Intensified Adjuvant Therapy for High-Risk Newly Diagnosed Glioblastoma With Subtotal Resection or Short-Term Progression

\*\*Brief Summary\*\*

The goal of this clinical trial is to learn whether intensified adjuvant treatment is safe and may help delay disease progression in adults with high-risk newly diagnosed glioblastoma. High-risk newly diagnosed glioblastoma in this study includes glioblastoma that has been partially removed by surgery or glioblastoma that shows early progression or recurrence before postoperative radiotherapy.

The main questions this study aims to answer are:

* Does intensified adjuvant treatment improve median progression-free survival in participants with high-risk newly diagnosed glioblastoma? * How long do participants survive after receiving this treatment? * What medical problems do participants have during or after intensified adjuvant treatment? * How often do participants develop radiation necrosis? * How does this treatment affect participants' quality of life?

Participants will:

* Receive postoperative concurrent radiotherapy and temozolomide chemotherapy. * Receive a higher radiation dose to the residual tumor or early recurrent/progressive lesion, while standard radiation doses are given to the tumor bed and surrounding high-risk and low-risk areas. * Receive adjuvant temozolomide after concurrent chemoradiotherapy. * Receive sintilimab and bevacizumab by intravenous infusion once every 21 days for up to 1 year. * Have regular blood tests, biochemical tests, thyroid function tests, myocardial enzyme tests, electrocardiograms, and other safety assessments. * Have enhanced brain MRI scans regularly to evaluate disease status. * Be followed by clinic visits and/or telephone calls to collect information about disease progression, survival, side effects, later cancer treatments, and quality of life.