Brain Mini-Workshop: Blood Brain Barrier and Targeted Drug Delivery

Drugs are currently being developed for the treatment of serious brain disorders including glioblastoma, Parkinson’s disease, and Alzheimer’s disease. These include chemotherapeutic drugs and those based on neurotrophic factors such as glial cell-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), and neurturin (NTN). Neurotrophic factors have therapeutic potential for neurological disorders such as Parkinson’s disease (PD) and Alzheimer’s disease (AD), and administration of GDNF and NTN has shown promise in preclinical studies. Despite their safety and effectiveness in preclinical studies, success of chemotherapeutic drugs and neurotrophic factors in clinical trials has been limited in part by the blood-brain barrier (BBB), which naturally protects the brain from potentially harmful agents in the blood. Success of these drugs is also limited by the method of administration. As shown in studies in mice, when NTN is administered systemically, only 0.05% of it reaches the brain. Clinically significant benefits often require direct injection of the compounds into the brain, which is risky, not practical for many patients, and therefor difficult to justify in the early stage of disease progression when the drugs are potentially the most effective. Several researchers are developing drug carriers or new routes of administration, but moving drugs across the BBB remains a challenge.