Abstract
Immunotherapy has revolutionized cancer care, yet resistance frequently undermines its efficacy. Although tumor-intrinsic resistance pathways have been mapped, how immune pressure regulates death-receptor vulnerability and anti-apoptotic buffering remains less defined. Using genome-wide CRISPR-Cas9 screening in cancer cells co-cultured with natural killer (NK) cells, we identify CFLAR, encoding cFLIP, as a dominant suppressor of death-receptor signaling that impairs NK- and T-cell cytotoxicity. CFLAR depletion sensitizes cancer cells to NK- and T-cell attack in vitro and in vivo. Single-cell and spatial transcriptomic analyses link high CFLAR expression to reduced lymphocyte infiltration and poorer responses to immune checkpoint blockade. Mechanistically, immune effector cell-induced inflammation increases CFLAR and death receptor 5 (DR5) expression in association with p38-MAPK signaling, balancing survival and death under immune pressure. The DR5 agonist conatumumab enhances lymphocyte-mediated killing and improves responses to cellular therapies, checkpoint blockade, and chemo-immunotherapy. Combining DR5 agonism with NKG2A blockade co-activates NK- and T-cell responses and overcomes anti-PD-1 resistance in MHC-I-deficient tumors. These findings identify the DR5-cFLIP axis as an immune-pressure-associated, pharmacologically targetable vulnerability and support rational combinations of DR5 agonists with multiple immunotherapies for refractory cancers.