BCL2L1 and small cell lung carcinoma: Structure-based design optimization of WEHI-539 led to the development and characterization at preclinical level of other selective inhibitors of Bcl-xL, such as A-1155463, showing in vivo antitumor activity in a xenograft model of SCLC, and A-1331852 increasing the sensitivity of rhabdomyosarcoma cells to several conventional chemotherapeutic agents without apparent toxicity [139,143,144].