A TAK1Cytokine Toxicity Checkpoint Controls Anti-Cancer Immunity

The success of cancer immunotherapies is currently limited to a subset of patients, which underscores the urgent need to identify the processes by which tumours evade immunity. Through screening a kinome-wide CRISPR/Cas9 sgRNA library we identified MAP3K7 (TAK1) as a suppressor of CD8+ T cell mediated killing. We demonstrate that TAK1 acts as a cancer-intrinsic checkpoint by integrating signals from T cell-secreted TNF and IFNy effector cytokines to elicit a cytoprotective response. This cytoprotective response profoundly limits the anti-cancer activity these key effector molecules and completely abrogates bystander killing by perforin deficient T cells. Inhibition of the TAK1 checkpoint effectively redirects the combined TNF/IFNy pathway activation to promote inflammatory cell death via RIPK1 and Caspase-8 and simultaneously amplifies the output of the IFNy pathway, thereby priming cells for cytokine-induced cell death. Mechanistically, TAK1 deficiency led to proteasomal degradation of cFLIP, enhancing the formation of Complex II and subversion of other cytoprotective responses. Targeting the TAK1 checkpoint led to profound attenuation of tumour growth in immune competent mice, with minimal impact in immune deficient counterparts. Adoptive cell therapy led to preferential elimination of TAK1 deficient clones. Collectively, our study uncovers a cancer-intrinsic checkpoint controlled by TAK1 activity that switches TNF and IFNy responses from cytoprotective to apoptosis. Cancer cells exploit this to limit cell death in the presence of the cytotoxic lymphoctye cytokines TNF and IFN{gamma} and therapeutic intervention can fully unleash the impact of these effector molecules both on the direct target and bystander cells. These findings highlight the clinical development of TAK1 biologics as a potential strategy to improve cancer immunotherapies through harnessing and enhancing the cytotoxic potential of CTL-derived cytokines. In BriefDjajawi et al. identify TAK1 as a cancer-intrinsic cytokine toxicity checkpoint that limits the efficacy of anti-cancer immune responses. Cancer cells exploit TAK1 activity to confers resistance to CD8+ T cell-derived TNF and IFN{gamma}-induced apoptosis, limiting both direct and bystander killing. Mechanistically, TAK1 loss acts through 1. cFLIP and RIPK1 to promote cell death, 2. The inactivation of pro-survival signals and 3. Via amplification of the IFNy response. Targeting of this TAK1 checkpoint enhanced anti-tumour immunity in vivo and improved adoptive cellular therapy. These findings identify a strategy employed by transformed cells to avoid destruction by inflammatory cytokines and provide new therapeutic vulnerabilities for enhancing immunotherapies. HighlightsO_LICRISPR screens identify TAK1 as a tumour-intrinsic survival checkpoint limiting destruction by CD8+ T cells. C_LIO_LITAK1 protects tumour cells from combined TNF and IFN{gamma}-induced apoptosis. C_LIO_LITAK1 loss destabilizes cFLIP, priming cells for STAT1 and RIPK1-dependent cell death. C_LIO_LITAK1 loss promotes tumour control in immune competent animals and enhances the efficacy of adoptive cell therapy. C_LI