Mutational profiling of newly diagnosed glioblastoma to identify predictive biomarkers of efficacy and safety of anlotinib combination therapy.

e14037 Background: Glioblastoma (GBM) is highly vascular tumor with the specific pathologic feature of microvascular proliferation. Our previous phase Ⅱ clinical trial (NCT04119674) has firstly demonstrated the antiangiogenic multikinase inhibitor anlotinib combined with STUPP regimen can lengthen progression-free survival (PFS) in patients with newly diagnosed GBM. However, no biomarker for angiogenic therapy has been proved yet. Therefore, the second analysis was performed to identify the predictive biomarkers. Methods: A total of 21 patients with newly diagnosed GBM were enrolled in the retrospective research. The methylation status of the MGMT gene promoter was examined using the MDxHealth PCR assay. DNA-based whole genome sequencing was undertaken to detect the genomic alterations of patients. Results: The differences of gene aberrances between patients who reached and those who did not reach the primary endpoint were observed. ATRX and MYO15A mutations were only found in patients who had yet not experienced relapse. On contrast, the mutations of PIK3CA, HEG1, HMCN1 and RP1L1 occurred only in the recurrent group. HEG1 (HR 6.0, 95% CI 1.2-28.8, p= 0.026) and RP1L1 (HR 12.5, 95% CI 2.1-74.3, p= 0.005), genes related to angiogenesis, were both independent biomarkers of PFS. RP1L1 was also significantly associated with shorter overall survival (OS) (HR 33.4, 95% CI 3.2-351.4, p= 0.003). Interestingly, PIK3CA alterations were significantly higher in patients with cerebral than in those without ( p= 0.032, OR 16.4). Conclusions: Our study suggested that alterations in HEG1, RP1L1 and PIK3CA could be novel biomarkers for the newly diagnosed GBM patients received anti-angiogenesis combination therapy, and provided now insights for the precise treatment of GBM.