Koselugo, known generically as selumetinib, is a medication specifically designed for the treatment of certain types of neurofibromatosis type 1 (NF1), a genetic disorder that can cause tumors to grow on nerves throughout the body. Approved by the U.S. Food and Drug Administration (FDA), Koselugo is particularly indicated for pediatric patients aged 2 years and older who have symptomatic, inoperable plexiform neurofibromas, which are tumors associated with NF1. As a MEK inhibitor, Koselugo works by targeting and inhibiting specific proteins in the signaling pathways that contribute to the growth and development of tumor cells. This mechanism helps in reducing the size of the tumors, although it does not cure the underlying genetic condition. The approval of Koselugo provides a significant advancement in the treatment options available for children suffering from this challenging aspect of NF1, offering hope for improved quality of life and symptom management.