Combination of PCR HRM with either RFLP or direct DNA sequencing was useful to detect K-RAS exon 2 and extended RAS mutations, respectively. Frequency of all RAS mutations in stage IV Indonesian (41%) was similar among Asians (41-49%), which tend to be lower than western (55%) CRC.

Introduction the objective was to evaluate the impact of IDH1 R132H mutation, MGMT methylation and PD-L1 expression in high grade glioma that received standard therapy (surgery, radiation and chemotherapy) to overall survival (OS). Methods this is a retrospective study of 35 high grade glioma cases. Genotyping of IDH1 gene alteration on the mutation hotspot R132 (Sanger sequencing method with Applied Biosystems 3500 Genetic Analyzer), EZ DNA Methylation-Gold kit (Zymo Research) is used to study the methylation, Cell line BT549 (ATCC HTB-122) and HCT-116 (ATCC CCL-247) were used as unmethylated control and partially methylated control respectively. Anti-human PD-L1 antibody clone E1L3N ® from Cell Signalling Technology (USA) and Rabbit XP ® were used to see PDL-1 expression. Results anaplastic astrocytoma cases had more MGMT promoter methylation (50%) than glioblastoma multiforme (GBM) (20%), more IDH1 R132H mutation (42%) than GBM (4.3%). Immunohistochemistry tumor proportion score method (TPS) identified 17% and 8.7% were PD-L1 positive in AA and GBM groups, respectively. Cases with IDH1 R132H mutation and MGMT methylation still showed better OS although with high PD-L1 expression. Conclusion IDH1 R132H mutation and MGMT methylation were good prognostic markers. High expression of PD-L1 apparently might not indicate poor overall survival in the presence of IDH1 R132 mutation and MGMT methylation.

Background: Glioblastoma (GBM) is the most common and fatal primary brain tumor in adults. Therefore, there is interest in conducting clinical trials of experimental treatments on patients with GBM, where patients with history of cancer are usually excluded. This practice can affect clinical trials accrual and limit potential therapeutic options for this population. The rationale behind this exclusion is that a history of malignancy could potentially interfere with the study outcomes. However, little is known about its real impact on survival of subsequent GBM. Methods: We used the SEER database of the National Cancer Institute to review patients with GBM diagnosed between 1973 and 2014. We calculated the overall and GBM-specific survival of these patients using unadjusted Kaplan-Meier test and multivariable covariate-adjusted Cox models. Results: Of the 51,158 GBM patients who were reviewed, 3076 had a prior malignancy. Unadjusted Kaplan-Meier test showed worse overall and GBM-specific survival with patients who had a prior history. However, after adjusting for multiple factors using cox regression models, a prior history was not associated with any significant difference in both overall and GBM-specific survival (HR ¼ 1.025 95% CI ¼ .986-1.066, P ¼ .213 and HR ¼ 1.005 95% CI ¼ .963 -1.049, P¼ .810, respectively). Conclusions: These results should be taken into consideration when putting inclusion/ exclusion criteria for GBM clinical trials. Legal entity responsible for the study: Individual group Funding: None Disclosure: All authors have declared no conflicts of interest.119O Mismatch repair deficiency (MMRD) and PD-L1 expression in high grade glioma (HGG) patients from Siloam Hospital Jakarta Indonesia

Results: There was a total of 25 patients with skull base meningiomas, out of which 9 of them were located in the cavernous sinus area. There were 6 female and 3 male patients. The mean age of the patients was 50.6 (36-70) years. The mean follow-up time postradiosurgery was 6.67 (4-12) months. The mean tumor volume before radiosurgery was 12.36 (1.51-34.45) cm 3 . The mean tumor volume after radiosurgery was 10.19 (0.98-28.80) cm 3 . The dose used was between 12 to 18 gray. Post-radiosurgery, clinical symptoms such as hypesthesia improved in 1 out of 2 patients (50%), seizures improved in 100% of patients, blurred vision improved in 2 out of 4 patients (50%), cranial nerve III, IV and VI function improved in 2 out of 4 patients (50%), headaches was no longer present in 50% patients and double vision improved in 100% of patients. Conclusions: Gamma knife radiosurgery reduces the tumor size and improves the clinical symptoms in patients with cavernous sinus meningiomas. However, large prospective studies should be done in order to further evaluate the long term effects of gamma knife for skull base meningiomas.