EZH2 Inhibitor

An EZH2 inhibitor is a targeted cancer drug that blocks an enzyme tumor cells use to silence genes that would otherwise restrain their growth. In mesothelioma, these drugs are studied mainly in patients whose tumors have lost the BAP1 tumor-suppressor gene, because those tumors often become dependent on EZH2 to survive. Tazemetostat (Tazverik) is the leading drug in this class.

Origin

The EZH2 gene was identified in the 1990s as part of the Polycomb repressive complex, a system that controls which genes are switched off in cells. Tazemetostat, developed by Epizyme, was the first EZH2 inhibitor approved by the FDA (in 2020) for epithelioid sarcoma and follicular lymphoma, and it has since been investigated in mesothelioma through clinical trials beginning around 2015.

Significance in Asbestos Context

For people with mesothelioma, EZH2 inhibitors are most relevant if tumor testing shows a BAP1 mutation or loss of BAP1 protein, a finding present in roughly half of mesothelioma cases. Laboratory studies and an early-phase clinical trial showed that BAP1-deficient mesotheliomas can be especially sensitive to EZH2 blockade, offering an oral treatment option when chemotherapy and immunotherapy have stopped working. Patients should ask their oncologist whether their tumor has been tested for BAP1 status (by immunohistochemistry or genetic sequencing) and whether an EZH2 inhibitor clinical trial is available at a mesothelioma specialty center. This information also matters legally: pathology and molecular testing reports documenting BAP1 loss, treatment history, and trial enrollment become part of the medical record used to establish diagnosis, prognosis, and damages in an asbestos claim.

Example Sentence

After her second line of chemotherapy failed, her oncologist reviewed the BAP1 testing on her pleural biopsy and referred her to a clinical trial of an EZH2 inhibitor at a regional cancer center.

Related Terms

BAP1, Tazemetostat, Targeted Therapy, Immunohistochemistry, Epithelioid Mesothelioma, Clinical Trial

Notes

• Ask your oncologist or pathologist whether your tumor has been tested for BAP1 loss (by immunohistochemistry) and for broader molecular profiling. This determines whether an EZH2 inhibitor is a reasonable option.
• Request that copies of all pathology, immunohistochemistry, and molecular testing reports be added to your medical file; these documents are important for both treatment decisions and any legal claim.
• If standard therapies are no longer working, ask about EZH2 inhibitor clinical trials at mesothelioma specialty centers (such as NCI-designated cancer centers) and check ClinicalTrials.gov using terms like "mesothelioma" and "tazemetostat."
• Keep a record of side effects, dosing changes, and response scans while on any targeted therapy; these affect both your care and the documentation of disease course in your case.