**2.6. Mammalian target of rapamycin (mTOR)**

The mammalian target of rapamycin (mTOR) is one of the key protein kinases that regulate cell growth, proliferation, and angiogenesis [49] and is integrated in the downstream cascade of HER. The inhibition of mTOR is thus an intriguing new therapeutic approach. Everolimus, an oral mTOR inhibitor, did not significantly improve mOS but could reduce the risk of disease progression (*p* < 0.001) when compared with the best supportive care (GRANITE-1 trial) [50].
