High YAP protein levels indicate improved treatment response in lung cancer patients

The authors aimed to determine whether levels of YAP protein could predict the success of treatment in patients with lung cancer.

YAP protein is a protein active in many cancers that can have a positive or negative effect depending on the location. When YAP protein is present in the nucleus (brain of the cancer cell) it can promote cancer cell growth. When it is present in the cytoplasm (area in the cell located outside the nucleus) it can promote cancer cell death.

YAP protein can be used to measure patient response to a specific treatment. Treatment can involve surgery to remove the cancer or treatment with drugs such as erlotinib (Tarceva) and gefitinib (IRESSA); tyrosine-kinase inhibitors (drugs that inhibit cancer cell growth and function). 

The aim of this study was to determine whether high levels of YAP protein could indicate improved treatment success in lung cancer patients.

205 patients who had undergone surgery to remove the lung cancer were used in this study with a follow-up time of 60.6 months. 99 patients experienced cancer recurrence. Patients with high levels of YAP in the cytoplasm had smaller and less advanced tumors, fewer cancer recurrences and fewer deaths.

High levels of YAP active in the cytoplasm was a significant predictor of treatment success, where patients with high YAP levels had a 34% reduced risk of experiencing shorter progression-free survival (stable cancer that does not progress after treatment) and had a 53% reduced risk of experiencing shorter overall survival compared to patients with low cytoplasm YAP levels.

36 patients had EGFR mutations (specific mutation active in lung cancer) and were treated with erlotinib or gefitinib. Of these, patients with high levels of YAP protein in the cytoplasm had a 66% reduced risk of experiencing shorter progression-free survival and a 71% reduced risk of experiencing shorter overall survival compared to patients with low levels of YAP in the cytoplasm.

The authors concluded that patients with high levels of YAP in the cytoplasm had better progression-free survival and overall survival when treated with erlotinib or geftinib.

This is the only study currently available comparing nuclear and cytoplasm YAP levels and requires further studies to be widely applied.

If you are considering treatment with erlotinib or geftinib please consult your doctor for potential risks and benefits.