The Innate Immune System and TRAIL-BCL-XL Axis Mediate a Sex Bias in Lung Cancer and Confer a Therapeutic Vulnerability in Females

There is a significant sex-bias in lung cancer with males showing increased mortality compared to females. A better mechanistic understanding of these differences could help identify therapeutic targets to personalize cancer therapies to each sex. After observing a clear sex-bias in humanized mice, with male patient-derived xenograft (PDX) lung tumors being more progressive and deadlier than female PDX lung tumors, we identified mouse tumor models of lung cancer with the same sex-bias. This sex-bias was not observed in models of breast, colon, melanoma, and renal cancers. In vivo, the sex-bias in growth and lethality required intact ovaries, functional innate natural killer (NK) cells and monocytes/macrophages, and the activating receptor NKG2D. Ex vivo cell culture models were sensitized to the anti-cancer effects of NKG2D-mediated NK cell and macrophage killing through the TRAIL-BCL-XL axis when cultured with serum from female mice with intact ovaries. In both flank and orthotopic models, the BCL-XL inhibitor navitoclax (ABT-263) improved tumor growth control in female mice and required NK cells, macrophages, and the TRAIL signaling pathway. This research suggests that navitoclax and TRAIL pathway agonists could be used as a personalized therapy to improve outcomes in women with lung cancer.