There are currently five FDA-approved targeted therapies in the United States available to treat first line EGFR positive lung adenocarcinoma. Tagrisso is currently the standard-of-care. These medications are referred to as tyrosine kinase inhibitors (TKIs). They block the activity of the EGFR protein.
Approved medications for lung adenocarcinoma include: Tagrisso (osimertinib) (Standard of care for first-line treatment) and:
- Tarceva (erlotinib)
- Gilotrif (afatinib)
- Iressa (gefitinib)
- Vizimpro (dacomitinib)
You may hear your oncologist talk about “generations” of these drugs. Tarceva and Iressa are first generation EGFR inhibitors, Gilotrif and Vizimpro are second generation EGFR inhibitors, and Tagrisso is a third-generation EGFR inhibitor. Tagrisso is also approved for those who have had progression on a first or second generation inhibitor and developed a T790M mutation.
Resistance to Treatment
Unfortunately, though lung cancers may respond very well to tyrosine kinase inhibitors at first, they almost always become resistant over time. The amount of time before resistance develops, however, can vary significantly. While the median time between the beginning of therapy and the development of resistance when using Tagrisso is approximately 19 months, many people have had lasting reponses of many years.
At the current time, we usually find out that a tumor has become resistant when it begins to grow again or to spread. A repeat tissue or liquid biopsy, followed by comprehensive biomarker testing should be done at that time to determine if there is another actionable mutation that is driving the resistance.
Treatment of Resistant EGFR Positive Lung Cancer
Just as there are several different types of EGFR mutations, there are several mechanisms by which cancers can become resistant. Cancer cells are always changing, and often develop mutations that make them resistant to current therapy.
There are many different types of resistance that have been identified and a variety of treatments and clinical trials are available and in development. Please view our 3-part webinar series sponsored by Blueprint Medicine that features expert oncologists in EGFR lung cancer.
Link to Brain Metastases
There is a high incidence of brain metastases in people with EGFR lung cancer. Fortunately, current standard-of-care Tagrisso is effective in crossing the blood-brain barrier—an area of tightly knit cells which line capillaries in the brain—and actively treating and reducing lung cancer that has spread to the brain.
There have also been advancements in radiation for treating limited numbers of brain metastases. This may be referred to as SRS, SBRT, gamma knife, cyber knife, etc. depending on where you are treated.