Background/Objectives: This study explores the potential of LB-100 (a protein phosphatase 2A—PP2A inhibitor) combined with adavosertib (a WEE1 kinase inhibitor) and doxorubicin (DOX), to overcome multidrug resistance (MDR) in cancer cells and enhance treatment efficacy. Methods: We evaluated LB-100 combinations with adavosertib and DOX in patient-derived glioblastoma and non-small cell lung carcinoma cells (NSCLCs) using a real-time cell analyzer. Effectiveness was also assessed through immunofluorescence assay, and interactions were analyzed via SynergyFinder+. We also examined P-glycoprotein (P-gp) expression and drug resistance genes’ expression in MDR glioblastoma and NSCLCs after LB-100 treatment, as well as LB-100 sensitizing effect on DOX and DOX accumulation. Results: LB-100 significantly boosts the effectiveness of adavosertib and DOX after multiple applications. It also enhances these drugs’ cytotoxicity in a single application without acting synergistically. Additionally, LB-100 reduces P-gp expression in MDR glioblastoma and NSCLCs, sensitizing them to DOX and increasing its accumulation. Conclusions: LB-100 enhances the effectiveness of drugs against MDR cancer cells, presenting a promising strategy to overcome drug resistance in glioblastoma and NSCLCs through P-gp modulation.

Background/Objectives: “Ring-like” intracranial aneurysms—historically described as “doughnut-like” or “donut sign”—represent a rare configuration in which a central thrombus coexists with a circumferential mural flow ring. Traditionally considered a radiologic curiosity, this morphology likely reflects a shear-driven hemodynamic state rather than a stable organized thrombus. We aimed to summarize all PubMed-documented cases of ring-like aneurysms, define their morphologic and clinical spectrum, and assess their hemodynamic significance, rupture risk, and treatment outcomes. An additional aim is to formalize the use of the term “ring-like aneurysm” as a distinct morphologic subtype and to clearly differentiate it from the neuroradiologic “donut sign,” which represents an imaging appearance rather than a specific anatomic configuration. Methods: A systematic PubMed search (1996–2024) was conducted using the following combinations of keywords and Boolean operators: (“ring-like aneurysm” OR “donut aneurysm” OR “doughnut aneurysm” OR “ring-shaped aneurysm” OR “circumferential lumen” OR “central thrombus”) AND (“intracranial” OR “cerebral” OR “basilar” OR “aneurysm”). Only English-language, PubMed-indexed reports describing true ring-like (donut-shaped) aneurysms were included. Non-indexed, non-English, and serpentine or fusiform aneurysms mimicking ring-like morphology were excluded. Extracted data included aneurysm location, size, presentation (ruptured, symptomatic, or incidental), treatment strategy, and clinical outcome. Statistical proportions were analyzed using descriptive methods, Wilson 95% confidence intervals, and a binomial test to compare the observed subarachnoid hemorrhage (SAH) rate against the expected conservative rupture proportion. Results: The search identified 16 individual patients reported in 10 publications. All aneurysms were large or giant (14–36 mm) displaying characteristic thrombosed pattern. Ruptured presentation occurred in 6 out of 16 cases (37.5%) and symptomatic unruptured in 10 (62.5%). No incidental cases were reported. Posterior circulation involvement was present in 44%, with a female predominance of 69%. Conclusions: Ring-like aneurysms constitute a distinct, shear-maintained hemodynamic entity combining mural jet flow with central thrombosis. Their frequent symptomatic or ruptured presentation supports the concept that this morphology represents a pre-ruptural configuration rather than a chronic thrombotic residue. Early recognition and targeted endovascular exclusion of the inflow zone are essential to prevent delayed rupture.