2.4. Evaluation

Routine testing included weekly laboratory tests including complete blood counts and basic metabolic panel, examinations at every clinical visit, and contrast‐enhanced brain MRI every 4 weeks.

Neuroradiologic response following treatment was determined by response assessment in neuro‐oncology (RANO) criteria. ²³ Complete response (CR) entailed disappearance of all contrast‐ and noncontrast enhancing tumor on consecutive MRIs with minimal 1‐month interval, and in the absence of corticosteroids. Partial response (PR) was defined by >50% reduction in tumor size derived by the sum of cross‐sectional radii on consecutive MRI scans of minimal 1‐month interval, and in the presence of stable or decreased corticosteroid dose. Progressive disease (PD) was defined as greater than 25% increase in tumor size or interval development of new lesions. Stable disease (SD) entailed all other scenarios and required confirmation MRI following best reported response. ²³ Patients continued ICI until they progressed or developed unacceptable AE, at which time patients either had bevacizumab added to their regimen or discontinued ICI.

AE were retrospectively determined for all patients and tabulated using Common Terminology Criteria for Adverse Events version 5.0. PFS and OS were defined as time from the day one of ICI until disease progression and death, respectively.