Lenalidomide is an immunomodulatory drug with multiple mechanisms of action. It binds to cereblon, a component of the CRL4 E3 ubiquitin ligase complex, altering its substrate specificity and leading to the ubiquitination and proteasomal degradation of specific proteins like IKZF1, IKZF3, and CK1α. These proteins are important for the survival and proliferation of malignant cells, especially in multiple myeloma and myelodysplastic syndromes. The degradation of these transcription factors reduces cancer cell growth and promotes apoptosis. Additionally, lenalidomide modulates the immune system by increasing interleukin-2 production, enhancing natural killer cell activity, and inhibiting pro-inflammatory cytokines, contributing to its antitumor and anti-inflammatory effects. It also inhibits angiogenesis by preventing the release of growth factors that support tumor blood vessel formation.