Assessing New Targeting Therapies as Treatment for Mesothelioma
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.