epz-6438 and Skin-Neoplasms

Tazemetostat (Tazverik™), a first-in-class, small molecule enhancer of zeste homolog 2 (EZH2) inhibitor, received accelerated approval in January 2020 in the USA for the treatment of adults and adolescents aged ≥ 16 years with locally advanced or metastatic epithelioid sarcoma not eligible for complete resection. Developed by Epizyme, in collaboration with Eisai, it is the first therapy to be approved specifically for the treatment of epithelioid sarcoma in the USA. The recommended dosage regimen is 800 mg twice daily, administered orally with or without food, until disease progression or unacceptable toxicity. Tazemetostat is also undergoing clinical development in various countries worldwide for use in several other tumour types, including diffuse large B-cell lymphoma and mesothelioma, with the US FDA accepting a New Drug Application and granting priority review for its use in the treatment of follicular lymphoma. This article summarizes the milestones in the development of tazemetostat leading to this first approval for the treatment of adults and adolescents aged ≥ 16 years with locally advanced or metastatic epithelioid sarcoma not eligible for complete resection.

Topics: Antineoplastic Agents; Benzamides; Biphenyl Compounds; Drug Approval; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Humans; Molecular Structure; Morpholines; Pyridones; Sarcoma; Skin Neoplasms

Polycomb group proteins, including Ezh2, are important candidate stem cell maintenance proteins in epidermal squamous cell carcinoma. We previously showed that epidermal cancer stem cells (ECS cells) represent a minority of cells in tumors, are highly enriched in Ezh2 and drive aggressive tumor formation. We now show that Ezh2 is required for ECS cell survival, migration, invasion and tumor formation and that this is associated with increased histone H3 trimethylation on lysine 27, a mark of Ezh2 action. We also show that Ezh2 knockdown or treatment with Ezh2 inhibitors, GSK126 or EPZ-6438, reduces Ezh2 level and activity, leading to reduced ECS cell spheroid formation, migration, invasion and tumor growth. These studies indicate that epidermal squamous cell carcinoma cells contain a subpopulation of cancer stem (tumor-initiating) cells that are enriched in Ezh2, that Ezh2 is required for optimal ECS cell survival and tumor formation and that treatment with Ezh2 inhibitors may be a strategy for reducing ECS cell survival and suppressing tumor formation.

Topics: Animals; Benzamides; Biphenyl Compounds; Cell Line, Tumor; Cell Movement; Cell Survival; Enhancer of Zeste Homolog 2 Protein; Gene Knockdown Techniques; Humans; Indoles; Mice, Inbred NOD; Morpholines; Neoplastic Stem Cells; Polycomb Repressive Complex 2; Pyridones; Skin Neoplasms; Xenograft Model Antitumor Assays