mutation cooperates with Trp53 and Atrx mutations to trigger development of brain tumors but only with ~30% penetrance and very long latency. To elucidate the molecular mechanisms underlying the malignant progression of IDH1-mutant LGG, we devised and deployed a direct in vivo CRISPR screen targeting genes commonly mutated in human IDH-mutant secondary glioblastoma. Stereotaxic delivery of a lentiviral sgRNA library targeting the mouse orthologs of these genes into the brain of Idh1 R132H ;Trp53;Atrx;Cas9 and control Idh1 wt ;Trp53;Atrx;Cas9 compound mutant mice resulted in rapid formation of tumors that recapitulate human Idh1-mutant glioblastoma. Deconvoluting the screen showed that PI3K pathway members Pten and Pik3ca as well as Notch1, Smarca4 and Fat1 are preferentially enriched in Idh1 R132H-tumors, while Rb1 and NF2 were enriched in Idh1 wt tumors. Co-mutation analysis further identified additional co-occurring driver combinations such as Bcor-Met, Olig2-Met, Olig2-Med12 or Bcor-Olig2. We validated the tumor suppressive function of Notch1 and Pten using conventional floxed knock-out alleles and found that Notch1 functions in a haploinsufficient manner. Interestingly, Idh1 R132H did not alter tumor latency or pathology in a high grade p53;Pten;Rb1 mutant background, indicating that the neomorphic IDH-mutations can drive low but not high grade glioma development. Our study provides a functional landscape of gliomagenesis suppressors in vivo.

Cerebral Glioblastoma: A Review on Genetic Alterations, Signaling Pathways, and Clinical Management

Context: Glioblastoma, previously known as glioblastoma multiforme (GBM), is a grade IV astrocytoma common in patients over the age of 45, on average. It is generally categorized into primary and secondary subtypes, based on research conducted by Hans Joachim Scherer. Evidence Acquisition: This review concentrates on cellular and genetic drawbacks that can lead to the appearance of glioblastoma. National Center for Biotechnology Information (NCBI) was the main source used for writing this review article, followed by Google scholar. The following keywords were used to retrieve articles: 'glioblastoma', 'brain tumors', 'glioma', 'LOH', and 'cellular and signaling pathways in glioblastoma'. Results: Several genetic alterations and cellular pathways are involved in the appearance and progression of glioblastoma, including loss of heterozygosity (LoH), TP53 mutation, isocitrate dehydrogenase 1 (IDH1) mutation, P16INK4/RB1 pathway, and EGFR/PTEN/Akt/mTOR pathway. The majority (70%) of primary glioblastomas are caused by (LoH), and it mostly occurs in older people. Secondary glioblastoma is mainly manifested by TP53 mutation and usually affects younger people. Understanding the alterations and cellular mechanisms involved in glioblastoma is important to develope new therapeutic regimes. Surgery, radiation therapy, temozolomide, and TTFields are the four most important therapeutic options available for treating patients. Conclusions: In this review, the genetic alterations and cellular pathways which could lead to the appearance of this tumor were highlighted, and the latest options for treating patients dealing with glioblastoma were discussed.

The extent of resection and adjuvant treatment are beneficial to the outcome of secondary glioblastoma

Backgroud: to investigate secondary glioblastoma (sGBM) patients undergoing resection and evaluate the impact of treatment on survival of malignant progression (PMS) and the prognostic factors of secondary glioblastoma. Method: the prognostic factors of secondary glioblastoma were analyzed retrospectively including gender, age, the interval between first diagnosis and second, the extent of resection, adjuvant treatment, postoperative Karnofsky score (KPS), 06-methylguanine-DNA methytransferase (MGMT) status, IDH1 mutation status, and PMS in patients with sGBM. Result: Thirty-four patients with sGBM were included in this study. Sixteen patients were female and eighteen were male. Median PMS in females was longer than male patients with sGBM (17.38 (95%CI 10.63–24.12) vs 10.06(95%CI 5.32–14.79), p = 0.032). 22(64.7%) patients achieved gross total resection (GTR),12(35.3%) patients achieved subtotal resection (STR). Kaplan-Meier analysis showed that GTR significantly improved survival after malignant progression (PMS) compared with STR (17.18(95%CI 10.97–23.40) vs 7.17(95%CI 4.97–9.36), p = 0.004). Adjuvant treatment after resection was executed in 17 (50.0%) patients, radiotherapy in one (2.9%) patient, chemotherapy in seven (20.6%) patients, and radio-chemotherapy in nine (26.5%) patients. Median preoperative KPS was 80(range 30–100), and 85(range 30–100) after surgery. The difference in PMS probability was significant between patients having a good postoperative clinical status (KPS༞70)versus poor (KPS ≤ 70). Long term survival could be achieved in patients with a good clinical status (16.57(95%CI 10.54–22.60) vs 9.00(95%CI 3.66–14.34), p = 0.02). Patients with a greater interval after initial diagnosis had longer survival than those with intervals less than 26.5 months (18.62(95%CI 10.81–26.43) vs 9.22(95%CI 5.61–12.83), p = 0.025). Conclusion: GTR and any adjuvant treatment significantly improved PMS in patients with secondary glioblastoma. Gender, postoperative KPS, time interval since the first diagnosis are associated with prognosis.

Analysis of phosphatidylcholines alterations in human glioblastoma multiform tissues ex vivo

Significant metabolism alteration is accompanying the cell malignization process. Energy metabolism disturbance leads to the activation of de novo synthesis and beta-oxidation processes of lipids and fatty acids in a cancer cell, which becomes an indicator of pathological processes inside the cell. The majority of studies dealing with lipid metabolism alterations in glial tumors are performed using the cell lines in vitro or animal models. However, such conditions do not entirely represent the physiological conditions of cell growth or possible cells natural variability. This work presents the results of the data obtained by applying ambient mass spectrometry to human glioblastoma multiform tissues. By analyzing a relatively large cohort of primary and secondary glioblastoma samples, we identify the alterations in cells lipid composition, which accompanied the development of grade IV brain tumors. We demonstrate that primary glioblastomas, as well as ones developed from astrocytomas, are enriched with mono- and diunsaturated phosphatidylcholines (PC 26:1, 30:2, 32:1, 32:2, 34:1, 34:2). Simultaneously, the saturated and polyunsaturated phosphatidylcholines and phosphatidylethanolamines decrease. These alterations are obviously linked to the availability of the polyunsaturated fatty acids and activation of the de novo lipid synthesis and beta-oxidation pathways under the anaerobic conditions in the tumor core.

Valganciclovir as Add-On to Standard Therapy in Secondary Glioblastoma

Patients with glioblastoma have a very poor prognosis despite aggressive therapeutic strategies. Cytomegalovirus has been detected in >90% of glioblastoma tumors. This virus can affect tumor progression and may represent a novel glioblastoma therapy target. We report, here, a retrospective survival analysis of patients with secondary glioblastoma who were treated with the anti-viral drug valganciclovir at Karolinska University Hospital in Stockholm. We performed survival analyses of eight patients with secondary glioblastoma who were treated with a standard dose of valganciclovir as an add-on to second-line therapy after their disease progression to glioblastoma. Thirty-six patients with secondary glioblastoma admitted during the same time period who received similar treatment and care served as contemporary controls. The patients treated with valganciclovir showed an increased median overall survival after progression to glioblastoma compared with controls (19.1 versus 12.7 months, p = 0.0072). This result indicates a potential positive effect of valganciclovir in secondary glioblastoma, which is in agreement with our previous observation that valganciclovir treatment improves the outcomes of patients with newly diagnosed glioblastoma. Larger randomized studies are warranted to prove this hypothesis.

Survival in patients with glioblastoma at a first progression does not correlate with isocitrate dehydrogenase (IDH)1 gene mutation status

Backgrounds Mutations in the isocitrate dehydrogenase (IDH)1 gene are favourable prognostic factors in newly diagnosed diffuse gliomas, whereas it remains controversial in the recurrent glioblastoma setting. Methods A total of 171 patients with newly diagnosed glioblastoma, either ‘primary’ glioblastoma or ‘secondary’ glioblastoma, treated at Kyorin University Hospital or Japanese Red Cross Medical Center from 2000 to 2015 were included. Patients with confirmed IDH1 status and O6-methylguanine-DNA methyltransferase promoter methylation status were retrospectively analysed for overall survival from the initial diagnosis (n = 147) and after the first progression (n = 122). Results IDH1 mutation but not IDH2 was noted in 19 of 147 patients with glioblastoma (12.9%). In patients with ‘primary’ glioblastoma (n = 136), median overall survival after the first progression was 13.5 and 10.5 months for mutant IDH1 and wild-type IDH1 glioblastoma, respectively (P = 0.747). Multivariate analysis revealed O6-methylguanine-DNA methyltransferase promoter methylation, and Karnofsky Performance status 60 or higher, were independent prognostic factors for better overall survival after the first progression. When ‘primary’ glioblastoma and ‘secondary’ glioblastoma were combined, median overall survival from the first progression was not significantly different between the mutant IDH1 group (10.1 months) and wild-type IDH1 group (10.5 months) (P = 0.559), whereas median overall survival from the initial diagnosis was significantly different (47.5 months vs.18.3 months, respectively; P = 0.035). Conclusions These results suggest that IDH1 mutation may not be a prognostic factor for survival at the first progression of patients with ‘primary’ glioblastoma and pretreated ‘secondary’ glioblastoma, and further warrant investigation in prospective studies.

Clinical characteristics and survival outcomes of secondary glioblastoma

Background Secondary glioblastoma (sGBM) is a specific, and prognostic factors of sGBM are still unclear. This study retrospectively investigated clinical prognosis factors of survival outcomes of sGBM.Methods All of 125 patients were recruited in this study. Clinical characteristics and survival outcomes were acquired from inpatient records and follow-ups. Kaplan‑Meier survival analysis and Cox survival analysis were applied to identifying prognostic factors.Results The median overall survival (OS) were 301 days. Gross total resection (GTR) (HR = 0.613, 95% confident interval (CI) = 0.408-0.923, p = 0.019), diagnosed sGBM without newly occurring symptoms when regular re-examination (DR) (HR= 0.481, 95% CI = 0.308-0.750, p = 0.001), higher postoperative Karnofsky Performance Status (KPS) score (HR = 0.977, 95% CI = 0.961-0.993, p = 0.006) were independently favorable prognosis factors for OS. GTR was the favorable factor for OS of sGBM patients of DR (HR = 0.238, 95% CI = 0.100-0.570, p = 0.001) and with new functional impairments (HR = 0.410, 95% CI = 0.205-0.821, p = 0.012). Additionally, postoperative KPS score not decreasing was the favorable factor for OS of sGBM patients with new functional impairments (HR = 0.401, 95% CI = 0.202-0.795, p = 0.009) and with new occurring epilepsy (HR = 0.295, 95% CI from 0.092 to 0.950, p = 0.041).Conclusions For patients with sGBM, GTR, higher postoperative KPS score, and diagnosed without newly occurring symptoms were favorable factors for the OS. The GTR was recommended for sGBM patients to improve survival outcomes.