Mesothelioma could soon be treated by tazemetostat, a new protein inhibitor. Research groups at the American Society of Clinical Oncology made presentations speaking about the effectiveness of the drug on different cancers, with one of them being mesothelioma. It was shown to be effective, and could eventually be a second-line treatment.
It is not a cure, but it could potentially help pleural mesothelioma patients extend their lives. The clinical trial was done at the UCLA Medical Center, University of California-San Francisco Cancer Center, Dana-Farber Cancer Institute in Boston, Massachusetts General Hospital, Mayo Clinic in Rochester, Minnesota, and the Memorial Sloan Kettering Cancer Center in New York City. The promising results need to be studied further to see just how effective the treatment is.
Tazemetostat works by blocking an enzyme called EZH2, inhibiting the genes that suppress tumor growth. This treatment is more effective when the tumor suppressing gene BAP1 is mutated, which occurs in 60 percent of pleural mesothelioma cases. When BAP1 is mutated, EZH2 is released in larger quantities, causing the cancer to grow much faster. People with the BAP1 gene mutation are more likely to develop mesothelioma, but they are more likely to respond to treatment once diagnosed.
The trial had 74 patients with relapsed or refractory pleural mesothelioma taking tazemetostat twice daily. Seventy of the patients had the BAP1 gene mutation. The disease control rate was 54 percent at the 12 week mark and 33 percent at the 24 week mark. Disease control occurs when the disease remains stable, there is a complete response to treatment, or there is a partial response. The stable disease rate was 62 percent at 12 weeks. The median progression free survival was 18 weeks while the median overall survival was 36 weeks. Two patients responded very well and had a response of 30 weeks. Only five percent of patients experienced serious side effects with the most common side effects being shortness of breath and anemia.
Tazemetostat was approved for a different cancer earlier this year. Patients with lymphoma and a high expression of EZH2 can take tazemetostat to treat their mesothelioma. The FDA also gave an accelerated approval for some patients with unresectable epithelioid sarcoma. There are no second line treatments for mesothelioma, but tazemetostat could be one in the future. Along with other treatments, tazemetostat is going through the approval process to become a potential second line treatment.
“Epizyme Announces U.S. FDA Accelerated Approval of TAZVERIK™ (tazemetostat) for Relapsed/Refractory Follicular Lymphoma” Epizyme Investor Center (June 18, 2020). [Link]
Marjorie Glass Zauderer et al., “Safety and efficacy of tazemetostat, an enhancer of zeste-homolog 2 inhibitor, in patients with relapsed or refractory malignant mesothelioma.” Journal of Clinical Oncology (2020). [Link]