This, in turn, facilitates the effective release of erlotinib into lung cancer cells, resulting in cancer cell death and ultimately enhancing the effectiveness of erlotinib for therapeutic purposes.559 Afatinib, another clinically approved drug targeting EGFR for treating lung cancer, is hydrophobic and has low bioavailability, making it easy to spread systemically and causing serious side effects. Here, EGFR is linked to lung cancer.