Citations

Radiotherapy (RT) of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)–expressing CRC cells systemically. However, abscopal tumor remissions are extremely rare, and the postirradiation immune escape mechanisms in CRC remain elusive. Here, we found that irradiated CRC cells used ATR-mediated DNA repair signaling pathway to up-regulate both CD47 and PD-L1, which through engagement of SIRPα and PD-1, respectively, prevented phagocytosis by antigen-presenting cells and thereby limited TAA cross-presentation and innate immune activation. This postirradiation CD47 and PD-L1 up-regulation was observed across various human solid tumor cells. Concordantly, rectal cancer patients with poor responses to neoadjuvant RT exhibited significantly elevated postirradiation CD47 levels. The combination of RT, anti-SIRPα, and anti–PD-1 reversed adaptive immune resistance and drove efficient TAA cross-presentation, resulting in robust TAA-specific CD8 T cell priming, functional activation of T effectors, and increased T cell clonality and clonal diversity. We observed significantly higher complete response rates to RT/anti-SIRPα/anti–PD-1 in both irradiated and abscopal tumors and prolonged survival in three distinct murine CRC models, including a cecal orthotopic model. The efficacy of triple combination therapy was STING dependent as knockout animals lost most benefit of adding anti-SIRPα and anti–PD-1 to RT. Despite activation across the myeloid stroma, the enhanced dendritic cell function accounts for most improvements in CD8 T cell priming. These data suggest ATR-mediated CD47 and PD-L1 up-regulation as a key mechanism restraining radiation-induced immune priming. RT combined with SIRPα and PD-1 blockade promotes robust antitumor immune priming, leading to systemic tumor regressions.

5011 Background: Emerging data suggest metastasis-directed therapy (MDT) improves outcomes in patients with oligometastatic castration-sensitive prostate cancer (omCSPC). Prostate-specific membrane antigen positron emission tomography (PSMA-PET/CT) can detect occult metastatic disease and has been proposed as a biomarker for treatment response. Herein we identify and validate a PSMA-PET biomarker for clinical outcomes following MDT in omCSPC. Methods: This was an international multi-institutional retrospective study of two completely independent cohorts of men with omCSPC, defined as ≤3 lesions, treated with metastasis-directed stereotactic ablative radiation therapy (SABR) who underwent PSMA-PET/CT prior to and 3-6 months after treatment. Pre- and post-SABR PSMA-PET/CT standardized uptake value (SUV) was measured for all lesions and PSMA response defined discretely using a cutpoint of ≥ 30% decrease in SUVmax. PSMA-PET response was correlated with lesion local control (LLC), radiographic progression-free survival (rPFS) defined using conventional and PET imaging, and metastasis-free survival (MFS) defined by conventional imaging alone. Results: A total of 131 patients with 261 treated metastases were included in the analysis, with median follow-up of 29 months (IQR 18.5-41.3). Following SABR, 78.4% of lesions experienced a partial or complete PSMA response. Multivariable analysis demonstrated SUV response significantly associated with improved LLC (HR = 9.97, 95%CI 3.92-25.4; p < 0.01). Patients with PSMA response in all lesions experienced significantly better rPFS (HR = 0.49, 95%CI 0.26-0.92; p = 0.03) compared to their counterparts and this maintained significance within both the discovery (p < 0.01) and validation (p = 0.01) cohorts. Within the discovery cohort, patients with PSMA response in all lesions also experienced significantly improved MFS (HR = 0.24, 95%CI 0.07-0.85; p = 0.03); analysis of the independent validation cohort is ongoing. Conclusions: Following SABR, PSMA-PET response is a robust and externally validated radiographic biomarker for rPFS and appears to be associated with MFS pending validation. This approach holds promise for guiding clinical management of omCSPC.

The endoplasmic reticulum (ER) is an intracellular organelle that fosters the correct folding of linear polypeptides and proteins, a process tightly governed by the ER‐resident enzymes and chaperones. Failure to shape the proper 3‐dimensional architecture of proteins culminates in the accumulation of misfolded or unfolded proteins within the ER, disturbs ER homeostasis, and leads to canonically defined ER stress. Recent studies have elucidated that cellular perturbations, such as lipotoxicity, can also lead to ER stress. In response to ER stress, the unfolded protein response (UPR) is activated to reestablish ER homeostasis (“adaptive UPR”), or, conversely, to provoke cell death when ER stress is overwhelmed and sustained (“maladaptive UPR”). It is well documented that ER stress contributes to the onset and progression of multiple hepatic pathologies including NAFLD, alcohol‐associated liver disease, viral hepatitis, liver ischemia, drug toxicity, and liver cancers. Here, we review key studies dealing with the emerging role of ER stress and the UPR in the pathophysiology of liver diseases from cellular, murine, and human models. Specifically, we will summarize current available knowledge on pharmacological and non‐pharmacological interventions that may be used to target maladaptive UPR for the treatment of nonmalignant liver diseases.

Albumin-interferon-α (alb-IFN) is a novel recombinant protein derived from IFN-α2b genetically fused to human albumin. The resulting single polypeptide combines in one molecule the antiviral properties of IFN-α with the long serum half-life of albumin. IFN-mediated biological responses stem from the engagement of IFN-α with its target receptor and subsequent modulation of IFN-specific gene (ISG) expression. To evaluate the pharmacodynamics of alb-IFN during the Phase I/II study conducted in patients with chronic hepatitis C (CHC) who had previously failed IFN-α-containing regimens, ISG induction was evaluated in peripheral blood and compared with antiviral response. Whole blood was obtained at day 0, day 7 and day 28 from 21 patients enrolled in the higher dose (500–900 μg) alb-IFN cohort, who received two injections on day 0 and day 14. Taqman real-time PCR was used to assess candidate ISG expression. There was sustained induction on day 7 and day 28 of the ISG's OAS1, IRF-7, IFI44 and IFI27. Although all patients showed a molecular response to alb-IFN, individual variability in pretreatment gene expression levels and fold of modulation during treatment was observed. At day 28, induction of OAS1, IFI44 and IRF7 showed pairwise correlation in individual patients ( P<0.05). Moreover, the induction of expression at day 28, and pretreatment levels of OAS1 and IFI44 correlated with hepatitis C virus RNA reduction at day 28 ( P<0.05). In conclusion, alb-IFN demonstrated robust induction of ISG that was consistent with the response associated with an IFN-α.

Abstract Objective. 4D-CBCT provides phase-resolved images valuable for radiomics analysis for outcome prediction throughout treatment courses. However, 4D-CBCT suffers from streak artifacts caused by under-sampling, which severely degrades the accuracy of radiomic features. Previously we developed group-patient-trained deep learning methods to enhance the 4D-CBCT quality for radiomics analysis, which was not optimized for individual patients. In this study, a patient-specific model was developed to further improve the accuracy of 4D-CBCT based radiomics analysis for individual patients. Approach. This patient-specific model was trained with intra-patient data. Specifically, patient planning 4D-CT was augmented through image translation, rotation, and deformation to generate 305 CT volumes from 10 volumes to simulate possible patient positions during the onboard image acquisition. 72 projections were simulated from 4D-CT for each phase and were used to reconstruct 4D-CBCT using FDK back-projection algorithm. The patient-specific model was trained using these 305 paired sets of patient-specific 4D-CT and 4D-CBCT data to enhance the 4D-CBCT image to match with 4D-CT images as ground truth. For model testing, 4D-CBCT were simulated from a separate set of 4D-CT scan images acquired from the same patient and were then enhanced by this patient-specific model. Radiomics features were then extracted from the testing 4D-CT, 4D-CBCT, and enhanced 4D-CBCT image sets for comparison. The patient-specific model was tested using 4 lung-SBRT patients’ data and compared with the performance of the group-based model. The impact of model dimensionality, region of interest (ROI) selection, and loss function on the model accuracy was also investigated. Main results. Compared with a group-based model, the patient-specific training model further improved the accuracy of radiomic features, especially for features with large errors in the group-based model. For example, the 3D whole-body and ROI loss-based patient-specific model reduces the errors of the first-order median feature by 83.67%, the wavelet LLL feature maximum by 91.98%, and the wavelet HLL skewness feature by 15.0% on average for the four patients tested. In addition, the patient-specific models with different dimensionality (2D versus 3D) or loss functions (L1 versus L1 + VGG + GAN) achieved comparable results for improving the radiomics accuracy. Using whole-body or whole-body+ROI L1 loss for the model achieved better results than using the ROI L1 loss alone as the loss function. Significance. This study demonstrated that the patient-specific model is more effective than the group-based model on improving the accuracy of the 4D-CBCT radiomic features analysis, which could potentially improve the precision for outcome prediction in radiotherapy.

CD36 is a microvascular endothelial cell (MVEC) receptor mediating angiostatic activity of TSP-1 and related proteins. We previously reported that lysophosphatidic acid (LPA), a biologically active lipid signaling mediator, inhibited MVEC CD36 transcription via PKD-1 signaling. Moreover, CD36 transcriptional repression abolished endothelial cell responses to TSP-1 in vitro and in vivo . We now show with luciferase transfection assays that LPA exposure significantly suppressed CD36 promoter activity in MVEC. Co-exposure to class II HDAC inhibitors SAHA or TSA reversed the inhibition of promoter activity and restored transcription. HDAC7 knockdown by shRNA also attenuated LPA-suppressed CD36 promoter activity and mRNA levels. Mechanistically, FoxO1 was found to directly interact with putative FoxO1 binding sites (FHRE) in proximal promoter in vitro by avidin-biotin-conjugated DNA-binding assay, and in vivo by chromatin IP assay. Furthermore, FHRE mutations significantly attenuated the promoter activity. Western blots and immunofluorescence microscopy showed increased nuclear accumulation of PKD-1, FoxO1 and HADC7 after MVEC were exposed to LPA. Co-IP of nuclear extracts showed a physical interaction of HDAC7 with FoxO1 that was attenuated with PKD-1 knockdown. These data demonstrate that HDAC7 modulation by LPA receptor/PKD-1 signaling pathway represses FoxO1-mediated CD36 transcriptional activity. Additionally, angiogenic transcription profiling of endothelial cells revealed significantly increased mRNA expression of 17 angiogenic genes in response to LPA, including ephrin B2 expression that was confirmed by Western Blots. Transduction of constitutively active PKD-1 (PKD-CA) into EC also increased ephrin B2 expression. Functionally, PKD-CA overexpression promoted branching morphogenesis of arterial endothelial cells in a three-dimensional spheroid assay. The data indicate that PKD-1 is a potent angiogenic and arteriogenic kinase in EC by down-regulating CD36 transcription and promoting arteriogenesis. PKD-1-FoxO1-CD36 signaling axis may have potential as an important target in cardiovascular ischemia and malignant tumors.

Abstract Background: The etiology of colorectal cancer is not fully understood. Methods: Using genetic variants and metabolomics data including 217 metabolites from the Framingham Heart Study (n = 1,357), we built genetic prediction models for circulating metabolites. Models with prediction R2 &gt; 0.01 (Nmetabolite = 58) were applied to predict levels of metabolites in two large consortia with a combined sample size of approximately 46,300 cases and 59,200 controls of European and approximately 21,700 cases and 47,400 controls of East Asian (EA) descent. Genetically predicted levels of metabolites were evaluated for their associations with colorectal cancer risk in logistic regressions within each racial group, after which the results were combined by meta-analysis. Results: Of the 58 metabolites tested, 24 metabolites were significantly associated with colorectal cancer risk [Benjamini–Hochberg FDR (BH-FDR) &lt; 0.05] in the European population (ORs ranged from 0.91 to 1.06; P values ranged from 0.02 to 6.4 × 10−8). Twenty one of the 24 associations were replicated in the EA population (ORs ranged from 0.26 to 1.69, BH-FDR &lt; 0.05). In addition, the genetically predicted levels of C16:0 cholesteryl ester was significantly associated with colorectal cancer risk in the EA population only (OREA: 1.94, 95% CI, 1.60−2.36, P = 2.6 × 10−11; OREUR: 1.01, 95% CI, 0.99−1.04, P = 0.3). Nineteen of the 25 metabolites were glycerophospholipids and triacylglycerols (TAG). Eighteen associations exhibited significant heterogeneity between the two racial groups (PEUR-EA-Het &lt; 0.005), which were more strongly associated in the EA population. This integrative study suggested a potential role of lipids, especially certain glycerophospholipids and TAGs, in the etiology of colorectal cancer. Conclusions: This study identified potential novel risk biomarkers for colorectal cancer by integrating genetics and circulating metabolomics data. Impact: The identified metabolites could be developed into new tools for risk assessment of colorectal cancer in both European and EA populations.

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with a dismal prognosis. Although combined treatment with gemcitabine and albumin-bound paclitaxel has improved the prognosis of PDAC, both intrinsic and acquired chemoresistance cloud the outcomes. Hence, there is an urgent need to explore new therapeutic targets and formulate innovative strategies for the more effective treatment of PDAC.Methods: We transduced pancreatic cancer cells with a protein kinase library, and transfected cells were selected by puromycin treatment, followed by continuous exposure to vehicle control or gemcitabine/paclitaxel chemotherapy for 21 days. Next-generation sequencing as well as MAGeCK-VISPR analysis were performed to the identify candidate genes. Finally, we used the CRISPR-Cas9 to knockout the target gene, confirming that it is a viable target for overcoming chemoresistance in vivo and in vitro.Results: We identified several cell cycle checkpoint kinases and DNA damage-related kinases as targets for overcoming chemoresistance. Among them, cyclin-dependent kinase 7 (CDK7) ranked highly in both screenings. We demonstrated that both gene knockout and pharmacological inhibition of CDK7 by THZ1 result in cell cycle arrest, apoptosis induction. Furthermore, THZ1 synergized with gemcitabine and paclitaxel in vitro and in vivo, resulting in enhanced antitumor effects.Conclusions: Our findings support the application of CRISPR-Cas9 screening in identifying novel therapeutic targets and provide new strategies for overcoming chemoresistance in pancreatic cancer.

AbstractPurposeTo demonstrate the feasibility of simultaneous dual‐contrast imaging in a large animal using a newly developed dual‐source energy‐integrating detector (EID)‐based multi‐energy computed tomography (MECT) system.MethodsTwo imaging tasks that may have potential clinical applications were investigated: head/neck (HN) CT angiography (CTA)/CT venography (CTV) with iodine and gadolinium, and small bowel imaging with iodine and bismuth in domestic swine. Dual‐source X‐ray beam configurations of 70 kV + Au120/Sn120 kV and 70 kV + Au140/Sn140 kV were used for the HN‐CTA/CTV and small bowel imaging studies, respectively. A test bolus scan was performed for each study. The regions of interest (ROIs) in the carotid artery and jugular vein for HN‐CTA/CTV imaging and abdominal aorta for small bowel imaging were used to determine the time‐attenuation curves, based on which the timing for contrast injection and the CT scan was determined. In the HN‐CTA/CTV study, an MECT scan was performed at the time point corresponding to the optimal arterial enhancement by iodine and the optimal venous enhancement by gadolinium. In the small bowel imaging study, an MECT scan was performed at the optimal time point to simultaneously capture the mesenteric arterial enhancement of iodine and the enteric enhancement of bismuth. Image‐based material decomposition was performed to decompose different materials for each study. To quantitatively characterize contrast material separation and misclassification, two ROIs on left common carotid artery and left internal jugular vein in HN‐CTA/CTV imaging and three ROIs on superior mesenteric artery, ileal lumen, and collapsed ileum (ileal wall) in small bowel imaging were placed to measure the mean concentration values and the standard deviations.ResultsIn the HN‐CTA/CTV study, common carotid arteries containing iodine and internal/external jugular veins containing gadolinium were clearly delineated from each other. Fine vessels such as cephalic veins and branches of external jugular veins were noticeable but clear visualization was hindered by image noise in gadolinium‐specific (CTV) images, as reviewed by a neuroradiologist. In the small bowel imaging study, the mesenteric arteries and collapsed bowel wall containing iodine and the small bowel loops containing bismuth were clearly distinctive from each other in the iodine‐ and bismuth‐specific images after material decomposition, as reviewed by an abdominal radiologist. Quantitative analyses showed that the misclassifications between the two contrast materials were less than 1.7 and 0.1 mg/ml for CTA/CTV and small bowel imaging studies, respectively.ConclusionsFeasibility of simultaneous CTA/CTV imaging in head and neck with iodine and gadolinium and simultaneous imaging of arterial and enteric phases of small bowel with iodine and bismuth, using a dual‐source EID‐MECT system, was demonstrated in a swine study. Compared to iodine and gadolinium in CTA/CTV, better delineation and classification of iodine and bismuth in small bowel imaging were achieved mainly due to wider separation between the corresponding two K‐edge energies.