Cyclodextrin-Based Formulations as a Promising Strategy to Overcome the Blood-Brain Barrier: Historical Overview and Prospects in Glioblastoma Treatment.

Glioblastoma (GB) is one of the most aggressive and treatment-resistant cancers affecting the central nervous system (CNS), predominantly in adults. Despite significant advancements in this field, GB treatment still relies primarily on conventional approaches, including surgical resection, radiotherapy, and chemotherapy, which, due to its complex pathological characteristics, resistance mechanisms, and restrictive nature of the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB), remain of limited efficacy. In this context, the development of innovative therapeutic strategies able to overcome these barriers, induce cancer cell death, and improve patient prognosis is crucial. Recently, nanoparticle platforms and focused ultrasounds seem to be promising approaches for cancer treatment. Nanoparticles enable targeting and controlled release, whilst focused ultrasounds enhance tissue permeation, increasing drug accumulation in a specific organ. However, nanoparticles can suffer from synthesis complexity, long-term biocompatibility and accumulation in the body with consequent toxicity, whereas focused ultrasounds require specialized equipment and can potentially cause thermal damage, hemorrhage, or cavitation injury. Cyclodextrins (CYDs) possess good properties and represent a versatile and safer alternative able to improve drug stability, solubility, and bioavailability, and depending on the type, dose, and administration route, can reduce local and systemic toxicity. Thus, CYDs emerge as promising novel excipients in GB treatment. Despite these advantages, CYD complexes suffer from receptor specificity, reducing their potential in precision medicine. By combining CYD complexes with polymeric or lipidic platforms, the advantages of CYD safety and drug solubilization together with their specific targeting can be obtained, thus enhancing selectivity and maximizing efficacy while minimizing recurrence and systemic toxicity. This review provides a comprehensive overview of GB pathology, conventional treatments, and emerging CYD-based strategies aimed at enhancing drug delivery and therapeutic efficacy.