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In the search for a cure and improved treatment options for mesothelioma, medical researchers continue to study what’s known as epidermal growth factor receptor (EGFR) inhibitors, which kill cancers with mutated EGFR. Mutant EGFR helps cancer cells— which are found in malignant mesothelioma— grow.

Recently, there have been new developments on targeting cancers driven by EGFR mutations.

EGFR Inhibitors And Lung Cancer

The standard of care for patients with non-small cell lung cancer (NSCLC) with an EGFR mutation is treatment with one or more EGFR inhibitors. EGFR mutations have been found in 1 in 10 patients of non-Asian descent diagnosed with NSCLC, and in about half of Asian patients.

At the 4th AACR International Conference on Frontiers of Basic Cancer Research, Dr. Pasi Janne from the Dana-Farber Cancer Institute stated, “Treatment with an EGFR TKI [inhibitor] leads to a response rate of about 60%.”

Dr. Janne provided a stimulating talk on mechanisms of resistance to EGFR inhibitors in lung cancer, pointing out that “acquired drug resistance inevitably develops in most if not all EGFR mutant lung cancer patients [who are] treated with EGFR inhibitors.” However, a new combination that inhibits both EGFR and a related protein known as MEK, appear to make it harder for the tumor to obtain resistance.

The development of two new EGFR inhibitors, known as AZD9291 and rociletinib, are progressing thanks to the FDA, who has designated them as breakthroughs. These inhibitors do not block the unmutated EGFR expressed in normal cells, and clinicians anticipate that they will have minimal side effects, though further clinical testing is needed.

Mesothelioma and Mutated EGFR

While a majority of mesothelioma cases do not seem to have the same EGFR mutations as other cancers, a 2010 study suggests that some mesothelioma tumors have unique, or novel, mutations in the EGFR gene. In other words, these mutations have not been detected in any cancer previously.

In the study, 25 mesothelioma patients were treated with surgery, but not the EGFR inhibitors. Researchers analyzed the survival rate of the mesothelioma patients with the novel EGFR mutations and without them. The mesothelioma patients without the novel EGFR mutations (13 of 18) had a median survival of 14 months. Surprisingly, the mesotheliomas of only 2 of the 7 patients (29%) with the novel mutations in EGFR developed progressive disease within 24 months, and these patients had longer survival times.

A clinical trial sponsored by the Dana-Farber Cancer Institute tested two EGFR inhibitors in 37 mesothelioma patients in order to find out whether treatment with one or both of these EGFR inhibitors delays progression of mesothelioma tumors. Results have yet to be posted.