Targeting TBK1 to overcome resistance to cancer immunotherapy.

Despite the success of PD-1 blockade in melanoma and other cancers, effective treatment strategies to overcome resistance to cancer immunotherapy are lacking1,2. Here we identify the innate immune kinase TANK-binding kinase 1 (TBK1)3 as a candidate immune-evasion gene in a pooled genetic screen4. Using a suite of genetic and pharmacological tools across multiple experimental model systems, we confirm a role for TBK1 as an immune-evasion gene. Targeting TBK1 enhances responses to PD-1 blockade by decreasing the cytotoxicity threshold to effector cytokines (TNF and IFNγ). TBK1 inhibition in combination with PD-1 blockade also demonstrated efficacy using patient-derived tumour models, with concordant findings in matched patient-derived organotypic tumour spheroids and matched patient-derived organoids. Tumour cells lacking TBK1 are primed to undergo RIPK- and caspase-dependent cell death in response to TNF and IFNγ in a JAK-STAT-dependent manner. Taken together, our results demonstrate that targeting TBK1 is an effective strategy to overcome resistance to cancer immunotherapy.

Heightened apoptotic priming of vascular cells across tissues and life span predisposes them to cancer therapy-induced toxicities.

Although major organ toxicities frequently arise in patients treated with cytotoxic or targeted cancer therapies, the mechanisms that drive them are poorly understood. Here, we report that vascular endothelial cells (ECs) are more highly primed for apoptosis than parenchymal cells across many adult tissues. Consequently, ECs readily undergo apoptosis in response to many commonly used anticancer agents including cytotoxic and targeted drugs and are more sensitive to ionizing radiation and BH3 mimetics than parenchymal cells in vivo. Further, using differentiated isogenic human induced pluripotent stem cell models of ECs and vascular smooth muscle cells (VSMCs), we find that these vascular cells exhibit distinct drug toxicity patterns, which are linked to divergent therapy-induced vascular toxicities in patients. Collectively, our results demonstrate that vascular cells are highly sensitive to apoptosis-inducing stress across life span and may represent a "weakest link" vulnerability in multiple tissues for development of toxicities.

Exploiting endogenous and therapy-induced apoptotic vulnerabilities in immunoglobulin light chain amyloidosis with BH3 mimetics.

Immunoglobulin light chain (AL) amyloidosis is an incurable hematologic disorder typically characterized by the production of amyloidogenic light chains by clonal plasma cells. These light chains misfold and aggregate in healthy tissues as amyloid fibrils, leading to life-threatening multi-organ dysfunction. Here we show that the clonal plasma cells in AL amyloidosis are highly primed to undergo apoptosis and dependent on pro-survival proteins MCL-1 and BCL-2. Notably, this MCL-1 dependency is indirectly targeted by the proteasome inhibitor bortezomib, currently the standard of care for this disease and the related plasma cell disorder multiple myeloma, due to upregulation of pro-apoptotic Noxa and its inhibitory binding to MCL-1. BCL-2 inhibitors sensitize clonal plasma cells to multiple front-line therapies including bortezomib, dexamethasone and lenalidomide. Strikingly, in mice bearing AL amyloidosis cell line xenografts, single agent treatment with the BCL-2 inhibitor ABT-199 (venetoclax) produces deeper remissions than bortezomib and triples median survival. Mass spectrometry-based proteomic analysis reveals rewiring of signaling pathways regulating apoptosis, proliferation and mitochondrial metabolism between isogenic AL amyloidosis and multiple myeloma cells that divergently alter their sensitivity to therapies. These findings provide a roadmap for the use of BH3 mimetics to exploit endogenous and induced apoptotic vulnerabilities in AL amyloidosis.

Biodistribution of 131I in mice is influenced by circadian variations.

Effects of radiation and biodistribution of radionuclides are often studied in animal models. Circadian rhythm affects many biological functions and may influence the biokinetics of radionuclides and observed responses. The aim of this study was to investigate if the time during the day of 131I injection affects the biodistribution and absorbed dose to tissues in mice. Biodistribution studies were conducted on male C57BL/6 N mice for three diurnal time-series: the animals were i.v. injected with 160 kBq 131I at 8 am, 12 pm or 4 pm. The activity concentration in organs and tissues was measured at 1 h to 7 days after administration and absorbed dose at day 7 was determined. Comparison between the three time-series showed statistically significant differences in activity concentration in all investigated tissues and organs. Administration performed at 12 pm resulted in general in higher absorbed dose to the organs than injection performed at 8 am and 4 pm. Time of day of administration affects the biodistribution of 131I in mice and consequently the absorbed dose to individual organs. These findings advocate that subsequent biodistribution studies and dosimetry calculations should consider time-point of administration as a variable that could influence the results.