Objective To evaluate the in vitro effects of a PI3K/m TOR dual inhibitor S1 alone or in combination with the multi-kinase inhibitor sorafenib on NCI-H446 SCLC cells. Methods The efficacy of S1 alone or in combination with sorafenib in NCI-H446 were evaluated through anti-proliferation assay, colony formation assay, transwell invasion assay, and wound healing assay. Results The NCI-H446 cells treated with S1 in 24, 48 and 72 h, resulted in reduced tumor cell proliferation with IC_50 of 92.82, 23.29 and 1.79...