Using a Pre-Radiation Window to Identify Potentially Active Cytotoxic Agents in Adults with Newly Diagnosed Glioblastoma

BACKGROUND

Therapies shown to improve outcomes in patients with recurrent cancers are commonly used in the neoadjuvant setting to optimize surgery, reduce radiation fields, and treat micro-metastatic disease. While pre-radiation chemotherapy (PRC) use has flourished in systemic cancers, it has not in glioblastomas. This review documents these trajectories and highlights the potential of PRC to rapidly and safely screen cytotoxic drugs for efficacy in patients with newly diagnosed glioblastoma.

METHODS

Prospective trials of adults with newly diagnosed systemic and brain cancers treated with PRC published between 1980 and 2023 were identified in PubMed. NCCN guidelines were used to document the standard use of PRC in patients with systemic and brain cancers.

RESULTS

Over 5,000 prospective PRC trials in solid tumors were identified. These accrued >1 million patients and resulted in neoadjuvant therapies being standard-of-care in ~28 systemic cancers. Only 50 similar trials (2,206 patients) were identified in high grade gliomas. In 13 trials containing PRC temozolomide (n=846), radiographic responses ranged from 6-53% with a median survival of ~13 months. Glioblastoma PRC trials were not associated with unexpected toxicities or major negative impacts on survival.

CONCLUSIONS

PRC in patients with glioblastoma appears safe and feasible. The pre-radiation window is ideally suited to rapidly screen cytotoxic agents for efficacy. It permits radiographic response as a primary outcome, small sample sizes, and initiation of standard therapies a few months after diagnosis. PRC may be most appropriate in patients with glioblastoma who are unlikely to benefit from temozolomide.

Pre-radiation Nivolumab plus ipilimumab in patients with newly diagnosed high-grade gliomas

The limited success of immune checkpoint inhibitors (ICIs) in the adjuvant setting for glioblastoma highlights the need to explore administering ICIs prior to immunosuppressive radiation. To address the feasibility and safety of this approach, we conducted a phase I study in patients with newly diagnosed Grade 3 and Grade 4 gliomas. Patients received nivolumab 300 mg every 2 weeks and ipilimumab 1 mg/kg every 6 weeks until disease progression or unacceptable toxicity. Fifteen patients were treated, with four patients on dexamethasone at treatment initiation and five tumors having MGMT promoter methylated. Treatment began a median of 38 days post-surgery. The most common treatment-related adverse events (AEs) were rash, pruritus, fatigue, nausea, and anorexia. Grade 3 AEs were lipase increased (n = 2), anorexia (n = 1), pruritus (n = 1), and rash (n = 3), and one Grade 4 cerebral edema occurred. Median progression-free survival (mPFS) was 1.3 months and median overall survival (mOS) was 19.3 months (95% CI, 12.9-NA). Three patients deferred conventional radiochemotherapy for over seven months while ten eventually received it. Progressing tumors tended to exhibit higher LAG-3 levels at baseline compared to shrinking tumors. Analysis of paired pre-treatment and post-progression tissue (n = 5) showed trends of up-regulated TGF-β, ERBB2, ERBB3, and ERBB4 signaling pathways, downregulated PPAR signaling, decreased B cell proportions, and increased monocytes proportions in tumors post-treatment. We show nivolumab plus ipilimumab can be safely administered prior to standard radiotherapy for newly diagnosed gliomas and is operationally feasible. Clinicaltrials.gov NCT03425292 registered February 7, 2018.