Alzheimer’s disease and clinical trials

Alzheimer's disease (AD) is spreading its root disproportionately among the worldwide population. Many genes have been identified as the hallmarks of AD. Based upon the knowledge, many clinical trials have been designed and conducted. Attempts have been made to alleviate the pathology associated with AD by targeting the molecular products of these genes. Irrespective of the understanding on the genetic component of AD, many clinical trials have failed and imposed greater challenges on the path of drug discovery. Therefore, this review aims to identify research and review articles to pinpoint the limitations of drug candidates (thiethylperazine, CT1812, crenezumab, CNP520, and lecanemab), which are under or withdrawn from clinical trials. Thorough analysis of the cross-talk pathways led to the identification of many confounding factors, which could interfere with the success of clinical trials with drug candidates such as thiethylperazine, CT1812, crenezumab, and CNP520. Though these drug candidates were enrolled in clinical trials, yet literature review shows many limitations. These limitations raise many questions on the rationale behind the enrollments of these drug candidates in clinical trials. A meticulous prior assessment of the outcome of clinical studies may stop risky clinical trials at their inceptions. This may save time, money, and resources.