Publications by authors named "Sanjiv S Gambhir"

435 Publications

Real-time point-of-care total protein measurement with a miniaturized optoelectronic biosensor and fast fluorescence-based assay.

Biosens Bioelectron 2021 May 26;180:112823. Epub 2020 Nov 26.

Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA. Electronic address:

Measurement of total protein in urine is key to monitoring kidney health in diabetes. However, most total protein assays are performed using large, expensive laboratory chemistry analyzers that are not amenable to point-of-care analysis or home monitoring and cannot provide real-time readouts. We developed a miniaturized optoelectronic biosensor using a vertical cavity surface-emitting laser (VCSEL), coupled with a fast protein assay based on protein-induced fluorescence enhancement (PIFE), that can dynamically measure protein concentrations in protein-spiked buffer, serum, and urine in seconds with excellent sensitivity (urine LOD = 0.023 g/L, LOQ = 0.075 g/L) and over a broad range of physiologically relevant concentrations. Comparison with gold standard clinical assays and standard fluorimetry tools showed that the sensor can accurately and reliably quantitate total protein in clinical urine samples from patients with diabetes. Our VCSEL biosensor is amenable to integration with miniaturized electronics, which could afford a portable, low-cost, easy-to-use device for sensitive, accurate, and real-time total protein measurements from small biofluid volumes.
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http://dx.doi.org/10.1016/j.bios.2020.112823DOI Listing
May 2021

Molecular imaging of a fluorescent antibody against epidermal growth factor receptor detects high-grade glioma.

Sci Rep 2021 Mar 11;11(1):5710. Epub 2021 Mar 11.

Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, 94305, USA.

The prognosis for high-grade glioma (HGG) remains dismal and the extent of resection correlates with overall survival and progression free disease. Epidermal growth factor receptor (EGFR) is a biomarker heterogeneously expressed in HGG. We assessed the feasibility of detecting HGG using near-infrared fluorescent antibody targeting EGFR. Mice bearing orthotopic HGG xenografts with modest EGFR expression were imaged in vivo after systemic panitumumab-IRDye800 injection to assess its tumor-specific uptake macroscopically over 14 days, and microscopically ex vivo. EGFR immunohistochemical staining of 59 tumor specimens from 35 HGG patients was scored by pathologists and expression levels were compared to that of mouse xenografts. Intratumoral distribution of panitumumab-IRDye800 correlated with near-infrared fluorescence and EGFR expression. Fluorescence distinguished tumor cells with 90% specificity and 82.5% sensitivity. Target-to-background ratios peaked at 14 h post panitumumab-IRDye800 infusion, reaching 19.5 in vivo and 7.6 ex vivo, respectively. Equivalent or higher EGFR protein expression compared to the mouse xenografts was present in 77.1% HGG patients. Age, combined with IDH-wildtype cerebral tumor, was predictive of greater EGFR protein expression in human tumors. Tumor specific uptake of panitumumab-IRDye800 provided remarkable contrast and a flexible imaging window for fluorescence-guided identification of HGGs despite modest EGFR expression.
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http://dx.doi.org/10.1038/s41598-021-84831-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7952570PMC
March 2021

A mathematical model of tumor regression and recurrence after therapeutic oncogene inactivation.

Sci Rep 2021 Jan 14;11(1):1341. Epub 2021 Jan 14.

Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, CA, USA.

The targeted inactivation of individual oncogenes can elicit regression of cancers through a phenomenon called oncogene addiction. Oncogene addiction is mediated by cell-autonomous and immune-dependent mechanisms. Therapeutic resistance to oncogene inactivation leads to recurrence but can be counteracted by immune surveillance. Predicting the timing of resistance will provide valuable insights in developing effective cancer treatments. To provide a quantitative understanding of cancer response to oncogene inactivation, we developed a new 3-compartment mathematical model of oncogene-driven tumor growth, regression and recurrence, and validated the model using a MYC-driven transgenic mouse model of T-cell acute lymphoblastic leukemia. Our mathematical model uses imaging-based measurements of tumor burden to predict the relative number of drug-sensitive and drug-resistant cancer cells in MYC-dependent states. We show natural killer (NK) cell adoptive therapy can delay cancer recurrence by reducing the net-growth rate of drug-resistant cells. Our studies provide a novel way to evaluate combination therapy for personalized cancer treatment.
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http://dx.doi.org/10.1038/s41598-020-78947-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7809285PMC
January 2021

A protease-activated, near-infrared fluorescent probe for early endoscopic detection of premalignant gastrointestinal lesions.

Proc Natl Acad Sci U S A 2021 Jan;118(1)

Department of Radiology, Bio-X Program and Molecular Imaging Program, Stanford University School of Medicine, Stanford, CA 94305;

Fluorescence imaging is currently being actively developed for surgical guidance; however, it remains underutilized for diagnostic and endoscopic surveillance of incipient colorectal cancer in high-risk patients. Here we demonstrate the utility and potential for clinical translation of a fluorescently labeled cathepsin-activated chemical probe to highlight gastrointestinal lesions. This probe stays optically dark until it is activated by proteases produced by tumor-associated macrophages and accumulates within the lesions, enabling their detection using an endoscope outfitted with a fluorescence detector. We evaluated the probe in multiple murine models and a human-scale porcine model of gastrointestinal carcinogenesis. The probe provides fluorescence-guided surveillance of gastrointestinal lesions and augments histopathological analysis by highlighting areas of dysplasia as small as 400 µm, which were visibly discernible with significant tumor-to-background ratios, even in tissues with a background of severe inflammation and ulceration. Given these results, we anticipate that this probe will enable sensitive fluorescence-guided biopsies, even in the presence of highly inflamed colorectal tissue, which will improve early diagnosis to prevent gastrointestinal cancers.
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http://dx.doi.org/10.1073/pnas.2008072118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817203PMC
January 2021

PET Imaging of TIGIT Expression on Tumor-Infiltrating Lymphocytes.

Clin Cancer Res 2021 Apr 6;27(7):1932-1940. Epub 2021 Jan 6.

Department of Radiology, Stanford University, Stanford, California.

Purpose: Therapeutic checkpoint inhibitors on tumor-infiltrating lymphocytes (TIL) are being increasingly utilized in the clinic. The T-cell immunoreceptor with Ig and ITIM domains (TIGIT) is an inhibitory receptor expressed on T and natural killer cells. The TIGIT signaling pathway is an alternative target for checkpoint blockade to current PD-1/CTLA-4 strategies. Elevated TIGIT expression in the tumor microenvironment correlates with better therapeutic responses to anti-TIGIT therapies in preclinical models. Therefore, quantifying TIGIT expression in tumors is necessary for determining whether a patient may respond to anti-TIGIT therapy. PET imaging of TIGIT expression on TILs can therefore aid diagnosis and in monitoring therapeutic responses.

Experimental Design: Antibody-based TIGIT imaging radiotracers were developed with the PET radionuclides copper-64 (Cu) and zirconium-89 (Zr). characterization of the imaging probes was followed by evaluation in both xenografts and syngeneic tumor models in mouse.

Results: Two anti-TIGIT probes were developed and exhibited immunoreactivity of >72%, serum stability of >95%, and specificity for TIGIT with both mouse TIGIT-expressing HeLa cells and -activated primary splenocytes. , the Zr-labeled probe demonstrated superior contrast than the Cu probe due to Zr's longer half-life matching the TIGIT antibody's pharmacokinetics. The Zr probe was used to quantify TIGIT expression on TILs in B16 melanoma in immunocompetent mice and confirmed by flow cytometry.

Conclusions: This study develops and validates novel TIGIT-specific Cu and Zr PET probes for quantifying TIGIT expression on TILs for diagnosis of patient selection for anti-TIGIT therapies.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-2725DOI Listing
April 2021

Giant Magnetoresistive Nanosensor Analysis of Circulating Tumor DNA Epidermal Growth Factor Receptor Mutations for Diagnosis and Therapy Response Monitoring.

Clin Chem 2021 Mar;67(3):534-542

Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA.

Background: Liquid biopsy circulating tumor DNA (ctDNA) mutational analysis holds great promises for precision medicine targeted therapy and more effective cancer management. However, its wide adoption is hampered by high cost and long turnaround time of sequencing assays, or by inadequate analytical sensitivity of existing portable nucleic acid tests to mutant allelic fraction in ctDNA.

Methods: We developed a ctDNA Epidermal Growth Factor Receptor (EGFR) mutational assay using giant magnetoresistive (GMR) nanosensors. This assay was validated in 36 plasma samples of non-small cell lung cancer patients with known EGFR mutations. We assessed therapy response through follow-up blood draws, determined concordance between the GMR assay and radiographic response, and ascertained progression-free survival of patients.

Results: The GMR assay achieved analytical sensitivities of 0.01% mutant allelic fraction. In clinical samples, the assay had 87.5% sensitivity (95% CI = 64.0-97.8%) for Exon19 deletion and 90% sensitivity (95% CI = 69.9-98.2%) for L858R mutation with 100% specificity; our assay detected T790M resistance with 96.3% specificity (95% CI = 81.7-99.8%) with 100% sensitivity. After 2 weeks of therapy, 10 patients showed disappearance of ctDNA by GMR (predicted responders), whereas 3 patients did not (predicted nonresponders). These predictions were 100% concordant with radiographic response. Kaplan-Meier analysis showed responders had significantly (P < 0.0001) longer PFS compared to nonresponders (N/A vs. 12 weeks, respectively).

Conclusions: The GMR assay has high diagnostic sensitivity and specificity and is well suited for detecting EGFR mutations at diagnosis and noninvasively monitoring treatment response at the point-of-care.
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http://dx.doi.org/10.1093/clinchem/hvaa307DOI Listing
March 2021

Tumor treating fields (TTFields) impairs aberrant glycolysis in glioblastoma as evaluated by [F]DASA-23, a non-invasive probe of pyruvate kinase M2 (PKM2) expression.

Neoplasia 2021 01 20;23(1):58-67. Epub 2020 Nov 20.

Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA; Departments of Bioengineering and Materials Science & Engineering, Stanford University, Stanford, CA, USA.

Despite the anti-proliferative and survival benefits from tumor treating fields (TTFields) in human glioblastoma (hGBM), little is known about the effects of this form of alternating electric fields therapy on the aberrant glycolysis of hGBM. [F]FDG is the most common radiotracer in cancer metabolic imaging, but its utility in hGBM is impaired due to high glucose uptake in normal brain tissue. With TTFields, radiochemistry, Western blot, and immunofluorescence microscopy, we identified pyruvate kinase M2 (PKM2) as a biomarker of hGBM response to therapeutic TTFields. We used [F]DASA-23, a novel radiotracer that measures PKM2 expression and which has been shown to be safe in humans, to detect a shift away from hGBM aberrant glycolysis in response to TTFields. Compared to unexposed hGBM, [F]DASA-23 uptake was reduced in hGBM exposed to TTFields (53%, P< 0.05) or temozolomide chemotherapy (33%, P > 0.05) for 3 d. A 6-d TTFields exposure resulted in a 31% reduction (P = 0.043) in 60-min uptake of [F]DASA-23. [F]DASA-23 was retained after a 10 but not 30-min wash-out period. Compared to [F]FDG, [F]DASA-23 demonstrated a 4- to 9-fold greater uptake, implying an improved tumor-to-background ratio. Furthermore, compared to no-TTFields exposure, a 6-d TTFields exposure caused a 35% reduction in [F]DASA-23 30-min uptake compared to only an 8% reduction in [F]FDG 30-min uptake. Quantitative Western blot analysis and qualitative immunofluorescence for PKM2 confirmed the TTFields-induced reduction in PKM2 expression. This is the first study to demonstrate that TTFields impairs hGBM aberrant glycolytic metabolism through reduced PKM2 expression, which can be non-invasively detected by the [F]DASA-23 radiotracer.
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http://dx.doi.org/10.1016/j.neo.2020.11.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7689378PMC
January 2021

Author Correction: Non-Invasive Photoacoustic Imaging of In Vivo Mice with Erythrocyte Derived Optical Nanoparticles to Detect CAD/MI.

Sci Rep 2020 Oct 30;10(1):19102. Epub 2020 Oct 30.

Molecular Imaging Program at Stanford, Stanford University School of Medicine, Stanford, CA, USA.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-75966-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599324PMC
October 2020

Two Patient Studies of a Companion Diagnostic Immuno-Positron Emission Tomography (PET) Tracer for Measuring Human CA6 Expression in Cancer for Antibody Drug Conjugate (ADC) Therapy.

Mol Imaging 2020 Jan-Dec;19:1536012120939398

Department of Radiology, Bio-X program, Molecular Imaging Program at Stanford (MIPS), Division of Nuclear Medicine and Molecular Imaging, Stanford University, Stanford, CA, USA.

An antigen binding fragment (BFab) derived from a tumor-associated mucin 1-sialoglycotope antigen (CA6) targeting antibody (huDS6) was engineered. We synthesized a companion diagnostic positron emission tomography (PET) tracer by radiolabeling BFab with [Cu] to measure CA6 expression on cancer tissues prior to anti-human CA6 (huDS6-DM4 antibody-drug conjugate) therapy for ovarian and breast cancer patients. After chemotherapy, the ovarian patient received PET scan with F-2-fluoro-2-deoxyglucose ([F]FDG: 10 mCi), followed by [Cu]-DOTA-BFab ([Cu]BFab; 5.5 mCi) 1 week later for PET scanning of CA6 expression and subsequent surgery. The breast cancer patient was treated with chemotherapy before primary tumor resection and subsequent [F]FDG-PET scan. 4 weeks later the patient received of [Cu]BFab (11.7 mCi) for CA6 PET scan. Whole body [F]FDG-PET of the breast cancer patient indicated FDG-avid tumor metastases to the liver, bilateral hila and thoracic spine, but no uptake was observed for the ovarian patient. Each patient was also imaged by PET/CT with [Cu]BFab at 1 and 24 hours after tracer administration. The [Cu]BFab tracer was well tolerated by both patients without adverse effects, and no significant tracer uptake was observed in both patients. Immunohistochemistry (IHC) data indicated CA6 expressions were weak to intermediate and matched with the [Cu]BFab-PET signals.
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http://dx.doi.org/10.1177/1536012120939398DOI Listing
October 2020

Molecular Imaging of Chimeric Antigen Receptor T Cells by ICOS-ImmunoPET.

Clin Cancer Res 2021 Feb 21;27(4):1058-1068. Epub 2020 Oct 21.

Division of Blood and Marrow Transplantation, Department of Medicine, Stanford University, Stanford, California.

Purpose: Immunomonitoring of chimeric antigen receptor (CAR) T cells relies primarily on their quantification in the peripheral blood, which inadequately quantifies their biodistribution and activation status in the tissues. Noninvasive molecular imaging of CAR T cells by PET is a promising approach with the ability to provide spatial, temporal, and functional information. Reported strategies rely on the incorporation of reporter transgenes or biolabeling, significantly limiting the application of CAR T-cell molecular imaging. In this study, we assessed the ability of antibody-based PET (immunoPET) to noninvasively visualize CAR T cells.

Experimental Design: After analyzing human CAR T cells and from patient samples to identify candidate targets for immunoPET, we employed a syngeneic, orthotopic murine tumor model of lymphoma to assess the feasibility of tracking of CAR T cells by immunoPET using the Zr-DFO-anti-ICOS tracer, which we have previously reported.

Results: Analysis of human CD19-CAR T cells during activation identified the Inducible T-cell COStimulator (ICOS) as a potential target for immunoPET. In a preclinical tumor model, Zr-DFO-ICOS mAb PET-CT imaging detected significantly higher signal in specific bone marrow-containing skeletal sites of CAR T-cell-treated mice compared with controls. Importantly, administration of ICOS-targeting antibodies at tracer doses did not interfere with CAR T-cell persistence and function.

Conclusions: This study highlights the potential of ICOS-immunoPET imaging for monitoring of CAR T-cell therapy, a strategy readily applicable to both commercially available and investigational CAR T cells..
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http://dx.doi.org/10.1158/1078-0432.CCR-20-2770DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7887027PMC
February 2021

Biodegradable fluorescent nanoparticles for endoscopic detection of colorectal carcinogenesis.

Adv Funct Mater 2019 Dec 10;29(51). Epub 2019 Oct 10.

Molecular Imaging Program at Stanford University (MIPS), Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA.

Early and comprehensive endoscopic detection of colonic dysplasia - the most clinically significant precursor lesion to colorectal adenocarcinoma - provides an opportunity for timely, minimally-invasive intervention to prevent malignant transformation. Here, the development and evaluation of biodegradable near-infrared fluorescent silica nanoparticles (FSN) is described that have the potential to improve adenoma detection during fluorescence-assisted white-light colonoscopic surveillance in rodent and human-scale models of colorectal carcinogenesis. FSNs are biodegradable (t of 2.7 weeks), well-tolerated, and enable detection and delineation of adenomas as small as 0.5 mm with high tumor-to-background ratios. Furthermore, in the human-scale, porcine model, the clinical feasibility and benefit of using FSN-guided detection of colorectal adenomas using video-rate fluorescence-assisted white-light endoscopy is demonstrated. Since nanoparticles of similar size (., 100-150-nm) or composition (., silica, silica/gold hybrid) have already been successfully translated to the clinic, and, clinical fluorescent/white light endoscopy systems are becoming more readily available, there is a viable path towards clinical translation of the proposed strategy for early colorectal cancer detection and prevention in high-risk patients.
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http://dx.doi.org/10.1002/adfm.201904992DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7546531PMC
December 2019

PET Reporter Gene Imaging and Ganciclovir-Mediated Ablation of Chimeric Antigen Receptor T Cells in Solid Tumors.

Cancer Res 2020 11 21;80(21):4731-4740. Epub 2020 Sep 21.

Department of Bioengineering, Stanford University School of Medicine, Stanford, California.

Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. In addition, the potential adverse effects of CAR T cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a PET reporter gene for imaging of T-cell trafficking in patients with brain tumor. The HSV1-TK enzyme can act as a suicide gene of transduced cells through treatment with the prodrug ganciclovir. Here we report the molecular engineering, imaging, and ganciclovir-mediated destruction of B7H3 CAR T cells incorporating a mutated version of the HSV1-tk gene (sr39tk) with improved enzymatic activity for ganciclovir. The sr39tk gene did not affect B7H3 CAR T-cell functionality and and studies in osteosarcoma models showed no significant effect on B7H3 CAR T-cell antitumor activity. PET/CT imaging with 9-(4-[F]-fluoro-3-[hydroxymethyl]butyl)guanine ([F]FHBG) of B7H3-sr39tk CAR T cells in an orthotopic model of osteosarcoma revealed tumor homing and systemic immune expansion. Bioluminescence and PET imaging of B7H3-sr39tk CAR T cells confirmed complete tumor ablation with intraperitoneal ganciclovir administration. This imaging and suicide ablation system can provide insight into CAR T-cell migration and proliferation during clinical trials while serving as a suicide switch to limit potential toxicities. SIGNIFICANCE: This study showcases the only genetically engineered system capable of serving the dual role both as an effective PET imaging reporter and as a suicide switch for CAR T cells.
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http://dx.doi.org/10.1158/0008-5472.CAN-19-3579DOI Listing
November 2020

Intravital imaging reveals synergistic effect of CAR T-cells and radiation therapy in a preclinical immunocompetent glioblastoma model.

Oncoimmunology 2020 05 13;9(1):1757360. Epub 2020 May 13.

Department of Bioengineering, Stanford University School of Medicine, Stanford, CA.

Recent advances in novel immune strategies, particularly chimeric antigen receptor (CAR)-bearing T-cells, have shown limited efficacy against glioblastoma (GBM) in clinical trials. We currently have an incomplete understanding of how these emerging therapies integrate with the current standard of care, specifically radiation therapy (RT). Additionally, there is an insufficient number of preclinical studies monitoring these therapies with high spatiotemporal resolution. To address these limitations, we report the first longitudinal fluorescence-based intravital microscopy imaging of CAR T-cells within an orthotopic GBM preclinical model to illustrate the necessity of RT for complete therapeutic response. Additionally, we detail the first usage of murine-derived CAR T-cells targeting the disialoganglioside GD2 in an immunocompetent tumor model. Cell culture assays demonstrated substantial GD2 CAR T-cell-mediated killing of murine GBM cell lines SB28 and GL26 induced to overexpress GD2. Complete antitumor response in advanced syngeneic orthotopic models of GBM was achieved only when a single intravenous dose of GD2 CAR T-cells was following either sub-lethal whole-body irradiation or focal RT. Intravital microscopy imaging successfully visualized CAR T-cell homing and T-cell mediated apoptosis of tumor cells in real-time within the tumor stroma. Findings indicate that RT allows for rapid CAR T-cell extravasation from the vasculature and expansion within the tumor microenvironment, leading to a more robust and lasting immunologic response. These exciting results highlight potential opportunities to improve intravenous adoptive T-cell administration in the treatment of GBM through concurrent RT. Additionally, they emphasize the need for advancements in immunotherapeutic homing to and extravasation through the tumor microenvironment.
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http://dx.doi.org/10.1080/2162402X.2020.1757360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7458609PMC
May 2020

Plasmonic and Electrostatic Interactions Enable Uniformly Enhanced Liquid Bacterial Surface-Enhanced Raman Scattering (SERS).

Nano Lett 2020 10 4;20(10):7655-7661. Epub 2020 Oct 4.

Department of Materials Science and Engineering, Stanford University School of Engineering, Stanford, California 94305, United States.

Surface-enhanced Raman spectroscopy (SERS) is a promising cellular identification and drug susceptibility testing platform, provided it can be performed in a controlled liquid environment that maintains cell viability. We investigate bacterial liquid-SERS, studying plasmonic and electrostatic interactions between gold nanorods and bacteria that enable uniformly enhanced SERS. We synthesize five nanorod sizes with longitudinal plasmon resonances ranging from 670 to 860 nm and characterize SERS signatures of Gram-negative and and Gram-positive and bacteria in water. Varying the concentration of bacteria and nanorods, we achieve large-area SERS enhancement that is independent of nanorod resonance and bacteria type; however, bacteria with higher surface charge density exhibit significantly higher SERS signal. Using cryo-electron microscopy and zeta potential measurements, we show that the higher signal results from attraction between positively charged nanorods and negatively charged bacteria. Our robust liquid-SERS measurements provide a foundation for bacterial identification and drug testing in biological fluids.
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http://dx.doi.org/10.1021/acs.nanolett.0c03189DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564787PMC
October 2020

Visualization of Activated T Cells by OX40-ImmunoPET as a Strategy for Diagnosis of Acute Graft-versus-Host Disease.

Cancer Res 2020 11 8;80(21):4780-4790. Epub 2020 Sep 8.

Department of Radiology, Molecular Imaging Program at Stanford (MIPS), Stanford University School of Medicine, Stanford, California.

Graft-versus-host disease (GvHD) is a major complication of allogeneic hematopoietic cell transplantation (HCT), mediated primarily by donor T cells that become activated and attack host tissues. Noninvasive strategies detecting T-cell activation would allow for early diagnosis and possibly more effective management of HCT recipients. PET imaging is a sensitive and clinically relevant modality ideal for GvHD diagnosis, and there is a strong rationale for the use of PET tracers that can monitor T-cell activation and expansion with high specificity. The TNF receptor superfamily member OX40 (CD134) is a cell surface marker that is highly specific for activated T cells, is upregulated during GvHD, and mediates disease pathogenesis. We recently reported the development of an antibody-based activated T-cell imaging agent targeting OX40. In the present study, we visualize the dynamics of OX40 expression in an MHC-mismatch mouse model of acute GvHD using OX40-immunoPET. This approach enabled visualization of T-cell activation at early stages of disease, prior to overt clinical symptoms with high sensitivity and specificity. This study highlights the potential utility of the OX40 PET imaging as a new strategy for GvHD diagnosis and therapy monitoring. SIGNIFICANCE: OX40-immunoPET imaging is a promising noninvasive strategy for early detection of GvHD, capable of detecting signs of GvHD pathology even prior to the development of overt clinical symptoms.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-1149DOI Listing
November 2020

Discovery and Optimization of Small-Molecule Ligands for V-Domain Ig Suppressor of T-Cell Activation (VISTA).

J Am Chem Soc 2020 09 10;142(38):16194-16198. Epub 2020 Sep 10.

Bio-X Program and Molecular Imaging Program at Stanford (MIPS), Stanford University, Stanford, California 94305, United States.

V-domain Ig suppressor of T-cell activation (VISTA) is an immune checkpoint that affects the ability of T-cells to attack tumors. A FRET-based high throughput screening identified NSC622608 as the first small-molecule ligand for VISTA. Investigation of the interaction of NSC622608 with VISTA using STD NMR and molecular modeling enabled the identification of a potential binding site in VISTA for NSC622608. Screening NSC622608 against a library of single-point VISTA mutants revealed the key residues in VISTA interacting with NSC622608. Further structural optimization resulted in a lead with submicromolar VISTA binding affinity. The lead compound blocked VISTA signaling in vitro, enhanced T-cell proliferation, and restored T-cell activation in the presence of VISTA-expressing cancer cell lines. This work would enable future development of small molecules targeting VISTA as immunomodulators and imaging probes.
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http://dx.doi.org/10.1021/jacs.0c07276DOI Listing
September 2020

Initial evaluation of (4S)-4-(3-[F]fluoropropyl)-L-glutamate (FSPG) PET/CT imaging in patients with head and neck cancer, colorectal cancer, or non-Hodgkin lymphoma.

EJNMMI Res 2020 Aug 28;10(1):100. Epub 2020 Aug 28.

Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.

Purpose: (4S)-4-(3-[F]Fluoropropyl)-L-glutamic acid ([F]FSPG) measures system x transporter activity and shows promise for oncologic imaging. We present data on tumor uptake of this radiopharmaceutical in human subjects with head and neck cancer (HNC), colorectal cancer (CRC), and non-Hodgkin lymphoma (NHL).

Methods: A total of 15 subjects with HNC (n = 5), CRC (n = 5), or NHL (n = 5) were recruited (mean age 66.2 years, range 44-87 years). 301.4 ± 28.1 MBq (8.1 ± 0.8 mCi) of [F]FSPG was given intravenously to each subject, and 3 PET/CT scans were obtained 0-2 h post-injection. All subjects also had a positive [F]FDG PET/CT scan within 1 month prior to the [F]FSPG PET scan. Semi-quantitative and visual comparisons of the [F]FSPG and [F]FDG scans were performed.

Results: [F]FSPG showed strong uptake in all but one HNC subject. The lack of surrounding brain uptake facilitated tumor delineation in the HNC patients. [F]FSPG also showed tumor uptake in all CRC subjects, but variable uptake in the NHL subjects. While the absolute [F]FDG SUV values were comparable or higher than [F]FSPG, the tumor-to-background SUV ratios were greater with [F]FSPG than [F]FDG.

Conclusions: [F]FSPG PET/CT showed promising results across 15 subjects with 3 different cancer types. Concordant visualization was mostly observed between [F]FSPG and [F]FDG PET/CT images, with some inter- and intra-individual uptake variability potentially reflecting differences in tumor biology. The tumor-to-background ratios were greater with [F]FSPG than [F]FDG in the cancer types evaluated. Future studies based on larger numbers of subjects and those with a wider array of primary and recurrent or metastatic tumors are planned to further evaluate the utility of this novel tracer.
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http://dx.doi.org/10.1186/s13550-020-00678-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7455665PMC
August 2020

Reduction Triggered Polymerization in Living Mice.

J Am Chem Soc 2020 09 31;142(36):15575-15584. Epub 2020 Aug 31.

Molecular Imaging Program at Stanford, Bio-X Program, Department of Radiology, School of medicine, Stanford University, Stanford, California 94305, United States.

"Smart" biomaterials that are responsive to physiological or biochemical stimuli have found many biomedical applications for tissue engineering, therapeutics, and molecular imaging. In this work, we describe polymerization of activatable biorthogonal small molecules in response to a reducing environment change . We designed a carbohydrate linker- and cyanobenzothiazole-cysteine condensation reaction-based small molecule scaffold that can undergo rapid condensation reaction upon physiochemical changes (such as a reducing environment) to form polymers (pseudopolysaccharide). The fluorescent and photoacoustic properties of a fluorophore-tagged condensation scaffold before and after the transformation have been examined with a dual-modality optical imaging method. These results confirmed the polymerization of this probe after both local and systemic administration in living mice.
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http://dx.doi.org/10.1021/jacs.0c07594DOI Listing
September 2020

Clinical Evaluation of (4S)-4-(3-[F]Fluoropropyl)-L-glutamate (F-FSPG) for PET/CT Imaging in Patients with Newly Diagnosed and Recurrent Prostate Cancer.

Clin Cancer Res 2020 Oct 21;26(20):5380-5387. Epub 2020 Jul 21.

Molecular Imaging Program at Stanford (MIPS), Department of Radiology, Stanford University, Stanford, California.

Purpose: (4S)-4-(3-[F]Fluoropropyl)--glutamic acid (F-FSPG) is a radiopharmaceutical for PET imaging of system x activity, which can be upregulated in prostate cancer. We present data on the first evaluation of patients with newly diagnosed or recurrent prostate cancer with this radiopharmaceutical.

Experimental Design: Ten patients with primary and 10 patients with recurrent prostate cancer were enrolled in this prospective multicenter study. After injection of 300 MBq of F-FSPG, three whole-body PET/CT scans were obtained. Visual analysis was compared with step-section histopathology when available as well as other imaging studies and clinical outcomes. Metabolic parameters were measured semiquantitatively. Expression levels of xCT and CD44 were evaluated by IHC for patients with available tissue samples.

Results: F-FSPG PET showed high tumor-to-background ratios with a relatively high tumor detection rate on a per-patient (89%) and per-lobe (87%) basis. The sensitivity was slightly higher with imaging at 105 minutes in comparison with 60 minutes. The maximum standardized uptake values (SUV) for cancer was significantly higher than both normal ( < 0.005) and benign pathology ( = 0.011), while there was no significant difference between normal and benign pathology ( = 0.120). In the setting of recurrence, agreement with standard imaging was demonstrated in 7 of 9 patients (78%) and 13 of 18 lesions (72%), and revealed true local recurrence in a discordant case. F-FSPG accumulation showed moderate correlation with CD44 expression.

Conclusions: F-FSPG is a promising tumor imaging agent for PET that seems to have favorable biodistribution and high cancer detection rate in patients with prostate cancer. Further studies are warranted to determine the diagnostic value for both initial staging and recurrence, and how it compares with other investigational radiotracers and conventional imaging modalities.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-0644DOI Listing
October 2020

Isotopically Encoded Nanotags for Multiplexed Ion Beam Imaging.

Adv Mater Technol 2020 Jul 6;5(7). Epub 2020 May 6.

Department of Radiology, Stanford University School of Medicine, Stanford, CA 94305, USA.

High-dimensional profiling of markers and analytes using approaches, such as barcoded fluorescent imaging with repeated labeling and mass cytometry has allowed visualization of biological processes at the single-cell level. To address limitations of sensitivity and mass-channel capacity, a nanobarcoding platform is developed for multiplexed ion beam imaging (MIBI) using secondary ion beam spectrometry that utilizes fabricated isotopically encoded nanotags. Use of combinatorial isotope distributions in 100 nm sized nanotags expands the labeling palette to overcome the spectral bounds of mass channels. As a proof-of-principle, a four-digit (i.e., 0001-1111) barcoding scheme is demonstrated to detect 16 variants of H, F, Br, and I elemental barcode sets that are encoded in silica nanoparticle matrices. A computational debarcoding method and an automated machine learning analysis approach are developed to extract barcodes for accurate quantification of spatial nanotag distributions in large ion beam imaging areas up to 0.6 mm. Isotopically encoded nanotags should boost the performance of mass imaging platforms, such as MIBI and other elemental-based bioimaging approaches.
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http://dx.doi.org/10.1002/admt.202000098DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7357881PMC
July 2020

New synthesis of 6″-[ F]fluoromaltotriose for positron emission tomography imaging of bacterial infection.

J Labelled Comp Radiopharm 2020 09 21;63(11):466-475. Epub 2020 Jul 21.

Bio-X Program and Molecular Imaging Program at Stanford (MIPS), Stanford University, Stanford, California, USA.

6″-[ F]fluoromaltotriose is a positron emission tomography tracer that can differentiate between bacterial infection and inflammation in vivo. Bacteria-specific uptake of 6″-[ F]fluoromaltotriose is attributed to the targeting of maltodextrin transporter in bacteria that is absent in mammalian cells. Herein, we report a new synthesis of 6″-[ F]fluoromaltotriose as a key step for its clinical translation. In comparison with the previously reported synthesis, the new synthesis features unambiguous assignment of the fluorine-18 position on the maltotriose unit. The new method utilizes direct fluorination of 2″,3″,4″-tri-O-acetyl-6″-O-trifyl-α-D-glucopyranosyl-(1-4)-O-2',3',6'-tri-O-acetyl-α-D-glucopyranosyl-(1-4)-1,2,3,6-tetra-O-acetyl-D-glucopyranose followed by basic hydrolysis. Radiolabeling of the new maltotriose triflate precursor proceeds using a single HPLC purification step, which results in shorter reaction time in comparison with the previously reported synthesis. Successful synthesis of 6″-[ F]fluoromaltotriose has been achieved in 3.5 ± 0.3% radiochemical yield (decay corrected, n = 7) and radiochemical purity above 95%. The efficient radiosynthesis of 6″-[ F]fluoromaltotriose would be critical in advancing this positron emission tomography tracer into clinical trials for imaging bacterial infections.
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http://dx.doi.org/10.1002/jlcr.3868DOI Listing
September 2020

Toward the Clinical Development and Validation of a Thy1-Targeted Ultrasound Contrast Agent for the Early Detection of Pancreatic Ductal Adenocarcinoma.

Invest Radiol 2020 11;55(11):711-721

From the Department of Radiology, Molecular Imaging Program at Stanford, Stanford University, Palo Alto, CA.

Early detection of pancreatic ductal adenocarcinoma (PDAC) represents the most significant step toward the treatment of this aggressive lethal disease. Previously, we engineered a preclinical Thy1-targeted microbubble (MBThy1) contrast agent that specifically recognizes Thy1 antigen overexpressed in the vasculature of murine PDAC tissues by ultrasound (US) imaging. In this study, we adopted a single-chain variable fragment (scFv) site-specific bioconjugation approach to construct clinically translatable MBThy1-scFv and test for its efficacy in vivo in murine PDAC imaging, and functionally evaluated the binding specificity of scFv ligand to human Thy1 in patient PDAC tissues ex vivo.

Materials And Methods: We recombinantly expressed the Thy1-scFv with a carboxy-terminus cysteine residue to facilitate its thioether conjugation to the PEGylated MBs presenting with maleimide functional groups. After the scFv-MB conjugations, we tested binding activity of the MBThy1-scFv to MS1 cells overexpressing human Thy1 (MS1Thy1) under liquid shear stress conditions in vitro using a flow chamber setup at 0.6 mL/min flow rate, corresponding to a wall shear stress rate of 100 seconds, similar to that in tumor capillaries. For in vivo Thy1 US molecular imaging, MBThy1-scFv was tested in the transgenic mouse model (C57BL/6J - Pdx1-Cre; KRas; Ink4a/Arf) of PDAC and in control mice (C57BL/6J) with L-arginine-induced pancreatitis or normal pancreas. To facilitate its clinical feasibility, we further produced Thy1-scFv without the bacterial fusion tags and confirmed its recognition of human Thy1 in cell lines by flow cytometry and in patient PDAC frozen tissue sections of different clinical grades by immunofluorescence staining.

Results: Under shear stress flow conditions in vitro, MBThy1-scFv bound to MS1Thy1 cells at significantly higher numbers (3.0 ± 0.8 MB/cell; P < 0.01) compared with MBNontargeted (0.5 ± 0.5 MB/cell). In vivo, MBThy1-scFv (5.3 ± 1.9 arbitrary units [a.u.]) but not the MBNontargeted (1.2 ± 1.0 a.u.) produced high US molecular imaging signal (4.4-fold vs MBNontargeted; n = 8; P < 0.01) in the transgenic mice with spontaneous PDAC tumors (2-6 mm). Imaging signal from mice with L-arginine-induced pancreatitis (n = 8) or normal pancreas (n = 3) were not significantly different between the two MB constructs and were significantly lower than PDAC Thy1 molecular signal. Clinical-grade scFv conjugated to Alexa Fluor 647 dye recognized MS1Thy1 cells but not the parental wild-type cells as evaluated by flow cytometry. More importantly, scFv showed highly specific binding to VEGFR2-positive vasculature and fibroblast-like stromal components surrounding the ducts of human PDAC tissues as evaluated by confocal microscopy.

Conclusions: Our findings summarize the development and validation of a clinically relevant Thy1-targeted US contrast agent for the early detection of human PDAC by US molecular imaging.
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http://dx.doi.org/10.1097/RLI.0000000000000697DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541735PMC
November 2020

The Project Baseline Health Study: a step towards a broader mission to map human health.

NPJ Digit Med 2020 5;3:84. Epub 2020 Jun 5.

Duke University, School of Medicine, Durham, NC USA.

The Project Baseline Health Study (PBHS) was launched to map human health through a comprehensive understanding of both the health of an individual and how it relates to the broader population. The study will contribute to the creation of a biomedical information system that accounts for the highly complex interplay of biological, behavioral, environmental, and social systems. The PBHS is a prospective, multicenter, longitudinal cohort study that aims to enroll thousands of participants with diverse backgrounds who are representative of the entire health spectrum. Enrolled participants will be evaluated serially using clinical, molecular, imaging, sensor, self-reported, behavioral, psychological, environmental, and other health-related measurements. An initial deeply phenotyped cohort will inform the development of a large, expanded virtual cohort. The PBHS will contribute to precision health and medicine by integrating state of the art testing, longitudinal monitoring and participant engagement, and by contributing to the development of an improved platform for data sharing and analysis.
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http://dx.doi.org/10.1038/s41746-020-0290-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7275087PMC
June 2020

PET Imaging of the Natural Killer Cell Activation Receptor NKp30.

J Nucl Med 2020 09 12;61(9):1348-1354. Epub 2020 Jun 12.

Department of Radiology, Stanford University, Stanford, California

Redirecting the immune system in cancer treatment has led to remarkable responses in a subset of patients. Natural killer (NK) cells are innate lymphoid cells being explored as they engage tumor cells in different mechanisms compared with T cells, which could be exploited for treatment of nonresponders to current immunotherapies. NK cell therapies are monitored through measuring peripheral NK cell concentrations or changes in tumor volume over time. The former does not detect NK cells at the tumor site, and the latter is inaccurate for immunotherapies because of pseudoprogression. Therefore, new imaging methods are required as companion diagnostics for optimizing immunotherapies. In this study, we developed and completed preclinical in vivo validation of 2 antibody-based PET probes specific for NKp30, an activation natural cytotoxicity receptor expressed by human NK cells. Quantitative, multicolor flow cytometry during a variety of NK cell activation conditions was completed on primary human NK cells and the NK92MI cell line. Human renal cell carcinoma (RCC) tumors were stained for the NK cell receptors CD56, NKp30, and NKp46 to determine expression on tumor-infiltrating NK cells. An NKp30 antibody was radiolabeled with Cu or Zr and evaluated in subcutaneous xenografts and adoptive cell transfer mouse models. Quantitative flow cytometry showed consistent expression of the NKp30 receptor during different activation conditions. NKp30 and NKp46 costained in RCC samples, demonstrating the expression of these receptors on tumor-infiltrating NK cells in human tumors, whereas tumor cells in one RCC sample expressed the peripheral NK marker CD56. Both PET tracers showed high stability and specificity in vitro and in vivo. Notably, Zr-NKp30Ab had higher on-target contrast than Cu-NKp30Ab at their respective terminal time points. Cu-NKp30Ab delineated NK cell trafficking to the liver and spleen in an adoptive cell transfer model. The consistent expression of NKp30 on NK cells makes it an attractive target for quantitative imaging. Immunofluorescence staining on human RCC samples demonstrated the advantages of NKp30 targeting versus CD56 for detection of tumor infiltrating NK cells. This work advances PET imaging of NK cells and supports the translation of imaging agents for immunotherapy monitoring.
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http://dx.doi.org/10.2967/jnumed.119.233163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456168PMC
September 2020

Low-frequency ultrasound-mediated cytokine transfection enhances T cell recruitment at local and distant tumor sites.

Proc Natl Acad Sci U S A 2020 06 19;117(23):12674-12685. Epub 2020 May 19.

Molecular Imaging Program at Stanford, Stanford University, Stanford, CA 94305;

Robust cytotoxic T cell infiltration has proven to be difficult to achieve in solid tumors. We set out to develop a flexible protocol to efficiently transfect tumor and stromal cells to produce immune-activating cytokines, and thus enhance T cell infiltration while debulking tumor mass. By combining ultrasound with tumor-targeted microbubbles, membrane pores are created and facilitate a controllable and local transfection. Here, we applied a substantially lower transmission frequency (250 kHz) than applied previously. The resulting microbubble oscillation was significantly enhanced, reaching an effective expansion ratio of 35 for a peak negative pressure of 500 kPa in vitro. Combining low-frequency ultrasound with tumor-targeted microbubbles and a DNA plasmid construct, 20% of tumor cells remained viable, and ∼20% of these remaining cells were transfected with a reporter gene both in vitro and in vivo. The majority of cells transfected in vivo were mucin 1/CD45 tumor cells. Tumor and stromal cells were then transfected with plasmid DNA encoding IFN-β, producing 150 pg/10 cells in vitro, a 150-fold increase compared to no-ultrasound or no-plasmid controls and a 50-fold increase compared to treatment with targeted microbubbles and ultrasound (without IFN-β). This enhancement in secretion exceeds previously reported fourfold to fivefold increases with other in vitro treatments. Combined with intraperitoneal administration of checkpoint inhibition, a single application of IFN-β plasmid transfection reduced tumor growth in vivo and recruited efficacious immune cells at both the local and distant tumor sites.
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http://dx.doi.org/10.1073/pnas.1914906117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293655PMC
June 2020

Reconstructed Apoptotic Bodies as Targeted "Nano Decoys" to Treat Intracellular Bacterial Infections within Macrophages and Cancer Cells.

ACS Nano 2020 05 4;14(5):5818-5835. Epub 2020 May 4.

Department of Radiology, Molecular Imaging Program at Stanford (MIPS), Stanford University School of Medicine, Stanford University, 3155 Porter Drive, Palo Alto, California 94305, United States.

() is a highly pathogenic facultative anaerobe that in some instances resides as an intracellular bacterium within macrophages and cancer cells. This pathogen can establish secondary infection foci, resulting in recurrent systemic infections that are difficult to treat using systemic antibiotics. Here, we use reconstructed apoptotic bodies (ReApoBds) derived from cancer cells as "nano decoys" to deliver vancomycin intracellularly to kill by targeting inherent "eat me" signaling of ApoBds. We prepared ReApoBds from different cancer cells (SKBR3, MDA-MB-231, HepG2, U87-MG, and LN229) and used them for vancomycin delivery. Physicochemical characterization showed ReApoBds size ranges from 80 to 150 nm and vancomycin encapsulation efficiency of 60 ± 2.56%. We demonstrate that the loaded vancomycin was able to kill intracellular efficiently in an model of infected RAW-264.7 macrophage cells, and U87-MG (p53-wt) and LN229 (p53-mt) cancer cells, compared to free-vancomycin treatment ( < 0.001). The vancomycin loaded ReApoBds treatment in infected macrophages showed a two-log-order higher CFU reduction than the free-vancomycin treatment group. studies revealed that ReApoBds can specifically target macrophages and cancer cells. Vancomycin loaded ReApoBds have the potential to kill intracellular infection in macrophages and cancer cells.
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http://dx.doi.org/10.1021/acsnano.0c00921DOI Listing
May 2020

Viral Delivery of CAR Targets to Solid Tumors Enables Effective Cell Therapy.

Mol Ther Oncolytics 2020 Jun 7;17:232-240. Epub 2020 Apr 7.

Department of Bioengineering, Stanford University School of Medicine, Stanford, CA 94305, USA.

Chimeric antigen receptor (CAR) T cell therapy has had limited efficacy for solid tumors, largely due to a lack of selectively and highly expressed surface antigens. To avoid reliance on a tumor's endogenous antigens, here we describe a method of tumor-selective delivery of surface antigens using an oncolytic virus to enable a generalizable CAR T cell therapy. Using CD19 as our proof of concept, we engineered a thymidine kinase-disrupted vaccinia virus to selectively deliver CD19 to malignant cells, and thus demonstrated potentiation of CD19 CAR T cell activity against two tumor types . In an immunocompetent model of B16 melanoma, this combination markedly delayed tumor growth and improved median survival compared with antigen-mismatched combinations. We also found that CD19 delivery could improve CAR T cell activity against tumor cells that express low levels of cognate antigen, suggesting a potential application in counteracting antigen-low escape. This approach highlights the potential of engineering tumors for effective adoptive cell therapy.
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http://dx.doi.org/10.1016/j.omto.2020.03.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7183102PMC
June 2020

Integrating genomic features for non-invasive early lung cancer detection.

Nature 2020 04 25;580(7802):245-251. Epub 2020 Mar 25.

Stanford Cancer Institute, Stanford University, Stanford, CA, USA.

Radiologic screening of high-risk adults reduces lung-cancer-related mortality; however, a small minority of eligible individuals undergo such screening in the United States. The availability of blood-based tests could increase screening uptake. Here we introduce improvements to cancer personalized profiling by deep sequencing (CAPP-Seq), a method for the analysis of circulating tumour DNA (ctDNA), to better facilitate screening applications. We show that, although levels are very low in early-stage lung cancers, ctDNA is present prior to treatment in most patients and its presence is strongly prognostic. We also find that the majority of somatic mutations in the cell-free DNA (cfDNA) of patients with lung cancer and of risk-matched controls reflect clonal haematopoiesis and are non-recurrent. Compared with tumour-derived mutations, clonal haematopoiesis mutations occur on longer cfDNA fragments and lack mutational signatures that are associated with tobacco smoking. Integrating these findings with other molecular features, we develop and prospectively validate a machine-learning method termed 'lung cancer likelihood in plasma' (Lung-CLiP), which can robustly discriminate early-stage lung cancer patients from risk-matched controls. This approach achieves performance similar to that of tumour-informed ctDNA detection and enables tuning of assay specificity in order to facilitate distinct clinical applications. Our findings establish the potential of cfDNA for lung cancer screening and highlight the importance of risk-matching cases and controls in cfDNA-based screening studies.
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http://dx.doi.org/10.1038/s41586-020-2140-0DOI Listing
April 2020

A mountable toilet system for personalized health monitoring via the analysis of excreta.

Nat Biomed Eng 2020 06 6;4(6):624-635. Epub 2020 Apr 6.

Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.

Technologies for the longitudinal monitoring of a person's health are poorly integrated with clinical workflows, and have rarely produced actionable biometric data for healthcare providers. Here, we describe easily deployable hardware and software for the long-term analysis of a user's excreta through data collection and models of human health. The 'smart' toilet, which is self-contained and operates autonomously by leveraging pressure and motion sensors, analyses the user's urine using a standard-of-care colorimetric assay that traces red-green-blue values from images of urinalysis strips, calculates the flow rate and volume of urine using computer vision as a uroflowmeter, and classifies stool according to the Bristol stool form scale using deep learning, with performance that is comparable to the performance of trained medical personnel. Each user of the toilet is identified through their fingerprint and the distinctive features of their anoderm, and the data are securely stored and analysed in an encrypted cloud server. The toilet may find uses in the screening, diagnosis and longitudinal monitoring of specific patient populations.
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http://dx.doi.org/10.1038/s41551-020-0534-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7377213PMC
June 2020