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Potent dendritic-cell cancer vaccines could be used to induce functional antitumour immunity without off-target toxicity.

While many functions of the p53 tumor suppressor affect mitochondrial processes, the role of altered mitochondrial physiology in a modulation of p53 response remains unclear. As mitochondrial respiration is affected in many pathologic conditions such as hypoxia and intoxications, the impaired electron transport chain could emit additional p53-inducing signals and thereby contribute to tissue damage. Here we show that a shutdown of mitochondrial respiration per se does not trigger p53 response, because inhibitors acting in the proximal and distal segments of the respiratory chain do not activate p53. However, strong p53 response is induced specifically after an inhibition of the mitochondrial cytochrome bc1 (the electron transport chain complex III). The p53 response is triggered by the deficiency in pyrimidines that is developed due to a suppression of the functionally coupled mitochondrial pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH). In epithelial carcinoma cells the activation of p53 in response to mitochondrial electron transport chain complex III inhibitors does not require phosphorylation of p53 at Serine 15 or up-regulation of p14 ARF . Instead, our data suggest a contribution of NQO1 and NQO2 in stabilization of p53 in the nuclei. The results establish the deficiency in pyrimidine biosynthesis as the cause of p53 response in the cells with impaired mitochondrial respiration.

High spliceosome activity is a dependency for cancer cells, making them more vulnerable to perturbation of the splicing machinery compared to normal cells. To identify splicing factors important for prostate cancer (PCa) fitness, we performed pooled shRNA screens in vitro and in vivo. Our screens identified heterogeneous nuclear ribonucleoprotein M (HNRNPM) as a regulator of PCa cell growth. RNA- and eCLIP-sequencing identified HNRNPM binding to transcripts of key homeostatic genes. HNRNPM binding to its targets prevents aberrant exon inclusion and backsplicing events. In both linear and circular mis-spliced transcripts, HNRNPM preferentially binds to GU-rich elements in long flanking proximal introns. Mimicry of HNRNPM-dependent linear-splicing events using splice-switching-antisense-oligonucleotides was sufficient to inhibit PCa cell growth. This suggests that PCa dependence on HNRNPM is likely a result of mis-splicing of key homeostatic coding and non-coding genes. Our results have further been confirmed in other solid tumors. Taken together, our data reveal a role for HNRNPM in supporting cancer cell fitness. Inhibition of HNRNPM activity is therefore a potential therapeutic strategy in suppressing growth of PCa and other solid tumors.

OBJECTIVES/GOALS: The major obstacle to an effective cure or remission for HIV infection is the integration of HIV into the genome of long-lived resting cells which constitute the so-called viral reservoir. With this study we want to elucidate the changes of the gut-associated HIV reservoir at different stages of viral suppression METHODS/STUDY POPULATION: Recent studies have shown that after long-term (>7 years) clinical suppression of peripheral HIV RNA, the circulating viral reservoir does not seem to decline further and, in fact may expand. The gastrointestinal associated lymphoid tissue (GALT) harbors by far the largest fraction of the latently infected cells, however not much is known about its changes over time.We thus quantified the HIV viral reservoir in the GALT by identifying HIV viral transcripts via 10X single-cell RNA sequencing at two GALT-sites in five PWH and compared the amount of HIV RNA found in the group of PWH with early (< 7years) vs late (> 7years) peripheral virological suppression (plasma HIV RNA <20copies/mL). RESULTS/ANTICIPATED RESULTS: Study participants had been diagnosed with HIV infection for a median (IQR) of 31 (32-34) years and had consistently undetectable peripheral blood HIV RNA for the previous 8 (4-15) years. In PWH with consistent viral suppression < 7yrs, 4 (2-6) HIV transcripts were identified in the ileum and 25 (13 – 38) in the colon. In PWH with consistent viral suppression > 7yrs, 0 (0-4) HIV transcripts were identified in the ileum and 7 (14-11) in the colon. Based on these preliminary results we plan to expand our cohort and confirm these results using Proviral DNA quantification. We anticipate that the viral decay in the GALT will follow a slower dynamic than what has been reported for the peripheral blood achieving a steady state after more than 7 years of peripheral viral suppression. DISCUSSION/SIGNIFICANCE: Despite the remarkable progress the survival and quality of life of PWH, after forty years from its first discovery, HIV infection remains uncurable. Considering its critical role, efforts are needed to better understand the dynamics of the GALT-associated HIV reservoir.

BackgroundAntiangiogenics combined with immune checkpoint blockade have become standard of care for recurrent endometrial cancer after standard platinum-based chemotherapy. To dissect mechanisms and define biomarkers associated with clinical outcomes to these combinations, we applied multidimensional immune monitoring to peripheral blood specimens collected from a randomized phase 2 trial of nivolumab with or without cabozantinib in 75 evaluable patients with recurrent endometrial cancer (NCI ETCTN 10104, NCT03367741). This trial demonstrated superiority of the combination to nivolumab alone.Methods and resultsUsing Olink proteomics, mass cytometry, tumor antigen-specific ELISA, and whole exome tumor sequencing, we identified longitudinal immune signatures specific to cabozantinib use, including an increase in plasma HO-1 and reduction in plasma vascular endothelial growth factor receptor 2, interleukin-12, and circulating plasmacytoid dendritic cells. Prior exposure to immunotherapy and carcinosarcoma histology had no adverse impact on clinical benefit or biomarkers, and copy-number high tumors were associated with increased plasma granzymes on combination treatment. Higher baseline plasma levels of myeloid-related markers (chemokine ligand 23/CCL23, colony-stimulating factor-1/macrophage colony-stimulating factor/CSF1) were associated with poor overall and progression-free survival, and lack of clinical benefit (defined as progressive or stable disease <6 months) following combination treatment (Kaplan-Meier, multivariate Cox, false discover rate <0.05). Patients with favorable outcomes had higher levels of activated T-cell markers (plasma ICOS-L, CD28) and exhibited spontaneous autoantibody titers to tumor antigen NY-ESO-1. Patients experiencing severe adverse events from the combination therapy had higher baseline levels of neutrophil-derived markers (CXCL1).ConclusionsOverall, this study highlights potential resistance and response mechanisms to nivolumab+cabozantinib and suggests prioritizing combination treatment in patients with activated T-cell immunogenicity profiles while exploring future combinatorial therapies targeting myeloid populations to overcome resistance.

BackgroundHigher cytotoxic T lymphocyte (CTL) numbers in the tumor microenvironment (TME) predict pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) and positive long-term outcomes in triple-negative breast cancer (TNBC). pCR to NAC is achieved only in 30–40% of patients. The combination of NAC with pembrolizumab increases the pCR rate but at the cost of immune-related adverse events (irAEs). Based on these considerations, we tested if systemic infusion of the chemokine modulatory regimen (CKM; selective toll-like receptor 3 (TLR3) agonist rintatolimod, interferon (IFN)-α2b, and cyclooxygenase-2 (COX-2) inhibitor celecoxib) regimen can be safely combined with NAC to enhance intratumoral CTL numbers and NAC effectiveness.MethodsPhase I study NCT04081389 evaluated nine patients with early-stage TNBC who received 3 weeks of paclitaxel with CKM (dose-escalation of IFN-α2b), followed by 9 weeks of paclitaxel alone, dose-dense doxorubicin and cyclophosphamide, and surgery. Primary and secondary endpoints were safety and clinical efficacy, respectively.ResultsThe combination treatment was well-tolerated with no dose-limiting toxicities or irAEs. 5/9 patients achieved pCR and one patient had microinvasive disease (ypTmic). We observed elevated IFN signature and uniform decreases in CTL numbers (average 8.3-fold) in the blood of all treated patients. This was accompanied by reciprocal uniform increases in CD8β (overall 5.9-fold), CD8α/FoxP3 (2.11-fold), and CCL5 (4.73-fold) transcripts in TME, particularly pronounced in patients with pCR. Multiplex immunohistochemistry revealed selectively increased numbers of CTL (but not regulatory T cells) in both the epithelial and stromal tumor compartments and early decreases in the numbers of αSMA+ vascular/stromal cells in the tumors of all pCR patients.ConclusionsCombined paclitaxel/CKM regimen was safe, with desirable TME changes and preliminary indications of promising pCR+ypTmic of 66%, comparable to the combination of NAC with pembrolizumab.

Myeloid cells are known to suppress antitumour immunity 1 . However, the molecular drivers of immunosuppressive myeloid cell states are not well defined. Here we used single-cell RNA sequencing of human and mouse non-small cell lung cancer (NSCLC) lesions, and found that in both species the type 2 cytokine interleukin-4 (IL-4) was predicted to be the primary driver of the tumour-infiltrating monocyte-derived macrophage phenotype. Using a panel of conditional knockout mice, we found that only deletion of the IL-4 receptor IL-4Rα in early myeloid progenitors in bone marrow reduced tumour burden, whereas deletion of IL-4Rα in downstream mature myeloid cells had no effect. Mechanistically, IL-4 derived from bone marrow basophils and eosinophils acted on granulocyte-monocyte progenitors to transcriptionally programme the development of immunosuppressive tumour-promoting myeloid cells. Consequentially, depletion of basophils profoundly reduced tumour burden and normalized myelopoiesis. We subsequently initiated a clinical trial of the IL-4Rα blocking antibody dupilumab 2 – 5 given in conjunction with PD-1/PD-L1 checkpoint blockade in patients with relapsed or refractory NSCLC who had progressed on PD-1/PD-L1 blockade alone (ClinicalTrials.gov identifier NCT05013450 ). Dupilumab supplementation reduced circulating monocytes, expanded tumour-infiltrating CD8 T cells, and in one out of six patients, drove a near-complete clinical response two months after treatment. Our study defines a central role for IL-4 in controlling immunosuppressive myelopoiesis in cancer, identifies a novel combination therapy for immune checkpoint blockade in humans, and highlights cancer as a systemic malady that requires therapeutic strategies beyond the primary disease site. Single-cell transcriptomics studies on human and mouse non-small cell lung cancer and conditional knockout mouse models show that IL-4 from bone marrow basophils drives the development of granulocyte-monocyte progenitors to myeloid cells that suppress antitumour immunity.

Sleep is integral to cardiovascular health 1 , 2 . Yet, the circuits that connect cardiovascular pathology and sleep are incompletely understood. It remains unclear whether cardiac injury influences sleep and whether sleep-mediated neural outputs contribute to heart healing and inflammation. Here we report that in humans and mice, monocytes are actively recruited to the brain after myocardial infarction (MI) to augment sleep, which suppresses sympathetic outflow to the heart, limiting inflammation and promoting healing. After MI, microglia rapidly recruit circulating monocytes to the brain’s thalamic lateral posterior nucleus (LPN) via the choroid plexus, where they are reprogrammed to generate tumour necrosis factor (TNF). In the thalamic LPN, monocytic TNF engages Tnfrsf1a -expressing glutamatergic neurons to increase slow wave sleep pressure and abundance. Disrupting sleep after MI worsens cardiac function, decreases heart rate variability and causes spontaneous ventricular tachycardia. After MI, disrupting or curtailing sleep by manipulating glutamatergic TNF signalling in the thalamic LPN increases cardiac sympathetic input which signals through the β2-adrenergic receptor of macrophages to promote a chemotactic signature that increases monocyte influx. Poor sleep in the weeks following acute coronary syndrome increases susceptibility to secondary cardiovascular events and reduces the heart’s functional recovery. In parallel, insufficient sleep in humans reprogrammes β2-adrenergic receptor-expressing monocytes towards a chemotactic phenotype, enhancing their migratory capacity. Collectively, our data uncover cardiogenic regulation of sleep after heart injury, which restricts cardiac sympathetic input, limiting inflammation and damage. Studies in humans and mice show that myocardial infarction recruits monocytes to the brain’s thalamus, promoting sleep, which in turn restricts cardiac inflammation and sympathetic signalling and assists healing.

Post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are debilitating, clinically heterogeneous and of unknown molecular etiology. A transcriptome-wide investigation was performed in 165 acutely infected hospitalized individuals who were followed clinically into the post-acute period. Distinct gene expression signatures of post-acute sequelae were already present in whole blood during acute infection, with innate and adaptive immune cells implicated in different symptoms. Two clusters of sequelae exhibited divergent plasma-cell-associated gene expression patterns. In one cluster, sequelae associated with higher expression of immunoglobulin-related genes in an anti-spike antibody titer-dependent manner. In the other, sequelae associated independently of these titers with lower expression of immunoglobulin-related genes, indicating lower non-specific antibody production in individuals with these sequelae. This relationship between lower total immunoglobulins and sequelae was validated in an external cohort. Altogether, multiple etiologies of post-acute sequelae were already detectable during SARS-CoV-2 infection, directly linking these sequelae with the acute host response to the virus and providing early insights into their development. Transcriptomic analyses of acute phase whole blood from a large cohort of patients with COVID-19 identify molecular determinants of post-infection long-term sequelae.

The Ccr4–Not complex is involved in several aspects of gene expression, including mRNA decay, translational repression and transcription. Structural, biochemical and functional analyses of the Not module, comprising the C-terminal regions of Not1, Not2 and Not5, suggest that it forms a platform for protein and nucleic acid interactions that are important for Ccr4–Not's many functions. The Ccr4–Not complex is involved in several aspects of gene expression, including mRNA decay, translational repression and transcription. We determined the 2.8-Å-resolution crystal structure of a 120-kDa core complex of the Saccharomyces cerevisiae Not module comprising the C-terminal arm of Not1, Not2 and Not5. Not1 is a HEAT-repeat scaffold. Not2 and Not5 have extended regions that wrap around Not1 and around their globular domains, the Not boxes. The Not boxes resemble Sm folds and interact with each other with a noncanonical dimerization surface. Disruption of the interactions within the ternary complex has severe effects on growth in vivo . The ternary complex forms a composite surface that binds poly(U) RNA in vitro , with a site at the Not5 Not box. The results suggest that the Not module forms a versatile platform for macromolecular interactions.