Lenalidomide-acetylene-C5-COOH is primarily utilized in the development of targeted cancer therapies, particularly in the design of proteolysis-targeting chimeras (PROTACs). These molecules are engineered to degrade specific disease-causing proteins by recruiting E3 ubiquitin ligases, leading to their ubiquitination and subsequent proteasomal degradation. This approach is especially promising in treating cancers that are resistant to conventional therapies, as it offers a mechanism to eliminate proteins that are otherwise undruggable. Additionally, its structure allows for precise modifications to enhance binding affinity and selectivity, making it a valuable tool in medicinal chemistry for optimizing drug candidates.