Endobronchial Inflammatory Myofibroblastic Tumour Masquerading as a Ruptured Hydatid Cyst.

Inflammatory myofibroblastic tumours (IMTs) represent a rare group of neoplastic lesions characterized by a diverse clinical presentation. Endobronchial involvement is infrequently reported, and its manifestation mimicking the symptoms of a ruptured hydatid cyst adds an additional layer of complexity to the diagnostic challenge. This case report delves into an exceptional clinical scenario where an endobronchial IMT masqueraded as a ruptured hydatid cyst, initially confounding the diagnostic team. Through a detailed examination of the patient's clinical history, radiological imaging, bronchoscopy findings and subsequent histopathological analysis, we aim to contribute to the existing medical literature and shed light on the nuances encountered in accurately identifying and differentiating these two entities.

Emerging In Vitro and In Vivo Models: Hope for the Better Understanding of Cancer Progression and Treatment.

Various cancer models have been developed to aid the understanding of the underlying mechanisms of tumor development and evaluate the effectiveness of various anticancer drugs in preclinical studies. These models accurately reproduce the critical stages of tumor initiation and development to mimic the tumor microenvironment better. Using these models for target validation, tumor response evaluation, resistance modeling, and toxicity comprehension can significantly enhance the drug development process. Herein, various in vivo or animal models are presented, typically consisting of several mice and in vitro models ranging in complexity from transwell models to spheroids and CRISPR-Cas9 technologies. While in vitro models have been used for decades and dominate the early stages of drug development, they are still limited primary to simplistic tests based on testing on a single cell type cultivated in Petri dishes. Recent advancements in developing new cancer therapies necessitate the generation of complicated animal models that accurately mimic the tumor's complexity and microenvironment. Mice make effective tumor models as they are affordable, have a short reproductive cycle, exhibit rapid tumor growth, and are simple to manipulate genetically. Human cancer mouse models are crucial to understanding the neoplastic process and basic and clinical research improvements. The following review summarizes different in vitro and in vivo metastasis models, their advantages and disadvantages, and their ability to serve as a model for cancer research.

Outcomes of Decompressive Surgery for Patients With Severe Cerebral Venous Thrombosis: DECOMPRESS2 Observational Study.

BACKGROUND: Decompressive neurosurgery is recommended for patients with cerebral venous thrombosis (CVT) who have large parenchymal lesions and impending brain herniation. This recommendation is based on limited evidence. We report long-term outcomes of patients with CVT treated by decompressive neurosurgery in an international cohort. METHODS: DECOMPRESS2 (Decompressive Surgery for Patients With Cerebral Venous Thrombosis, Part 2) was a prospective, international cohort study. Consecutive patients with CVT treated by decompressive neurosurgery were evaluated at admission, discharge, 6 months, and 12 months. The primary outcome was death or severe disability (modified Rankin Scale scores, 5-6) at 12 months. The secondary outcomes included patient and caregiver opinions on the benefits of surgery. The association between baseline variables before surgery and the primary outcome was assessed by multivariable logistic regression. RESULTS: A total of 118 patients (80 women; median age, 38 years) were included from 15 centers in 10 countries from December 2011 to December 2019. Surgery (115 craniectomies and 37 hematoma evacuations) was performed within a median of 1 day after diagnosis. At last assessment before surgery, 68 (57.6%) patients were comatose, fixed dilated pupils were found unilaterally in 27 (22.9%) and bilaterally in 9 (7.6%). Twelve-month follow-up data were available for 113 (95.8%) patients. Forty-six (39%) patients were dead or severely disabled (modified Rankin Scale scores, 5-6), of whom 40 (33.9%) patients had died. Forty-two (35.6%) patients were independent (modified Rankin Scale scores, 0-2). Coma (odds ratio, 2.39 [95% CI, 1.03-5.56]) and fixed dilated pupil (odds ratio, 2.22 [95% CI, 0.90-4.92]) were predictors of death or severe disability. Of the survivors, 56 (78.9%) patients and 61 (87.1%) caregivers expressed a positive opinion on surgery. CONCLUSIONS: Two-thirds of patients with severe CVT were alive and more than one-third were independent 1 year after decompressive surgery. Among survivors, surgery was judged as worthwhile by 4 out of 5 patients and caregivers. These results support the recommendation to perform decompressive neurosurgery in patients with CVT with impending brain herniation.

SPACe (Swift Phenotypic Analysis of Cells): an open-source, single cell analysis of Cell Painting data.

Phenotypic profiling by high throughput microscopy has become one of the leading tools for screening large sets of perturbations in cellular models. Of the numerous methods used over the years, the flexible and economical Cell Painting (CP) assay has been central in the field, allowing for large screening campaigns leading to a vast number of data-rich images. Currently, to analyze data of this scale, available open-source software ( i.e. , CellProfiler) requires computational resources that are not available to most laboratories worldwide. In addition, the image-embedded cell-to-cell variation of responses within a population, while collected and analyzed, is usually averaged and unused. Here we introduce SPACe ( S wift P henotypic A nalysis of Ce lls), an open source, Python-based platform for the analysis of single cell image-based morphological profiles produced by CP experiments. SPACe can process a typical dataset approximately ten times faster than CellProfiler on common desktop computers without loss in mechanism of action (MOA) recognition accuracy. It also computes directional distribution-based distances (Earth Mover's Distance - EMD) of morphological features for quality control and hit calling. We highlight several advantages of SPACe analysis on CP assays, including reproducibility across multiple biological replicates, easy applicability to multiple (∼20) cell lines, sensitivity to variable cell-to-cell responses, and biological interpretability to explain image-based features. We ultimately illustrate the advantages of SPACe in a screening campaign of cell metabolism small molecule inhibitors which we performed in seven cell lines to highlight the importance of testing perturbations across models.

Novel treatment with double scope technique for disconnected pancreatic duct syndrome with external pancreatic fistula.

Background and study aims External pancreatic fistula in association with disconnected pancreatic duct syndrome is a common sequelae of the percutaneous step-up approach for infected pancreatic necrosis and is associated with significant morbidity. The present study aimed to report the initial outcome of a novel technique of two-scope guided tractogastrostomy for management of this condition. Patients and methods The present study was a retrospective analysis of data from patients with external pancreatic fistula and disconnected pancreatic duct syndrome, who underwent two-scope-guided tractogastrostomy. All the patients had a 24F or larger drain placed in the left retroperitoneum. Transgastric echo endoscopy and sinus tract endoscopy were performed simultaneously to place a stent between the gastric lumen and the sinus tract. Technical success was defined as placement of the stent between the tract and the stomach. Clinical success was defined as successful removal of the percutaneous drain without the occurrence of pancreatic fluid collection, ascites, external fistula, or another intervention 12 weeks after the procedure. Results Three patients underwent two scope-guided tractogastrostomy. Technical and clinical success were achieved in all the patients. No procedure-related side effects or recurrence occurred in any of the patients. Conclusions Two-scope-guided tractogastrostomy for treatment of external pancreatic fistula due to disconnected pancreatic duct syndrome is a feasible technique and can be further evaluated.

Cancer-associated fibroblast-derived acetate promotes pancreatic cancer development by altering polyamine metabolism via the ACSS2-SP1-SAT1 axis.

The ability of tumour cells to thrive in harsh microenvironments depends on the utilization of nutrients available in the milieu. Here we show that pancreatic cancer-associated fibroblasts (CAFs) regulate tumour cell metabolism through the secretion of acetate, which can be blocked by silencing ATP citrate lyase (ACLY) in CAFs. We further show that acetyl-CoA synthetase short-chain family member 2 (ACSS2) channels the exogenous acetate to regulate the dynamic cancer epigenome and transcriptome, thereby facilitating cancer cell survival in an acidic microenvironment. Comparative H3K27ac ChIP-seq and RNA-seq analyses revealed alterations in polyamine homeostasis through regulation of SAT1 gene expression and enrichment of the SP1-responsive signature. We identified acetate/ACSS2-mediated acetylation of SP1 at the lysine 19 residue that increased SP1 protein stability and transcriptional activity. Genetic or pharmacologic inhibition of the ACSS2-SP1-SAT1 axis diminished the tumour burden in mouse models. These results reveal that the metabolic flexibility imparted by the stroma-derived acetate enabled cancer cell survival under acidosis via the ACSS2-SP1-SAT1 axis.

The MUC1-HIF-1α signaling axis regulates pancreatic cancer pathogenesis through polyamine metabolism remodeling.

Dysregulation of polyamine metabolism has been implicated in cancer initiation and progression; however, the mechanism of polyamine dysregulation in cancer is not fully understood. In this study, we investigated the role of MUC1, a mucin protein overexpressed in pancreatic cancer, in regulating polyamine metabolism. Utilizing pancreatic cancer patient data, we noted a positive correlation between MUC1 expression and the expression of key polyamine metabolism pathway genes. Functional studies revealed that knockdown of spermidine/spermine N1-acetyltransferase 1 (SAT1), a key enzyme involved in polyamine catabolism, attenuated the oncogenic functions of MUC1, including cell survival and proliferation. We further identified a regulatory axis whereby MUC1 stabilized hypoxia-inducible factor (HIF-1α), leading to increased SAT1 expression, which in turn induced carbon flux into the tricarboxylic acid cycle. MUC1-mediated stabilization of HIF-1α enhanced the promoter occupancy of the latter on SAT1 promoter and corresponding transcriptional activation of SAT1, which could be abrogated by pharmacological inhibition of HIF-1α or CRISPR/Cas9-mediated knockout of HIF1A. MUC1 knockdown caused a significant reduction in the levels of SAT1-generated metabolites, N1-acetylspermidine and N8-acetylspermidine. Given the known role of MUC1 in therapy resistance, we also investigated whether inhibiting SAT1 would enhance the efficacy of FOLFIRINOX chemotherapy. By utilizing organoid and orthotopic pancreatic cancer mouse models, we observed that targeting SAT1 with pentamidine improved the efficacy of FOLFIRINOX, suggesting that the combination may represent a promising therapeutic strategy against pancreatic cancer. This study provides insights into the interplay between MUC1 and polyamine metabolism, offering potential avenues for the development of treatments against pancreatic cancer.

High mobility group box 1 cytokine targeted topical delivery of resveratrol embedded nanoemulgel for the management of atopic dermatitis.

Resveratrol is a polyphenolic compound showing anti-inflammatory activity by inhibition of high mobility group box 1 cytokine responsible for the activation of nuclear factor-κB pathway in atopic dermatitis. To evaluate the efficacy of resveratrol through topical route we have developed resveratrol-loaded nanoemulgel for the effective management of atopic dermatitis in mice model. The resveratrol-loaded nanoemulsion (0.5%, 0.75% and 1% w/w) was optimized by spontaneous nano-emulsification. The optimized resveratrol-loaded nanoemulsions showed average globule size in the 180-230 nm range and found to be monodispersed. The resveratrol nanoemulgel was prepared with a SEPINEO™ P 600 gel base and propylene glycol. Ex vivo permeation and retention study resulted in significantly higher skin retention of resveratrol from resveratrol-loaded nanoemulgel than free resveratrol-loaded gel. Preclinical efficacy of resveratrol nanoemulgel displayed promising therapeutic outcomes where, western blotting of skin tissues disclosed a significant reduction in the relative expression of high mobility group box 1, the receptor for advanced glycation end products, toll-like receptor-4 and phosphorylated nuclear factor-κB. Further, real-time polymerase chain reaction also disclosed a significant reduction in pro-inflammatory cytokines such as thymic stromal lymphopoietin, interleukin-4, interleukin-13, interleukin-31, tumor necrosis factor-α and interleukin-6. The histopathological examination of skin sections showed improvement in the skin condition. Collectively, the findings from our study showcased the significant improvement in the atopic dermatitis skin condition in mice model after topical application of resveratrol loaded nanoemulgel.

Characterization of flavonoids with potent and subtype-selective actions on estrogen receptors alpha and beta.

The initial step in estrogen-regulated transcription is the binding of a ligand to its cognate receptors, named estrogen receptors (ERα and ERß). Phytochemicals present in foods and environment can compete with endogenous hormones to alter physiological responses. We screened 224 flavonoids in our engineered biosensor ERα and ERß PRL-array cell lines to characterize their activity on several steps of the estrogen signaling pathway. We identified 83 and 96 flavonoids that can activate ERα or ERß, respectively. While most act on both receptors, many appear to be subtype-selective, including potent flavonoids that activate ER at sub-micromolar concentrations. We employed an orthogonal assay using a transgenic zebrafish in vivo model that validated the estrogenic potential of these compounds. To our knowledge, this is the largest study thus far on flavonoids and the ER pathway, facilitating the identification of a new set of potential endocrine disruptors acting on both ERα and ERß.

eEF1A2 promotes PTEN-GSK3ß-SCF complex-dependent degradation of Aurora kinase A and is inactivated in breast cancer.

The translation elongation factor eEF1A promotes protein synthesis. Its methylation by METTL13 increases its activity, supporting tumor growth. However, in some cancers, a high abundance of eEF1A isoforms is associated with a good prognosis. Here, we found that eEF1A2 exhibited oncogenic or tumor-suppressor functions depending on its interaction with METTL13 or the phosphatase PTEN, respectively. METTL13 and PTEN competed for interaction with eEF1A2 in the same structural domain. PTEN-bound eEF1A2 promoted the ubiquitination and degradation of the mitosis-promoting Aurora kinase A in the S and G2 phases of the cell cycle. eEF1A2 bridged the interactions between the SKP1-CUL1-FBXW7 (SCF) ubiquitin ligase complex, the kinase GSK3ß, and Aurora-A, thereby facilitating the phosphorylation of Aurora-A in a degron site that was recognized by FBXW7. Genetic ablation of Eef1a2 or Pten in mice resulted in a greater abundance of Aurora-A and increased cell cycling in mammary tumors, which was corroborated in breast cancer tissues from patients. Reactivating this pathway using fimepinostat, which relieves inhibitory signaling directed at PTEN and increases FBXW7 expression, combined with inhibiting Aurora-A with alisertib, suppressed breast cancer cell proliferation in culture and tumor growth in vivo. The findings demonstrate a therapeutically exploitable, tumor-suppressive role for eEF1A2 in breast cancer.

Metabolomic Investigations into Hypoxia-Mediated Metabolic Reprogramming of Pancreatic Cancer Cells.

Hypoxia is a crucial microenvironmental factor that defines tumor cell growth and aggressiveness. Cancer cells adapt to hypoxia by altering their metabolism. These alterations impact various cellular and physiological functions, including energy metabolism, vascularization, invasion and metastasis, genetic instability, cell immortalization, stem cell maintenance, and resistance to chemotherapy (Li et al. Technol Cancer Res Treat 20:15330338211036304, 2021). Hypoxia-inducible factor-1α (HIF-1α) is known to be a critical regulator of glycolysis that directly regulates the transcription of multiple key enzymes of the glycolysis pathway. Moreover, HIF-1α stabilization can be directly modulated by TCA-derived metabolites, including 2-ketoglutarate and succinate (Infantino et al, Int J Mol Sci 22(22), https://doi.org/10.3390/ijms22115703 , 2021). Overall, the molecular mechanisms underlying the adaptation of cellular metabolism to hypoxia impact the metabolic phenotype of cancer cells. Such adaptations include increased glucose uptake, increased lactate production, and increased levels of other metabolites that stabilize HIF-1α, leading to a vicious circle of hypoxia-induced tumor growth.

Performance evaluation of data embedding schemes for two-dimensional display field communication.

Display field communication (DFC) is an unobtrusive display-to-camera technology that transmits data within the frequency domain of images, ensuring that the embedded data are hidden and do not disrupt the viewing experience. The display embeds data into image frames, while the receiver captures the display and extracts it. Two-dimensional DFC (2D-DFC) focuses on embedding data in the width and height of an image. This study explores two methods to minimize the error rate in 2D-DFC without affecting the quality of the displayed image. The orthogonal method embeds data in the orthogonal direction of an image. On the other hand, the diagonal embedding method strategically embeds the data in the diagonal direction. Experiments show the diagonal method maintains a higher peak signal-to-noise ratio and surpasses the orthogonal embedding method in terms of bit error rate. 2D-DFC is expected to have practical applications in digital signage, advertising and informational displays at airports and train stations, as well as at large-scale displays for events, sports arenas, and performance venues.

Clinical course and molecular characterization of human Bocavirus associated with acute lower respiratory tract infections in tertiary care hospital of north India.

Respiratory samples from 139 hospitalized children were screened for the Human Bocavirus (HBoV) genome. Positive samples were sequenced for partial VP1/VP2 gene followed by molecular and phylogenetic analyses. HBoV positivity was noted in 7.2% (10/139) patients. All HBoV positive children presented with fever followed by cough and respiratory distress (90%; 9/10). Three children developed multisystemic viral illness with one fatality. Eight children required intensive care management and mechanical ventilation required for 5 children. Nucleotide percent identity of partial VP1/VP2 gene of HBoV study strains were ranging from 97.52% to 99.67%. Non-synonymous amino acid mutations in VP1 protein revealed T591S (n=8) and Y517S (n=1) mutations in comparison to HBoVSt1 strain where N475S (n=8) and S591T (n=2) mutations in comparison to HBoVSt2 strain. One study strain showed A556P, H556P, I561S and M562R non-synonymous mutations. All the study strains belong to HBoV1 type. Seven HBoV strains belong to same lineage and three belong to another lineage. For evolutionary dynamics, GTR+I substitution model with uncorrelated relaxed lognormal clock and Bayesian Skyline tree prior showed 9.0 x 10-4 [95% HPD interval: 3.1 x10-6, 2.1 x 10-3] nucleotide substitutions/site/year. The clinical suspicion and virological screening is necessary for identification HBoV in children.

Papillary Tumors of Pineal Region: A Single-Center Experience in Management of 11 Cases.

BACKGROUND: Papillary tumors of pineal region (PTPR) comprise a very rare subset of pineal region tumors that have been recently described. Literature on the management and outcome of PTPR is scarce owing to the rarity of these tumors. To address this lacuna, we analyzed our experience in management of PTPR. METHODS: We retrospectively analyzed the outcome of 11 patients with histopathologically proven PTPR who underwent surgical excision at our center. RESULTS: Mean patient age was 33.3 years (range, 12-45 years), and male-to-female ratio was 1.75:1. Headache was the most common presentation followed by visual disturbances, altered sensorium, Perinaud syndrome, and seizures. Cerebrospinal fluid diversion was required in 6 patients. Krause approach was the most common approach used for tumor excision (9/11 cases). There was no perioperative mortality. Two patients were lost to follow-up. In the remaining 9 patients, the average follow-up period was 45 months (range, 12-79 months). On first postoperative magnetic resonance imaging, 8 patients showed no evidence of residual tumor (gross total resection), while 1 patient had small residual tumor (near-total resection) that remained stable during follow-up. Four patients underwent adjuvant chemoradiotherapy. None of the patients developed recurrence during follow-up. CONCLUSIONS: PTPR are a rare subgroup of pineal region tumors with distinct cells of origin but presentation similar to other pineal region tumors. Surgical resection constitutes the mainstay of management, and the extent of resection appears to be the most important determinant of prognosis. The role of adjuvant therapy still needs to be determined.

Correction of pediatric cervical kyphosis: our experience and systematic-literature review.

BACKGROUND: Pediatric cervical kyphosis is a distinct entity with diverse etiology (congenital, syndromic, traumatic, metabolic or neoplastic). Surgical correction in pediatric population is challenging due to their growing spine and low blood volume. PURPOSE: To analyse their presentation, surgical techniques and outcome of pediatric cervical kyphosis and systematically review the pertinent literature. DESIGN: Retrospective study. PATIENT SAMPLE: 16 patients aged ≤ 18 years who underwent correction for cervical kyphosis between 2009 and 2021. OUTCOME MEASURES: Nurick's grading, mJOA score and Global cobb's angle. METHODS: Clinical parameters (Nurick grading and mJOA score) were noted from database on admission and on follow-up at 6 months. Radiological parameters of assessment included Global Cobb's angle. The C2-C7 Cobb angle was the angle of C2 vertebra lower end plate and C7 vertebra lower end plate. For C1-2 kyphosis, anterior border of C1 and anterior border of C2 angle was taken. Radiographic parameters were studied on CT and radiographs of cervical spine to assess for stability, the degree of deformity correction and fusion status at 6 months follow-up. RESULTS: 16 patients with mean age of 14.2 ± 3 years (9 syndromic, 4 post-traumatic, 2 metabolic and 1 post-laminectomy). All underwent surgical correction, 6 underwent Antero-posterior spinal fusion, 6 underwent Posterior spinal fusion and 4 underwent Anterior spinal fusion. There was significant clinical improvement postoperatively with-Nurick grade (pre vs. post: 2.8 vs. 1.8, p = 0.004), mJOA score (pre vs. post: 11.3 vs. 14, p = 0.003). There was significant deformity correction of Cobb's angle from 40.7 ± 26.5° to 14.9 ± 10° (p = 0.001). Early complications included intraoperative hemodynamic instability (3) and wound complication (1). Mean follow-up was 76.9 ± 59.3 months. CONCLUSION: Pediatric cervical kyphosis is a debilitating condition which are managed surgically. Approach has to be individualized to the pathology and good results can be achieved. Patients should be screened for syndromic association and followed-up regularly.

Marine diatom algae cultivation in simulated dairy wastewater and biomass valorization.

Liquid byproducts and organic wastes generated from dairy processing units contribute as the largest source of industrial food wastewater. Though bacteria-mediated treatment strategies are largely implemented, a more effective and innovative management system is needed of the hour. Thus, the current study involves the cultivation of centric diatoms, Chaetoceros gracilis, and Thalassiosira weissflogii in simulated dairy wastewater (SDWW) formulated using varying amounts of milk powder with artificial seawater f/2 media (ASW). The results revealed that cell density and biomass productivity were highest in the 2.5% SDWW treatment cultures of both the strains, the maximum being in C. gracilis (7.5 × 106 cells mL - 1; 21.1 mg L-1 day-1). Conversely, the total carotenoid, chrysolaminarin, and phenol content were negatively impacted by SDWW. However, a considerable enhancement in the total lipid content was reported in the 2.5% SDWW culture of both species. Furthermore, the fatty acid profiling revealed that though the total polyunsaturated fatty acid (PUFA) content was highest in the control setups, the total mono polyunsaturated fatty acid (MUFA) content was higher in the 5% SDWW setups (30.66% in C. gracilis and 33.21% in T. weissflogii). In addition to it, in the cultures utilizing energy from external carbon sources provided by SDWW, the biodiesel produced was also enhanced owing to the heightened cetane number. Thus, the current study evidently highlights the organic carbon acquisition potential of marine diatoms with the scope of providing sustainable biorefinery.

Dasatinib loaded mucoadhesive lecithin-chitosan hybrid nanoparticles for its augmented oral delivery, in-vitro efficacy and safety.

Dasatinib (DAS) is an oral tyrosine kinase inhibitor; however, its efficacy is significantly subsided by its low oral bioavailability. The present research aimed to improve DAS's oral delivery and efficacy in triple-negative breast cancer by fabricating its mucoadhesive lecithin-chitosan hybrid nanoparticles (DAS-L/CS-NPs). DAS-L/CS-NPs were optimized using Box-Behnken design which showed mean particle size and percent entrapment efficiency of 179.7 ± 5.42 nm and 64.65 ± 0.06 %, respectively. DAS-L/CS-NPs demonstrated sustained release profile in different release media up to 48 h and showed 10 times higher apparent permeability coefficient and flux than free DAS suspension. The binding of DAS-L/CS-NPs to the mucus layer was demonstrated via ex-vivo mucoadhesion study and change in absorbance using turbidimetry. In cell culture studies, DAS-L/CS-NPs revealed a 4.14-fold decrease in IC50, significantly higher cellular uptake and mitochondrial membrane depolarization, 3.82-fold increased reactive oxygen species generation and 2.10-fold enhanced apoptosis in MDA-MB-231 cells than free DAS. In in-vivo pharmacokinetic assessment, DAS-L/CS-NPs showed a 5.08-fold and 3.74-fold rise in AUC (0-t) and Cmax than free DAS suspension, respectively. An acute toxicity study revealed a good safety profile of DAS-L/CS-NPs. In a nutshell, proposed hybrid nanoparticles are promising carriers for improved oral delivery of poorly water-soluble drugs.

DHODH inhibition enhances the efficacy of immune checkpoint blockade by increasing cancer cell antigen presentation.

Pyrimidine nucleotide biosynthesis is a druggable metabolic dependency of cancer cells, and chemotherapy agents targeting pyrimidine metabolism are the backbone of treatment for many cancers. Dihydroorotate dehydrogenase (DHODH) is an essential enzyme in the de novo pyrimidine biosynthesis pathway that can be targeted by clinically approved inhibitors. However, despite robust preclinical anticancer efficacy, DHODH inhibitors have shown limited single-agent activity in phase 1 and 2 clinical trials. Therefore, novel combination therapy strategies are necessary to realize the potential of these drugs. To search for therapeutic vulnerabilities induced by DHODH inhibition, we examined gene expression changes in cancer cells treated with the potent and selective DHODH inhibitor brequinar (BQ). This revealed that BQ treatment causes upregulation of antigen presentation pathway genes and cell surface MHC class I expression. Mechanistic studies showed that this effect is 1) strictly dependent on pyrimidine nucleotide depletion, 2) independent of canonical antigen presentation pathway transcriptional regulators, and 3) mediated by RNA polymerase II elongation control by positive transcription elongation factor B (P-TEFb). Furthermore, BQ showed impressive single-agent efficacy in the immunocompetent B16F10 melanoma model, and combination treatment with BQ and dual immune checkpoint blockade (anti-CTLA-4 plus anti-PD-1) significantly prolonged mouse survival compared to either therapy alone. Our results have important implications for the clinical development of DHODH inhibitors and provide a rationale for combination therapy with BQ and immune checkpoint blockade.