GL-331 is a synthetic derivative of podophyllotoxin belongs to the class of semisynthetic lignans and is structurally related to etoposide and teniposide, which are well-known anticancer agents. GL-331 functions primarily as a topoisomerase II inhibitor, interfering with DNA replication and transcription in rapidly dividing cells, making it a potential chemotherapeutic agent. Preclinical studies have demonstrated its cytotoxic effects against various tumor cell lines, and it has shown promise in overcoming multidrug resistance in certain cancer models.