Tazemetostat is primarily used in the treatment of certain types of cancer, particularly those associated with mutations in the EZH2 gene. It functions as an inhibitor of EZH2, a histone methyltransferase protein involved in the regulation of gene expression. By blocking EZH2, tazemetostat helps to restore normal gene activity, which can slow down or stop the growth of cancer cells.

One of the key applications of tazemetostat is in the treatment of epithelioid sarcoma, a rare and aggressive soft tissue cancer. It is FDA-approved for adults and pediatric patients aged 16 years and older with locally advanced or metastatic epithelioid sarcoma who are not candidates for complete resection. It is specifically indicated for patients whose tumors have lost the INI1/SMARCB1 gene, a condition that makes the cancer more dependent on EZH2 activity. Tazemetostat has shown promise in providing a therapeutic option for these patients.

Additionally, tazemetostat is FDA-approved for the treatment of relapsed or refractory follicular lymphoma in adults after two or more lines of systemic therapy in patients whose tumors are EZH2 mutation-positive. It is also being investigated for use in other cancers, such as other types of non-Hodgkin lymphoma and various solid tumors. Clinical trials are ongoing to explore its efficacy in these and other malignancies, potentially expanding its application in oncology.

Overall, tazemetostat represents a targeted approach to cancer treatment, offering hope for patients with specific genetic alterations in their tumors.