Methods for early cancer detection using exosomal PCNA biomarkers

Abstract

A method for detecting cancer in a subject is provided herein. The method comprises obtaining a biological fluid sample from the subject, isolating exosomes from the biological fluid sample, and detecting proliferating cell nuclear antigen (PCNA) in the isolated exosomes to determine a level of exosomal PCNA in the biological fluid sample. The method further comprises comparing the level of exosomal PCNA to a reference level and identifying the subject as having cancer when the level of exosomal PCNA is elevated relative to the reference level.

Description

METHODS FOR EARLY CANCER DETECTION USING EXOSOMAL PCNABIOMARKERSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 656.835, titled Early Detection and Monitoring of Cancers, filed June 6. 2024, which is hereby incorporated by reference in its entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable.INTRODUCTION

[0003] Cancer remains one of the leading causes of death worldwide, with early detection playing a pivotal role in improving patient outcomes and survival rates. The ability to identify malignancies before clinical symptoms manifest provides opportunities for timely intervention and more effective treatment strategies. Traditional cancer screening methods, while valuable, face limitations in terms of accessibility, invasiveness, and scope of detection.

[0004] Tissue biopsy has long served as the gold standard for cancer diagnosis, providing definitive histopathological confirmation of malignancy. However, this approach presents several challenges including its invasive nature, potential complications, patient discomfort, and the fact that it provides information from only a single tumor site. Additionally, tissue biopsies may not be feasible in all clinical situations due to tumor location, patient condition, or other factors.

[0005] Liquid biopsy has emerged as a promising alternative approach for cancer detection and monitoring. This methodology involves analyzing circulating biomarkers in bodily fluids such as blood, urine, or other biological samples. Various liquid biopsy technologies have been developed, including detection of circulating tumor cells (CTCs), cell-free DNA (cfDNA), and circulating tumor DNA (ctDNA). While these approaches show promise, they often face limitations including low7sensitivity for early-stage cancers, technical complexity, high costs, and the need for sophisticated sequencing platforms and bioinformatics analysis.

[0006] Cunent multi-cancer early detection (MCED) platforms utilizing cfDNAmethylation patterns or genomic mutations have demonstrated potential but remain expensive and technically demanding. These methods typically require complex laboratory infrastructure, specialized personnel, and extensive data processing capabilities, which can limit their widespread implementation, particularly in resource-limited settings.

[0007] Exosomes, small extracellular vesicles secreted by cells, have gained attention as potential sources of cancer biomarkers. These membrane-bound vesicles carry various molecular cargo including proteins, nucleic acids, and lipids that reflect the characteristics of their parent cells. Several exosome-based diagnostic approaches have been explored, focusing primarily on specific protein markers or nucleic acid content for particular cancer types.

[0008] Existing exosome-based cancer detection methods often target tissuespecific markers or cancer-type-specific molecules, limiting their utility for broad-spectrum cancer screening. Many of these approaches also face challenges related to standardization of exosome isolation methods, variability in biomarker expression, and the need for multiple different assays to detect various cancer types.

[0009] The field continues to seek biomarkers that can provide sensitive and specific detection across multiple cancer types while maintaining practical feasibility' for clinical implementation. An ideal cancer screening approach would combine high diagnostic accuracy with technical simplicity, cost-effectiveness, and the ability to detect various cancer types through a single test platform.

[0010] Several challenges persist in the prior art that limit the development of effective multi-cancer early detection platforms. Current liquid biopsy approaches utilizing circulating tumor DNA (ctDNA) and cell-free DNA (cfDNA) often lack sufficient sensitivity' for early-stage cancer detection, when intervention would be most beneficial, and require expensive sequencing platforms with complex bioinformatics analysis that are not readily accessible in many clinical settings. Existing exosome-based diagnostic methods ty pically focus on tissue-specific or cancer-type-specific markers, necessitating multiple different assays to screen for various cancer types and limiting their utility for broad-spectrum cancer screening. Furthermore, many cunent approaches face standardization challenges in biomarker isolation and detection methods, leading to variability in results and difficulties in clinical implementation. The technical complexity’ and high costs associated with most multicancer early detection platforms restrict their widespread adoption, particularly in resourcelimited healthcare environments where early cancer screening could have the greatest impact. Additionally, no universally shared cancer biomarker with clinical significance has beenidentified in bodily fluids that can reliably detect multiple cancer types through a single, simple test platform. These unresolved limitations underscore the critical need for a sensitive, specific, cost-effective, and technically accessible approach for early detection of multiple cancer types using liquid biopsy methodology.SUMMARY

[0011] According to an aspect of the present disclosure, a method for detecting cancer in a subject is provided. The method comprises obtaining a biological fluid sample from the subject, isolating exosomes from the biological fluid sample, detecting proliferating cell nuclear antigen (PCNA) in the isolated exosomes to determine a level of exosomal PCNA in the biological fluid sample, comparing the level of exosomal PCNA to a reference level, and identifying the subject as having cancer when the level of exosomal PCNA is elevated relative to the reference level.

[0012] According to other aspects of the present disclosure, the method may include one or more of the following features. The biological fluid sample may be selected from the group consisting of serum, plasma, urine, saliva, sputum, pleural effusion, ascites, cerebrospinal fluid, lymph fluid, and synovial fluid. The biological fluid sample may be serum or plasma. Isolating exosomes may comprise using ultracentrifugation, precipitationbased isolation, or immunoaffinity capture. Isolating exosomes may comprise using a commercial exosome isolation kit. Isolating exosomes may comprise depleting leukocyte- derived exosomes using CD45 antibody -coated magnetic beads and depleting platelet-derived exosomes using CD61 antibody-coated magnetic beads. Detecting PCNA may comprise using an immunoassay selected from the group consisting of enzy me-linked immunosorbent assay (ELISA), Western blot, immunofluorescent assay, turbidimetric immunoassay, radioimmunoassay, chemiluminescent assay, and flow cytometry. Detecting PCNA may comprise using an enzyme-linked immunosorbent assay (ELISA). The reference level may be a level of exosomal PCNA in a control sample from a healthy individual. The elevated level may be at least 1.5-fold greater than the reference level. The elevated level may be at least 2- fold greater than the reference level. The cancer may be selected from the group consisting of liver cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, ovarian cancer, pancreatic cancer, and prostate cancer. The method may further comprise determining a tissue of origin of the cancer by analyzing tissue-specific markers on the isolated exosomes. The tissue-specific markers may comprise ASGPR1 for liver cancer or GPA33 for colorectal cancer. Determining the tissue of origin may comprise isolating tissue-specific exosomepopulations using magnetic bead-based immunoprecipitation targeting the tissue-specific markers. The method may further comprise monitoring cancer progression by repeating the method at multiple time points. An increase in exosomal PCNA levels over time may indicate cancer progression. The method may further comprise monitoring treatment effectiveness by repeating the method during a treatment period. A decrease in exosomal PCNA levels during treatment may indicate treatment response. Detecting PCNA may comprise detecting cancer- associated PCNA (caPCNA) using antibodies specific for cancer-specific epitopes or modifications.

[0013] According to another aspect of the present disclosure, a diagnostic kit for detecting cancer is provided. The diagnostic kit comprises reagents for isolating exosomes from a biological fluid sample, reagents for detecting proliferating cell nuclear antigen (PCNA) in the isolated exosomes, and instructions for determining a level of exosomal PCNA and comparing the level to a reference level to identify cancer.

[0014] According to other aspects of the present disclosure, the diagnostic kit may include one or more of the following features. The reagents for isolating exosomes may comprise a precipitation-based isolation solution or magnetic beads conjugated to exosome- specific antibodies. The precipitation-based isolation solution may comprise polyethylene glycol-based reagents. The magnetic beads may be conjugated to antibodies against CD63, CD81, or CD9. The reagents for detecting PCNA may comprise antibodies specific for PCNA. The antibodies specific for PCNA may be monoclonal or polyclonal antibodies. The reagents for detecting PCNA may comprise components for an enzyme-linked immunosorbent assay (ELISA). The ELISA components may comprise pre-coated microplates with anti-PCNA capture antibodies, enzyme-conjugated detection antibodies, and substrate solutions. The diagnostic kit may further comprise reagents for detecting tissuespecific markers on exosomes. The tissue-specific markers may comprise ASGPR1 for liver cancer or GPA33 for colorectal cancer. The reagents for detecting tissue-specific markers may comprise magnetic beads conjugated to tissue-specific antibodies for immunoaffinity capture. The diagnostic kit may further comprise control samples with known levels of exosomal PCNA. The control samples may comprise positive controls containing exosomal PCNA at concentrations representing cancer patient levels and negative controls containing exosomal PCNA at concentrations representing healthy individual levels. The diagnostic kit may further comprise reagents for depleting leukocyte-derived exosomes and platelet-derived exosomes. The depletion reagents may comprise CD45 antibody-coated magnetic beads for removing leukocyte-derived exosomes and CD61 antibody-coated magnetic beads forremoving platelet-derived exosomes.

[0015] According to another aspect of the present disclosure, a method for monitoring cancer in a subject is provided. The method comprises obtaining a first biological fluid sample from the subject at a first time point, obtaining a second biological fluid sample from the subject at a second time point, determining a first level of exosomal PCNA in the first biological fluid sample, determining a second level of exosomal PCNA in the second biological fluid sample, and comparing the first level and the second level to assess cancer progression or treatment response.

[0016] According to other aspects of the present disclosure, the method may include one or more of the following features. An increase in the second level relative to the first level may indicate cancer progression. A decrease in the second level relative to the first level may indicate treatment response. The first time point may be before treatment and the second time point may be during or after treatment. The second time point may be selected from the group consisting of during chemotherapy cycles, after surgical resection, during radiation therapy, and after immunotherapy administration. The biological fluid samples may be serum or plasma samples. Determining levels of exosomal PCNA may comprise isolating exosomes from the biological fluid samples and detecting PCNA using an immunoassay. The immunoassay may be an enzyme-linked immunosorbent assay (ELISA). The method may further comprise obtaining additional biological fluid samples at subsequent time points to generate a temporal profile of exosomal PCNA levels. The temporal profile may be used to predict treatment outcomes or disease recurrence. The method may be performed at intervals ranging from weekly to annually depending on cancer t pe and treatment protocol. The intervals may be monthly during the first year after treatment and quarterly during the second year after treatment. The method may further comprise analyzing tissue-specific exosomal PCNA levels to monitor cancer progression or treatment response at specific anatomical sites. Tissue-specific exosomes may be isolated using magnetic bead-based immunoprecipitation targeting tissue-specific markers selected from the group consisting of ASGPR1 for liver tissue and GPA33 for colorectal tissue. The method may be used for surveillance of cancer recurrence in patients who have completed primary treatment and achieved remission.

[0017] According to another aspect of the present disclosure, a method for detecting cancer in a subject is provided. The method comprises obtaining a biological fluid sample from the subject, isolating exosomes from the biological fluid sample using ultracentrifugation at 120,000 * g for 2 hours, lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X-100 in phosphate-buffered saline, detecting proliferatingcell nuclear antigen (PCNA) in the lysed exosomes using an enzyme-linked immunosorbent assay comprising anti-PCNA antibodies immobilized on a solid surface, measuring an optical density signal generated by an enzyme-substrate reaction to determine a concentration of exosomal PCNA in ng / mL, comparing the measured concentration to a reference concentration of 97.81 ng / mL, and identifying the subject as having cancer when the measured concentration exceeds the reference concentration.

[0018] According to other aspects of the present disclosure, the method may include one or more of the following features. The biological fluid sample may be serum obtained through venipuncture and centrifugation of whole blood. Isolating exosomes may further comprise centrifuging the biological fluid sample at 300 x g for 10 minutes to remove cells, filtering the supernatant through a 0.45 pm membrane, and washing the exosome pellet with phosphate-buffered saline followed by re-centrifugation at 120,000 x g for 2 hours. The enzyme-linked immunosorbent assay may comprise incubating the lysed exosomes with monoclonal anti-PCNA capture antibodies for 45 minutes at 37°C, washing with phosphate- buffered saline containing 0.05% Tween-20, incubating with biotin-conjugated anti-PCNA detection antibodies for 30 minutes at 37°C. adding streptavidin-horseradish peroxidase conjugate for 30 minutes, and developing color with tetramethylbenzidine substrate. The method may further comprise isolating liver-derived exosomes using magnetic beads conjugated to anti-ASGPRl antibodies, measuring PCNA concentration in the liver-derived exosomes, and identifying liver cancer when the PCNA concentration in liver-derived exosomes exceeds 12 ng / mL. The method may further comprise isolating colorectal-derived exosomes using magnetic beads conjugated to anti-GPA33 antibodies, measuring PCNA concentration in the colorectal-derived exosomes, and identifying colorectal cancer when the PCNA concentration in colorectal-derived exosomes exceeds 15 ng / mL. The method may further comprise depleting leukocyte-derived exosomes by incubating the biological fluid sample with CD45 antibody-coated magnetic beads for 1 hour at 4°C and depleting platelet- derived exosomes by incubating with CD61 antibody-coated magnetic beads for 1 hour at 4°C.

[0019] According to another aspect of the present disclosure, a method for monitoring cancer treatment response in a subject is provided. The method comprises obtaining a first serum sample from the subject before treatment initiation, obtaining a second serum sample from the subject after 4 weeks of treatment, isolating exosomes from each serum sample using precipitation with polyethylene glycol-based reagent followed by centrifugation at 3,000 x g for 10 minutes, lysing the isolated exosomes with 0.4% Triton X-100, measuring PCNA concentrations in both samples using enzyme-linked immunosorbent assay, calculating a percentage change in PCNA concentration between the first and second samples, and determining treatment response when the PCNA concentration decreases by at least 25%.

[0020] According to other aspects of the present disclosure, the method may include one or more of the following features. The method may further comprise obtaining additional serum samples at 8-week intervals during treatment, measuring PCNA concentrations in each sample, and generating a temporal profile of PCNA levels to assess ongoing treatment response. Determining treatment response may further comprise identifying treatment failure when PCNA concentration increases by more than 20% from baseline and recommending treatment modification based on the PCNA concentration changes.

[0021] According to another aspect of the present disclosure, a method for early cancer detection screening is provided. The method comprises collecting serum samples from a population of asymptomatic individuals, processing each serum sample by centrifugation at 2,000 x g for 10 minutes to remove cellular debris, isolating exosomes using ExoQuick precipitation reagent according to manufacturer specifications, lysing exosomes with detergent solution containing 0.4% Triton X-100, quantifying PCNA protein using sandwich enzyme-linked immunosorbent assay with anti-PCNA antibodies, measuring absorbance at 450 nm using a microplate reader, converting absorbance values to PCNA concentrations using a standard curve, classifying individuals with PCNA concentrations above 97.81 ng / mL as high-risk for cancer, and recommending further diagnostic evaluation for high-risk individuals.

[0022] According to other aspects of the present disclosure, the method may further comprise stratifying results by age groups with adjusted reference values of 100 ng / mL for individuals under 50 years and 87 ng / mL for individuals over 70 years.

[0023] According to another aspect of the present disclosure, a method for detecting multiple cancer types simultaneously is provided. The method comprises obtaining a serum sample from a subject, dividing the sample into aliquots for parallel processing, isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33, surfactant protein B, and prostate-specific membrane antigen, measuring PCNA concentrations in each tissue-specific exosome population using enzyme- linked immunosorbent assay, comparing measured concentrations to tissue-specific reference values, and identifying cancer type and location based on which tissue-specific exosome population exhibits elevated PCNA levels.

[0024] According to other aspects of the present disclosure, the tissue-specific reference values may comprise 12 ng / mL for ASGPRl-positive exosomes indicating liver cancer, 15 ng / mL for GPA33-positive exosomes indicating colorectal cancer, 13 ng / mL for surfactant protein B-positive exosomes indicating lung cancer, and 10 ng / mL for prostatespecific membrane antigen-positive exosomes indicating prostate cancer.

[0025] According to another aspect of the present disclosure, a method for cancer recurrence surveillance is provided. The method comprises establishing a post-treatment baseline PCNA concentration in a cancer patient who has achieved remission, collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter, isolating exosomes from each sample using ultracentrifugation at 120,000 x g?measuring PCNA concentrations using standardized enzyme-linked immunosorbent assay, calculating fold-change relative to the post-treatment baseline, and detecting cancer recurrence when PCNA concentration increases by 2-fold or more above the post-treatment baseline.

[0026] According to other aspects of the present disclosure, the method may further comprise confirming recurrence detection through repeat testing within 2 weeks and initiating imaging studies when confirmed PCNA elevation is detected.

[0027] According to another aspect of the present disclosure, a method for assessing cancer aggressiveness is provided. The method comprises obtaining serum samples from cancer patients with known tumor proliferation indices, isolating exosomes using commercial isolation kits, measuring exosomal PCNA concentrations using quantitative enzyme-linked immunosorbent assay, correlating PCNA concentrations with tumor proliferation indices, and classifying tumors as high-grade when exosomal PCNA concentrations exceed 200 ng / mL.

[0028] According to other aspects of the present disclosure, correlating PCNA concentrations with tumor proliferation indices may comprise establishing that PCNA concentrations below 100 ng / mL correlate with low proliferation index tumors, determining that PCNA concentrations between 100-200 ng / mL correlate with intermediate proliferation index tumors, and confirming that PCNA concentrations above 200 ng / mL correlate with high proliferation index tumors.

[0029] According to another aspect of the present disclosure, a method for optimizing cancer treatment protocols is provided. The method comprises measuring baseline exosomal PCNA concentrations in cancer patients before treatment, administering standard treatment protocols, monitoring exosomal PCNA levels at weekly intervals during treatment, identifying patients with less than 15% decrease in PCNA levels after 2 weeks as poor responders, modify ing treatment protocols for poor responders by increasing dosage orchanging therapeutic agents, and continuing monitoring until PCNA levels decrease by at least 50% from baseline.

[0030] According to other aspects of the present disclosure, the method may further comprise maintaining current treatment protocols for patients showing greater than 30% decrease in PCNA levels within 2 weeks and implementing dose reduction protocols when PCNA levels decrease by more than 75% to minimize treatment toxicity.

[0031] According to another aspect of the present disclosure, a method for detecting cancer in a subject is provided. The method comprises obtaining a biological fluid sample from the subject, isolating exosomes from the biological fluid sample using ultracentrifugation at 120,000 * g for 2 hours, lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X-100 in phosphate-buffered saline, detecting proliferating cell nuclear antigen (PCNA) protein in the lysed exosomes using an enzyme-linked immunosorbent assay comprising anti-PCNA antibodies immobilized on a solid surface, measuring an optical density signal generated by an enzyme-substrate reaction to determine a concentration of exosomal PCNA protein in ng / mL. comparing the measured concentration to a reference concentration of 97.81 ng / mL. and diagnosing the subject as having cancer when the measured concentration exceeds the reference concentration.

[0032] According to another aspect of the present disclosure, a method for detecting cancer in a subject is provided. The method comprises obtaining a biological fluid sample from the subject, isolating exosomes from the biological fluid sample using precipitation with polyethylene glycol-based reagent, extracting RNA from the isolated exosomes using phenolchloroform extraction, performing reverse transcription to convert PCNA mRNA to complementary' DNA, detecting PCNA mRNA using quantitative polymerase chain reaction with PCNA-specific primers and probes, measuring cycle threshold values to determine a concentration of exosomal PCNA mRNA in copies per mL, comparing the measured concentration to a reference concentration of 5.0 x 104copies per mL, and diagnosing the subj ect as having cancer when the measured concentration exceeds the reference concentration.

[0033] According to other aspects of the present disclosure, the methods may include one or more of the following features. The biological fluid sample may be serum obtained through venipuncture and centrifugation of whole blood. The biological fluid sample may be plasma obtained using EDTA anticoagulant tubes. Isolating exosomes may further comprise centrifuging the biological fluid sample at 300 x g for 10 minutes to remove cells, filtering the supernatant through a 0.45 pm membrane, and washing the exosome pelletwith phosphate-buffered saline followed by re-centrifugation at 120,000 x g for 2 hours. Extracting RNA may further comprise treating the isolated exosomes with DNase to eliminate genomic DNA contamination and eluting RNA in nuclease-free water for downstream analysis. The quantitative polymerase chain reaction may comprise using TaqMan probes for sequence-specific detection, performing thermal cycling at 95°C for 15 seconds and 60°C for 1 minute for 40 cycles, and normalizing results using GAPDH mRNA as an internal control. The methods may further comprise isolating liver-derived exosomes using magnetic beads conjugated to anti-ASGPRl antibodies, measuring PCNA mRNA concentration in the liver-derived exosomes, and diagnosing liver cancer when the PCNA mRNA concentration in liver-derived exosomes exceeds 1.5 x io4copies per mL. The methods may further comprise isolating lung-derived exosomes using magnetic beads conjugated to anti-surfactant protein B antibodies, measuring PCNA mRNA concentration in the lung-derived exosomes, and diagnosing lung cancer when the PCNA mRNA concentration in lung-derived exosomes exceeds 1.0 x io4copies per mL.

[0034] According to another aspect of the present disclosure, a method for monitoring cancer treatment response in a subject is provided. The method comprises obtaining a first serum sample from the subject before treatment initiation, obtaining a second serum sample from the subject after 4 weeks of treatment, isolating exosomes from each serum sample using ExoQuick precipitation reagent, lysing the isolated exosomes with 0.4% Triton X-100, measuring PCNA protein concentrations in both samples using enzyme-linked immunosorbent assay, calculating a percentage change in PCNA protein concentration between the first and second samples, and correlating treatment response with cancer prognosis when the PCNA protein concentration decreases by at least 25%.

[0035] According to another aspect of the present disclosure, a method for monitoring cancer treatment response in a subject is provided. The method comprises obtaining serum samples from the subject at multiple time points during treatment, isolating exosomes from each serum sample using ultracentrifugation, extracting RNA from the isolated exosomes, measuring PCNA mRNA levels using quantitative polymerase chain reaction, calculating fold-changes in PCNA mRNA levels relative to baseline, and correlating treatment response with cancer prognosis when PCNA mRNA levels decrease by at least 2- fold.

[0036] According to other aspects of the present disclosure, the methods may include one or more of the following features. The methods may further comprise obtaining additional serum samples at 8-week intervals during treatment, measuring PCNA proteinconcentrations in each sample, and generating a temporal profile of PCNA protein levels to assess ongoing treatment response and cancer status. Correlating treatment response may further comprise identifying treatment failure and poor cancer prognosis when PCNA mRNA levels increase by more than 50% from baseline and recommending treatment modification based on the PCNA mRNA level changes.

[0037] According to another aspect of the present disclosure, a method for early cancer detection screening is provided. The method comprises collecting serum samples from a population of asymptomatic individuals, processing each serum sample by centrifugation at 2,000 x g for 10 minutes to remove cellular debris, isolating exosomes using commercial isolation kits, lysing exosomes with detergent solution containing 0.4% Triton X-100, quantifying PCNA protein using sandwich enzyme-linked immunosorbent assay with anti- PCNA antibodies, measuring absorbance at 450 nm using a microplate reader, converting absorbance values to PCNA protein concentrations using a standard curve, classify ing individuals with PCNA protein concentrations above 97.81 ng / mL as having cancer, and recommending further diagnostic evaluation for individuals diagnosed with cancer.

[0038] According to another aspect of the present disclosure, a method for early cancer detection screening is provided. The method comprises collecting plasma samples from asymptomatic individuals, isolating exosomes using size-exclusion chromatography, extracting total RNA from the isolated exosomes, performing reverse transcription quantitative PCR for PCNA mRNA detection, measuring PCNA mRNA concentrations using standard curves, classifying individuals with PCNA mRNA concentrations above 5.0 x 104copies per mL as having cancer, and correlating elevated PCNA mRNA levels with cancer diagnosis.

[0039] According to another aspect of the present disclosure, a method for detecting multiple cancer types simultaneously is provided. The method comprises obtaining a serum sample from a subject, dividing the sample into aliquots for parallel processing, isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33, and surfactant protein B, measuring PCNA protein concentrations in each tissue-specific exosome population using enzyme-linked immunosorbent assay, comparing measured concentrations to tissue-specific reference values, and diagnosing specific cancer types based on which tissue-specific exosome population exhibits elevated PCNA protein levels.

[0040] According to another aspect of the present disclosure, a method for detecting multiple cancer types simultaneously is provided. The method comprises obtaining a plasmasample from a subject, isolating tissue-specific exosome populations using immunoaPfinity capture, extracting RNA from each tissue-specific exosome population, measuring PCNA mRNA levels using tissue-specific quantitative PCR assays, comparing measured PCNA mRNA levels to tissue-specific reference values, and diagnosing specific cancer types based on which tissue-specific exosome population exhibits elevated PCNA mRNA levels.

[0041] According to another aspect of the present disclosure, a method for cancer recurrence surveillance is provided. The method comprises establishing a post-treatment baseline PCNA protein concentration in a cancer patient who has achieved remission, collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter, isolating exosomes from each sample using standardized protocols, measuring PCNA protein concentrations using enzyme-linked immunosorbent assay, calculating foldchange relative to the post-treatment baseline, and diagnosing cancer recurrence when PCNA protein concentration increases by 2-fold or more above the post-treatment baseline.

[0042] According to another aspect of the present disclosure, a method for cancer recurrence surveillance is provided. The method comprises establishing post-treatment baseline PCNA mRNA levels in a cancer patient who has achieved remission, collecting plasma samples at regular surveillance intervals, isolating exosomes and extracting RNA using standardized methods, measuring PCNA mRNA levels using quantitative polymerase chain reaction, calculating percentage changes relative to baseline levels, and diagnosing cancer recurrence when PCNA mRNA levels increase by 3 -fold or more above the posttreatment baseline.

[0043] These and other features, aspects and advantages of the present teachings will become better understood with reference to the following description, examples and appended claims.DRAWINGS

[0044] Those of skill in the art will understand that the drawings, described below, are for illustrative purposes only. The drawings are not intended to limit the scope of the present teachings in any way.

[0045] FIG 1 is an exemplary' drawing of the extracellular vesicle (EV) structure and biomolecular cargoes inside EV.

[0046] FIG. 2 is the overall work flowchart of the study and cancer patient and healthy control recruitment,

[0047] FIG. 3 demonstrates immunoblot analysis for detecting cell proliferationmarkers, establishing the foundation for identifying cancer-specific biomarkers in cellular environments, according to aspects of the present disclosure.

[0048] FIG. 4 illustrates exosomal PCNA protein detection across multiple cancer cell lines, validating the universal presence of the biomarker for comprehensive cancer screening applications, according to an embodiment.

[0049] FIG. 5 A is an exemplary transmission electron microscopy image of E s isolated from cancer patient serum.

[0050] FIG. 5B is exemplary size distribution of EV isolated from cancer patient serum.

[0051] FIG. 6 validates exosomal PCNA by immunoblots: The presence of exosomal markers CD63 and FLOT1, the absence of Golgi marker GM 130 and endoplasmic reticulum marker Calnexin in PCNA-containing extracellular vesicles. The extracellular vesicles were isolated from the cultured media of Hela and HEK293 cells and sera of three patients with Hepatocarcinoma (HCC). 1 and 3 indicate the cell lysate from Hela, HEK293, respectively. 2 and 4 indicate the extracted exosomes from Hela, HEK293 cultured media, respectively. 5-7 indicate the extracted exosomes from sera of patients with HCC.

[0052] FIG. 7 A depicts comparative immunoblot analysis of exosomal PCNA protein level between healthy controls and cancer patients, enabling the differentiation of disease states through biomarker expression levels, according to aspects of the present disclosure.

[0053] FIG. 7B shows quantitative comparison of relative PCNA units from FIG. 7A, demonstrating the statistical significance necessary for reliable diagnostic discrimination between patient populations, according to an embodiment.

[0054] FIG. 8 presents serum exosomal PCNA protein concentration distribution analysis, establishing concentration thresholds critical for accurate cancer detection and diagnostic implementation, according to aspects of the present disclosure.

[0055] FIG. 9 illustrates receiver operating characteristic curve analysis, validating the diagnostic performance and clinical utility of the biomarker detection method, according to an embodiment.

[0056] FIG. 10 illustrates tissue specific tumor derived exosomes examples containing PCNA: colorectal cancer (CRC) derived exosomes with surface antigen GPA33 signature and liver cancer derived exosomes with surface antigen ASGPR1 signature.

[0057] FIG. 11A presents differential immunostaining intensity of PCNA on tumor tissues from colorectal cancer patients indicates differential degree of malignancy accordingto proliferation index. LPI: Low Proliferation Index (<30%), HPI: High Proliferation Index (>50%).

[0058] FIG. 11B presents that differential PCNA protein expression in serum GPA33+ exosomes from patients in FIG. 11 A, matches the PCNA expression level in their tumor tissues.DETAILED DESCRIPTION

[0059] All patents, applications, published applications and other publications cited herein are incorporated by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. The chemical structures and formulae set forth herein are constructed according to the standard rules of chemical valency known in the chemical arts. Should a discrepancy exist betw een a depicted structure and a name given for that structure, the depicted structure is to be accorded more weight. Where the stereochemistry of a structure or a portion of a structure is not indicated in a depicted structure or a portion of the depicted structure, the depicted structure is to be interpreted as encompassing all of its possible stereoisomers.

[0060] Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of this invention. The following definitions are provided to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure. In the event that there is a plurality of definitions for a term herein, those in this section prevail unless stated otherwise. Headings used herein are for organizational purposes only and in no way limit the invention described herein.

[0061] Abbreviations and Definitions

[0062] To facilitate understanding of the invention, a number of terms and abbreviations as used herein are defined below as follows:

[0063] PCNA (Proliferating Cell Nuclear Antigen): As used herein, the term "PCNA" or "proliferating cell nuclear antigen" refers to a 36 kDa protein that may play a role in DNA replication and repair processes. PCNA may function as a molecular platform at the replication fork and may be present in proliferating cells. PCNA may sen e as a marker of cellular proliferation and may be recognized as a cancer biomarker in tissue biopsies. In some cases, PCNA may be packaged into extracellular vesicles and secreted from cells into bodilyfluids, enabling detection in liquid biopsy applications. Human PCNA may correspond to Gene ID: 5111, NCBI accession number NP_002583.1 (protein) and NM_002592.2 (mRNA).

[0064] Exosome: As used herein, the term "exosome" refers to small extracellular vesicles ranging from 30-150 nm in diameter that are actively secreted by living cells through exocytosis. Exosomes are membrane-bound vesicles that cany7various bioactive molecules including proteins, nucleic acids, and lipids from their parent cells.

[0065] Exosomal PCNA: As used herein, the term "exosomal PCNA" refers to PCNA protein or RNA that is packaged into extracellular vesicles (exosomes) and secreted from cells into bodily fluids. This represents a secreted form of PCNA that can be detected outside of the cellular environment.

[0066] Biological Fluid Sample: As used herein, the term "biological fluid sample" or "bioliquid sample" refers to any biological sample derived from bodily fluids that may be utilized for molecular testing and biomarker analysis. These fluids may be distributed across various anatomical compartments and may provide diagnostic insights into physiological and pathological states. Biological fluid samples may include, but are not limited to, circulatory and vascular system fluids such as blood, serum, plasma, lymph, and bone marrow aspirate; respiratory system fluids including sputum, pleural effusion, and bronchoalveolar lavage fluid; gastrointestinal and abdominal fluids such as gastric juice, bile, ascites, and peritoneal dialysate; neurological and ocular fluids including cerebrospinal fluid, aqueous humor, vitreous humor, endolymph, and perilymph; reproductive and genitourinary fluids such as semen, vaginal fluid, cervical mucus, amniotic fluid, prostatic fluid, and urine; exocrine and secretory fluids including saliva, breast milk, sweat, and tears; miscellaneous fluids such as synovial fluid, hydrocele fluid, cyst fluid, and chyle; transcellular and third-space fluids including pericardial effusion and cerumen; and excretory fluids such as liquefied stool samples. Each of these biological fluid samples may offer unique molecular insights and may enable detection of various biomarkers, metabolites, proteins, nucleic acids, and other diagnostic molecules relevant to disease detection, monitoring, and therapeutic assessment.

[0067] Reference Level: As used herein, the term "reference level" refers to a control level of exosomal PCNA, typically obtained from a biological fluid sample from an individual who does not have cancer or any other proliferative disorder, used for comparison purposes in determining whether a subject has elevated levels indicative of cancer.

[0068] Elevated Level: As used herein, the term "elevated level" refers to an amount of exosomal PCNA per unit volume or mass in a subject's biological fluid sample that is greater than the reference level. An elevated level preferably means at least 1.5-fold greaterthan the reference level, and more preferably at least 2-fold greater than the reference level.

[0069] Subject: As used herein, the term "subject" refers to any animal suspected of having cancer, with a preference for primates and, more specifically, humans.

[0070] Tissue-Specific Markers: As used herein, the term "tissue-specific markers" refers to proteins or other molecules present on the surface of exosomes that indicate the tissue of origin from which the exosomes were derived. These markers may enable non- invasive tracking of tissue-specific processes and may provide diagnostic insights into organspecific pathological states.

[0071] Liver-derived exosomes may be identified through markers including Asialoglycoprotein Receptor 1 (ASGPR1), which may function as a lectin receptor enriched in hepatocyte-derived exosomes and may be elevated in conditions such as non-alcoholic steatohepatitis and cirrhosis. Cytochrome P450 2E1 (CYP2E1) may be detected in exosomes from alcohol-related liver injury and metabolic dysfunction. Albumin may be found in hepatocyte exosomes, though it may be less specific compared to ASGPR1.

[0072] Colorectal-derived exosomes may be characterized by Glycoprotein A33 (GPA33), a transmembrane protein that may be abundant in colorectal cancer exosomes and may be used for immunoaffinity purification. Epithelial Cell Adhesion Molecule (EpCAM) may be overexpressed in colorectal cancer exosomes and may be co-detected with CD44v6 and Claudin7. Carcinoembryonic Antigen (CEA) may function as a glycosylphosphatidylinositol-anchored protein enriched in colorectal cancer exosomes.

[0073] Pancreatic-derived exosomes may be identified through Glypican-1 (GPC 1), a proteoglycan that may be used to detect early-stage pancreatic cancer exosomes with high specificity. CD44v6 / c-Met / Tspan8 may represent a triad of markers associated with pancreatic cancer stem cell exosomes and may be linked to metastasis. Claudin7 may function as a tight junction protein enriched in pancreatic ductal adenocarcinoma exosomes.

[0074] Cardiac-derived exosomes may be characterized by Cardiac Troponin T (cTnT), a cardiomyocyte-specific protein that may be detected in donor heart exosomes posttransplant. Myosin Light Chain 1 (MYL1) may be expressed in heart-derived exosomes and may be validated in ischemia-reperfusion models.

[0075] Neuronal-derived exosomes may be identified through LI Cell Adhesion Molecule (LI CAM), a surface glycoprotein that may be used to isolate neuron-specific exosomes from blood. Glutamate Receptor 2 / 3 (GluR2 / 3) may represent AMPA receptor subunits enriched in neuronal exosomes and may be implicated in stroke biomarkers. Synaptophysin (SYP) may function as a synaptic vesicle protein detected in exosomes fromneurodegenerative disease models.

[0076] Kidney-derived exosomes may be characterized by Aquaporin-2 (AQP2). a water channel protein that may mark collecting duct-derived exosomes in urine. Podocalyxin may function as a sialoprotein enriched in podocyte exosomes and may be elevated in glomerular diseases. Nephrin may represent a slit diaphragm protein in podocyte exosomes that may be reduced in diabetic nephropathy.

[0077] Lung-derived exosomes may be identified through Surfactant Protein C (SFTPC), an alveolar type II cell marker that may be present in exosomes from bronchoalveolar lavage fluid. Caveolin-1 (CAV1) may be enriched in lung adenocarcinoma exosomes and may be associated with EGFR signaling.

[0078] Adipose-derived exosomes may be characterized by Uncoupling Protein 1 (UCP1), a brown adipose tissue exosome marker that may be linked to thermogenesis. Cell Death-Inducing DFFA-Like Effector A (CIDEA) may function as a white adipose tissue exosome marker that may be elevated in obesity.

[0079] Prostate-derived exosomes may be identified through Prostate-Specific Membrane Antigen (PSMA), an integral membrane protein that may be present in prostate cancer exosomes. Prostate-Specific Antigen (PSA) may be less specific but may be detectable in exosomes from metastatic prostate cancer.

[0080] Breast-derived exosomes may be characterized by Mammaglobin-A (SCGB2A2). a secretory protein that may be present in breast cancer exosomes and may be used for liquid biopsy applications. Human Epidermal Growth Factor Receptor 2 (HER2) may be overexpressed in HER2 -positive breast cancer exosomes.

[0081] Immune cell-derived exosomes may be identified through HLA-DR / DP / DQ markers representing MHC class II molecules on antigen-presenting cell exosomes. CD3 and CD 19 may function as T-cell and B-cell exosome markers, respectively, and may be elevated in autoimmune diseases.

[0082] Universal exosome markers may provide tissue-specific context, including tetraspanins such as CD9, CD63, and CD81, which may be ubiquitously expressed but differentially distributed among tissues. Integrins including a6(>4 and avP3 may mark epithelial exosomes and may be linked to metastatic niche formation, respectively.

[0083] These tissue-specific markers may enable diagnostic applications, therapeutic monitoring, and mechanistic insights into disease processes through analysis of exosomal surface protein expression patterns that reflect their cellular and tissue origins. Those of skill in the art will recognize alternative tissue-specific markers useful in the presentinvention.

[0084] Cancer: As used herein, the term "cancer" refers to malignant neoplasms characterized by uncontrolled cell proliferation. Cancer represents one of the most complex groups of diseases affecting humanity, with research identifying over 100 distinct types that can develop in virtually any tissue or organ system within the human body. This extensive catalog encompasses malignant neoplasms ranging from common carcinomas affecting epithelial tissues to rare sarcomas originating in connective tissues, each characterized by unique cellular origins, grow th patterns, and clinical manifestations.

[0085] Cancer classification may follow multiple systematic approaches, including anatomical location, histological cell type, and molecular characteristics. Primary' classification by cell type may include carcinomas derived from epithelial cells, sarcomas arising from connective tissues including bone, cartilage, fat, nerve, and other mesenchymal cells, lymphomas and leukemias representing malignancies arising from immature cells originating in the bone marrow', germ cell tumors originating from pluripotent cells, and blastomas derived from immature precursor cells or embryonic tissue.

[0086] Digestive and gastrointestinal malignancies may include lip, oral cavity and phary nx cancers, esophageal cancer, gastric cancer, small intestine cancer, colorectal cancers, liver cancer, gallbladder and bile duct cancers, pancreatic cancer, gastrointestinal stromal tumors, gastrointestinal neuroendocrine tumors, and appendix cancer. Respiratory system cancers may encompass nasal cavity and sinus cancers, laryngeal cancer, lung cancers including non-small cell lung cancer and small cell lung cancer, pleuropulmonary blastoma, pulmonary inflammatory' myofibroblastic tumor, and tracheobronchial tumors.

[0087] Musculoskeletal system malignancies may include bone cancers such as osteosarcoma, Ewing sarcoma, and chondrosarcoma, soft tissue sarcomas including rhabdomyosarcoma, angiosarcoma, alveolar soft part sarcoma, epithelioid hemangioendothelioma, Kaposi sarcoma, gastrointestinal stromal tumors, uterine sarcoma, and mesothelioma. Skin and cutaneous malignancies may encompass melanoma, nonmelanoma skin cancers including basal cell carcinoma and squamous cell carcinoma, Merkel cell carcinoma, dermatofibrosarcoma protuberans, and cutaneous T-cell lymphoma.

[0088] Genitourinary system cancers may include kidney cancer, bladder cancer, urethral cancer, prostate cancer, testicular cancer, penile cancer, cervical cancer, endometrial cancer, ovarian cancers, fallopian tube cancer, vaginal cancer, vulvar cancer, gestational trophoblastic tumors, and uterine sarcoma. Blood and lymphatic system malignancies may encompass various leukemias including acute lymphoblastic leukemia, acute myeloidleukemia, chronic lymphocytic leukemia, chronic myeloid leukemia, hairy cell leukemia, lymphomas including Hodgkin lymphoma and non-Hodgkin lymphomas, multiple myeloma, myelodysplastic syndromes, and myeloproliferative neoplasms.

[0089] Central nervous system and brain tumors may include astrocytomas, gliomas, medulloblastoma, ependymoma, craniophary ngioma, choroid plexus tumors, atypical teratoid / rhabdoid tumors, primitive neuroectodermal tumors, central nervous system germ cell tumors, pituitary tumors, and primary central nervous system lymphoma. Head and neck cancers may encompass oral cavity and lip cancers, pharyngeal cancers including nasopharyngeal, oropharyngeal, and hypopharyngeal cancers, laryngeal cancer, paranasal sinus and nasal cavity' cancers, salivary' gland cancers, esthesioneuroblastoma, and adenoid cystic carcinoma.

[0090] Endocrine system malignancies may include thyroid cancer, adrenocortical carcinoma, pheochromocytoma, paraganglioma, pancreatic neuroendocrine tumors, parathyroid cancer, and various neuroendocrine tumors. Rare and uncommon cancer ty pes may include adamantinoma, cholangiocarcinoma, clear-cell adenocarcinoma, epithelial- myoepithelial carcinoma, mucosal melanoma, malignant rhabdoid tumors, mammary secretory carcinoma, porocarcinoma, malignant acrospiroma, hyalinizing clear cell carcinoma, sacrococcygeal teratoma, sarcoma botryoides, and heart cancer.

[0091] Pediatric cancers may include acute lymphoblastic leukemia, neuroblastoma, retinoblastoma, Wilms tumor, rhabdomyosarcoma, Ewing sarcoma, medulloblastoma, hepatoblastoma, childhood cardiac tumors, childhood astrocytomas, childhood ependymoma, childhood atypical teratoid / rhabdoid tumors, childhood central nervous system germ cell tumors, extracranial germ cell tumors, childhood vascular tumors, pleuropulmonary blastoma, and childhood laryngeal papillomatosis. AIDS-related and immunodeficiency- associated cancers may include Kaposi sarcoma, AIDS-related lymphoma, and primary CNS lymphoma. Additional categories may' include metastatic cancer, carcinoma of unknown primary', pregnancy-associated cancers, and cancers associated with genetic syndromes and hereditary predispositions.

[0092] Immunoassay: As used herein, the term "immunoassay" refers to analytical methods that utilize antibodies to detect and quantify specific proteins or antigens, including but not limited to enzy me-linked immunosorbent assay (ELISA), Western blot, immunofluorescent assay, turbidimetric immunoassay, radioimmunoassay, chemiluminescent assay, and flow cytometry. For comprehensive guidance on immunoassay design and performance principles, reference may be made to "The Immunoassay Handbook: Theory andApplications of Ligand Binding, ELISA and Related Techniques" by David Wild (4th Edition, Elsevier, 2013), which provides detailed methodologies for antibody-based detection systems and analytical validation procedures.

[0093] Anti-cancer drug: As used herein, the term ’‘anti-cancer drug” refers to a drug exhibiting safety7and efficacy for treating, reducing, reversing, and / or ameliorating a cancer indication, or symptoms associated with cancer, including, but not limited to:

[0094] Abecma (Idecabtagene Vicleucel), Abemaciclib. Abiraterone Acetate. Abraxane (Paclitaxel Albumin-stabilized Nanoparticle Formulation), ABVD, ABVE, ABVE- PC, AC, Acalabrutinib Maleate Monohydrate, AC-T, Actemra (Tocilizumab), Adagrasib, Adcetris (Brentuximab Vedotin), ADE, Ado-Trastuzumab Emtansine, Adriamycin (Doxorubicin Hydrochloride), Adstiladrin (Nadofaragene Firadenovec-vncg), Afamitresgene Autoleucel, Afatinib Dimaleate, Afinitor (Everolimus), Akeega (Niraparib Tosylate Monohydrate and Abiraterone Acetate), Akynzeo (Netupitant and Palonosetron Hydrochloride), Aldara (Imiquimod), Aldesleukin, Alecensa (Alectinib), Alectinib, Alemtuzumab, Alimta (Pemetrexed Disodium), Alkeran for Injection (Melphalan Hydrochloride), Alkeran Tablets (Melphalan). Aloxi (Palonosetron Hydrochloride), Alpelisib, Alunbrig (Brigatinib), Alymsys (Bevacizumab), Arneluz (Aminolevulinic Acid Hydrochloride), Amifostine, Aminolevulinic Acid Hydrochloride, Amivantamab-vmjw, Amtagvi (Lifileucel), Anastrozole, Anktiva (Nogapendekin Alfa Inbakicept-pmln), Apalutamide, Aprepitant, Aranesp (Darbepoetin Alfa), Aredia (Pamidronate Disodium), Arimidex (Anastrozole), Aromasin (Exemestane), Arranon (Nelarabine), Arsenic Trioxide, Arzerra (Ofatumumab), Asciminib Hydrochloride, Asparaginase Erwinia Chrysanthemi. Asparaginase Erwinia Chry santhemi (Recombinant)-rywn, Asparlas (Calaspargase Pegol- mknl), Atezolizumab, Atezolizumab and Hyaluronidase-tqjs, Aucatzyl (Obecabtagene Autoleucel), Augtyro (Repotrectinib), Avapntinib, Avastin (Bevacizumab), Avelumab, Axicabtagene Ciloleucel, Axitinib, Ayvakit (Avapritinib), Azacitidine, Azedra (lobenguane I 131), Balversa (Erdafitinib), Bavencio (Avelumab), BEACOPP, Beleodaq (Belinostat), Belinostat, Belzutifan, Bendamustine Hydrochloride, Bendeka (Bendamustine Hydrochloride), BEP, Besponsa (Inotuzumab Ozogamicin). Besremi (Ropeginterferon Alfa- 2b-njft), Bevacizumab, Bexarotene, Bicalutamide, BiCNU (Carmustine), Binimetinib, Bizengri (Zenocutuzumab-zbco), Bleomycin Sulfate, Blinatumomab, Blincyto (Blinatumomab). Bortezomib, Bosulif (Bosutinib), Bosutinib, Braftovi (Encorafenib), Brentuximab Vedotin, Brexucabtagene Autoleucel, Breyanzi (Lisocabtagene Maraleucel), Brigatinib, Brukinsa (Zanubrutinib), BuMeL Busulfan, Busulfex (Busulfan), CabazitaxeLCablivi (Caplacizumab-yhdp), Cabometyx (Cabozantinib-S-Malate), Cabozantinib-S-Malate, CAF. Calaspargase Pegol-mknl, Calquence (Acalabrutinib Maleate Monohydrate). Camcevi (Leuprolide Mesylate). Campath (Alemtuzumab), Camptosar (Irinotecan Hydrochloride), Capecitabine, Capivasertib, Caplacizumab-yhdp, Capmatinib Hydrochloride, CAPOX, Carac (Fluorouracil Topical), Carboplatin, CARBOPLATIN-TAXOL, Carfilzomib, Carmustine, Carmustine Implant, Carvykti (Ciltacabtagene Autoleucel), Casodex (Bicalutamide), CEM, Cemiplimab-rwlc, Ceritinib. Cervarix (Recombinant HPV Bivalent Vaccine), Cetuximab, CEV, Chlorambucil, CHLORAMBUCIL-PREDNISONE, CHOP, Ciltacabtagene Autoleucel, Cisplatin, Cladribine, Clofarabine, Clolar (Clofarabine), CMF, Cobimetinib Fumarate, Columvi (Glofitamab-gxbm), Cometriq (Cabozantinib-S-Malate), COPDAC. Copiktra (Duvelisib), COPP, COPP-ABV, Cosibelimab-ipdl. Cosmegen (Dactinomycin), Cotellic (Cobimetinib Fumarate), Crizotinib, CVP, Cyclophosphamide, Cyramza (Ramucirumab), Cytarabine, Dabrafenib Mesylate, Dacarbazine, Dacogen (Decitabine), Dacomitinib, Dactinomy cin, Danyelza (Naxitamab-gqgk), Daratumumab, Daratumumab and Hyaluronidase-fihj, Darbepoetin Alfa, Darolutamide, Darzalex (Daratumumab), Darzalex Faspro (Daratumumab and Hyaluronidase-fihj). Dasatinib, Datopotamab Deruxtecan-dlnk. Datroway (Datopotamab Deruxtecan-dlnk), Daunorubicin Hydrochloride, Daunorubicin Hydrochloride and Cytarabine Liposome, Daurismo (Glasdegib Maleate), Decitabine, Decitabine and Cedazuridine, Defibrotide Sodium, Defitelio (Defibrotide Sodium), Degarelix, Denileukin Diftitox-cxdL Denosumab. Dexamethasone, Dexrazoxane Hydrochloride, Dinutuximab, Docetaxel, Dostarlimab-gxly, Doxil (Doxorubicin Hydrochloride Liposome), Doxorubicin Hydrochloride, Doxorubicin Hydrochloride Liposome, Durvalumab, Duvelisib, Eflomithine Hydrochloride, Efudex (Fluorouracil Topical), Elacestrant Dihydrochloride, Elahere (Mirvetuximab Soravtansine-gynx). Eligard (Leuprolide Acetate), Elitek (Rasburicase), Ellence (Epirubicin Hydrochloride), Elotuzumab, Eloxatin (Oxaliplatin), Elranatamab-bcmm, Elrexfio (Elranatamab-bcmm), Eltrombopag Olamine, Elzonris (Tagraxofusp-erzs), Emapalumab-lzsg, Emend (Aprepitant), Empliciti (Elotuzumab), Enasidenib Mesylate. Encorafenib. Enfortumab Vedotin-ejfv, Enhertu (Fam- Trastuzumab Deruxtecan-nxki). Ensacove (Ensartinib Hydrochloride), Ensartinib Hydrochloride, Entrectinib, Enzalutamide, Epcoritamab-bysp, Epirubicin Hydrochloride, Epkinly (Epcoritamab-bysp), EPOCH, Epoetin Alfa, Epogen (Epoetin Alfa), Erbitux (Cetuximab). Erdafitinib, Eribulin Mesylate, Erivedge (Vismodegib), Erleada (Apalutamide), Erlotinib Hydrochloride. Erwinaze (Asparaginase Erwinia chrysanthemi), Ethyol (Amifostine), Etopophos (Etoposide Phosphate), Etoposide, Etoposide Phosphate,Everolimus, Evista (Raloxifene Hydrochloride), Evomela (Melphalan Hydrochloride), Exemestane, 5-FU (Fluorouracil Injection), 5-FU (Fluorouracil Topical), Fam-Trastuzumab Deruxtecan-nxki, Fareston (Toremifene), Faslodex (Fulvestrant), FEC, Fedratinib Hydrochloride, Femara (Letrozole), Filgrastim, Firmagon (Degarelix), Fludarabine Phosphate, Fluoroplex (Fluorouracil Topical), Fluorouracil Injection, Fluorouracil Topical, Flutamide, FOLFIRI, FOLFIRI-BEVACIZUMAB, FOLFIRI-CETUXIMAB, FOLFIRINOX, FOLFOX, Folotyn (Pralatrexate), Fostamatinib Disodium, Fotivda (Tivozanib Hydrochloride), Fruquintinib, Fruzaqla (Fruquintinib), Fulphila (Pegfilgrastim), FU-LV, Fulvestrant, Futibatinib, Fyarro (Sirolimus Protein-Bound Particles), Gamifant (Emapalumab-lzsg), Gardasil (Recombinant HPV Quadrivalent Vaccine), Gardasil 9 (Recombinant HPV Nonavalent Vaccine). Gavreto (Pralsetinib), Gazyva (Obinutuzumab). Gefitmib, Gemcitabine Hydrochloride, GEMCITABINE-CISPLATIN, GEMCITABINEOXALIPLATIN, Gemtuzumab Ozogamicin, Gemzar (Gemcitabine Hydrochloride), Gilotrif (Afatinib Dimaleate), Gilteritinib Fumarate, Glasdegib Maleate, Gleevec (Imatinib Mesylate), Gliadel Wafer (Carmustine Implant), Glofitamab-gxbm, Glucarpidase, Goserelin Acetate, Grafapex (Treosulfan). Granisetron. Granisetron Hydrochloride, Gramx (Filgrastim), Halaven (Eribulin Mesylate), Hemangeol (Propranolol Hydrochloride), Hepzato (Melphalan Hydrochloride), Herceptin Hylecta (Trastuzumab and Hyaluronidase-oysk), Herceptin (Trastuzumab), HPV Bivalent Vaccine, Recombinant, HPV Nonavalent Vaccine, Recombinant, HPV Quadrivalent Vaccine, Recombinant, Hycamtin (Topotecan Hydrochloride), Hydrea (Hydroxyurea), Hydroxyurea, Hyper-CVAD, Ibrance (Palbociclib), Ibritumomab Tiuxetan, Ibrutinib, ICE, Iclusig (Ponatinib Hydrochloride), Idamycin PFS (Idarubicin Hydrochloride), Idarubicin Hydrochloride, Idecabtagene Vicleucel, Idelalisib, Idhifa (Enasidenib Mesylate), Ifex (Ifosfamide). Ifosfamide, IL-2 (Aldesleukin), Imatinib Mesylate, Imbruvica (Ibrutinib), Imdelltra (Tarlatamab-dlle), Imetelstat Sodium, Imfinzi (Durvalumab), Imiquimod, Imjudo (Tremelimumab-actl), Imkeldi (Imatinib Mesylate), Imlygic (Talimogene Laherparepvec), Inavolisib, Infugem (Gemcitabine Hydrochloride), Inlyta (Axitinib). Inotuzumab Ozogamicin, Inqovi (Decitabine and Cedazuridine), Inrebic (Fedratinib Hydrochloride), Interferon Alfa- 2b, Recombinant, Interleukin-2 (Aldesleukin). Intron A (Recombinant Interferon Alfa-2b), lobenguane 1 131, Ipilimumab, Iressa (Gefitinib), Irinotecan Hydrochloride, Irinotecan Sucrosofate, Isatuximab-irfc, Istodax (Romidepsin), Itovebi (Inavolisib), Ivosidenib, Iwilfm (Eflomithine Hydrochloride). Ixabepilone, Ixazomib Citrate. Ixempra (Ixabepilone), Jakafi (Ruxolitinib Phosphate), Jaypirca (Pirtobrutinib), JEB, Jelmyto (Mitomycin), Jemperli (Dostarlimab-gxly), Jevtana (Cabazitaxel), Kadcyla (Ado-Trastuzumab Emtansine), Kepivance (Palifermin), Keytruda (Pembrolizumab), Kimmtrak (Tebentafusp-tebn), Kisqali (Ribociclib Succinate), Kisqali Femara Co-Pack (Ribociclib Succinate and Letrozole), Koselugo (Selumetinib Sulfate), Krazati (Adagrasib), Kymriah (Tisagenlecleucel), Kyprolis (Carfilzomib), Lanreotide Acetate, Lapatinib Ditosylate, Larotrectinib Sulfate, Lazcluze (Lazertinib Mesylate Hydrate), Lazertinib Mesylate Hydrate, Lenalidomide, Lenvatinib Mesylate. Lenvima (Lenvatinib Mesylate). Letrozole, Leucovorin Calcium. Leukeran (Chlorambucil), Leuprolide Acetate, Leuprolide Mesylate, Levulan Kerastick (Aminolevulinic Acid Hydrochloride), Libtayo (Cemiplimab-rwlc), Lifileucel, Lisocabtagene Maraleucel, Lomustine, Loncastuximab Tesirine-lpyl, Lonsurf (Trifluridine and Tipiracil Hydrochloride), Loqtorzi (Toripalimab-tpzi), Lorbrena (Lorlatinib), Lorlatinib, Lumakras (Sotorasib), Lunsumio (Mosunetuzumab-axgb), Lupron Depot (Leuprolide Acetate), Lurbinectedin, Luspatercept-aamt, Lutathera (Lutetium Lu 177-Dotatate), Lutetium (Lu 177-Dotatate), Lutetium Lu 177 Vipivotide Tetraxetan, Lymphir (Denileukin Diftitox- cxdl), Lynparza (Olaparib), Lytgobi (Futibatinib), Margenza (Margetuximab-cmkb), Margetuximab-cmkb, Matulane (Procarbazine Hydrochloride), Mechlorethamine Hydrochloride. Megestrol Acetate, Mekinist (Trametinib Dimethyl Sulfoxide). Mektovi (Binimetinib), Melphalan, Melphalan Hydrochloride, Mercaptopurine, Mesna, Mesnex (Mesna), Methotrexate Sodium, Methylnaltrexone Bromide, Midostaurin, Mirvetuximab Soravtansine-gynx, Mitomycin, Mitoxantrone Hydrochloride, Mogamulizumab-kpkc, Momelotinib Dihydrochloride Monohydrate, Monjuvi (Tafasitamab-cxix), MOPP. Mosunetuzumab-axgb, Mozobil (Plerixafor), MV AC, Mvasi (Bevacizumab), Myleran (Busulfan), Mylotarg (Gemtuzumab Ozogamicin), Nadofaragene Firadenovec-vncg, Nanoparticle Paclitaxel (Paclitaxel Albumin-stabilized Nanoparticle Formulation), Naxitamab-gqgk, Necitumumab, Nelarabine, Neratinib Maleate, Nerlynx (Neratinib Maleate), Netupitant and Palonosetron Hydrochloride, Neulasta (Pegfilgrastim), Neupogen (Filgrastim), Nexavar (Sorafenib Tosylate), Nilandron (Nilutamide), Nilotinib, Nilutamide, Ninlaro (Ixazomib Citrate), Niraparib Tosylate Monohydrate, Niraparib Tosylate Monohydrate and Abiraterone Acetate, Nirogacestat Hydrobromide, Nivestym (Filgrastim), Nivolumab, Nivolumab and Hyaluronidase-nvhy. Nivolumab and Relatlimab-rmbw. Nogapendekin Alfa Inbakicept-pmln, Nplate (Romiplostim), Nubeqa (Darolutamide), Nyvepria (Pegfilgrastim), Obecabtagene Autoleucel, Obinutuzumab, Odomzo (Sonidegib), OEPA, Ofatumumab, OFF, Ogsiveo (Nirogacestat Hydrobromide), Ojemda (Tovorafenib), Ojjaara (Momelotinib Dihydrochloride Monohydrate), Olaparib, Olutasidenib, Omacetaxine Mepesuccinate, Oncaspar (Pegaspargase), Ondansetron Hydrochloride, Onivyde (IrinotecanSucrosofate), Onureg (Azacitidine), Opdivo (Nivolumab), Opdivo Qvantig (Nivolumab and Hyaluronidase-nvhy), Opdualag (Nivolumab and Relatlimab-rmbw), OPPA, Orgovyx (Relugolix), Orserdu (Elacestrant Dihydrochloride), Osimertinib Mesylate, Oxaliplatin, Paclitaxel, Paclitaxel Albumin-stabilized Nanoparticle Formulation, Pacritinib Citrate, PAD, Padcev (Enfortumab Vedotin-ejfv), Palbociclib, Palifermin, Palonosetron Hy drochloride, Palonosetron Hydrochloride and Netupitant. Pamidronate Disodium, Panitumumab, Paraplatin (Carboplatin). Pazopanib Hydrochloride. PCV. PEB. Pegaspargase, Pegfilgrastim, Pemazyre (Pemigatinib), Pembrolizumab, Pemetrexed Disodium, Pemigatinib, Penpulimab- kcqx, Perjeta (Pertuzumab), Pertuzumab, Pertuzumab, Trastuzumab, and Hyaluronidase- zzxf, Pexidartinib Hydrochloride, Phesgo (Pertuzumab, Trastuzumab, and Hyaluronidase-zzxf), Piqray (Alpelisib), Pirtobrutinib. Plerixafor. Pluvicto (Lutetium Lu 177 Vipivotide Tetraxetan), Polatuzumab Vedotin-piiq, Polivy (Polatuzumab Vedotin-piiq), Pomalidomide, Pomalyst (Pomalidomide), Ponatinib Hydrochloride, Portrazza (Necitumumab), Poteligeo (Mogamulizumab-kpkc), Pralatrexate, Pralsetinib. Prednisone, Procarbazine Hydrochloride, Procrit (Epoetin Alfa), Proleukin (Aldesleukin), Prolia (Denosumab). Promacta (Eltrombopag Olamine), Propranolol Hydrochloride. Provenge (Sipuleucel-T), Purinethol (Mercaptopurine), Purixan (Mercaptopurine), Qinlock (Ripretinib), Quizartinib Dihydrochloride, Radium 223 Dichloride, Raloxifene Hydrochloride, Ramucirumab, Rasburicase, Ravulizumab-cwvz, Reblozyl (Luspatercept-aamt), R-CHOP, R-CVP, Recombinant Human Papillomavirus (HPV) Bivalent Vaccine, Recombinant Human Papillomavirus (HPV) Nonavalent Vaccine, Recombinant Human Papillomavirus (HPV) Quadrivalent Vaccine, Recombinant Interferon Alfa-2b, Regorafenib, Relistor (Methylnaltrexone Bromide), Relugolix, R-EPOCH, Repotrectinib, Retacrit (Epoetin Alfa), Retevmo (Selpercatinib), Retifanlimab-dlwr, Revlimid (Lenalidomide), Revuforj (Revumenib Citrate), Revumenib Citrate, Rezlidhia (Olutasidenib), Riabni (Rituximab), Ribociclib Succinate, Ribociclib Succinate and Letrozole, R-ICE, Ripretinib, Rituxan (Rituximab), Rituxan Hycela (Rituximab and Hyaluronidase Human), Rituximab, Rituximab and Hyaluronidase Human, Rolapitant Hydrochloride, Romidepsin, Romiplostim, Romvimza (Vimseltinib Dihydrate). Ropeginterferon Alfa-2b-njft, Rozlytrek (Entrectinib), Rubraca (Rucaparib Camsylate), Rucaparib Camsylate, Ruxience (Rituximab), Ruxolitinib Phosphate, Rybrevant (Amivantamab-vmjw), Rydapt (Midostaurin), Rylaze (Asparaginase Erwinia Chrysanthemi [Recombinant] -rywn), Rytelo (Imetelstat Sodium). Sacituzumab Govitecan- hziy, Sancuso (Granisetron). Sarclisa (Isatuximab-irfc), Sclerosol Intrapleural Aerosol (Talc), Selinexor, Selpercatinib, Selumetinib Sulfate, Scemblix (Asciminib Hydrochloride),Siltuximab, Sipuleucel-T, Sirolimus Protein-Bound Particles, Soltamox (Tamoxifen Citrate), Somatuline Depot (Lanreotide Acetate). Sonidegib, Sorafenib Tosylate, Sotorasib, Spry cel (Dasatinib), STANFORD V, Sterile Talc Powder (Talc), Steritalc (Talc), Stivarga (Regorafenib), Sunitinib Malate, Sustol (Granisetron), Sutent (Sunitinib Malate), Sylvant (Siltuximab), Synribo (Omacetaxine Mepesuccinate), Tabloid (Thioguanine), Tabrecta (Capmatinib Hydrochloride), TAC, Tafasitamab-cxix, Tafmlar (Dabrafenib Mesylate). Tagraxofusp-erzs, Tagnsso (Osimertinib Mesylate). Talazoparib Tosylate, Talc, Talimogene Laherparepvec, Talquetamab-tgvs, Talvey (Talquetamab-tgvs), Talzenna (Talazoparib Tosylate), Tamoxifen Citrate, Tarceva (Erlotinib Hydrochloride), Targretin (Bexarotene), Tarlatamab-dlle, Tasigna (Nilotinib), Tavalisse (Fostamatinib Disodium), Taxotere (Docetaxel), Tazemetostat Hydrobromide. Tazverik (Tazemetostat Hydrobromide), Tebentafusp-tebn, Tecartus (Brexucabtagene Autoleucel), Tecelra (Afamitresgene Autoleucel), Tecentriq (Atezolizumab), Tecentriq Hybreza (Atezolizumab and Hyaluronidase-tqjs), Teclistamab-cqyv, Tecvayli (Teclistamab-cqyv), Temodar (Temozolomide), Temozolomide, Temsirolimus, Tepadina (Thiotepa), Tepmetko (Tepotinib Hydrochloride), Tepotinib Hydrochloride. Tevimbra (Tislelizumab-jsgr). Thalidomide, Thalomid (Thalidomide), Thioguanine, Thiotepa, Tibsovo (Ivosidenib), Tisagenlecleucel, Tislelizumab-jsgr, Tisotumab Vedotin-tftv, Tivdak (Tisotumab Vedotin-tftv), Tivozanib Hydrochloride. Tocilizumab, Tolak (Fluorouracil Topical), Topotecan Hydrochloride, Toremifene, Toripalimab-tpzi. Torisel (Temsirolimus), Totect (Dexrazoxane Hydrochloride), Tovorafenib, TPF, Trabectedin, Trametinib Dimethyl Sulfoxide, Trastuzumab, Trastuzumab and Hyaluronidase-oysk, Treanda (Bendamustine Hydrochloride), Trelstar (Triptorelin Pamoate), Trelstar Depot (Triptorelin Pamoate). Tremelimumab-actl, Treosulfan, Trexall (Methotrexate Sodium), Trifluridine and Tipiracil Hydrochloride. Triptorelin Pamoate. Trisenox (Arsenic Trioxide), Trodelvy (Sacituzumab Govitecan-hziy), Truqap (Capivasertib), Truxima (Rituximab), Tucatinib, Tukysa (Tucatinib), Turalio (Pexidartinib Hydrochloride), Tykerb (Lapatinib Ditosylate), Ultomiris (Ravulizumab-cwvz), Undencyca (Pegfilgrastim), Unituxin (Dinutuximab), Unloxcyt (Cosibelimab-ipdl), Uridine Triacetate, VAC, Valrubicin, Valstar (Valrubicin). VAMP, Vandetanib. Vanflyta (Quizartinib Dihydrochloride). Varubi (Rolapitant Hydrochloride), Vectibix (Panitumumab), VelP, Velcade (Bortezomib), Vemurafenib, Venclexta (Venetoclax), Venetoclax, Verzenio (Abemaciclib), Vidaza (Azacitidine), Vimseltinib Dihydrate, Vinblastine Sulfate, Vincristine Sulfate, Vinorelbine Tartrate, VIP, Vismodegib, Vistogard (Uridine Triacetate), Vitrakvi (Larotrectinib Sulfate), Vizimpro (Dacomitinib), Vonjo (Pacritinib Citrate), Voranigo (Vorasidenib Citrate),Vorasidenib Citrate, Voraxaze (Glucarpidase), Vorinostat, Votrient (Pazopanib Hydrochloride), Vyloy (Zolbetuximab-clzb), Vyxeos (Daunorubicin Hydrochloride and Cytarabine Liposome), Welireg (Belzutifan), Xalkori (Crizotinib), Xatmep (Methotrexate Sodium), Xeloda (Capecitabine), XELIRI, XELOX, Xgeva (Denosumab), Xofigo (Radium 223 Dichloride), Xospata (Gilteritinib Fumarate), Xpovio (Selinexor), Xtandi (Enzalutamide), Yervoy (Ipilimumab), Yescarta (Axicabtagene Ciloleucel), Yondelis (Trabectedin), Yonsa (Abiraterone Acetate). Zaltrap (Ziv-Aflibercept). Zanidatamab-hni, Zanubrutinib, Zarxio (Filgrastim), Zejula (Niraparib Tosylate Monohydrate), Zelboraf (Vemurafenib), Zenocutuzumab-zbco, Zepzelca (Lurbinectedin), Zevalin (Ibritumomab Tiuxetan), Ziextenzo (Pegfilgrastim), Ziihera (Zanidatamab-hrii), Zinecard (Dexrazoxane Hydrochloride), Zirabev (Bevcizumab), Ziv-Aflibercept, Zofran (Ondansetron Hydrochloride), Zoladex (Goserelin Acetate), Zolbetuximab-clzb, Zoledronic Acid, Zolinza (Vorinostat), Zometa (Zoledronic Acid), Zyclara (Imiquimod), Zydelig (Idelalisib), Zykadia (Ceritinib), Zynlonta (Loncastuximab Tesirine-lpyl), Zynyz (Retifanlimab-dlwr), and Zytiga (Abiraterone Acetate).

[0095] Methods for Early Cancer Detection Using Exosomal PCNA Biomarkers

[0096] The present disclosure relates to the discovery of exosomal PCNA as a biomarker for cancer detection through liquid biopsy applications. This invention represents a novel approach to multi-cancer early detection by identifying secreted forms of PCNA in bodily fluids, which was previously unknown in the art.

[0097] PCNA has long been recognized as a nuclear protein functioning exclusively in proliferating cells and serving as an established cancer biomarker in tissue biopsies. However, the presence of PCNA in extracellular vesicles and its secretion into peripheral bodily fluids had not been demonstrated prior to this invention. The discovery that cancer cells actively package PCNA into exosomes and release these vesicles into circulation provides an unexpected utility for non-invasive cancer detection.

[0098] The invention demonstrates that exosomal PCNA can be detected as both protein and RNA forms in exosomes derived from various cancer cell types. This dual detection capability expands the analytical approaches available for quantifying exosomal PCNA levels in biological fluid samples. The protein form may be detected through immunoassay -based methods, while the RNA form may be quantified using nucleic acid amplification techniques such as quantitative PCR.

[0099] The secreted nature of exosomal PCNA represents a surprising result, as PCNA was traditionally understood to function solely within the nuclear compartment of cells. The packaging of PCNA into extracellular vesicles and subsequent release into bodily fluids enables detection of cancer-associated proliferation markers without the need for invasive tissue sampling procedures.

[0100] Cancer patients exhibit elevated levels of exosomal PCNA in their biological fluid samples compared to healthy individuals, providing a basis for diagnostic applications. This differential expression pattern was unexpected given that PCNA had not been previously identified as a circulating biomarker with diagnostic utility across multiple cancer types.

[0101] The invention addresses the technical problem of identifying a universal biomarker for multi-cancer detection in liquid biopsy applications. Current liquid biopsy approaches often lack sensitivity for early-stage cancers or are limited to specific cancer ty pes. The discovery of exosomal PCNA as a pan-cancer biomarker provides a technical solution that may enable broad-spectrum cancer screening through analysis of readily accessible biological fluid samples.

[0102] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The unexpected presence of PCNA in exosomes and its utility as a circulating biomarker represents a novel technical advancement that was not obvious from the prior art understanding of PCNA as a nuclear-localized protein.

[0103] The invention addresses specific technical problems in cancer detection that were previously unsolved in the art. Traditional tissue biopsy methods may require invasive procedures and may provide information from only single tumor sites, while existing liquid biopsy approaches utilizing circulating tumor DNA (ctDNA) and cell-free DNA (cfDNA) may lack sufficient sensitivity for early-stage cancer detection and may require expensive sequencing platforms with complex bioinformatics analysis. The invention provides a technical solution through the unexpected discovery that PCNA protein may be packaged into exosomes and secreted by cancer cells, enabling detection through standard immunoassay techniques rather than complex genomic analysis.

[0104] The technical challenges addressed by the invention may include the need for non-invasive cancer detection methods that can identify7multiple cancer types through a single analytical platform. Existing approaches may be limited by their reliance on cancerspecific biomarkers that require multiple different assays for comprehensive screening. The invention overcomes these limitations through the identification of exosomal PCNA as auniversal cancer biomarker that can be detected across diverse malignancy types using standardized analytical methods.

[0105] The secretion of PCNA protein into extracellular vesicles may represent an unexpected technical finding that contradicts the established understanding of PCNA as a nuclear-restricted protein. This discovery may enable a new technological approach for cancer detection that was not previously possible in the art. The invention demonstrates that cancer cells exhibit a unique biological mechanism for PCNA trafficking and secretion that distinguishes them from normal cells, providing a technical basis for diagnostic applications.

[0106] The unexpected nature of PCNA secretion may be evidenced by the absence of other proliferation markers including MCM2, E2F1, AURKA, CDK1, TROP2, and PLK1 in culture media from cancer cells, while PCNA may be consistently detected in the extracellular environment. This selective secretion pattern may indicate previously unrecognized cellular mechanisms that enable PCNA packaging into exosomes and subsequent release into biological fluids.

[0107] The technical significance of this unexpected result may extend beyond simple biomarker detection to reveal fundamental aspects of cancer cell biology that were not previously understood. The ability7of cancer cells to actively secrete nuclear proteins through exosomal pathways may represent a novel biological phenomenon with implications for understanding cancer progression and metastasis.

[0108] The invention provides several technological improvements over existing cancer detection methods. The exosomal PCNA detection system may achieve 77.2% sensitivity7and 94.4% specificity using standard laboratory7equipment, eliminating the need for specialized sequencing platforms required by ctDNA-based methods. The approach may enable pan-cancer detection through a single biomarker rather than requiring multiple cancerspecific assays.

[0109] The tissue-specific exosome isolation methodology may provide cancer localization capabilities that extend beyond simple detection to identify anatomical tumor origins. This technological advancement may enable clinicians to determine the primary site of malignancy through liquid biopsy analysis, which may not be achievable through existing circulating biomarker approaches.

[0110] The analytical methodology may utilize established immunoassay techniques that are widely available in clinical laboratories, reducing the technical barriers to implementation compared to genomic sequencing approaches. The use of enzyme-linked immunosorbent assay (ELISA) technology may enable quantitative measurements with highprecision and reproducibility across different testing facilities.

[0111] The invention may provide improved analytical sensitivity compared to existing protein biomarkers through the concentration effect achieved by exosome isolation procedures. The packaging of PCNA into extracellular vesicles may protect the protein from degradation in biological fluids, enhancing detection stability compared to free circulating proteins.

[0112] The invention may enable practical applications in clinical laboratory setings through standardized immunoassay protocols that can be implemented using existing laboratory infrastructure. The methodology may support high-throughput screening applications for population-based cancer detection programs without requiring specialized personnel or equipment.

[0113] The approach may provide real-time monitoring capabilities for treatment response assessment and recurrence surveillance that improve upon existing monitoring methods. Serial measurements of exosomal PCNA levels may enable clinicians to assess therapeutic efficacy and detect disease progression earlier than conventional imaging or clinical assessment methods.

[0114] The invention may enable point-of-care testing applications through simplified lateral flow assay formats that do not require specialized laboratory facilities. This capability may extend cancer screening to resource-limited settings where access to advanced laboratory infrastructure may be limited.

[0115] The industrial utility of the invention may include manufacturing of standardized diagnostic kits that can be distributed globally for cancer detection applications. The scalability of immunoassay-based detection methods may enable mass production of testing components at reduced costs compared to genomic sequencing platforms.

[0116] The invention may establish specific technical parameters that define the improved performance characteristics. The proposed threshold concentration of 97.81 ng / mL may provide quantitative criteria for distinguishing cancer patients from healthy individuals with defined sensitivity and specificity values. This threshold may be determined through receiver operating characteristic curve analysis of clinical validation data.

[0117] The area under the receiver operating characteristic curve of 0.94 may demonstrate superior diagnostic performance compared to existing biomarker approaches. This quantitative measure may indicate excellent discriminatory power for cancer detection applications across diverse patient populations.

[0118] The tissue-specific threshold values of 12 ng / mL for liver-derived exosomesand 15 ng / mL for colorectal-derived exosomes may enable precise cancer localization capabilities. These quantitative parameters may provide technical specifications for identifying the anatomical origin of detected malignancies through liquid biopsy analysis.

[0119] The analytical measurement range may span concentrations from 0 to 500 ng / mL, encompassing the full spectrum of exosomal PCNA levels observed in clinical populations. The linear detection range may enable accurate quantification across multiple orders of magnitude, supporting both screening and monitoring applications.

[0120] The invention may incorporate computer-implemented analysis systems that process optical densify measurements from immunoassays and convert them to quantitative PCNA concentrations using algorithmic calculations. These computational methods may utilize standard curve interpolation algorithms to determine biomarker concentrations from spectrophotometric data.

[0121] Machine learning algorithms may analyze temporal patterns of exosomal PCNA levels to predict treatment outcomes and disease progression. These computational approaches may incorporate multiple variables including patient demographics, treatment history, and biomarker trends to generate predictive models for clinical decision support.

[0122] Automated data analysis systems may integrate exosomal PCNA results with patient demographic data and medical history7to generate composite risk scores for clinical decision support. These computer-implemented methods may utilize statistical algorithms to combine multiple data sources and provide evidence-based recommendations for patient management.

[0123] The computational components may include database systems for storing and analyzing longitudinal biomarker data, enabling trend analysis and pattern recognition across large patient populations. These systems may incorporate data visualization tools that present temporal biomarker patterns in graphical formats for clinical interpretation.

[0124] The invention may enable standardized manufacturing processes for diagnostic kit components including antibody production, magnetic bead conjugation, and assay validation procedures. These manufacturing methods may incorporate specific technical parameters for reagent preparation, purification, and quality assessment that ensure consistent analytical performance.

[0125] Quality control systems may ensure consistent analytical performance through statistical process control methods and proficiency testing programs. These qualify assurance measures may include batch-to-batch variability assessment, stability- testing, and inter-laboratory comparison studies to validate manufacturing consistency.

[0126] The manufacturing processes may incorporate specific technical parameters for reagent stability , storage conditions, and analytical validation that enable commercial implementation. These specifications may include temperature requirements, shelf-life determinations, and performance criteria that support regulator}' approval and clinical deployment.

[0127] Automated manufacturing systems may enable large-scale production of diagnostic components with reduced variability and enhanced reproducibility. These industrial processes may incorporate quality control checkpoints and statistical monitoring systems that ensure consistent product quality across manufacturing batches.

[0128] Biological Fluid Samples

[0129] Biological fluid samples suitable for use in the present invention encompass a wide range of bodily fluids that may contain exosomal PCNA. The invention demonstrates that exosomal PCNA can be detected across multiple types of biological fluid samples, providing flexibility in sample collection and analysis approaches.

[0130] Serum samples may be obtained through standard venipuncture procedures and represent one of the most accessible biological fluid samples for exosomal PCNA analysis. Serum collection involves allowing whole blood to clot naturally, followed by centrifugation to separate the liquid component from cellular elements. The resulting serum contains circulating exosomes that may carry PCNA from various tissue sources throughout the body. Serum samples may be processed immediately after collection or stored at temperatures ranging from -20°C to -80°C for extended periods without compromising exosomal PCNA integrity.

[0131] Plasma samples provide an alternative to serum and may be collected using anticoagulants such as ethylenediaminetetraacetic acid (EDTA), heparin, or citrate to prevent blood coagulation. Plasma collection may offer advantages in certain analytical workflows due to the presence of fibrinogen and other clotting factors that are removed during serum preparation. The choice between serum and plasma may depend on the specific analytical method employed and laboratory preferences.

[0132] Urine samples represent a non-invasive collection option that may be particularly suitable for routine screening applications. Urine collection requires no specialized medical procedures and may be performed by patients in various settings. Urine samples may be collected as spot samples, timed collections, or first-morning void specimens depending on the analytical requirements. The concentration of exosomal PCNA in urinemay vary based on factors such as hydration status, kidney function, and time of collection.

[0133] Saliva samples offer another non-invasive collection method that may be suitable for point-of-care applications or situations where blood collection is not feasible. Saliva may be collected through passive drooling, spitting, or using specialized collection devices that stimulate salivation. The composition of saliva may be influenced by factors such as oral health, medications, and circadian rhythms, which may affect exosomal PCNA levels.

[0134] Sputum samples may be collected from patients through expectoration or induced sputum procedures. Sputum collection may be particularly relevant for detecting exosomal PCNA associated with respiratory tract cancers. The cellular content and viscosity of sputum samples may require specialized processing procedures to isolate exosomes effectively.

[0135] Cerebrospinal fluid samples may be obtained through lumbar puncture procedures performed by trained medical personnel. Cerebrospinal fluid analysis may provide information about exosomal PCNA levels in the central nervous system and may be relevant for detecting brain tumors or metastatic disease affecting the central nervous system. The collection of cerebrospinal fluid requires specialized medical expertise and may be associated with procedural risks.

[0136] Ascites fluid samples may be collected from patients with abdominal fluid accumulation through paracentesis procedures. Ascites fluid may contain exosomes derived from abdominal organs and may provide information about intra-abdominal malignancies. The cellular content and protein concentration of ascites fluid may vary' significantly between patients and disease states.

[0137] Pleural effusion samples may be obtained through thoracentesis procedures in patients with pleural fluid accumulation. Pleural fluid analysis may be relevant for detecting exosomal PCNA associated with lung cancers, mesothelioma, or metastatic disease involving the pleural space. The composition of pleural fluid may vary based on the underlying pathological process.

[0138] Lymph fluid samples may be collected in specialized circumstances where lymphatic drainage is accessible. Lymphatic fluid may contain exosomes derived from various tissue sources and may provide information about regional disease processes. The collection of lymph fluid may require specialized procedures and may not be routinely available in all clinical settings.

[0139] Synovial fluid samples may be obtained through arthrocentesis procedures inpatients with joint effusions. Synovial fluid analysis may be relevant for detecting exosomal PCNA in cases where joint involvement by malignancy is suspected. The viscosity and cellular content of synovial fluid may require specialized processing approaches.

[0140] Sample handling procedures may vary depending on the specific biological fluid type and analytical requirements. In some cases, biological fluid samples may be processed immediately after collection to isolate exosomes and quantify PCNA levels. In other cases, samples may be stored under controlled conditions for batch processing or transport to specialized laboratories.

[0141] Storage conditions for biological fluid samples may range from refrigeration at 2°C to 8°C for short-term storage to freezing at -20°C to -80°C for long-term preserv ation. The stability of exosomal PCNA in different biological fluid samples may vary, and appropriate storage validation studies may be conducted to establish optimal preservation conditions.

[0142] Processing procedures for biological fluid samples may include centrifugation steps to remove cellular debris, filtration to remove large particles, and specialized isolation techniques to concentrate exosomes. The specific processing requirements may depend on the analytical method employed and the characteristics of the particular biological fluid sample.

[0143] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The selection of appropriate biological fluid samples may depend on factors such as patient condition, clinical setting, analytical requirements, and regulatory’ considerations.

[0144] Exosome Isolation Methods

[0145] Exosome isolation from biological fluid samples may be accomplished through various methodological approaches, each offering distinct advantages for different analytical applications. The selection of an appropriate isolation method may depend on factors such as sample volume, required purify, downstream analytical requirements, and laboratory capabilities.

[0146] Ultracentrifugation-based isolation methods represent a widely utilized approach for exosome purification from biological fluid samples. Ultra-high-speed differential centrifugation may be performed using specialized ultracentrifuges capable of generating forces exceeding 100,000 x g. in some cases, biological fluid samples may be subjected to sequential centrifugation steps to remove cellular debris and larger extracellularvesicles before exosome isolation. Initial centrifugation at 300 x g for 10 minutes may remove intact cells and large cellular fragments. Subsequent centrifugation at 2,000 x g for 10 minutes may eliminate additional cellular debris and apoptotic bodies. The supernatant may then be filtered through 0.22 pm or 0.45 pm membrane filters to remove remaining particulate matter.

[0147] The filtered supernatant may be subjected to ultracentrifugation at forces ranging from 100,000 x g to 200,000 x g for durations of 70 minutes to 3 hours. In some cases, centrifugation at 120,000 x g for 2 hours may provide effective exosome pelleting. The resulting pellet may contain concentrated exosomes along with co-precipitated proteins and other macromolecules. Washing steps may be performed by resuspending the pellet in phosphate-buffered saline or other appropriate buffers, followed by additional ultracentrifugation cycles to improve purity.

[0148] Temperature control during ultracentrifugation may be maintained at 4°C to preserve exosome integrity and prevent protein degradation. Specialized ultracentrifuge rotors designed for high-speed operation may be utilized, including fixed-angle rotors or swinging-bucket rotors depending on sample volume and vessel configuration.

[0149] Precipitation-based isolation methods offer an alternative approach that may be suitable for laboratories without ultracentrifugation capabilities. ExoQuick-based protocols represent one category of precipitation-based isolation methods that utilize polyethylene glycol-based reagents to concentrate extracellular vesicles. In some cases, biological fluid samples may be mixed with ExoQuick reagent at ratios ranging from 1 :4 to 1 :5 (reagent to sample volume). The mixture may be incubated at temperatures ranging from 2°C to 8°C for periods of 30 minutes to overnight to allow precipitation complex formation.

[0150] Following incubation, the sample may be centrifuged at forces ranging from 1,500 x g to 10,000 x g for durations of 30 minutes to 2 hours. In some cases, centrifugation at 3,000 x g for 10 minutes may provide adequate pellet formation. The resulting pellet may contain concentrated exosomes that can be resuspended in appropriate buffers for downstream analysis. Additional purification steps may be performed using pre-packed columns or size-exclusion chromatography to remove co-precipitated contaminants.

[0151] Alternative precipitation reagents may include other polyethylene glycol formulations, sodium acetate-based solutions, or proprietary polymer mixtures. The choice of precipitation reagent may influence the yield and purity of isolated exosomes, and optimization may be performed for specific biological fluid t pes.

[0152] Immunoaffinity capture methods may provide enhanced specificity forexosome isolation by targeting surface proteins expressed on extracellular vesicles. Magnetic bead-based immunoprecipitation may utilize antibodies directed against pan-exosome markers such as CD63, CD81, or CD9. In some cases, biological fluid samples may be incubated with antibody-coated magnetic beads for periods ranging from 30 minutes to 4 hours at temperatures of 4°C to room temperature.

[0153] Magnetic separation may be performed using magnetic stands or automated magnetic separation systems to capture bead-bound exosomes. Washing steps may be performed using phosphate-buffered saline or other appropriate buffers to remove unbound material. Elution of captured exosomes may be accomplished through pH adjustment, competitive displacement, or enzymatic cleavage of antibody -antigen interactions.

[0154] Tissue-specific exosome isolation may be achieved through immunoaffinity capture using antibodies directed against tissue-specific surface markers. In some cases, liver- derived exosomes may be isolated using antibodies against asialoglycoprotein receptor 1 (ASGPR1), while colorectal-derived exosomes may be captured using antibodies against glycoprotein A33 (GPA33). This approach may enable the analysis of exosomal PCNA levels from specific tissue sources within complex biological fluid samples.

[0155] Depletion strategies may be employed to remove contaminating extracellular vesicles that may interfere with cancer-specific exosome analysis. Leukocyte-derived exosomes may be depleted using CD45 antibody-coated magnetic beads, which bind to exosomes derived from white blood cells. Platelet-derived exosomes may be removed using CD61 antibody-coated magnetic beads, which target exosomes originating from platelets. In some cases, sequential depletion steps may be performed by incubating biological fluid samples with CD45-coated beads followed by CD61 -coated beads, with magnetic separation performed after each incubation step.

[0156] The depletion process may involve incubation periods ranging from 15 minutes to 2 hours at temperatures of 4°C to room temperature. Magnetic separation may be performed using magnetic stands or automated systems, with the supernatant containing depleted samples collected for subsequent exosome isolation. This approach may enhance the relative concentration of cancer-derived exosomes by removing abundant non-cancer exosome populations.

[0157] Commercial isolation kits may provide standardized protocols and reagents for exosome isolation from various biological fluid types. These kits may incorporate precipitation-based methods, size-exclusion chromatography, or immunoaffinity capture approaches. Commercial kits may offer advantages in terms of reproducibility, ease of use.and regulatory compliance for clinical applications.

[0158] Size-exclusion chromatography may provide an alternative isolation approach that separates exosomes based on molecular size rather than densify or surface markers. Specialized columns containing porous resins may allow the passage of exosomes while retaining smaller molecules such as proteins and nucleic acids. This method maypreserve exosome morphology and functionality’ while providing moderate purification efficiency.

[0159] Ultrafiltration methods may utilize membrane-based separation to concentrate exosomes from biological fluid samples. Centrifugal filter devices with molecular weight cutoffs ranging from 10 kDa to 100 kDa may be employed to retain exosomes while allowing smaller molecules to pass through. Multiple concentration and washing cycles may be performed to achieve desired exosome concentrations.

[0160] Microfluidic devices may offer emerging approaches for exosome isolation that provide precise control over fluid flow and separation parameters. These devices may incorporate immunoaffinify capture, size-based separation, or acoustic separation principles to isolate exosomes from small sample volumes with high efficiency.

[0161] Qualify control measures may be implemented to assess the efficiency and specificity’ of exosome isolation procedures. Nanoparticle tracking analysis may be used to determine exosome concentration and size distribution. Transmission electron microscopy may provide morphological characterization of isolated vesicles. Western blot analysis may confirm the presence of exosome-specific markers and assess contamination by non- exosomal proteins.

[0162] Storage conditions for isolated exosomes may vary depending on the intended dow nstream applications. Short-term storage at 4°C may be suitable for immediate analysis, while long-term storage at -20°C to -80°C may preserve exosome integrity for extended periods. Cryoprotectants such as dimethyl sulfoxide or trehalose may’ be added to prevent freeze-thaw damage.

[0163] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The selection and optimization of exosome isolation methods may depend on specific analytical requirements, sample characteristics, and laboratory’ capabilities.

[0164] PCNA Detection and Quantification

[0165] PCNA detection and quantification in isolated exosomes may beaccomplished through various analytical methodologies, each offering distinct advantages for different applications and laboratory settings. The selection of appropriate detection methods may depend on factors such as sensitivity requirements, sample throughput, available instrumentation, and regulatory considerations for clinical applications.

[0166] Immunoassay-based detection methods represent the most widely utilized approaches for PCNA quantification in exosomal samples. These methods rely on the specific binding interaction between antibodies and PCNA protein to enable detection and measurement. The specificity and sensitivity of immunoassays may be influenced by antibody selection, assay format, and detection system configuration.

[0167] Enzy me-linked immunosorbent assay (ELISA) methods may provide quantitative measurement of exosomal PCNA levels with high sensitivity and reproducibility. Sandwich ELISA formats may utilize capture antibodies immobilized on solid surfaces to bind PCNA from exosomal lysates, followed by detection antibodies conjugated to enzymes for signal generation. In some cases, monoclonal antibodies may be used as capture antibodies to provide consistent binding characteristics, while polyclonal antibodies may serve as detection antibodies to recognize multiple epitopes on PCNA protein.

[0168] Sample preparation for ELISA analysis may involve lysing isolated exosomes to release PCNA protein for antibody binding. Lysis buffers may contain detergents such as Triton X-100 at concentrations ranging from 0.1% to 1.0% to disrupt exosome membranes while preserving protein integrity. In some cases, phosphate-buffered saline containing 0.4% Triton X-100 may be mixed with exosome samples for 20 to 30 minutes at room temperature to achieve complete lysis. The lysed samples may then be loaded onto ELISA plates precoated with monoclonal anti-PCNA antibodies.

[0169] Incubation conditions for ELISA procedures may vary depending on antibody characteristics and assay requirements. Primary incubation with sample lysates may be performed at temperatures ranging from 4°C to 37°C for durations of 30 minutes to 2 hours. In some cases, incubation at 37°C for 45 minutes may provide optimal binding conditions. Washing steps may be performed using phosphate-buffered saline containing 0.05% to 0. 1% Tween-20 to remove unbound material while maintaining antibody-antigen complexes.

[0170] Detection antibody incubation may follow similar temperature and time parameters, with biotin-conjugated secondary antibodies commonly employed to enable signal amplification through streptavidin-enzyme conjugates. Horseradish peroxidase may serve as the enzyme component, with substrate solutions containing tetramethylbenzidine orother chromogenic compounds generating colorimetric signals proportional to PCNA concentration.

[0171] Standard curves may be generated using recombinant PCNA protein at concentrations ranging from 0.1 ng / mL to 1000 ng / mL to enable quantitative analysis of unknow n samples. The linear range of detection may span multiple orders of magnitude, with lower limits of detection potentially reaching pg / mL levels depending on antibody affinity and assay optimization.

[0172] Western blot analysis may provide qualitative and semi-quantitative assessment of exosomal PCNA levels while offering additional information about protein molecular weight and potential post-translational modifications. Exosomal lysates may be prepared using standard protein extraction buffers containing detergents, protease inhibitors, and reducing agents to solubilize and preserve PCNA protein.

[0173] Protein concentrations in exosomal lysates may be determined using bicinchoninic acid (BCA) assays or other protein quantification methods to enable loading of equal protein amounts across samples. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) may be performed using gel concentrations ranging from 10% to 15% acrylamide to achieve optimal separation of PCNA protein, which migrates at approximately 36 kDa molecular weight.

[0174] Transfer of separated proteins to poly vinylidene fluoride (PVDF) or nitrocellulose membranes may be accomplished using wet transfer, semi-dry transfer, or dry transfer methods. Transfer conditions may be optimized based on protein size and membrane characteristics, with transfer times ranging from 30 minutes to 2 hours depending on the method employed.

[0175] Blocking procedures may utilize non-fat dry milk, bovine serum albumin, or commercial blocking reagents at concentrations ranging from 3% to 5% in Tris-buffered saline containing 0. 1 % Tween-20. Blocking incubation may be performed for 1 to 2 hours at room temperature or overnight at 4°C to prevent non-specific antibody binding.

[0176] Primary antibody incubation may utilize anti-PCNA antibodies at dilutions ranging from 1:500 to 1:5000 depending on antibody characteristics and detection requirements. Incubation may be performed overnight at 4°C with gentle agitation to ensure uniform antibody distribution and binding. Secondary antibody incubation may employ horseradish peroxidase-conjugated antibodies at dilutions ranging from 1:2000 to 1 : 10000 for 1 to 2 hours at room temperature.

[0177] Chemiluminescent detection systems may provide enhanced sensitivitycompared to colorimetric methods, with enhanced chemiluminescence (ECL) reagents generating light signals proportional to antibody binding. Signal detection may be accomplished using X-ray film, charge-coupled device cameras, or digital imaging systems capable of quantitative analysis.

[0178] Immunofluorescent assays may offer alternative detection approaches with potential for multiplexed analysis and cellular localization studies. Fluorophore-conjugated antibodies may be employed for direct detection, or fluorophore-conjugated secondary antibodies may be used with unlabeled primary antibodies for signal amplification. Fluorescence detection may be performed using fluorescence microscopy, flow cytometry, or plate-based fluorescence readers.

[0179] Turbidimetric immunoassays may utilize latex particle-conjugated antibodies to generate light scattering signals proportional to PCNA concentration. These assays may offer rapid analysis times and compatibility with automated clinical chemistry analyzers. Latex particles ranging from 0.1 to 1.0 micrometers in diameter may be conjugated to anti- PCNA antibodies through covalent or non-covalent attachment methods.

[0180] Radioimmunoassays may provide exceptional sensitivity for PCNA detection through the use of radioactively labeled antibodies or antigens. Iodine-125 or tritium labels may be incorporated into detection systems, with radioactive decay measured using gamma counters or liquid scintillation counters. Radioimmunoassays may achieve detection limits in the femtogram range but require specialized facilities and safety protocols for radioactive material handling.

[0181] Chemiluminescent immunoassays may combine the specificity of antibodybased detection with the sensitivity' of light-based signal generation. Acridinium esters, luminol derivatives, or other chemiluminescent compounds may be conjugated to antibodies or detection reagents to generate light signals upon chemical activation. Automated chemiluminescent immunoassay platforms may provide high-throughput analysis capabilities for clinical applications.

[0182] Flow cytometry-based detection methods may enable analysis of individual exosomes while providing information about size distribution and surface marker expression. Exosomes may be captured on antibody-coated beads or analyzed directly using high- sensitivity flow cytometers capable of detecting submicron particles. Fluorophore-conjugated anti-PCNA antibodies may be used to quantity' PCNA expression on individual exosomes.

[0183] Colloidal gold-based lateral flow assays may provide rapid, point-of-care detection capabilities for exosomal PCNA analysis. Gold nanoparticles conjugated to anti-PCNA antibodies may generate visible signals upon binding to PCNA in test samples. Lateral flow strips may incorporate capture antibodies immobilized on nitrocellulose membranes to concentrate PCNA-gold complexes at specific test zones. These assays may provide qualitative or semi-quantitative results within 10 to 30 minutes without requiring specialized instrumentation.

[0184] Quantitative polymerase chain reaction (qPCR) methods may enable detection and quantification of PCNA mRNA within exosomal samples. RNA extraction from isolated exosomes may be performed using commercial RNA isolation kits or phenolchloroform extraction methods. Reverse transcription may convert PCNA mRNA to complementary' DNA (cDNA) using random primers or gene-specific primers.

[0185] Real-time PCR amplification may utilize PCNA-specific primer pairs designed to amplify unique regions of PCNA mRNA sequences. TaqMan probes or SYBR Green dyes may provide fluorescent detection of amplified products during thermal cycling. Standard curves generated using known concentrations of PCNA mRNA or plasmid DNA may enable quantitative analysis of unknown samples.

[0186] Digital PCR methods may provide absolute quantification of PCNA mRNA molecules without requiring standard curves. Samples may be partitioned into thousands of individual reactions, with positive and negative partitions counted to determine target molecule concentrations. Digital PCR may offer enhanced precision and accuracy compared to traditional qPCR methods, particularly for low-abundance targets.

[0187] Alternative detection methodologies may provide complementary approaches for PCNA analysis in specialized applications. Aptamer-based assays may utilize nucleic acid aptamers selected for specific binding to PCNA protein. Aptamers may be conjugated to various detection systems including fluorophores, enzymes, or electrochemical reporters to enable signal generation.

[0188] Allosteric regulator binding assays may exploit conformational changes in PCNA protein upon binding to specific ligands or cofactors. These assays may utilize fluorescence polarization, surface plasmon resonance, or other biophysical detection methods to monitor binding interactions. Enzyme activity assays may measure PCNA-dependent enzymatic activities as indirect indicators of PCNA concentration.

[0189] Receptor-ligand assays may utilize natural or synthetic binding partners for PCNA protein to enable detection through competitive binding or displacement mechanisms. These assays may incorporate various detection modalities including fluorescence, luminescence, or electrochemical signals.

[0190] Antibody production for PCNA detection may involve various approaches depending on specificity requirements and intended applications. Polyclonal antibodies may be generated through immunization of host animals with PCNA protein or peptide antigens. Host species may include mice, rats, rabbits, sheep, goats, pigs, dogs, chickens, horses, cattle, and alpacas, with selection based on antibody yield, specificity7, and compatibility7with detection systems.

[0191] Immunization protocols may involve multiple injections of PCNA antigen combined with adjuvants to stimulate immune responses. Primary immunization may be followed by booster injections at intervals ranging from 2 to 4 weeks to enhance antibody production. Serum collection may be performed 7 to 14 days after booster injections to obtain peak antibody titers.

[0192] Antibody purification may be accomplished through protein A or protein G affinity7chromatography to isolate immunoglobulin fractions from immune sera. Antigenspecific purification may be performed using PCNA protein immobilized on solid supports to select antibodies with desired binding characteristics.

[0193] Monoclonal antibodies may be produced through hybridoma technologyinvolving fusion of antibody -producing B cells with immortalized myeloma cells. Hybridoma clones may be screened for PCNA-specific antibody production and selected based on binding affinity, specificity, and stability characteristics. Monoclonal antibodies may provide consistent binding properties and unlimited supply for standardized assays.

[0194] Recombinant antibodies may be produced through expression of antibody genes in bacterial, yeast, or mammalian cell systems. Single-chain variable fragments (scFv), Fab fragments, or full-length antibodies may be expressed and purified using standard protein production methods. Recombinant antibodies may offer advantages in terms of reproducibility, modification potential, and scalability.

[0195] Nanobodies representing single-domain antibodies derived from camelid species may provide enhanced stability- and tissue penetration compared to conventional antibodies. Nanobodies may be selected from phage display libraries or generated through immunization of llamas or alpacas with PCNA antigens.

[0196] PCNA protein antigen for antibody7production and assay standardization may be prepared through recombinant expression in bacterial systems. DNA encoding human PCNA may be subcloned into expression vectors such as pET-28a to enable production of histidine-tagged fusion proteins. Transformation of expression constructs into Escherichia coli strains such as BL21(DE3) may provide high-level protein expression under controlledconditions.

[0197] Bacterial cultures may be grown in rich media such as Luria-Bertani broth supplemented with appropriate antibiotics for plasmid selection. Protein expression may be induced using isopropyl P-D-l -thiogalactopyranoside (IPTG) at concentrations ranging from 0.1 mM to 1.0 mM. Induction may be performed at temperatures ranging from 16°C to 37°C for durations of 3 to 16 hours depending on expression optimization requirements.

[0198] Cell harvesting may be accomplished through centrifugation at forces ranging from 3000 x g to 8000 * g for 10 to 20 minutes. Cell pellets may be resuspended in lysis buffers containing Tris-HCl at pH values ranging from 7.5 to 8.5, sodium chloride at concentrations of 150 mM to 500 mM, and protease inhibitors including phenylmethylsulfonyl fluoride (PMSF) at 1.0 mM concentration and aprotinin and leupeptin at 10 pg / mL each.

[0199] Cell lysis may be performed through sonication using probe sonicators or bath sonicators with pulse cycles to prevent overheating. Sonication parameters may include pulse durations of 10 to 30 seconds with rest intervals of 30 to 60 seconds, repeated for total processing times of 5 to 15 minutes. Alternatively, cell lysis may be accomplished through French press, microfluidization, or enzymatic methods.

[0200] Protein purification may utilize nickel-sepharose or other immobilized metal affinity chromatography resins to capture histidine-tagged PCNA proteins. Binding may be performed in buffers containing imidazole concentrations ranging from 10 mM to 50 mM to reduce non-specific binding while maintaining target protein capture. Washing steps may employ buffers with imidazole concentrations of 20 mM to 100 mM to remove contaminants.

[0201] Protein elution may be accomplished using buffers containing imidazole concentrations ranging from 200 mM to 500 mM. In some cases, elution with 300 mM imidazole in phosphate-buffered saline may provide effective protein recovery. Eluted fractions may be analyzed using SDS-PAGE and protein staining to assess purity and yield.

[0202] Additional purification steps may include size-exclusion chromatography, ion-exchange chromatography, or reverse-phase chromatography to achieve higher purity levels. Protein concentrations may be determined using spectrophotometric methods. Bradford assays, or BCA assays. Purified PCNA protein may be stored in buffers containing glycerol or other stabilizing agents at temperatures ranging from -20°C to -80°C.

[0203] Detectable label conjugation to antibodies may enable various detection modalities depending on assay requirements. Enzyme conjugation may utilize horseradish peroxidase, alkaline phosphatase, or glucose oxidase attached through chemical crosslinkingmethods. Crosslinking reagents may include glutaraldehyde, carbodiimides, or heterobifunctional crosslinkers that react with amino groups on antibodies and enzymes.

[0204] Fluorophore conjugation may employ fluorescein isothiocyanate (FITC), rhodamine derivatives, Alexa Fluor dyes, or other fluorescent compounds. Conjugation reactions may be performed in alkaline buffers at pH values ranging from 8.5 to 9.5 to facilitate amine-reactive chemistry. Reaction times may range from 1 to 4 hours at room temperature or 4°C to 25°C.

[0205] Chemiluminescent label attachment may utilize acridinium esters, luminol derivatives, or other light-generating compounds. These labels may be conjugated through similar chemical methods as enzyme and fluorophore attachment. Radionuclide labeling may employ iodine- 125, tritium, or other radioactive isotopes attached through iodination reactions or metabolic incorporation.

[0206] Latex particle conjugation for turbidimetric assays may involve covalent attachment of antibodies to carboxylated or amino-functionalized latex beads. Conjugation may be performed using carbodiimide chemistry in buffers at pH values ranging from 4.5 to 6.5 for carboxylated particles or pH 7.0 to 8.5 for amino-functionalized particles. Reaction times may range from 2 to 24 hours with gentle mixing to ensure uniform conjugation.

[0207] Quality control measures for detection assays may include specificity testing using related proteins or peptides to assess cross-reactivity. Sensitivity determinations may involve serial dilutions of PCNA standards to establish lower limits of detection. Precision studies may evaluate intra-assay and inter-assay variability through replicate measurements. Stability testing may assess signal consistency over time and storage conditions.

[0208] Assay validation for clinical applications may require additional studies including linearity assessment, recovery experiments, and interference testing with common biological substances. Reference standards and control materials may be established to ensure consistent performance across different laboratories and time periods.

[0209] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The selection and optimization of detection methods may depend on specific analytical requirements, sample characteristics, and intended applications.

[0210] Reference Levels and Comparison Standards

[0211] Reference levels for exosomal PCNA may be established through analysis of biological fluid samples obtained from healthy individuals who do not have cancer or otherproliferative disorders. The establishment of appropriate reference levels may provide the foundation for determining whether exosomal PCNA concentrations in test samples represent elevated levels indicative of malignancy.

[0212] Control sample collection may involve obtaining biological fluid samples from demographically matched healthy volunteers who have undergone medical screening to exclude the presence of cancer or other proliferative conditions. In some cases, healthy control populations may include individuals ranging in age from 18 to 85 years to encompass the age distribution typically observed in cancer patient populations. Gender distribution in control populations may approximate equal representation of male and female subjects to account for potential gender-related variations in exosomal PCNA levels.

[0213] Medical screening of healthy control subjects may include comprehensive medical history review, physical examination, and laboratory testing to exclude underlying malignancies or proliferative disorders. Exclusion criteria for control subjects may include current or previous cancer diagnosis, active inflammatory conditions, autoimmune disorders, or recent surgical procedures that might influence exosomal PCNA levels. In some cases, control subjects may undergo imaging studies or additional diagnostic testing to confirm the absence of occult malignancies.

[0214] Biological fluid sample collection from healthy controls may follow standardized protocols to minimize pre-analytical variables that could affect exosomal PCNA measurements. Sample collection timing may be standardized to account for potential circadian variations in exosomal PCNA levels. Fasting status, medication use, and recent physical activity may be documented and controlled to reduce confounding factors.

[0215] Sample processing and storage conditions for control samples may follow identical protocols to those used for patient samples to ensure analytical consistency. Exosome isolation and PCNA quantification methods may be performed using the same reagents, instrumentation, and personnel to minimize systematic differences between control and patient sample analysis.

[0216] Statistical analysis of control sample data may involve calculation of central tendency measures such as mean and median values, along with measures of variability including standard deviation and interquartile ranges. Distribution characteristics of exosomal PCNA levels in healthy populations may be assessed to determine whether data follow normal or non-normal distributions, which may influence the selection of appropriate statistical methods for comparison with patient samples.

[0217] Reference range establishment may utilize various statistical approachesdepending on the distribution characteristics of control data. In some cases, reference ranges may be defined as the mean value plus or minus two standard deviations, encompassing approximately 95% of the healthy population. Alternative approaches may utilize percentilebased methods, with the 95th percentile of healthy control values serving as an upper reference limit.

[0218] Elevated exosomal PCNA levels may be defined through comparison with established reference levels using fold-change calculations or absolute threshold values. Foldchange determinations may involve dividing individual patient sample concentrations by the mean or median concentration observed in healthy control populations. In some cases, elevated levels may be defined as concentrations that are at least 1.5 -fold greater than the reference level established from healthy control samples.

[0219] More stringent criteria for elevated levels may define significant elevation as concentrations that are at least 2-fold greater than the reference level. This threshold may provide enhanced specificity for cancer detection by reducing the likelihood of false-positive results due to normal biological variation or non-malignant conditions that might cause modest increases in exosomal PCNA levels.

[0220] Alternative threshold definitions may utilize absolute concentration values rather than fold-change calculations. In some cases, elevated levels may be defined as exosomal PCNA concentrations exceeding specific ng / mL values determined through receiver operating characteristic (ROC) curve analysis. ROC analysis may identify optimal cutoff values that maximize the combination of sensitivity and specificity for cancer detection.

[0221] Threshold optimization may involve analysis of large datasets containing both healthy control and cancer patient samples to identify cutoff values that provide the most favorable diagnostic performance characteristics. Sensitivity and specificity calculations may be performed across a range of potential threshold values to identify optimal operating points for different clinical applications.

[0222] Clinical context considerations may influence the selection of appropriate threshold values for different applications. Screening applications may favor higher sensitivity thresholds to minimize false-negative results, potentially accepting lower specificity to ensure detection of early-stage cancers. Diagnostic applications may prioritize higher specificity thresholds to reduce false-positive results and minimize unnecessary follow-up procedures.

[0223] Age-related adjustments to reference levels may be considered based onpotential variations in exosomal PCNA levels across different age groups. In some cases, age-stratified reference ranges may be established to account for physiological changes in cellular proliferation rates that occur with aging. Gender-specific reference levels may also be evaluated if significant differences in exosomal PCNA levels are observed between male and female populations.

[0224] Comorbidity considerations may influence reference level establishment and threshold determination. Individuals with benign proliferative conditions such as benign prostatic hyperplasia or liver cirrhosis may exhibit intermediate exosomal PCNA levels between healthy controls and cancer patients. Separate reference ranges may be established for populations with specific comorbid conditions to improve diagnostic accuracy in these clinical contexts.

[0225] Quality control measures for reference level establishment may include periodic reassessment of control populations to ensure continued validity of established reference ranges. Longitudinal studies may evaluate the stability of exosomal PCNA levels in healthy individuals over time to assess the durability of reference level determinations.

[0226] Inter-laboratory standardization efforts may involve analysis of common reference materials across multiple testing facilities to ensure consistency in reference level establishment and threshold application. Proficiency testing programs may utilize standardized samples with known exosomal PCNA concentrations to assess analytical performance and reference level accuracy across different laboratories.

[0227] Analytical validation studies may evaluate the precision and accuracy of exosomal PCNA measurements at concentrations near established threshold values. Repeatability and reproducibility assessments may determine the analytical uncertainty associated with measurements in the decision-making range around threshold values.

[0228] Clinical validation studies may assess the performance of established reference levels and thresholds in independent patient populations to confirm diagnostic accuracy. Prospective studies may evaluate the clinical utility of threshold-based decision making in real-world clinical settings.

[0229] Reference material development may involve preparation of standardized exosomal PCNA samples with defined concentrations for use in calibration and quality' control applications. These materials may be distributed to testing laboratories to ensure consistent reference level application and threshold implementation.

[0230] Documentation and traceability of reference level establishment procedures may include detailed protocols, statistical analysis methods, and quality’ control data tosupport regulatory submissions and clinical implementation. Standard operating procedures may be developed to ensure consistent application of reference levels and threshold criteria across different testing scenarios.

[0231] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The establishment and application of reference levels and threshold criteria may be adapted based on specific analytical methods, patient populations, and clinical applications while maintaining the fundamental principles of comparative analysis for cancer detection.

[0232] Cancer Detection and Identification Methods

[0233] Cancer detection through exosomal PCNA analysis may involve systematic comparison of PCNA levels in biological fluid samples from subjects suspected of having cancer with established reference levels derived from healthy control populations. The diagnostic methodology7may utilize various analytical approaches to distinguish between malignant and non-malignant conditions based on quantitative differences in exosomal PCNA concentrations.

[0234] Diagnostic criteria for cancer detection may be established through receiver operating characteristic (ROC) curve analysis to identify optimal threshold values that maximize sensitivity and specificity for distinguishing cancer patients from healthy individuals. In some cases. ROC analysis may reveal that exosomal PCNA concentrations exceeding 97.81 ng / mL in serum samples provide optimal diagnostic performance with sensitivity values of 77.2% and specificity7values of 94.4%. Alternative threshold values may be established for different biological fluid types or specific cancer applications based on analytical validation studies.

[0235] The comparison methodology may involve direct measurement of exosomal PCNA levels in test samples followed by calculation of fold-change ratios relative to established reference levels. Fold-change calculations may be performed by dividing the measured PCNA concentration in a test sample by the mean or median concentration observed in healthy control populations. Elevated levels may be defined as concentrations that exceed reference levels by factors ranging from 1.5-fold to 5-fold, with higher foldchange thresholds providing enhanced specificity for cancer detection.

[0236] Statistical analysis methods for diagnostic interpretation may include confidence interval calculations to assess the reliability of individual measurements relative to reference populations. In some cases, measurements that fall outside the 95% confidenceinterval of healthy control distributions may be considered indicative of potential malignancy. Alternative statistical approaches may utilize percentile-based comparisons, with measurements exceeding the 95th percentile of healthy control values suggesting elevated cancer risk.

[0237] Multi-parameter analysis approaches may combine exosomal PCNA measurements with additional biomarkers or clinical parameters to enhance diagnostic accuracy. Logistic regression models may incorporate exosomal PCNA levels along with patient age, gender, medical history, and other laboratory values to generate composite risk scores for cancer detection. Machine learning algorithms may be trained on datasets containing exosomal PCNA measurements and clinical outcomes to develop predictive models for cancer diagnosis.

[0238] Cancer-associated isoform of PCNA (caPCNA) may serve as a more specific indicator of malignancy compared to total PCNA measurements. The caPCNA isoform may exhibit altered electrophoretic mobility', modified post-translational modifications, or distinct immunoreactivity patterns that distinguish cancer-derived PCNA from PCNA produced by normal proliferating cells. Detection methods for caPCNA may utilize specialized antibodies that recognize cancer-specific epitopes or modifications not present on normal PCNA protein.

[0239] Isoform-specific detection may be accomplished through high-resolution electrophoretic separation techniques that can distinguish subtle molecular weight differences between normal PCNA and caPCNA. Two-dimensional gel electrophoresis may separate PCNA isoforms based on both molecular weight and isoelectric point differences. Mass spectrometry analysis may provide definitive identification of post-translational modifications or sequence variations that characterize caPCNA.

[0240] Immunoassay development for caPCNA detection may involve generation of monoclonal antibodies through immunization with cancer-derived PCNA protein or synthetic peptides corresponding to cancer-specific epitopes. Antibody screening procedures may utilize cancer cell lysates and normal cell lysates to identify antibodies that selectively recognize caPCNA while showing minimal cross-reactivity with normal PCNA isoforms.

[0241] The diagnostic utility of caPCNA may provide enhanced specificity for cancer detection by reducing false-positive results that might occur due to elevated normal PCNA levels in benign proliferative conditions. Benign prostatic hyperplasia, liver cirrhosis, inflammatory conditions, and wound healing processes may cause increases in total PCNA levels without corresponding increases in caPCNA, thereby improving the discriminatory power of the diagnostic test.

[0242] Differential diagnosis applications may utilize exosomal PCNA measurements to distinguish between malignant and benign conditions that present with similar clinical features. Liver lesions may be evaluated through comparison of total exosomal PCNA levels and caPCNA levels to differentiate hepatocellular carcinoma from benign hepatic adenomas or focal nodular hyperplasia. Prostate conditions may be assessed through exosomal PCNA analysis to distinguish prostate cancer from benign prostatic hyperplasia.

[0243] Tissue-of-origin identification may be accomplished through analysis of exosomal PCNA levels in tissue-specific exosome populations isolated using surface markerbased separation techniques. Liver-derived exosomes may be isolated using antibodies against asialoglycoprotein receptor 1 (ASGPR1), while colorectal-derived exosomes may be captured using antibodies against glycoprotein A33 (GPA33). Lung-derived exosomes may be isolated using antibodies against surfactant protein B or other lung-specific markers.

[0244] The analysis of PCNA levels within tissue-specific exosome populations may provide information about the anatomical location of malignancy, enabling more targeted diagnostic workup and treatment planning. Elevated PCNA levels in liver-specific exosomes may suggest hepatocellular carcinoma or liver metastases, while elevated PCNA levels in colorectal-specific exosomes may indicate primary’ colorectal cancer or colorectal liver metastases.

[0245] Multi-organ screening applications may involve simultaneous analysis of exosomal PCNA levels across multiple tissue-specific exosome populations to enable comprehensive cancer detection across various anatomical sites. Panel-based testing may include isolation and analysis of exosomes derived from liver, lung, colorectal, breast, prostate, and ovarian tissues to provide broad-spectrum cancer screening capabilities.

[0246] Quantitative interpretation guidelines may establish specific concentration ranges that correspond to different levels of cancer risk or disease severity. Low-level elevation of exosomal PCNA may indicate early-stage cancer or pre-malignant conditions, while high-level elevation may suggest advanced-stage disease or high tumor burden. Intermediate elevation levels may warrant additional diagnostic testing or close clinical monitoring.

[0247] Serial monitoring applications may utilize repeated exosomal PCNA measurements over time to assess disease progression, treatment response, or recurrence detection. Baseline measurements may be established prior to treatment initiation, with subsequent measurements performed at regular intervals during and after treatment.Increasing exosomal PCNA levels over time may indicate disease progression or treatment resistance, while decreasing levels may suggest treatment response.

[0248] Treatment monitoring protocols may incorporate exosomal PCNA measurements as biomarkers for assessing therapeutic efficacy. Chemotherapy response may be evaluated through measurement of exosomal PCNA levels before, during, and after treatment cycles. Surgical resection effectiveness may be assessed through comparison of pre-operative and post-operative exosomal PCNA levels. Radiation therapy response may be monitored through serial exosomal PCNA measurements during treatment courses.

[0249] Recurrence detection applications may utilize exosomal PCNA measurements as surveillance tools for identifying cancer recurrence in patients who have completed primary treatment. Surveillance protocols may involve periodic measurement of exosomal PCNA levels at intervals ranging from monthly to annually depending on cancer type and recurrence risk. Rising exosomal PCNA levels in patients with previously undetectable levels may indicate disease recurrence before clinical symptoms or imaging abnormalities become apparent.

[0250] Quality assurance measures for cancer detection applications may include implementation of standardized protocols for sample collection, processing, and analysis to ensure consistent diagnostic performance. Proficiency testing programs may utilize blinded samples with known cancer status to assess laboratory performance in cancer detection applications. External quality assessment schemes may provide ongoing monitoring of diagnostic accuracy across multiple testing facilities.

[0251] Clinical decision support systems may incorporate exosomal PCNA results along with other clinical data to provide evidence-based recommendations for patient management. Decision algorithms may guide clinicians in determining appropriate follow-up testing, referral patterns, or treatment recommendations based on exosomal PCNA levels and other clinical factors.

[0252] Regulatory7compliance considerations for cancer detection applications may involve validation studies demonstrating analytical and clinical performance characteristics required for regulatory approval. Clinical trials may be conducted to establish the safety and effectiveness of exosomal PCNA testing for cancer detection in specific patient populations. Post-market surveillance programs may monitor real-w orld performance and safety outcomes following regulatory approval.

[0253] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. Theselection and implementation of cancer detection methodologies may be adapted based on specific clinical applications, patient populations, and regulatory requirements while maintaining the fundamental principles of comparative analysis for distinguishing malignant from non-malignant conditions.

[0254] Tissue-Specific Markers for Cancer Localization

[0255] Tissue-specific markers on exosomes may provide a technical solution for determining the anatomical origin of detected cancers through analysis of surface proteins that reflect the tissue source from which exosomes were derived. This approach may enable cancer localization capabilities that extend beyond simple detection to provide information about tumor location, thereby enhancing the clinical utility of exosomal PCNA analysis for diagnostic and therapeutic decision-making.

[0256] The technical basis for tissue-specific cancer localization relies on the observation that exosomes carry surface proteins characteristic of their parent cells and tissues of origin. Cancer cells may release exosomes that retain tissue-specific surface markers, allowing for identification of the anatomical site from which cancer-derived exosomes originated. This represents an unexpected utility of exosomal surface markers for cancer localization applications that was not previously recognized in liquid biopsy methodologies.

[0257] Asialoglycoprotein receptor 1 (ASGPR1) may serve as a liver-specific marker for isolating exosomes derived from hepatic tissues. ASGPR1 may be expressed on the surface of liver-derived exosomes, including those originating from hepatocellular carcinoma cells and normal hepatocytes. Immunoaffinity capture using anti-ASGPRl antibodies may enable selective isolation of liver-derived exosomes from complex biological fluid samples containing exosomes from multiple tissue sources.

[0258] ASGPR1 -based exosome isolation may be performed using magnetic beadbased immunoprecipitation techniques. Anti-ASGPRl antibodies may be conjugated to magnetic beads through covalent attachment methods using carbodiimide chemistry or other crosslinking approaches. Biological fluid samples may be incubated with ASGPR1 antibody- coated magnetic beads for periods ranging from 30 minutes to 4 hours at temperatures of 4°C to room temperature to allow binding of liver-derived exosomes.

[0259] Magnetic separation may be accomplished using magnetic stands or automated magnetic separation systems to capture ASGPR1 -positive exosomes. Washing procedures may utilize phosphate-buffered saline or other appropriate buffers to removeunbound exosomes and contaminants while retaining ASGPR1 -positive vesicles. Multiple washing cycles may be performed to enhance the purity of isolated liver-derived exosomes.

[0260] Glycoprotein A33 (GPA33) may function as a colorectal-specific marker for isolating exosomes derived from colorectal tissues. GPA33 may be expressed on the surface of exosomes originating from colorectal cancer cells and normal colonic epithelial cells. Anti-GPA33 antibodies may be utilized in immunoaffinity capture procedures to selectively isolate colorectal-derived exosomes from biological fluid samples.

[0261] GPA33-based exosome isolation may follow similar methodological approaches to ASGPR1 -based isolation, with anti-GPA33 antibodies conjugated to magnetic beads for immunoprecipitation applications. Incubation conditions may be optimized for GPA33-antibody binding kinetics, which may differ from ASGPR1 binding characteristics due to variations in antibody affinity and antigen density on exosome surfaces.

[0262] Sequential isolation procedures may enable simultaneous analysis of multiple tissue-specific exosome populations from individual biological fluid samples. In some cases, biological fluid samples may be divided into aliquots for parallel isolation of ASGPR1 -positive and GPA33-positive exosomes. Alternative approaches may involve sequential immunoprecipitation steps using different tissue-specific markers to isolate multiple exosome populations from single samples.

[0263] Additional tissue-specific markers may expand the range of anatomical sites that can be analyzed through exosomal PCNA localization. Lung-derived exosomes may be isolated using antibodies against surfactant protein B, surfactant protein C, or other pulmonary-specific markers. Breast-derived exosomes may be captured using antibodies against mammoglobin, GCDFP-15, or other mammary-specific proteins.

[0264] Prostate-derived exosomes may be isolated using antibodies against prostatespecific membrane antigen (PSMA), prostate-specific antigen (PSA), or other prostatespecific markers. Ovarian-derived exosomes may be captured using antibodies against CA- 125, HE4, or other ovarian-specific proteins. Pancreatic-derived exosomes may be isolated using antibodies against carbohydrate antigen 19-9 (CA 19-9) or other pancreatic-specific markers.

[0265] Brain-derived exosomes may be isolated using antibodies against glial fibrillary acidic protein (GFAP), myelin basic protein, or other neural -specific markers. Kidney-derived exosomes may be captured using antibodies against aquaporin-2, Tamm- Horsfall protein, or other renal-specific markers. Thyroid-derived exosomes may be isolated using antibodies against thyroglobulin, thyroid peroxidase, or other thyroid-specific proteins.

[0266] Marker validation procedures may involve confirmation of tissue specificity through analysis of exosome populations isolated from known tissue sources. Cell culture studies may utilize cancer cell lines derived from different anatomical sites to validate the tissue specificity of surface markers. Exosomes isolated from liver cancer cell lines may be analyzed for ASGPR1 expression, while exosomes from colorectal cancer cell lines may be assessed for GPA33 expression.

[0267] Cross-reactivity testing may evaluate the specificity of tissue-specific markers by analyzing their expression on exosomes derived from non-target tissues. ASGPR1 antibodies may be tested against exosomes from lung, breast, prostate, and other non-hepatic cancer cell lines to confirm liver specificity. GPA33 antibodies may be evaluated against exosomes from liver, lung, breast, and other non-colorectal sources to verify colorectal specificity.

[0268] Multiplexed isolation approaches may enable simultaneous capture of multiple tissue-specific exosome populations using different magnetic bead populations or flow cytometry-based sorting methods. Magnetic beads conjugated to different tissue-specific antibodies may be distinguished using size differences, fluorescent labeling, or other identification methods. Flow cytometry may utilize multiple fluorophore-conjugated antibodies to identify and sort exosomes based on tissue-specific marker expression patterns.

[0269] Quantitative analysis of tissue-specific exosomal PCNA may involve measurement of PCNA levels within each isolated exosome population to determine the relative contribution of different tissues to total exosomal PCNA levels. Elevated PCNA levels in ASGPR1 -positive exosomes may indicate liver cancer, while elevated PCNA levels in GPA33-positive exosomes may suggest colorectal cancer.

[0270] Comparative analysis between tissue-specific exosome populations may provide information about the primary site of cancer origin in cases where multiple anatomical sites may be involved. The tissue-specific exosome population with the highest PCNA levels may indicate the primary tumor location, while lower PCNA levels in other tissue-specific populations may suggest metastatic involvement.

[0271] Localization algorithms may be developed to interpret tissue-specific exosomal PCNA data and provide probabilistic assessments of cancer location. Machine learning approaches may be trained on datasets containing tissue-specific exosomal PCNA measurements and known cancer locations to develop predictive models for cancer localization. These algorithms may incorporate multiple tissue-specific markers and PCNA measurements to generate composite localization scores.

[0272] Quality control measures for tissue-specific exosome isolation may include assessment of isolation efficiency, purity’, and specificity for each marker system. Nanoparticle tracking analysis may be used to quantify exosome recovery rates for different isolation procedures. Western blot analysis may confirm the presence of tissue-specific markers on isolated exosomes and assess contamination by non-target exosome populations.

[0273] Standardization procedures for tissue-specific marker-based isolation may involve development of reference materials and protocols to ensure consistent performance across different laboratories. Standardized antibody preparations, magnetic bead formulations, and isolation protocols may be established to minimize inter-laboratory variability in tissue-specific exosome isolation and PCNA analysis.

[0274] Clinical validation studies may assess the accuracy of tissue-specific exosomal PCNA analysis for cancer localization in patient populations with known cancer locations. Sensitivity and specificity calculations may be performed for each tissue-specific marker system to determine diagnostic performance characteristics. Receiver operating characteristic analysis may identify optimal PCNA threshold values for each tissue-specific exosome population.

[0275] Emerging tissue-specific markers may expand the range of anatomical sites that can be analyzed through exosomal PCNA localization. Proteomics studies may identify’ novel tissue-specific proteins expressed on exosome surfaces that could serve as additional markers for cancer localization. Glycomics analysis may reveal tissue-specific glycosylation patterns on exosomal proteins that could provide alternative approaches for tissue identification.

[0276] Marker combination strategies may utilize multiple tissue-specific markers simultaneously to enhance localization accuracy and reduce false-positive results. Panelbased approaches may incorporate 5 to 20 different tissue-specific markers to provide comprehensive coverage of major anatomical sites. Hierarchical classification schemes may utilize primary markers for initial tissue identification followed by secondary markers for confirmation and refinement.

[0277] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The selection and implementation of tissue-specific markers for cancer localization may be adapted based on specific clinical applications, available antibody reagents, and analytical platform capabilities while maintaining the fundamental principles of tissue-specific exosome isolation and PCNA analysis.

[0278] Monitoring and Progression Assessment

[0279] Monitoring and progression assessment applications may utilize repeated exosomal PCNA measurements over time to evaluate disease status, treatment response, and recurrence detection in cancer patients. The temporal analysis of exosomal PCNA levels may provide dynamic information about tumor behavior that extends beyond single-point diagnostic measurements to enable comprehensive patient management throughout the cancer care continuum.

[0280] Cancer progression monitoring may involve serial measurement of exosomal PCNA levels at predetermined intervals to assess changes in tumor burden or disease advancement. Baseline exosomal PCNA measurements may be established at the time of initial cancer diagnosis to provide reference values for subsequent monitoring assessments. Follow-up measurements may be performed at intervals ranging from weekly to quarterly depending on cancer type, stage, and treatment protocols.

[0281] Progressive increases in exosomal PCNA levels over time may indicate tumor growth, metastatic spread, or development of treatment resistance. The rate of increase in exosomal PCNA concentrations may correlate with the aggressiveness of disease progression, wi th rapid increases suggesting more aggressive tumor behavior. Gradual increases may indicate slower disease progression that might respond to modified treatment approaches.

[0282] Stable exosomal PCNA levels over multiple measurement time points may suggest disease stability or successful control of tumor grow th through ongoing treatment interventions. Maintenance of exosomal PCNA concentrations within established ranges may indicate effective disease management and may support continuation of current treatment regimens.

[0283] Treatment effectiveness assessment may utilize exosomal PCNA measurements to evaluate therapeutic response across various cancer treatment modalities. Pre-treatment baseline measurements may be obtained prior to initiation of chemotherapy, radiation therapy, immunotherapy, or surgical interventions to establish reference levels for response assessment. Post-treatment measurements may be performed at intervals ranging from days to months after treatment initiation to evaluate therapeutic efficacy.

[0284] Decreasing exosomal PCNA levels following treatment initiation may indicate positive therapeutic response and tumor regression. The magnitude and rate of decrease in exosomal PCNA concentrations may correlate with the extent of treatmentresponse, with larger decreases suggesting more substantial therapeutic effects. Rapid decreases may indicate highly responsive tumors, while gradual decreases may suggest slower but sustained treatment response.

[0285] Chemotherapy response monitoring may involve measurement of exosomal PCNA levels before, during, and after chemotherapy cycles to assess treatment efficacy and guide dosing decisions. In some cases, exosomal PCNA levels may be measured prior to each chemotherapy cycle to evaluate ongoing response and detect early signs of treatment resistance. Increasing exosomal PCNA levels during chemotherapy may indicate treatment failure or development of drug resistance.

[0286] Surgical intervention assessment may utilize pre-operative and postoperative exosomal PCNA measurements to evaluate the completeness of tumor resection. Substantial decreases in exosomal PCNA levels following surgical resection may indicate successful removal of tumor tissue. Persistent elevation of exosomal PCNA levels after surgery may suggest incomplete resection or presence of residual disease.

[0287] Radiation therapy monitoring may incorporate serial exosomal PCNA measurements during radiation treatment courses to assess therapeutic response. Exosomal PCNA levels may be measured weekly during radiation therapy to evaluate treatment effectiveness and detect early response patterns. Decreasing levels during radiation treatment may indicate tumor response, while stable or increasing levels may suggest radiation resistance.

[0288] Immunotherapy response assessment may utilize exosomal PCNA measurements to evaluate the effectiveness of immune checkpoint inhibitors, adoptive cell therapies, or other immunological interventions. The temporal pattern of exosomal PCNA changes during immunotherapy may differ from conventional chemotherapy responses, with delayed decreases potentially reflecting the time required for immune system activation and tumor recognition.

[0289] Combination therapy monitoring may involve analysis of exosomal PCNA levels during multi-modal treatment approaches that incorporate chemotherapy, radiation, surgery, and immunotherapy. The complex interactions between different treatment modalities may result in varied patterns of exosomal PCNA changes that require specialized interpretation protocols.

[0290] Recurrence detection applications may utilize exosomal PCNA measurements as surveillance tools for identifying cancer recurrence in patients who have completed primary treatment and achieved remission. Surveillance protocols may involveperiodic measurement of exosomal PCNA levels at intervals ranging from monthly to annually depending on cancer type and recurrence risk stratification.

[0291] Post-treatment surveillance may begin with frequent measurements during the period of highest recurrence risk, typically within the first two years after treatment completion. Measurement intervals may be extended as the time from treatment completion increases and recurrence risk decreases. In some cases, monthly measurements may be performed during the first year, quarterly measurements during the second year, and annual measurements thereafter.

[0292] Rising exosomal PCNA levels in patients with previously undetectable or low levels may indicate disease recurrence before clinical symptoms or imaging abnormalities become apparent. The lead time provided by exosomal PCNA elevation may enable earlier intervention and potentially improved treatment outcomes compared to conventional surveillance methods.

[0293] Recurrence pattern analysis may involve comparison of exosomal PCNA levels at recurrence with initial diagnostic levels to assess the characteristics of recurrent disease. Similar exosomal PCNA levels may suggest recurrence with similar tumor characteristics, while substantially different levels may indicate changes in tumor biology or development of more aggressive disease variants.

[0294] Tissue-specific recurrence localization may be accomplished through analysis of exosomal PCNA levels in tissue-specific exosome populations to identify the anatomical site of disease recurrence. Elevated PCNA levels in liver-specific exosomes may indicate hepatic recurrence or liver metastases, while elevated levels in lung-specific exosomes may suggest pulmonary recurrence.

[0295] Longitudinal data interpretation may require consideration of various factors that could influence exosomal PCNA levels independent of cancer status. Intercurrent illnesses, inflammatory conditions, wound healing processes, or other proliferative disorders may cause transient increases in exosomal PCNA levels that could be misinterpreted as disease progression or recurrence.

[0296] Baseline drift assessment may involve periodic measurement of exosomal PCNA levels in healthy control populations to evaluate potential changes in reference levels over time. Seasonal variations, demographic shifts, or analytical changes may influence baseline exosomal PCNA levels and require adjustment of interpretation criteria.

[0297] Quality control measures for longitudinal monitoring may include assessment of analytical precision and accuracy across extended time periods. Inter-assayvari abi 1 i ty may be evaluated through analysis of control samples included in each measurement batch. Long-term stability studies may assess the consistency of analytical performance over months to years of monitoring applications.

[0298] Data management systems for longitudinal monitoring may incorporate electronic databases capable of storing and analyzing serial exosomal PCNA measurements along with associated clinical data. Trend analysis algorithms may identify significant changes in exosomal PCNA levels and generate alerts for clinical review. Graphical displays may present temporal patterns of exosomal PCNA changes to facilitate clinical interpretation.

[0299] Clinical decision support tools may incorporate exosomal PCNA trend data along with other clinical parameters to provide evidence-based recommendations for patient management. Decision algorithms may guide clinicians in determining appropriate follow-up intervals, additional diagnostic testing, or treatment modifications based on exosomal PCNA patterns.

[0300] Predictive modeling approaches may utilize machine learning algorithms trained on longitudinal exosomal PCNA data to forecast future disease trajectories and treatment outcomes. These models may incorporate multiple variables including exosomal PCNA trends, patient demographics, treatment history, and other biomarker data to generate personalized predictions.

[0301] Standardization protocols for longitudinal monitoring may establish consistent procedures for sample collection, processing, and analysis across multiple time points and testing facilities. Standardized timing protocols may specify optimal intervals between measurements and relationships to treatment schedules. Sample handling procedures may ensure consistent pre-analytical conditions that minimize variability unrelated to disease status.

[0302] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The implementation of monitoring and progression assessment methodologies may be adapted based on specific cancer types, treatment protocols, and clinical settings while maintaining the fundamental principles of temporal analysis for disease management applications.

[0303] Diagnostic Kit Components

[0304] Diagnostic kit components may provide standardized reagent systems and protocols for detecting cancer through exosomal PCNA analysis in clinical laboratory and point-of-care settings. These kits may incorporate various analytical methodologies and maybe configured to support different testing environments ranging from centralized clinical laboratories to home-based testing applications.

[0305] Exosome isolation reagents may constitute a fundamental component of diagnostic kits for exosomal PCNA analysis. Precipitation-based isolation reagents may include polyethylene glycol formulations, sodium acetate solutions, or proprietary7polymer mixtures that enable concentration of extracellular vesicles from biological fluid samples. In some cases, ExoQuick reagent may be provided in pre-measured aliquots suitable for processing specific sample volumes ranging from 100 pL to 1 mL. Alternative precipitation reagents may include Total Exosome Isolation reagent, ExoSpin reagent, or other commercially available formulations that provide comparable isolation efficiency.

[0306] Magnetic bead-based isolation components may include antibody-conjugated magnetic particles for immunoaffinity capture of exosomes. Anti-CD63 magnetic beads may enable capture of pan-exosome populations, while anti-CD81 or anti-CD9 magnetic beads may provide alternative approaches for general exosome isolation. Tissue-specific magnetic beads may incorporate antibodies against ASGPR1 for liver-derived exosomes, GPA33 for colorectal-denved exosomes, or other tissue-specific markers for targeted isolation applications.

[0307] Depletion reagents may include CD45 antibody-coated magnetic beads for removing leukocyte-derived exosomes and CD61 antibody-coated magnetic beads for eliminating platelet-derived exosomes. These depletion components may enhance the relative concentration of cancer-derived exosomes by removing abundant non-cancer exosome populations that could interfere with PCNA analysis.

[0308] Size-exclusion chromatography columns may be provided as pre-packed separation media for exosome isolation based on molecular size differences. These columns may contain porous resins with defined exclusion limits that allow passage of exosomes while retaining smaller contaminants such as free proteins and nucleic acids. Column formats may range from spin columns for small sample volumes to gravity -flow columns for larger sample processing applications.

[0309] Ultrafiltration devices may include centrifugal filter units with molecular weight cutoffs ranging from 10 kDato 100 kDa for concentrating exosomes from biological fluid samples. These devices may enable volume reduction and buffer exchange while retaining exosomal particles. Multiple filter units may be provided to accommodate different sample volumes and concentration requirements.

[0310] PCNA detection reagents may include antibody-based components forimmunoassay applications. Primary antibodies against PCNA may be provided as monoclonal or polyclonal preparations with defined specificity and affinity characteristics. In some cases, mouse monoclonal anti-PCNA antibodies may be supplied at concentrations ranging from 0. 1 mg / mL to 2.0 mg / mL in stabilizing buffers containing bovine serum albumin and sodium azide preservative.

[0311] Secondary’ antibodies may include enzyme-conjugated preparations for colorimetric detection systems. Horseradish peroxidase-conjugated anti-mouse antibodies may be provided for use with mouse primary antibodies, while alkaline phosphatase- conjugated antibodies may serve as alternative enzy me systems. Biotin-conjugated secondary’ antibodies may be included for use with streptavi din-enzyme conjugate systems that provide signal amplification capabilities.

[0312] Enzyme-linked immunosorbent assay components may include pre-coated microplates with capture antibodies immobilized on solid surfaces. Ninety-six-well microplates may be coated with anti-PCNA antibodies at densities ranging from 1 pg / mL to 10 pg / mL and may be provided in sealed packages with desiccant to maintain antibodystability. Alternative plate formats may include 384-well plates for high-throughput applications or 48-well plates for smaller sample batches.

[0313] Substrate solutions for enzyme detection may include tetramethylbenzidine (TMB) for horseradish peroxidase systems or para-nitrophenyl phosphate (pNPP) for alkaline phosphatase systems. These substrates may be provided as ready-to-use solutions or as concentrated stocks requiring dilution prior to use. Stop solutions may include sulfuric acid or phosphoric acid formulations for terminating enzyme reactions and stabilizing colorimetric signals.

[0314] Washing buffers may include phosphate-buffered saline containing 0.05% to 0.1% Tween-20 for removing unbound reagents during immunoassay procedures. These buffers may be provided as concentrated stocks requiring dilution or as ready-to-use solutions. Buffer volumes may be calculated to provide sufficient washing capacity- for the number of assays included in each kit.

[0315] Blocking reagents may include bovine serum albumin, non-fat dry milk, or proprietary blocking formulations for preventing non-specific antibody binding. These reagents may be provided as powder formulations requiring reconstitution or as liquid concentrates requiring dilution. Blocking buffer compositions may be optimized for specific antibody combinations and assay formats.

[0316] Sample diluents may include buffered solutions for diluting biological fluidsamples to appropriate concentrations for analysis. These diluents may contain protein stabilizers, detergents for exosome lysis, and preservatives for maintaining sample integrity. In some cases, sample diluents may contain 0.1% to 1.0% Triton X-100 for disrupting exosome membranes and releasing PCNA protein for antibody binding.

[0317] Standard reference materials may include purified PCNA protein preparations with defined concentrations for generating calibration curves. Recombinant human PCNA may be provided at concentrations ranging from 0. 1 ng / mL to 1000 ng / mL in stabilizing buffers. Multiple standard concentrations may be included to enable construction of multi-point calibration curves spanning the analytical measurement range.

[0318] Quality control samples may include positive and negative control materials with known PCNA concentrations for assessing assay performance. Positive controls may contain exosomal PCNA at concentrations representing ty pical cancer patient levels, while negative controls may contain exosomal PCNA at concentrations representing healthy individual levels. These controls may be prepared from pooled biological fluid samples or synthetic matrices spiked with defined PCNA concentrations.

[0319] Western blot reagents may include components for electrophoretic separation and immunodetection of PCNA protein. Pre-cast polyacrylamide gels may be provided with acry lamide concentrations ranging from 10% to 15% for optimal PCNA separation. Transfer membranes may include poly vinylidene fluoride or nitrocellulose membranes with defined pore sizes and protein binding capacities.

[0320] Chemiluminescent detection reagents may include enhanced chemiluminescence (ECL) solutions for visualizing antibody-bound proteins on Western blots. These reagents may be provided as two-component systems requiring mixing prior to use or as ready -to-use formulations with extended shelf life. Detection sensitivity may enable visualization of PCNA protein at concentrations ranging from picogram to nanogram levels.

[0321] Molecular weight markers may7include pre-stained protein standards for monitoring electrophoretic separation and transfer efficiency. These markers may span molecular weight ranges from 10 kDa to 250 kDa with defined bands at regular intervals. PCNA protein migration may be identified relative to the 36 kDa marker band.

[0322] Semi-quantitative measurement using colloidal gold lateral flow strips may provide point-of-care or home testing capabilities for exosomal PCNA detection. These strips may incorporate gold nanoparticles conjugated to anti-PCNA antibodies for generating visible signals upon binding to PCNA in test samples. Lateral flow devices may include sample application zones, conjugate release zones, test zones, and control zones arranged onnitrocellulose membrane substrates.

[0323] Gold nanoparticle conjugates may include anti-PCNA antibodies attached to colloidal gold particles ranging from 20 nm to 100 nm in diameter. Conjugation may be accomplished through passive adsorption or covalent attachment methods using carbodiimide chemistry. Conjugate stability may be maintained through lyophilization or storage in stabilizing buffers containing sucrose, trehalose, or other protective agents.

[0324] Capture antibodies may be immobilized at test zones on lateral flow strips to bind PCNA-gold complexes and generate visible test lines. These antibodies may recognize different epitopes on PCNA protein compared to gold-conjugated antibodies to enable sandwich-type detection formats. Antibody immobilization may be accomplished through physical adsorption or covalent attachment to membrane surfaces.

[0325] Control zones may incorporate antibodies that bind to gold-conjugated antibodies independent of PCNA presence to provide assay validity’ confirmation. Control line formation may indicate proper sample flow and reagent function, while absence of control lines may suggest assay failure or improper sample application.

[0326] Sample preparation components for lateral flow assays may include lysis buffers for disrupting exosomes and releasing PCNA protein. These buffers may contain detergents such as Triton X-100 or sodium dodecyl sulfate at concentrations sufficient to permeabilize exosome membranes while maintaining PCNA protein integrity . Buffer volumes may be pre-measured to provide appropriate dilution ratios for biological fluid samples.

[0327] Interpretation guides may include visual reference charts showing expected signal intensities for different PCNA concentration ranges. These guides may provide semi- quantitative assessment capabilities by comparing test line intensities to reference standards. Color intensity scales may correspond to PCNA concentration ranges representing healthy, intermediate, and elevated levels.

[0328] Result interpretation may be accomplished within 10 to 30 minutes after sample application without requiring specialized instrumentation. Visual assessment may enable classification of results as negative, weakly positive, moderately positive, or strongly positive based on test line intensity. Digital imaging systems may’ provide enhanced sensitivity’ and quantitative analysis capabilities for lateral flow results.

[0329] Storage and stability' components may include desiccant packets, sealed packaging, and temperature indicators for maintaining reagent integrity during storage and transport. Lateral flow strips may be individually packaged in sealed pouches with desiccantto prevent moisture exposure. Temperature-sensitive indicators may provide visual confirmation that storage temperature requirements have been maintained.

[0330] Quantitative polymerase chain reaction components may enable detection of PCNA mRNA in exosomal samples. RNA extraction reagents may include lysis buffers, binding columns, and elution buffers for isolating total RNA from exosome preparations. These reagents may be optimized for small sample volumes and low RNA concentrations Apical of exosomal preparations.

[0331] Reverse transcription reagents may include reverse transcriptase enzymes, random primers, and reaction buffers for converting PCNA mRNA to complementary DNA. These components may be provided as master mix formulations or individual reagents requiring assembly prior to use. Reaction volumes may be optimized for compatibility with downstream PCR amplification procedures.

[0332] PCR amplification reagents may include DNA polymerase, primer pairs specific for PCNA sequences, and fluorescent detection probes. TaqMan probe systems may provide sequence-specific detection with enhanced specificity compared to SYBR Green dyebased detection. Primer sequences may be designed to amplify unique regions of PCNA mRNA while avoiding genomic DNA contamination.

[0333] Standard curves for quantitative PCR may include synthetic PCNA RNA or plasmid DNA preparations with defined copy numbers. Serial dilutions may span concentration ranges from 102 to 108 copies per reaction to enable quantification across multiple orders of magnitude. Standard materials may be provided as lyophilized preparations requiring reconstitution or as frozen stocks requiring thawing prior to use.

[0334] Internal control reagents may include primers and probes for housekeeping genes or synthetic spike-in controls for assessing RNA extraction efficiency and PCR performance. These controls may enable normalization of PCNA measurements and identification of technical failures that could affect result interpretation.

[0335] Instrumentation compatibility may include reagent formulations optimized for specific PCR platforms such as Applied Biosystems, Bio-Rad, or Roche systems. Reaction volumes may be scaled for compatibility with different instrument formats ranging from 96-well to 384-well plate configurations.

[0336] Kit packaging may include individual component storage at appropriate temperatures ranging from -20°C to room temperature depending on reagent stability requirements. Frozen components may include enzymes and standards, while room temperature components may include buffers and plastic consumables. Packaging mayinclude clear labeling of storage requirements and expiration dates for each component.

[0337] Instruction manuals may provide detailed protocols for sample collection, processing, and analysis procedures. Step-by-step procedures may include timing requirements, temperature specifications, and quality control checkpoints. Troubleshooting guides may address common technical issues and provide solutions for assay optimization.

[0338] Training materials may include video demonstrations, online tutorials, or hands-on training programs for laboratory personnel implementing exosomal PCNA testing. Certification programs may ensure consistent performance across different testing sites and operators.

[0339] Regulatory documentation may include analytical validation data, clinical performance studies, and quality management system documentation required for regulatory submissions. These materials may support applications for in vitro diagnostic device approval or laboratory-developed test implementation.

[0340] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The selection and configuration of diagnostic kit components may be adapted based on specific analytical requirements, testing environments, and regulatory considerations while maintaining the fundamental principles of exosomal PCNA detection for cancer diagnosis applications.

[0341] Experimental Validation - Cell Culture Studies

[0342] Experimental validation studies may demonstrate the presence of PCNA protein in cancer cell culture media and exosomes through systematic analysis of multiple cancer cell lines. These studies may provide evidence that cancer cells actively secrete PCNA protein into their surrounding environment, which represents an unexpected finding given the traditional understanding of PCNA as a nuclear-localized protein.

[0343] Cell culture methodology may utilize cancer cell lines obtained from the American Type Culture Collection (ATCC) to ensure standardized and reproducible experimental conditions. Cancer cell lines may be maintained in optimal growth media containing fetal bovine serum concentrations ranging from 5% to 10%, L-glutamine at 2 mM concentration, and penicillin-streptomycin at 100 U / mL. Culture conditions may be maintained in humidified incubators with 5% carbon dioxide atmosphere at 37°C temperature. Media replacement may be performed at regular intervals, with subculture procedures initiated when cell confluence reaches 85% to 90%.

[0344] Proliferation marker screening may involve analysis of thirt -six different cell proliferation markers in culture media from HEK293. HeLa, and COS7 cancer cell lines using dot scan immunoassay techniques. This comprehensive screening approach may enable identification of secreted proliferation markers that could serve as liquid biopsy biomarkers. The screening methodology may utilize antibodies directed against various cell cycle proteins, DNA replication factors, and proliferation-associated antigens.

[0345] PCNA detection in culture media may be accomplished through immunoblot analysis comparing seven proliferation markers including PCNA, CDK1, AURKA, PLK1, MCM2, E2F1, and TROP2. Cell lysates may serve as positive controls to confirm antibody specificity and protein expression within cancer cells. The immunoblot methodology may utilize standard protein extraction procedures. SDS-PAGE separation, and chemiluminescent detection systems.

[0346] FIG. 3 may illustrate the immunoblot analysis results showing the presence of seven cell proliferation markers in lysates and media from three cancer cell types. The analysis may demonstrate that PCNA protein exhibits detectable immunoreactivity in both cell lysates and culture media across all tested cancer cell lines. In contrast, the other six proliferation markers including MCM2, E2F1, AURKA, CDK1, TROP2, and PLK1 may be detected in cell lysates but may be absent from culture media. This differential secretion pattern may indicate that PCNA possesses unique properties that enable its release from cancer cells into the extracellular environment.

[0347] The molecular weight characteristics of detected PCNA may correspond to approximately 36 kDa as observed through electrophoretic separation. MCM2 may migrate at approximately 102 kDa, E2F1 at 65 kDa, AURKA at 46 kDa. CDK1 at 34 kDa, TROP2 at 36 kDa, and PLK1 at 68 kDa. The consistent detection of PCNA in culture media across multiple cancer cell lines may suggest a conserved mechanism for PCNA secretion that is shared among different cancer types.

[0348] Antibody validation studies may involve production of two different PCNA antibodies directed against distinct epitopes to confirm the specificity of PCNA detection in culture media. These antibodies may be generated through in-house production methods to ensure optimal sensitivity and specificity for PCNA detection applications. Both antibodies may demonstrate consistent detection of PCNA protein in cell lysates and culture media from proliferating cancer cells, while showing absence of signal in non-proliferating cell preparations.

[0349] Immunoprecipitation assays may provide additional confirmation of PCNApresence in culture media through specific antibody -mediated capture and detection. These assays may utilize anti-PCNA antibodies immobilized on protein A / G-Sepharose beads to capture PCNA protein from culture media samples. The immunoprecipitated material may be analyzed through SDS-PAGE and immunoblot detection to confirm PCNA identity and molecular weight characteristics.

[0350] Extended cancer cell line analysis may involve testing of thirty different cancer cell types to evaluate the generalizability of PCNA secretion across diverse cancer origins. FIG. 4 may demonstrate the immunoblot analysis of exosomal PCNA levels in media from these thirty cultured cancer cell lines. The analysis may include control samples comprising HEK293 cell lysate, embry onic mouse brain tissue lysate, and mature mouse brain tissue lysate to provide reference standards for PCNA signal specificity.

[0351] The thirty cancer cell lines may represent diverse anatomical origins including liver cancer cell lines such as SMMC-7721, HepG2, Hep3B, Huh-7, and MHCC97. Lung cancer representation may include A549, SKMES1, and NCIH460 cell lines. Gastric cancer cell lines may encompass MGC803, SGC-7901, AGS, HSC-38, SGC-7801. and HSC- 66. Breast cancer cell lines may include MDA-MB-436, MDA-MB-435, BT474. and MCF7. Colorectal cancer representation may involve HCT116, SW480, HT29, and Caco-2 cell lines.

[0352] Ovarian cancer cell lines may include SKOV3, A2780, and OVCAR3. Pancreatic cancer representation may encompass PANC-1, CAPAN-1, and PANC02 cell lines. Brain cancer cell lines may include U87MG and SHSY5Y. This diverse panel of cancer cell lines may provide comprehensive coverage of major cancer types to evaluate the universality of PCNA secretion across different malignancies.

[0353] The immunoblot results may demonstrate consistent detection of PCNA protein in culture media from all thirty tested cancer cell lines. The signal intensity may vary between different cell lines, potentially reflecting differences in proliferation rates, PCNA expression levels, or secretion efficiency. However, the universal presence of detectable PCNA in culture media may indicate that PCNA secretion represents a common characteristic of cancer cells regardless of their tissue of origin.

[0354] Quantitative analysis of exosomal PCNA may reveal that PCNA protein comprises 3.17% to 5.24% of total exosomal protein content as determined through enzy me- linked immunosorbent assay measurements. This substantial proportion may indicate that PCNA represents a major component of the exosomal protein cargo secreted by cancer cells. The quantitative measurements may be performed using standardized ELISA protocols with purified PCNA protein standards to enable accurate concentration determinations.

[0355] Exosome depletion experiments may demonstrate that PCNA protein detection in culture media may be eliminated following removal of exosomes through ultracentrifugation or other isolation procedures. This observation may confirm that PCNA protein in culture media may be associated with exosomal vesicles rather than existing as free protein. The depletion experiments may involve comparison of PCNA levels in whole culture media versus exosome-depleted media to establish the exosomal association of secreted PCNA.

[0356] Size fractionation studies may utilize ultrafiltration techniques to separate culture media components into molecular weight fractions including greater than 100 kDa, 50 kDa to 100 kDa, and 10 kDa to 50 kDa ranges. PCNA protein may be detected in the 50 kDa to 100 kDa fraction, which may be consistent with association with larger molecular complexes or vesicular structures rather than free monomeric protein. This size distribution may support the hypothesis that PCNA may be packaged into extracellular vesicles for secretion.

[0357] The experimental validation results may represent unexpected findings that challenge the conventional understanding of PCNA as a nuclear-restricted protein. The demonstration that cancer cells actively secrete PCNA protein into culture media may indicate previously unrecognized cellular mechanisms for PCNA trafficking and release. This secretion may occur through exosomal packaging and vesicular transport pathways that enable PCNA to reach the extracellular environment.

[0358] The universal nature of PCNA secretion across diverse cancer cell types may suggest that this phenomenon represents a fundamental characteristic of malignant transformation rather than a cell type-specific property. The conservation of PCNA secretion across different cancer origins may indicate that common cellular pathways may be involved in PCNA packaging and release, potentially related to altered cellular trafficking or membrane dynamics in cancer cells.

[0359] The substantial quantity of PCNA protein detected in exosomes may indicate that PCNA secretion represents an active cellular process rather than passive leakage or cell death-related release. The consistent detection across multiple cell lines and culture conditions may suggest that PCNA secretion may be regulated and may serve biological functions beyond the traditional nuclear roles of PCNA in DNA replication and repair.

[0360] These experimental validation studies may provide the foundation for understanding PCNA secretion as a cancer-associated phenomenon that enables liquid biopsy applications. The demonstration of PCNA presence in cancer cell culture media may supportthe hypothesis that similar secretion may occur in cancer patients, leading to detectable PCNA levels in biological fluid samples. The cell culture validation may serve as a model system for understanding the mechanisms and characteristics of PCNA secretion that may be relevant to clinical applications.

[0361] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The experimental validation methodologies may be adapted for different cancer cell types, culture conditions, and analytical approaches while maintaining the fundamental principles of demonstrating PCNA secretion by cancer cells.

[0362] Clinical Validation - Patient Studies

[0363] Clinical validation studies may demonstrate the presence of exosomal PCNA protein in human serum samples and may establish differential expression patterns between cancer patients and healthy control subjects. These studies may provide evidence that the secretion of PCNA protein observed in cancer cell culture systems may translate to detectable levels in human biological fluid samples, thereby supporting the clinical utility of exosomal PCNA as a biomarker for cancer detection.

[0364] Patient sample collection may involve obtaining serum specimens from cancer patients with pathologically confirmed malignancies and demographically matched healthy control subjects. The clinical study may be conducted according to the principles of the Declaration of Helsinki with appropriate ethical approval from institutional review boards. Written informed consent may be obtained from each study participant prior to sample collection to ensure compliance with ethical research standards.

[0365] The study population may include cancer patients representing various malignancy types to evaluate the pan-cancer detection capabilities of exosomal PCNA analysis. Cancer patient enrollment may encompass individuals with liver cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, ovarian cancer, pancreatic cancer, and prostate cancer to provide comprehensive coverage of major cancer types. The diversity of cancer types may enable assessment of whether exosomal PCNA elevation represents a universal characteristic of malignancy rather than a cancer type-specific phenomenon.

[0366] Healthy control subject selection may involve individuals without known cancer or proliferative disorders who undergo medical screening to confirm the absence of underlying malignancies. Control subjects may be matched to cancer patients based on demographic characteristics such as age and gender to minimize confounding variables thatcould influence exosomal PCNA levels. The control population may provide reference values for establishing normal ranges of exosomal PCNA concentrations in biological fluid samples.

[0367] Sample processing procedures may follow standardized protocols to ensure consistent handling of both cancer patient and healthy control specimens. Serum separation may be accomplished through centrifugation of whole blood samples followed by collection of the liquid component. Serum samples may be stored under controlled temperature conditions to preserve exosomal integrity and PCNA protein stability prior to analysis.

[0368] Exosome isolation from serum samples may be performed using established purification protocols to concentrate extracellular vesicles for subsequent PCNA analysis. The isolation methodology may utilize precipitation-based approaches, ultracentrifugation techniques, or immunoaffmity capture methods depending on the analytical requirements and sample characteristics. Isolated exosomes may be characterized to confirm vesicle integrity and assess isolation efficiency.

[0369] Immunoblot analysis methodology may enable qualitative and semi- quantitative assessment of exosomal PCNA levels in serum samples from study participants. The immunoblot approach may utilize specific anti-PCNA antibodies to detect PCNA protein following electrophoretic separation and membrane transfer procedures. This analytical method may provide information about PCNA molecular weight characteristics and relative abundance between different sample groups.

[0370] FIG. 7A may illustrate the immunoblot analysis results comparing exosomal PCNA protein levels between healthy controls and cancer patients. The analysis may include serum samples from twenty -six healthy control subjects labeled Hl through H26 in the upper panels, and serum samples from twenty-six cancer patients labeled Cl through C26 in the lower panels. An internal control sample labeled I may appear in both sections, representing a mixture of sera from three healthy subjects used for standardization and uality control purposes.

[0371] The immunoblot detection may reveal the presence of PCNA protein in serum samples from all study participants, indicating that exosomal PCNA may be detectable in both healthy individuals and cancer patients. However, visual inspection of the immunoblot signals may suggest differences in PCNA protein levels between the two study groups. Cancer patient samples may exhibit stronger immunoreactive signals compared to healthy control samples, suggesting elevated exosomal PCNA concentrations in malignancy.

[0372] The molecular weight of detected PCNA protein may correspond to approximately 36 kDa as determined through electrophoretic migration patterns. Thismolecular weight may be consistent with the known characteristics of PCNA protein and may confirm the specificity of antibody detection. The consistent molecular weight across all samples may indicate that the detected protein represents authentic PCNA rather than cross- reactive proteins or degradation products.

[0373] Densitometric quantification of immunoblot signals may provide semi- quantitative assessment of exosomal PCNA levels across study participants. FIG. 7B may demonstrate the densitometric analysis results comparing relative PCNA signal intensities between healthy controls and cancer patients. The quantification methodology may involve measurement of band intensity using digital imaging systems and analysis software capable of generating numerical values proportional to protein abundance.

[0374] The densitometric analysis may reveal that healthy control subjects exhibit lower relative PCNA signal intensities compared to cancer patients. Healthy control measurements may cluster around approximately 0.9 relative units, while cancer patient measurements may center around approximately 1.5 relative units. This difference may represent a substantial elevation in exosomal PCNA levels associated with malignancy.

[0375] Statistical analysis of the densitometric data may demonstrate a statistically significant difference betw een healthy controls and cancer patients. The statistical significance may be indicated through appropriate statistical testing methods such as t-tests or Mann-Whitney U tests depending on data distribution characteristics. Error bars may be included in the graphical representation to indicate measurement variability and statistical uncertainty.

[0376] The magnitude of difference between study groups may suggest that exosomal PCNA elevation in cancer patients represents a robust biomarker signal rather than subtle variations that might be difficult to detect reliably. The fold-change difference between cancer patients and healthy controls may exceed the threshold levels established for defining elevated exosomal PCNA concentrations, thereby supporting the diagnostic utility of this biomarker.

[0377] Sample size considerations may influence the statistical power and reliability of the clinical validation results. The inclusion of twenty-six subjects in each study group may provide adequate statistical power for detecting meaningful differences in exosomal PCNA levels while maintaining practical feasibility7for initial validation studies. Larger sample sizes may be utilized in subsequent validation studies to confirm these initial findings and establish more precise estimates of diagnostic performance characteristics.

[0378] The clinical validation results may represent unexpected findings thatdemonstrate the translation of cell culture observations to human clinical samples. The detection of elevated exosomal PCNA levels in cancer patients may confirm that the PCNA secretion phenomenon observed in cancer cell lines may occur in human malignancies. This translation from in vitro to clinical observations may support the biological relevance and clinical utility of exosomal PCNA as a cancer biomarker.

[0379] The pan-cancer elevation of exosomal PCNA levels may indicate that this biomarker possesses broad-spectrum detection capabilities that could enable multi-cancer screening applications. The consistent elevation across different cancer types may suggest that exosomal PCNA reflects fundamental characteristics of malignant transformation that are shared among diverse cancer origins. This universality may distinguish exosomal PCNA from cancer type-specific biomarkers that have limited applicability.

[0380] The surprising utility of exosomal PCNA as a circulating biomarker may challenge conventional understanding of PCNA biology' and cellular trafficking. The demonstration that nuclear PCNA protein can be packaged into exosomes and secreted into circulation may reveal previously unrecognized cellular mechanisms for protein trafficking and intercellular communication. This unexpected biological pathway may have implications beyond cancer detection for understanding cellular physiology and disease mechanisms.

[0381] Quality' control measures implemented in the clinical validation studies may include standardized sample collection procedures, consistent processing protocols, and analytical controls to ensure reliable and reproducible results. The inclusion of internal control samples may enable assessment of inter-assay variability and detection of potential technical issues that could affect result interpretation. Blinded analysis procedures may minimize bias in sample processing and data interpretation.

[0382] The clinical validation findings may provide the foundation for larger-scale studies to establish the diagnostic performance characteristics of exosomal PCNA testing. Sensitivity and specificity calculations may require analysis of larger patient populations with diverse cancer types and stages to determine the clinical utility' of this biomarker for cancer detection applications. Receiver operating characteristic analysis may identify optimal threshold values for distinguishing cancer patients from healthy individuals.

[0383] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The clinical validation methodologies may be adapted for different patient populations, cancer types, and analytical approaches while maintaining the fundamental principles of demonstrating differential exosomal PCNA expression between cancer patients and healthycontrols.

[0384] Diagnostic Performance Analysis

[0385] Diagnostic performance evaluation may involve comprehensive analysis of exosomal PCNA concentration distributions and receiver operating characteristic curve assessment to establish the clinical utility of this biomarker for cancer detection applications. The performance analysis may utilize data from large-scale clinical studies to determine sensitivity, specificity, and diagnostic accuracy parameters that support clinical implementation of exosomal PCNA testing.

[0386] Concentration distribution analysis may involve measurement of exosomal PCNA levels across diverse patient populations to characterize the range of concentrations observed in cancer patients compared to healthy control subjects. The distribution analysis may encompass 365 study participants including 161 healthy controls and 204 cancer patients representing various malignancy ty pes. This sample size may provide statistical power for detecting meaningful differences in exosomal PCNA concentrations while enabling precise estimation of diagnostic performance characteristics.

[0387] Cancer patient enrollment may include individuals with liver cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, ovarian cancer, pancreatic cancer, and prostate cancer to evaluate pan-cancer detection capabilities. The cancer patient population may comprise 114 males with an average age of 65.08 ± 10. 12 years ranging from 35 to 88 years, and 90 females with an average age of 63.27 ± 7.55 years ranging from 46 to 82 years. This demographic distribution may provide representation across age groups and gender categories that reflect typical cancer patient populations.

[0388] Healthy control subject characteristics may include 85 males with an average age of 61.79 ± 11.52 years ranging from 34 to 86 years, and 76 females with an average age of 60. 16 ± 6.09 years ranging from 48 to 86 years. The demographic matching between cancer patients and healthy controls may minimize confounding variables that could influence exosomal PCNA levels independent of cancer status. Age and gender distributions may be comparable between study groups to ensure valid statistical comparisons.

[0389] FIG. 8 may illustrate the scatter plot analysis of serum PCNA levels comparing healthy controls and cancer patients as detected through enzyme-linked immunosorbent assay measurements. The scatter plot may display individual data points representing PCNA concentrations measured in ng / mL for each study participant. The y-axis may span concentrations ranging from 0 to approximately 500 ng / mL to encompass the fullrange of observed values across both study groups.

[0390] The scatter plot distribution may demonstrate distinct concentration patterns between healthy controls and cancer patients. Healthy control subjects may exhibit PCNA concentrations clustered primarily in the lower concentration range between 0 and 150 ng / mL. The control group data points may show relatively tight clustering around lower concentration values with limited variability between individual measurements. This concentration distribution may establish the normal range of exosomal PCNA levels in individuals without cancer or proliferative disorders.

[0391] Cancer patient data points may display substantially higher PCNA concentrations with greater variability extending up to approximately 400 ng / mL. The cancer group distribution may show broader scatter compared to healthy controls, potentially reflecting differences in cancer types, disease stages, or individual patient characteristics. The elevated concentration range in cancer patients may demonstrate clear separation from healthy control values, indicating diagnostic uti 1 i ty for distinguishing malignant from non- malignant conditions.

[0392] Horizontal lines in the scatter plot may indicate mean values for each study group, with the cancer group displaying a notably higher mean concentration compared to the control group. The mean difference between groups may represent a substantial elevation in exosomal PCNA levels associated with malignancy. Statistical significance may be indicated through p-value notation showing p<0.001, demonstrating highly significant differences between cancer patients and healthy controls.

[0393] The magnitude of concentration differences may suggest robust biomarker performance with clear separation between disease and non-disease populations. The minimal overlap between concentration distributions may indicate potential for high diagnostic accuracy with appropriate threshold selection. Individual cancer patients may exhibit PCNA concentrations that exceed the highest values observed in healthy controls, suggesting strong discriminatory power for cancer detection.

[0394] Receiver operating characteristic curve analysis may provide quantitative assessment of diagnostic performance across various threshold concentrations. FIG. 9 may demonstrate the ROC curve showing the relationship between sensitivity and specificity for exosomal PCNA testing. The curve may display sensitivity percentages on the y-axis ranging from 0% to 100%, while the x-axis may show 100% minus specificity percentages also ranging from 0% to 100%.

[0395] The ROC curve shape may demonstrate superior diagnostic performancecompared to random chance, as indicated by substantial deviation from the diagonal reference line extending from the bottom left to top right comer of the graph. The curve may exhibit a steep initial rise in sensitivity with minimal decrease in specificity, indicating favorable diagnostic characteristics. The curve may reach approximately 95% sensitivity at around 20% false positive rate, demonstrating high detection capability with acceptable specificity levels.

[0396] The area under the receiver operating characteristic curve (AUROC) may provide a single metric for overall diagnostic performance assessment. The AUROC value may reach 0.94 with 95% confidence intervals ranging from 0.92 to 0.97, indicating excellent diagnostic accuracy. AUROC values approaching 1.0 may represent ideal diagnostic performance, while values near 0.5 may indicate performance equivalent to random chance. The observed AUROC value may demonstrate substantial diagnostic utility' for clinical applications.

[0397] Optimal threshold determination may involve identification of concentration cutoff values that maximize the combination of sensitivity and specificity for cancer detection. The optimal cutoff value may be established at 97.81 ng / mL based on ROC curve analysis that balances detection capability with false positive rates. Alternative threshold values may be considered for different clinical applications, with higher thresholds providing enhanced specificity at the expense of sensitivity, and lower thresholds offering improved sensitivity with reduced specificity.

[0398] Sensitivity analysis may reveal that exosomal PCNA testing achieves 77.2% sensitivity for cancer detection at the optimal threshold concentration. This sensitivity level may indicate that approximately three-quarters of cancer patients may be correctly identified through exosomal PCNA testing. The sensitivity performance may vary’ across different cancer types, disease stages, and patient characteristics, with some malignancies potentially exhibiting higher detection rates than others.

[0399] Specificity assessment may demonstrate 94.4% specificity for distinguishing cancer patients from healthy controls. This specificity level may indicate that approximately 94% of healthy individuals may be correctly classified as non-cancer through exosomal PCNA testing. The high specificity may minimize false positive results that could lead to unnecessary' anxiety, additional testing, or inappropriate medical interventions in healthy individuals.

[0400] Positive predictive value calculations may indicate that 45% of individuals with elevated exosomal PCNA levels may have cancer. The positive predictive value maydepend on the prevalence of cancer in the tested population, with higher cancer prevalence leading to improved positive predictive values. In screening populations with lower cancer prevalence, positive predictive values may be reduced, while diagnostic populations with higher cancer prevalence may exhibit enhanced positive predictive values.

[0401] Negative predictive value assessments may demonstrate high accuracy for ruling out cancer in individuals with normal exosomal PCNA levels. The combination of high sensitivity and specificity may result in negative predictive values exceeding 95% in many clinical scenarios. High negative predictive values may provide confidence that individuals with normal exosomal PCNA levels have low probability of harboring undetected malignancies.

[0402] Clinical utility considerations may involve evaluation of how exosomal PCNA testing performance compares to existing cancer detection methods and screening approaches. The sensitivity and specificity7characteristics may position exosomal PCNA testing as a valuable tool for cancer screening, early detection, and diagnostic workup. The non-invasive nature of liquid biopsy testing may provide advantages over tissue-based diagnostic approaches that require invasive procedures.

[0403] Subgroup analysis may reveal variations in diagnostic performance across different cancer types, patient demographics, and disease characteristics. Liver cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, ovarian cancer, pancreatic cancer, and prostate cancer may exhibit different patterns of exosomal PCNA elevation that influence detection sensitivity. Early-stage cancers may demonstrate lower exosomal PCNA levels compared to advanced-stage disease, potentially affecting sensitivity for early detection applications.

[0404] Age-related performance variations may influence diagnostic accuracy in different patient populations. Older patients may exhibit baseline differences in exosomal PCNA levels that could affect threshold selection and performance characteristics. Genderspecific analysis may reveal differences in diagnostic performance between male and female patients that could inform gender-stratified testing approaches.

[0405] Comorbidity effects may influence diagnostic performance in patients with benign proliferative conditions or inflammatory disorders. Conditions such as benign prostatic hyperplasia, liver cirrhosis, or chronic inflammatory diseases may cause intermediate elevations in exosomal PCNA levels that could affect specificity for cancer detection. Separate analysis of patients with specific comorbidities may enable development of adjusted threshold criteria for these populations.

[0406] Multi-cancer detection capabilities may represent a unique advantage of exosomal PCNA testing compared to cancer type-specific biomarkers. The ability to detect various cancer types through a single test may enable broad-spectrum screening applications that could identify malignancies across multiple anatomical sites. This pan-cancer detection capability may provide clinical utility for identifying cancers of unknown primary7origin or for comprehensive screening in high-risk populations.

[0407] Comparison with existing biomarkers may demonstrate the relative performance of exosomal PCNA testing compared to established cancer detection methods. Traditional tumor markers such as prostate-specific antigen (PSA), carcinoembryonic antigen (CEA), or alpha-fetoprotein (AFP) may exhibit cancer type-specific detection capabilities but may lack the broad-spectrum detection potential of exosomal PCNA. The sensitivity and specificity characteristics of exosomal PCNA may compare favorably to these established biomarkers while offering expanded detection capabilities.

[0408] Imaging-based detection methods such as computed tomography, magnetic resonance imaging, or positron emission tomography may provide anatomical and functional information about cancer presence but may have limitations for detecting early-stage disease or small tumor burdens. Exosomal PCNA testing may complement imaging approaches by providing molecular evidence of cancer presence that could enhance overall diagnostic accuracy when used in combination.

[0409] Cost-effectiveness considerations may influence the clinical adoption of exosomal PCNA testing based on the balance between diagnostic performance and testing costs. The high sensitivity and specificity characteristics may justify testing costs through improved cancer detection rates and reduced false positive results. Early cancer detection enabled by exosomal PCNA testing may lead to improved treatment outcomes and reduced healthcare costs associated with advanced-stage disease management.

[0410] Quality assurance measures for diagnostic performance assessment may include validation studies across multiple testing sites and patient populations to confirm reproducibility of performance characteristics. Inter-laboratory proficiency testing may ensure consistent analytical performance and diagnostic accuracy across different testing facilities. Ongoing performance monitoring may track real-world diagnostic outcomes to validate laboratory-based performance estimates.

[0411] Regulatory considerations for diagnostic performance validation may involve clinical trials designed to meet regulatory requirements for in vitro diagnostic device approval. The sensitivity and specificity data may support regulatory submissions for cancerdetection applications. Post-market surveillance studies may monitor real-world performance and safety outcomes following regulatory approval and clinical implementation.

[0412] The unexpected utility of exosomal PCNA as a pan-cancer biomarker may represent a surprising result given the traditional understanding of PCNA as a nucl ear- localized protein. The demonstration of high diagnostic accuracy across multiple cancer types may indicate previously unrecognized biological pathways for PCNA secretion and circulation. This surprising utility may distinguish exosomal PCNA from other proliferation markers that remain cell-associated and do not exhibit similar diagnostic potential in liquid biopsy applications.

[0413] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The diagnostic performance characteristics may be further optimized through refinement of analytical methods, threshold selection criteria, and patient population stratification while maintaining the fundamental principles of exosomal PCNA-based cancer detection.

[0414] System Integration and Method Implementation

[0415] System integration and method implementation may encompass the coordinated operation of multiple analytical components and procedural elements to enable comprehensive cancer detection through exosomal PCNA analysis. The integrated methodology may combine sample collection protocols, exosome isolation procedures, PCNA detection systems, and result interpretation algorithms to provide a complete diagnostic workflow suitable for clinical implementation across various healthcare settings.

[0416] The integrated workflow may begin with standardized sample collection procedures that ensure consistent pre-analytical conditions across different clinical environments. Sample collection protocols may specify timing requirements relative to patient fasting status, medication administration, and circadian rhythms to minimize biological variability that could affect exosomal PCNA measurements. Collection tube selection may involve use of serum separator tubes, EDTA tubes, or specialized exosome preservation tubes depending on the downstream analytical requirements and storage duration.

[0417] Sample transport and storage systems may maintain exosomal integrity through controlled temperature conditions and standardized handling procedures. Transport containers may incorporate temperature monitoring devices to ensure maintenance of appropriate storage conditions during specimen shipment from collection sites to analyticallaboratories. Cold chain management may utilize refrigerated transport systems maintaining temperatures between 2°C and 8°C for short-term transport or frozen transport systems maintaining temperatures below -20°C for extended transport durations.

[0418] Laboratory information management systems may integrate sample tracking, analytical workflow management, and result reporting functions to ensure accurate specimen identification and data integrity throughout the analytical process. Barcode labeling systems may enable automated specimen identification and reduce manual transcription errors. Electronic data capture systems may record analytical parameters, quality control results, and instrument performance metrics to support result validation and troubleshooting procedures.

[0419] Automated sample processing systems may integrate exosome isolation, PCNA detection, and quantification procedures to enable high-throughput analytical capabilities suitable for clinical laboratory environments. Robotic liquid handling systems may perform precise pipetting operations for sample dilution, reagent addition, and washing procedures. Automated incubation systems may maintain consistent temperature and timing conditions for immunoassay procedures. Integrated detection systems may combine optical measurement capabilities with data analysis software to generate quantitative PCNA concentration results.

[0420] Quality control integration may incorporate multiple levels of analytical validation to ensure reliable and accurate results across different testing scenarios. Internal quality control samples may be processed with each analytical batch to monitor assay performance and detect systematic errors. External quality assessment programs may provide ongoing validation of analytical accuracy through analysis of standardized reference materials. Proficiency testing participation may demonstrate laboratory competency and ensure consistency with other testing facilities.

[0421] Analytical validation protocols may establish performance characteristics including precision, accuracy, linearity, and analytical measurement range for exosomal PCNA testing systems. Precision studies may evaluate repeatability and reproducibility across multiple operators, instruments, and testing days. Accuracy assessments may compare measured concentrations with known reference values using certified reference materials or spiked samples. Linearity evaluations may determine the concentration range over which measurements exhibit proportional relationships with actual PCNA concentrations.

[0422] Interference testing may assess the impact of common biological substances and medications on exosomal PCNA measurements to identify potential sources of analytical error. Hemolysis, lipemia, and icterus may represent common sample conditions that couldaffect immunoassay performance. Medication interference studies may evaluate the effects of anticoagulants, chemotherapy agents, and other drugs on PCNA detection accuracy. Matrix effects may be assessed through comparison of measurements in different biological fluid types and sample preparation conditions.

[0423] Clinical decision support systems may integrate exosomal PCNA results with patient demographic data, medical history, and other laboratory values to provide comprehensive risk assessment and management recommendations. Decision algorithms may incorporate age-adjusted reference ranges, gender-specific threshold values, and comorbidity considerations to optimize diagnostic accuracy for individual patients. Risk stratification models may combine exosomal PCNA levels with other clinical parameters to generate composite risk scores for cancer detection.

[0424] Result interpretation guidelines may provide standardized criteria for classify ing exosomal PCNA measurements as normal, borderline elevated, or significantly elevated based on established threshold values and clinical validation data. Interpretation protocols may account for patient-specific factors including age, gender, medical history, and concurrent medications that could influence exosomal PCNA levels. Clinical correlation recommendations may guide healthcare providers in determining appropriate follow-up testing and management strategies based on exosomal PCNA results.

[0425] Electronic health record integration may enable seamless incorporation of exosomal PCNA results into patient medical records and clinical workflow systems. Automated result reporting may transmit analytical findings to ordering physicians through secure electronic interfaces. Alert systems may notify healthcare providers of abnormal results requiring immediate attention or follow-up action. Trending capabilities may display serial exosomal PCNA measurements over time to facilitate monitoring of disease progression or treatment response.

[0426] Multi-site implementation strategies may address the challenges of deploying exosomal PCNA testing across diverse healthcare environments including academic medical centers, community hospitals, and outpatient clinics. Standardization protocols may ensure consistent analytical performance across different testing sites through harmonized procedures, reagent specifications, and quality control requirements. Training programs may provide education and certification for laboratory personnel implementing exosomal PCNA testing procedures.

[0427] Regulatory compliance frameworks may address the requirements for clinical implementation of exosomal PCNA testing including analytical validation, clinicalvalidation, and quality management system documentation. Regulatory submissions may include performance data, clinical studies, and manufacturing information required for in vitro diagnostic device approval. Post-market surveillance programs may monitor real-world performance and safety outcomes following regulatory approval and clinical deployment.

[0428] Cost-effectiveness analysis may evaluate the economic impact of exosomal PCNA testing implementation including analytical costs, personnel requirements, and infrastructure investments. Cost-benefit assessments may compare testing expenses with potential savings from early cancer detection, reduced false positive rates, and improved treatment outcomes. Reimbursement strategies may address coverage policies and payment mechanisms for exosomal PCNA testing in different healthcare systems.

[0429] Point-of-care implementation may utilize simplified testing platforms that enable exosomal PCNA analysis in non-laboratory settings including physician offices, urgent care centers, and home testing environments. Lateral flow assay systems may provide rapid qualitative or semi-quantitative results within 15 to 30 minutes without requiring specialized instrumentation. Digital health platforms may integrate point-of-care testing results with telemedicine consultations and remote patient monitoring systems.

[0430] Workflow optimization may address the integration of exosomal PCNA testing into existing clinical pathways for cancer screening, diagnosis, and monitoring. Screening protocols may incorporate exosomal PCNA testing into routine health maintenance examinations or targeted screening programs for high-risk populations. Diagnostic algorithms may utilize exosomal PCNA results to guide additional testing recommendations including imaging studies, tissue biopsies, or specialist referrals.

[0431] Treatment monitoring integration may incorporate serial exosomal PCNA measurements into cancer care protocols to assess therapeutic response and detect disease recurrence. Monitoring schedules may specify optimal timing for exosomal PCNA testing relative to treatment cycles, surgical procedures, and follow-up appointments. Response criteria may define significant changes in exosomal PCNA levels that indicate treatment effectiveness or disease progression.

[0432] Data analytics platforms may utilize machine learning algorithms and artificial intelligence systems to enhance the interpretation and clinical utility7of exosomal PCNA testing results. Predictive models may incorporate exosomal PCNA trends along with other clinical data to forecast disease trajectories and treatment outcomes. Pattern recognition algorithms may identify subtle changes in exosomal PCNA levels that could indicate early disease recurrence or treatment resistance.

[0433] Interoperability standards may enable integration of exosomal PCNA testing systems with existing laboratory information systems, electronic health records, and clinical decision support tools. Data exchange protocols may utilize standardized formats and communication interfaces to ensure seamless information transfer between different healthcare systems. Cybersecurity measures may protect patient data and analytical results during electronic transmission and storage.

[0434] Scalability considerations may address the capacity requirements for implementing exosomal PCNA testing across large healthcare networks or population-based screening programs. Throughput optimization may involve batch processing strategies, automated sample handling systems, and parallel analytical platforms to accommodate high sample volumes. Resource allocation may include staffing requirements, equipment capacity, and reagent supply chain management for large-scale implementation.

[0435] Continuous improvement processes may incorporate ongoing monitoring of analytical performance, clinical outcomes, and operational efficiency to optimize exosomal PCNA testing implementation. Performance metrics may include analytical turnaround times, result accuracy, customer satisfaction, and clinical impact measures. Feedback mechanisms may enable identification of improvement opportunities and implementation of corrective actions to enhance testing uality and efficiency.

[0436] International implementation considerations may address regulatory requirements, analytical standards, and clinical practices across different countries and healthcare systems. Harmonization efforts may align analytical methods, quality control procedures, and result interpretation criteria to enable consistent global implementation. Cultural and linguistic adaptations may ensure appropriate communication of testing procedures and results across diverse patient populations.

[0437] Emergency and urgent care applications may utilize rapid exosomal PCNA testing to support clinical decision-making in acute care settings. Point-of-care testing capabilities may enable immediate assessment of cancer risk in patients presenting with suspicious symptoms or clinical findings. Rapid result availability may facilitate timely referrals and treatment initiation in emergency department and urgent care environments.

[0438] Pediatric implementation considerations may address the unique requirements for exosomal PCNA testing in children and adolescents including age-specific reference ranges, sample volume limitations, and specialized collection procedures. Pediatric validation studies may establish performance characteristics and clinical utility in younger patient populations. Child-friendly collection methods may minimize patient discomfort andanxiety during sample collection procedures.

[0439] Geriatric implementation strategies may account for the specific needs of elderly patients including multiple comorbidities, medication interactions, and age-related physiological changes that could affect exosomal PCNA levels. Geriatric-specific interpretation criteria may adjust for baseline differences in exosomal PCNA concentrations associated with aging. Simplified testing procedures may accommodate physical limitations and cognitive considerations in elderly patient populations.

[0440] Those skilled in the art will recognize that various modifications and variations can be made without departing from the spirit and scope of the invention. The system integration and method implementation approaches may be adapted based on specific healthcare environments, patient populations, and regulatory requirements while maintaining the fundamental principles of comprehensive exosomal PCNA-based cancer detection workflows.

[0441] EXAMPLES

[0442] Aspects of the present teachings may be further understood in light of the following examples, which should not be construed as limiting the scope of the present teachings in any way.

[0443] Example 1: Detection of Exosomal PCNA in Cancer Cell Culture Media

[0444] This example demonstrates the presence of PCNA protein in exosomes secreted by cancer cells into culture media, establishing the fundamental basis for exosomal PCNA as a cancer biomarker.

[0445] Materials and Methods:

[0446] Cancer cell lines including HEK293, HeLa, and COS7 are obtained from ATCC and cultured in optimal media containing 5-10% fetal bovine serum, 2 mM L- glutamine, and 100 U / mL penicillin-streptomycin. Cells are maintained in a humidified incubator with 5% CO2 at 37°C. When cells reach 85-90% confluence, they are washed three times with phosphate-buffered saline and cultured in media containing 5% exosome-free FBS for 24 hours.

[0447] Culture media are collected and centrifuged at 300 x g for 10 minutes to remove cells and debris. The supernatant is filtered through 0.45 pm membranes and subjected to ultracentrifugation at 120,000 x g for 2 hours. The pellet is resuspended in 50 mL exosome-free PBS and centrifuged again at 120,000 x g for 2 hours. The final exosomepellet is resuspended in lysis buffer containing 50 mM Tris-HCl (pH 8.0), 0.5% Triton X- 100, 150 mM NaCl, and protease inhibitors.

[0448] Western blot analysis is performed using standard protocols. Equal amounts of protein are separated by SDS-PAGE on 10-15% polyacrylamide gels and transferred to PVDF membranes. Membranes are blocked with 5% skim milk in TBST for 1 hour at room temperature, then incubated overnight at 4°C with primary antibodies against PCNA (1 :2000 dilution). MCM2 (1:2000), E2F1 (1: 1000), CDK1 (1 :2000), AURKA (1 :2000), PLK1 (1: 1000), and TROP2 (1 :2000). After washing, membranes are incubated with horseradish peroxidase-conjugated secondary antibodies (1 :5000) for 1 hour at room temperature. Immunoreactive bands are detected using ECL chemiluminescent detection.

[0449] Expected Results:

[0450] PCNA protein is detected in both cell lysates and culture media from all three cancer cell lines, appearing as a distinct band at approximately 36 kDa molecular weight. In contrast, the other six proliferation markers (MCM2, E2F1, AURKA, CDK1, PLK1, TROP2) are present in cell lysates but absent from culture media. This demonstrates that PCNA is uniquely secreted by cancer cells into the extracellular environment, while other proliferation markers remain intracellular. The consistent detection of PCNA across multiple cancer cell lines indicates that PCNA secretion represents a common characteristic of malignant cells. Quantitative analysis reveals that exosomal PCNA comprises 3.17% to 5.24% of total exosomal protein content, indicating substantial enrichment of this biomarker in cancer cell-derived exosomes.

[0451] Example 2: Comparative Analysis of Exosomal PCNA Levels in Cancer Patients versus Healthy Controls

[0452] This example establishes the clinical uti I ity of exosomal PCNA as a diagnostic biomarker by demonstrating elevated levels in cancer patients compared to healthy individuals.

[0453] Materials and Methods:

[0454] Serum samples are collected from 204 cancer patients with pathologically confirmed malignancies including liver cancer (n=26), lung cancer (n=20), gastric cancer (n=26), colorectal cancer (n=30), breast cancer (n=30), ovarian cancer (n=22), pancreatic cancer (n=20), and prostate cancer (n=30). Control samples are obtained from 161 healthy volunteers who undergo medical screening to exclude cancer or proliferative disorders. All participants provide written informed consent according to Declaration of Helsinki principles.

[0455] Exosomes are isolated from 250 pL serum samples using ExoQuick reagent according to manufacturer instructions. Briefly, 67 pL ExoQuick solution is mixed with serum and incubated for 30 minutes at 4°C, followed by centrifugation at 3,000 x g for 10 minutes. The pellet is resuspended and further purified using pre-packed columns. For ELISA analysis, isolated exosomes are lysed by mixing with equal volume of PBS containing 0.4% Triton X-100 for 30 minutes at room temperature.

[0456] PCNA levels are measured using sandwich ELISA with plates precoated with monoclonal anti-PCNA antibodies. Lysed samples (50 pL) are incubated at 37°C for 45 minutes, followed by four washes and incubation with biotin-conjugated detection antibodies at 37°C for 30 minutes. After washing, streptavidin-HRP is added and incubated for 30 minutes. Color development is achieved using TMB substrate, and absorbance is measured at 450 nm. PCNA concentrations are determined by interpolation from standard curves generated using recombinant PCNA protein.

[0457] Expected Results:

[0458] Cancer patients exhibit significantly elevated exosomal PCNA levels compared to healthy controls (p<0.001 ). Healthy control subjects show PCNA concentrations clustered between 0-150 ng / mL with a mean of approximately 60 ng / mL. Cancer patients display a broader distribution with concentrations ranging up to 400 ng / mL and a mean of approximately 150 ng / mL, representing a 2.5-fold elevation. Receiver operating characteristic curve analysis reveals an area under the curve of 0.94 (95% CI: 0.92-0.97). indicating excellent diagnostic performance. At the optimal cutoff value of 97.81 ng / mL, the assay achieves 77.2% sensitivity and 94.4% specificity for cancer detection. The elevation is observed across all cancer types tested, demonstrating the pan-cancer detection capability of exosomal PCNA. These results establish exosomal PCNA as a robust biomarker for distinguishing cancer patients from healthy individuals with high diagnostic accuracy.

[0459] Example 3: Tissue-Specific Cancer Localization Using Exosomal PCNA Analysis

[0460] This example demonstrates the ability to determine cancer tissue of origin through analysis of PCNA levels in tissue-specific exosome populations, enabling cancer localization capabilities.

[0461] Materials and Methods:

[0462] Serum samples are collected from 20 hepatocellular carcinoma patients. 20 colorectal cancer patients, and 20 healthy controls. Tissue-specific exosomes are isolatedusing magnetic bead-based immunoprecipitation targeting surface markers specific to different tissues. For liver-derived exosomes, anti-ASGPRl antibodies are conjugated to magnetic beads using carbodiimide chemistry. For colorectal-derived exosomes, anti-GPA33 antibodies are similarly conjugated to magnetic beads.

[0463] Serum samples (500 pL) are incubated with antibody-coated magnetic beads for 2 hours at 4°C with gentle rotation. Magnetic separation is performed using magnetic stands, and captured exosomes are washed three times with PBS. Bound exosomes are eluted using pH adjustment or competitive displacement methods. The purity and yield of isolated tissue-specific exosomes are verified using nanoparticle tracking analysis and Western blot confirmation of tissue-specific markers.

[0464] PCNA levels within each tissue-specific exosome population are quantified using the same ELISA methodology described in Example 2. Exosomes are lysed with 0.4% Triton X-100, and PCNA concentrations are measured in triplicate for each sample. Statistical analysis is performed using ANOVA followed by post-hoc testing to compare PCNA levels across different exosomal subsets and patient groups.

[0465] Expected Results:

[0466] Hepatocellular carcinoma patients show significantly elevated PCNA levels in AS GPR1 -positive (liver-derived) exosomes compared to healthy controls, with concentrations reaching 20 - 380ng / mL versus < 12 ng / mL in controls. PCNA levels in GP A33-positive exosomes from these patients remain within normal ranges. Conversely, colorectal cancer patients exhibit elevated PCNA levels in GPA33-positive (colorectal- derived) exosomes (15-300 ng / mL) while maintaining normal levels in ASGPR1 -positive exosomes. Healthy controls show low PCNA levels in both tissue-specific exosome populations (< 15 ng / mL). ROC analysis for tissue-specific PCNA detection achieves area under the curve values >0.85 for both liver and colorectal cancer localization. This tissuespecific enrichment of PCNA enables accurate identification of cancer anatomical origin, with the highest PCNA levels indicating the primary tumor location. The approach successfully distinguishes liver cancer from colorectal cancer with >90% accuracy, demonstrating the utility of tissue-specific exosomal PCNA analysis for cancer localization in liquid biopsy applications.

[0467] Example 4: Detection of PCNA Protein in Exosomes and Correlation to Cancer Diagnosis

[0468] This example demonstrates the methodology for detecting PCNA proteinwithin isolated exosomes and correlating the findings to cancer diagnosis in a clinical setting.

[0469] Materials and Methods:

[0470] A 45-year-old male patient presents with elevated liver enzymes and abdominal discomfort. A 5 rnL blood sample is collected via venipuncture into a serum separator tube and allowed to clot for 30 minutes at room temperature. The sample is centrifuged at 1,500 x g for 10 minutes to obtain serum, which is stored at -80°C until analysis.

[0471] For exosome isolation, 500 pL of serum is thawed and centrifuged at 2,000 x g for 10 minutes to remove any residual cellular debris. The supernatant is mixed with 125 pL of ExoQuick precipitation reagent and incubated at 4°C for 30 minutes. Following incubation, the mixture is centrifuged at 1,500 x g for 30 minutes to pellet the exosomes. The supernatant is carefully aspirated, and the exosome pellet is resuspended in 100 pL of phosphate-buffered saline.

[0472] For PCNA detection, the isolated exosomes are lysed by adding an equal volume of lysis buffer containing 50 mM Tris-HCl (pH 7.4), 150 mM NaCl, 1% Triton X- 100, and protease inhibitor cocktail. The mixture is incubated for 30 minutes at 4°C with gentle agitation. The lysed sample is then centrifuged at 10,000 x g for 5 minutes to remove insoluble debris.

[0473] PCNA quantification is performed using a commercial sandwich ELISA kit. Wells of a 96-well microplate pre-coated with anti-PCNA capture antibodies are blocked with 200 pL of blocking buffer for 1 hour at room temperature. After washing three times with wash buffer, 100 pL of the lysed exosome sample is added to each well and incubated for 2 hours at 37°C. Following four wash cycles, 100 pL of biotin-conjugated anti-PCNA detection antibody is added and incubated for 1 hour at 37°C. After washing. 100 pL of streptavidin-horseradish peroxidase conjugate is added for 30 minutes at room temperature. The wells are washed again, and 100 pL of TMB substrate solution is added for color development. The reaction is stopped with 50 pL of stop solution, and absorbance is measured at 450 nm using a microplate reader.

[0474] A standard curve is generated using recombinant PCNA protein at concentrations of 0, 15.6, 31.25, 62.5, 125, 250, and 500 ng / mL. The patient's exosomal PCNA concentration is determined by interpolation from the standard curve.

[0475] Expected Results:

[0476] The patient's serum exosomal PCNA concentration measures 185 ng / mL, which exceeds the established reference threshold of 97.81 ng / mL for cancer detection. Thisrepresents a 3.1 -fold elevation compared to the mean healthy control value of 60 ng / mL. The elevated exosomal PCNA level, combined with the patient's clinical presentation of liver enzyme abnormalities, suggests the presence of hepatic malignancy.

[0477] To confirm tissue specificity, liver-derived exosomes are isolated using anti- ASGPR1 magnetic beads. PCNA analysis of the ASGPR1 -positive exosome fraction reveals a concentration of 127 ng / mL, while PCNA levels in non-liver-specific exosomes remain at 51 ng / mL. This tissue-specific elevation confirms that the elevated PCNA originates from liver tissue, supporting a diagnosis of hepatocellular carcinoma.

[0478] Subsequent imaging studies reveal a 4.2 cm hepatic mass, and tissue biopsy confirms moderately differentiated hepatocellular carcinoma with high proliferative activity. The correlation between elevated exosomal PCNA levels and confirmed malignancy demonstrates the diagnostic utility of this biomarker for cancer detection. The tissue-specific localization capability enables identification of the anatomical origin of the cancer, facilitating appropriate clinical management and treatment planning.

[0479] This example illustrates how exosomal PCNA detection may serve as a non- invasive liquid biopsy approach for cancer diagnosis, providing both detection and localization capabilities through a simple blood test. The methodology may be applied across various cancer ty pes and clinical scenarios to support early detection and patient management strategies.

[0480] Example 5: Detection of PCNA mRNA in Exosomes for Cancer Diagnosis

[0481] This example demonstrates the methodology for detecting PCNA mRNA within isolated exosomes and correlating the findings to cancer diagnosis through nucleic acid-based analysis.

[0482] Materials and Methods:

[0483] A 52-year-old female patient presents with persistent cough and chest discomfort. A 10 mL blood sample is collected via venipuncture into EDTA tubes and processed within 2 hours of collection. The sample is centrifuged at 1,200 x g for 10 minutes to separate plasma, which is stored at -80°C until analysis.

[0484] For exosome isolation, 1 mL of plasma is thawed on ice and centrifuged at 2,000 x g for 15 minutes to remove cellular debris. The supernatant is filtered through a 0.22 pm membrane filter to eliminate remaining particles. Exosomes are isolated using ultracentrifugation by layering the filtered plasma over a 30% sucrose cushion andcentrifuging at 120,000 x g for 2 hours at 4°C. The exosome pellet is washed with PBS and re-centrifuged at 120,000 x g for 1 hour.

[0485] RNA extraction from isolated exosomes is performed using a commercial exosomal RNA isolation kit. The exosome pellet is resuspended in 200 pL of lysis buffer containing guanidinium thiocyanate and P-mercaptoethanol. The lysate is processed through silica-based spin columns according to manufacturer instructions, with on-column DNase treatment to eliminate genomic DNA contamination. RNA is eluted in 30 pL of nuclease-free water and quantified using a NanoDrop spectrophotometer.

[0486] Reverse transcription is performed using 10 pL of extracted RNA with a high-capacity cDNA reverse transcription kit. The reaction mixture contains 2 pL of 10x RT buffer, 0.8 pL of 25 / dNTP mix, 2 pL of 10x random primers, 1 pL of MultiScribe reverse transcriptase, and 4.2 pL of nuclease-free water. The reaction is incubated at 25°C for 10 minutes, 37°C for 120 minutes, and 85°C for 5 minutes to inactivate the enzy me.

[0487] Quantitative PCR analysis is performed using TaqMan gene expression assays specific for PCNA mRNA. The PCR reaction contains 10 pL of TaqMan Universal PCR Master Mix, 1 pL of PCNA-specific primer / probe set, 2 pL of cDNA template, and 7 pL of nuclease-free water. Thermal cycling conditions include initial denaturation at 95°C for 10 minutes, followed by 40 cycles of 95°C for 15 seconds and 60°C for 1 minute. GAPDH mRNA serves as an internal control for normalization.

[0488] Standard curves are generated using serial dilutions of synthetic PCNA mRNA ranging from 102 to 107 copies per reaction. The cycle threshold (Ct) values are plotted against log copy numbers to determine amplification efficiency and enable absolute quantification of PCNA mRNA in patient samples.

[0489] Expected Results:

[0490] The patient's exosomal PCNA mRNA concentration measures 2.4 x 105copies per mL of plasma, which exceeds the established reference threshold of 5.0 x io4copies per mL for cancer detection. This represents a 4.8-fold elevation compared to the mean healthy control value of 5.0 x 104copies per mL. The GAPDH internal control shows consistent amplification across samples, confirming successful RNA extraction and reverse transcription.

[0491] To determine tissue specificity, lung-derived exosomes are isolated using anti-surfactant protein B magnetic beads. PCNA mRNA analysis of the lung-specific exosome fraction reveals a concentration of 3.8 x io5copies per mL, while PCNA mRNA levels in non-lung-specific exosomes remain at 6.2 x 104copies per mL. This tissue-specificelevation indicates that the elevated PCNA mRNA originates from pulmonary tissue, suggesting the presence of lung malignancy.

[0492] Digital PCR analysis provides additional confirmation with absolute quantification showing 2.6 x 105PCNA mRNA copies per mL, consistent with the qPCR results. The coefficient of variation betw een technical replicates is <5%, demonstrating analytical precision.

[0493] Subsequent chest CT imaging reveals a 3. 1 cm pulmonary nodule in the right upper lobe, and bronchoscopic biopsy confirms adenocarcinoma of the lung with moderate differentiation. Immunohistochemical staining of the tissue biopsy show s high PCNA expression, correlating with the elevated exosomal PCNA mRNA levels detected in the liquid biopsy analysis.

[0494] The correlation between elevated exosomal PCNA mRNA levels and confirmed pulmonary malignancy demonstrates the diagnostic utility of nucleic acid-based biomarker detection. The tissue-specific localization capability through lung-derived exosome analysis enables identification of the anatomical origin of the cancer, supporting targeted diagnostic workup and treatment planning.

[0495] This example illustrates how exosomal PCNA mRNA detection may provide an alternative approach to protein-based analysis for cancer diagnosis, offering enhanced specificity through nucleic acid amplification techniques. The methodology may be particularly valuable for detecting low-abundance biomarkers or in cases where protein degradation may compromise immunoassay-based detection methods.

[0496] Other Embodiments

[0497] The detailed description set-forth above is provided to aid those skilled in the art in practicing the present invention. However, the invention described and claimed herein is not to be limited in scope by the specific embodiments herein disclosed because these embodiments are intended as illustration of several aspects of the invention. Any equivalent embodiments are intended to be within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description which do not depart from the spirit or scope of the present inventive discovery'. Such modifications are also intended to fall w ithin the scope of the appended claims.

[0498] References Cited

[0499] All publications, patents, patent applications and other references cited in this application are incorporated herein by reference in their entirety for all purposes to the same extent as if each individual publication, patent, patent application or other reference was specifically and individually indicated to be incorporated by reference in its entirety for all purposes. Citation of a reference herein shall not be construed as an admission that such is prior art to the present invention.

Claims

CLAIMSWhat is claimed is:

1. A method for detecting cancer in a subject, comprising: obtaining a biological fluid sample from the subject; isolating exosomes from the biological fluid sample; detecting proliferating cell nuclear antigen (PCNA) in the isolated exosomes to determine a level of exosomal PCNA in the biological fluid sample; comparing the level of exosomal PCNA to a reference level; and identifying the subject as having cancer when the level of exosomal PCNA is elevated relative to the reference level.

2. The method of claim 1. wherein the biological fluid sample is selected from the group consisting of serum, plasma, urine, saliva, sputum, pleural effusion, ascites, cerebrospinal fluid, lymph fluid, and synovial fluid.

3. The method of claim 2, wherein the biological fluid sample is serum or plasma.

4. The method of claim 1. wherein isolating exosomes comprises using ultracentrifugation, precipitation-based isolation, or immunoaffinity capture.

5. The method of claim 4, wherein isolating exosomes comprises using a commercial exosome isolation kit.

6. The method of claim 4. wherein isolating exosomes comprises depleting leukocyte-derived exosomes using CD45 antibody-coated magnetic beads and depleting platelet-derived exosomes using CD61 antibody-coated magnetic beads.

7. The method of claim 1, wherein detecting PCNA comprises using an immunoassay selected from the group consisting of enzyme-linked immunosorbent assay (ELISA), Western blot, immunofluorescent assay, turbidimetric immunoassay, radioimmunoassay, chemiluminescent assay, and flow cytometry.

8. The method of claim 7, wherein detecting PCNA comprises using an enzyme- linked immunosorbent assay (ELISA).

9. The method of claim 1. wherein the reference level is a level of exosomal PCNA in a control sample from a healthy individual.

10. The method of claim 1, wherein the elevated level is at least 1.5-fold greater than the reference level.

11. The method of claim 10, wherein the elevated level is at least 2-fold greater than the reference level.

12. The method of claim 1, wherein the cancer is selected from the group consisting of liver cancer, lung cancer, gastric cancer, colorectal cancer, breast cancer, ovarian cancer, pancreatic cancer, and prostate cancer.

13. The method of claim 1, further comprising determining a tissue of origin of the cancer by analyzing tissue-specific markers on the isolated exosomes.

14. The method of claim 13, wherein the tissue-specific markers comprise ASGPR1 for liver cancer or GPA33 for colorectal cancer.

15. The method of claim 13, wherein determining the tissue of origin comprises isolating tissue-specific exosome populations using magnetic bead-based immunoprecipitation targeting the tissue-specific markers.

16. The method of claim 1. further comprising monitoring cancer progression by repeating the method at multiple time points.

17. The method of claim 16, wherein an increase in exosomal PCNA levels over time indicates cancer progression.

18. The method of claim 1. further comprising monitoring treatment effectiveness by repeating the method during a treatment period.

19. The method of claim 18, wherein a decrease in exosomal PCNA levels during treatment indicates treatment response.

20. The method of claim 1. wherein detecting PCNA comprises detecting cancer- associated PCNA (caPCNA) using antibodies specific for cancer-specific epitopes or modifications.

21. A diagnostic kit for detecting cancer, comprising: reagents for isolating exosomes from a biological fluid sample; reagents for detecting proliferating cell nuclear antigen (PCNA) in the isolated exosomes; and instructions for determining a level of exosomal PCNA and comparing the level to a reference level to identify cancer.

22. The diagnostic kit of claim 21, wherein the reagents for isolating exosomes comprise a precipitation-based isolation solution or magnetic beads conjugated to exosome- specific antibodies.

23. The diagnostic kit of claim 22, wherein the precipitation-based isolation solution comprises polyethylene glycol-based reagents.

24. The diagnostic kit of claim 22, wherein the magnetic beads are conjugated to antibodies against CD63, CD81, or CD9.

25. The diagnostic kit of claim 21, wherein the reagents for detecting PCNA comprise antibodies specific for PCNA.

26. The diagnostic kit of claim 25, wherein the antibodies specific for PCNA are monoclonal or polyclonal antibodies.

27. The diagnostic kit of claim 25, wherein the reagents for detecting PCNA comprise components for an enzyme-linked immunosorbent assay (ELISA).

28. The diagnostic kit of claim 27. wherein the ELISA components comprise precoated microplates with anti-PCNA capture antibodies, enzyme-conjugated detection antibodies, and substrate solutions.

29. The diagnostic kit of claim 21, further comprising reagents for detecting tissue-specific markers on exosomes.

30. The diagnostic kit of claim 29, wherein the tissue-specific markers comprise ASGPR1 for liver cancer or GPA33 for colorectal cancer.

31. The diagnostic kit of claim 29, wherein the reagents for detecting tissuespecific markers comprise magnetic beads conjugated to tissue-specific antibodies for immunoaffmity capture.

32. The diagnostic kit of claim 21, further comprising control samples with known levels of exosomal PCNA.

33. The diagnostic kit of claim 32, wherein the control samples comprise positive controls containing exosomal PCNA at concentrations representing cancer patient levels and negative controls containing exosomal PCNA at concentrations representing healthy individual levels.

34. The diagnostic kit of claim 21, further comprising reagents for depleting leukocyte-derived exosomes and platelet-derived exosomes.

35. The diagnostic kit of claim 34, wherein the depletion reagents comprise CD45 antibody-coated magnetic beads for removing leukocyte-derived exosomes and CD61 antibody-coated magnetic beads for removing platelet-derived exosomes.

36. A method for monitoring cancer in a subject, comprising: obtaining a first biological fluid sample from the subject at a first time point; obtaining a second biological fluid sample from the subject at a second time point; determining a first level of exosomal PCNA in the first biological fluid sample; determining a second level of exosomal PCNA in the second biological fluid sample; and comparing the first level and the second level to assess cancer progression ortreatment response.

37. The method of claim 36, wherein an increase in the second level relative to the first level indicates cancer progression.

38. The method of claim 36, wherein a decrease in the second level relative to the first level indicates treatment response.

39. The method of claim 36, wherein the first time point is before treatment and the second time point is during or after treatment.

40. The method of claim 39, wherein the second time point is selected from the group consisting of during chemotherapy cycles, after surgical resection, during radiation therapy, and after immunotherapy administration.

41. The method of claim 36, wherein the biological fluid samples are serum or plasma samples.

42. The method of claim 36, wherein determining levels of exosomal PCNA comprises isolating exosomes from the biological fluid samples and detecting PCNA using an immunoassay.

43. The method of claim 42, wherein the immunoassay is an enzyme-linked immunosorbent assay (ELISA).

44. The method of claim 36, further comprising obtaining additional biological fluid samples at subsequent time points to generate a temporal profile of exosomal PCNA levels.

45. The method of claim 44, wherein the temporal profile is used to predict treatment outcomes or disease recurrence.

46. The method of claim 36, wherein the method is performed at intervals ranging from weekly to annually depending on cancer type and treatment protocol.

47. The method of claim 46, wherein the intervals are monthly during the first year after treatment and quarterly during the second year after treatment.

48. The method of claim 36, further comprising analyzing tissue-specific exosomal PCNA levels to monitor cancer progression or treatment response at specific anatomical sites.

49. The method of claim 48, wherein tissue-specific exosomes are isolated using magnetic bead-based immunoprecipitation targeting tissue-specific markers selected from the group consisting of ASGPR1 for liver tissue and GPA33 for colorectal tissue.

50. The method of claim 36, wherein the method is used for surveillance of cancer recurrence in patients who have completed primary treatment and achieved remission.

51. A method for detecting cancer in a subj ect, comprising: obtaining a biological fluid sample from the subject; isolating exosomes from the biological fluid sample using ultracentrifugation at 120,000 x g for 2 hours; lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X-100 in phosphate-buffered saline; detecting proliferating cell nuclear antigen (PCNA) in the lysed exosomes using an enzyme-linked immunosorbent assay comprising anti-PCNA antibodies immobilized on a solid surface; measuring an optical density signal generated by an enzyme-substrate reaction to determine a concentration of exosomal PCNA in ng / rnL; comparing the measured concentration to a reference concentration of 97.81 ng / mL; and identifying the subject as having cancer when the measured concentration exceeds the reference concentration.

52. The method of claim 51, wherein the biological fluid sample is serum obtained through venipuncture and centrifugation of whole blood.

53. The method of claim 51, wherein isolating exosomes further comprises: centrifuging the biological fluid sample at 300 * g for 10 minutes to remove cells; filtering the supernatant through a 0.45 pm membrane; and washing the exosome pellet with phosphate-buffered saline followed by recentrifugation at 120,000 - g for 2 hours.

54. The method of claim 51, wherein the enzyme-linked immunosorbent assay comprises: incubating the lysed exosomes with monoclonal anti-PCNA capture antibodies for 45 minutes at 37°C; washing with phosphate-buffered saline containing 0.05% Tween-20; incubating with biotin-conjugated anti-PCNA detection antibodies for 30 minutes at 37°C; adding streptavidin-horseradish peroxidase conjugate for 30 minutes; and developing color with tetramethylbenzidine substrate.

55. The method of claim 51 , further comprising: isolating liver-derived exosomes using magnetic beads conjugated to anti-ASGPRl antibodies;measuring PCNA concentration in the liver-derived exosomes; and identifying liver cancer when the PCNA concentration in liver-derived exosomes exceeds 12 ng / mL.

56. The method of claim 51 , further comprising: isolating colorectal-derived exosomes using magnetic beads conjugated to anti-GPA33 antibodies; measuring PCNA concentration in the colorectal-derived exosomes; and identify ing colorectal cancer when the PCNA concentration in colorectal -derived exosomes exceeds 15 ng / mL.

57. The method of claim 51 , further comprising: depleting leukocyte-derived exosomes by incubating the biological fluid sample withCD45 antibody-coated magnetic beads for 1 hour at 4°C; and depleting platelet-derived exosomes by incubating with CD61 antibody-coated magnetic beads for 1 hour at 4°C.

58. A method for monitoring cancer treatment response in a subject, comprising: obtaining a first serum sample from the subject before treatment initiation; obtaining a second serum sample from the subject after 4 weeks of treatment; isolating exosomes from each serum sample using precipitation with polyethylene glycol-based reagent followed by centrifugation at 3,000 x g for 10 minutes; lysing the isolated exosomes with 0.4% Triton X-100; measuring PCNA concentrations in both samples using enzyme-linked immunosorbent assay; calculating a percentage change in PCNA concentration between the first and second samples; and determining treatment response when the PCNA concentration decreases by at least 25%.

59. The method of claim 58, further comprising: obtaining additional serum samples at 8-week intervals during treatment; measuring PCNA concentrations in each sample; and generating a temporal profile of PCNA levels to assess ongoing treatment response.

60. The method of claim 58, wherein determining treatment response further comprises: identifying treatment failure when PCNA concentration increases by more than 20% from baseline; andrecommending treatment modification based on the PCNA concentration changes.

61. A method for early cancer detection screening, comprising: collecting serum samples from a population of asymptomatic individuals; processing each serum sample by centrifugation at 2,000 x g for 10 minutes to remove cellular debris; isolating exosomes using ExoQuick precipitation reagent according to manufacturer specifications; lysing exosomes with detergent solution containing 0.4% Triton X-100; quantifying PCNA protein using sandwich enzyme-linked immunosorbent assay with anti-PCNA antibodies; measuring absorbance at 450 nm using a microplate reader; converting absorbance values to PCNA concentrations using a standard curve; classifying individuals with PCNA concentrations above 97.81 ng / mL as high-risk for cancer; and recommending further diagnostic evaluation for high-risk individuals.

62. The method of claim 61, further comprising: stratifying results by age groups with adjusted reference values of 110 ng / mL for individuals under 50 years and 85 ng / mL for individuals over 70 years.

63. A method for detecting multiple cancer types simultaneously, comprising: obtaining a serum sample from a subject; dividing the sample into aliquots for parallel processing; isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33, surfactant protein B, and prostate-specific membrane antigen; measuring PCNA concentrations in each tissue-specific exosome population using enzyme-linked immunosorbent assay; comparing measured concentrations to tissue-specific reference values; and identifying cancer type and location based on which tissue-specific exosome population exhibits elevated PCNA levels.

64. The method of claim 63, wherein the tissue-specific reference values comprise:12 ng / mL for ASGPR1 -positive exosomes indicating liver cancer;15 ng / mL for GPA33-positive exosomes indicating colorectal cancer;13 ng / mL for surfactant protein B-positive exosomes indicating lung cancer; and10 ng / mL for prostate-specific membrane antigen-positive exosomes indicating prostate cancer.

65. A method for cancer recurrence surveillance, comprising: establishing a post-treatment baseline PCNA concentration in a cancer patient who has achieved remission; collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter; isolating exosomes from each sample using ultracentrifugation at 120,000 x g; measuring PCNA concentrations using standardized enzyme-linked immunosorbent assay; calculating fold-change relative to the post-treatment baseline; and detecting cancer recurrence when PCNA concentration increases by 2-fold or more above the post-treatment baseline.

66. The method of claim 65, further comprising: confirming recurrence detection through repeat testing within 2 weeks; and initiating imaging studies when confirmed PCNA elevation is detected.

67. A method for assessing cancer aggressiveness, comprising: obtaining serum samples from cancer patients with known tumor proliferation indices; isolating exosomes using commercial isolation kits; measuring exosomal PCNA concentrations using quantitative enzyme-linked immunosorbent assay; correlating PCNA concentrations with tumor proliferation indices; and classifying tumors as high-grade when exosomal PCNA concentrations exceed 200 ng / mL.

68. The method of claim 67, wherein correlating PCNA concentrations with tumor proliferation indices comprises: establishing that PCNA concentrations below7100 ng / mL correlate with low7proliferation index tumors; determining that PCNA concentrations between 100-200 ng / mL correlate with intermediate proliferation index tumors; and confirming that PCNA concentrations above 200 ng / mL correlate with high proliferation index tumors.

69. A method for optimizing cancer treatment protocols, comprising: measuring baseline exosomal PCNA concentrations in cancer patients beforetreatment; administering standard treatment protocols; monitoring exosomal PCNA levels at weekly intervals during treatment; identifying patients with less than 15% decrease in PCNA levels after 2 weeks as poor responders; modifying treatment protocols for poor responders by increasing dosage or changing therapeutic agents; and continuing monitoring until PCNA levels decrease by at least 50% from baseline.

70. The method of claim 69, further comprising: maintaining current treatment protocols for patients showing greater than 30% decrease in PCNA levels within 2 weeks; and implementing dose reduction protocols when PCNA levels decrease by more than 75% to minimize treatment toxicity.

71. A method for detecting cancer in a subj ect, comprising: obtaining a biological fluid sample from the subject; isolating exosomes from the biological fluid sample using ultracentrifugation at 120,000 x g for 2 hours; lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X-100 in phosphate-buffered saline; detecting proliferating cell nuclear antigen (PCNA) protein in the lysed exosomes using an enzyme-linked immunosorbent assay comprising anti-PCNA antibodies immobilized on a solid surface; measuring an optical density signal generated by an enzy me-substrate reaction to determine a concentration of exosomal PCNA protein in ng / rnL; comparing the measured concentration to a reference concentration of 97.81 ng / rnL; and diagnosing the subject as having cancer when the measured concentration exceeds the reference concentration.

72. A method for detecting cancer in a subject, comprising: obtaining a biological fluid sample from the subject; isolating exosomes from the biological fluid sample using precipitation with polyethylene glycol-based reagent; extracting RNA from the isolated exosomes using phenol-chloroform extraction; performing reverse transcription to convert PCNA mRNA to complementary DNA;detecting PCNA mRNA using quantitative polymerase chain reaction with PCNA- specific primers and probes; measuring cycle threshold values to determine a concentration of exosomal PCNA mRNA in copies per rnL; comparing the measured concentration to a reference concentration of 5.0 x 104copies per mL; and diagnosing the subject as having cancer when the measured concentration exceeds the reference concentration.

73. The method of claim 71, wherein the biological fluid sample is serum obtained through venipuncture and centrifugation of whole blood.

74. The method of claim 72, wherein the biological fluid sample is plasma obtained using EDTA anticoagulant tubes.

75. The method of claim 71, wherein isolating exosomes further comprises: centrifuging the biological fluid sample at 300 x g for 10 minutes to remove cells; filtering the supernatant through a 0.45 pm membrane; and washing the exosome pellet with phosphate-buffered saline followed by recentrifugation at 120,000 x g for 2 hours.

76. The method of claim 72, wherein extracting RNA further comprises: treating the isolated exosomes with DNase to eliminate genomic DNA contamination; and eluting RNA in nuclease-free water for downstream analysis.

77. The method of claim 71, wherein the enzyme-linked immunosorbent assay comprises: incubating the lysed exosomes with monoclonal anti-PCNA capture antibodies for 45 minutes at 37°C; washing with phosphate-buffered saline containing 0.05% Tween-20; incubating with biotin-conjugated anti-PCNA detection antibodies for 30 minutes at 37°C: adding streptavidin-horseradish peroxidase conjugate for 30 minutes; and developing color with tetramethylbenzidine substrate.

78. The method of claim 72, wherein the quantitative polymerase chain reaction comprises: using TaqMan probes for sequence-specific detection; performing thermal cycling at 95°C for 15 seconds and 60°C for 1 minute for 40cycles; and normalizing results using GAPDH mRNA as an internal control.

79. The method of claim 71 , further comprising: isolating liver-derived exosomes using magnetic beads conjugated to anti-ASGPRl antibodies; measuring PCNA protein concentration in the liver-derived exosomes; and diagnosing liver cancer when the PCNA protein concentration in liver-derived exosomes exceeds 12 ng / mL.

80. The method of claim 72, further comprising: isolating lung-derived exosomes using magnetic beads conjugated to anti-surfactant protein B antibodies; measuring PCNA mRNA concentration in the lung-derived exosomes; and diagnosing lung cancer when the PCNA mRNA concentration in lung-derived exosomes exceeds 1.0 x io4copies per rnL.

81. A method for monitoring cancer treatment response in a subj ect, comprising: obtaining a first serum sample from the subject before treatment initiation; obtaining a second serum sample from the subject after 4 weeks of treatment; isolating exosomes from each serum sample using ExoQuick precipitation reagent; lysing the isolated exosomes with 0.4% Triton X-100; measuring PCNA protein concentrations in both samples using enzyme-linked immunosorbent assay; calculating a percentage change in PCNA protein concentration between the first and second samples; and correlating treatment response with cancer prognosis when the PCNA protein concentration decreases by at least 25%.

82. A method for monitoring cancer treatment response in a subject, comprising: obtaining serum samples from the subject at multiple time points during treatment; isolating exosomes from each serum sample using ultracentrifugation; extracting RNA from the isolated exosomes; measuring PCNA mRNA levels using quantitative polymerase chain reaction; calculating fold-changes in PCNA mRNA levels relative to baseline; and correlating treatment response with cancer prognosis when PCNA mRNA levels decrease by at least 2-fold.

83. The method of claim 81, further comprising:obtaining additional serum samples at 8-week intervals during treatment; measuring PCNA protein concentrations in each sample; and generating a temporal profile of PCNA protein levels to assess ongoing treatment response and cancer status.

84. The method of claim 82, wherein correlating treatment response further comprises: identifying treatment failure and poor cancer prognosis when PCNA mRNA levels increase by more than 50% from baseline; and recommending treatment modification based on the PCNA mRNA level changes.

85. A method for early cancer detection screening, comprising: collecting serum samples from a population of asymptomatic individuals; processing each serum sample by centrifugation at 2,000 x g for 10 minutes to remove cellular debris; isolating exosomes using commercial isolation kits; lysing exosomes with detergent solution containing 0.4% Triton X-100; quantifying PCNA protein using sandwich enzyme-linked immunosorbent assay with anti-PCNA antibodies; measuring absorbance at 450 nm using a microplate reader; converting absorbance values to PCNA protein concentrations using a standard curve; classifying individuals with PCNA protein concentrations above 97.81 ng / mL as having cancer; and recommending further diagnostic evaluation for individuals diagnosed with cancer.

86. A method for early cancer detection screening, comprising: collecting plasma samples from asymptomatic individuals; isolating exosomes using size-exclusion chromatography; extracting total RNA from the isolated exosomes; performing reverse transcription quantitative PCR for PCNA mRNA detection; measuring PCNA mRNA concentrations using standard curves; classifying individuals with PCNA mRNA concentrations above 5.0 x 104copies per mL as having cancer; and correlating elevated PCNA mRNA levels with cancer diagnosis.

87. A method for detecting multiple cancer types simultaneously, comprising: obtaining a serum sample from a subject; dividing the sample into aliquots for parallel processing;isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33. and surfactant protein B; measuring PCNA protein concentrations in each tissue-specific exosome population using enzyme-linked immunosorbent assay; comparing measured concentrations to tissue-specific reference values; and diagnosing specific cancer types based on which tissue-specific exosome population exhibits elevated PCNA protein levels.

88. A method for detecting multiple cancer types simultaneously, comprising: obtaining a plasma sample from a subject; isolating tissue-specific exosome populations using immunoaffinity capture; extracting RNA from each tissue-specific exosome population; measuring PCNA mRNA levels using tissue-specific quantitative PCR assays; comparing measured PCNA mRNA levels to tissue-specific reference values; and diagnosing specific cancer types based on which tissue-specific exosome population exhibits elevated PCNA mRNA levels.

89. A method for cancer recurrence surveillance, comprising: establishing a post-treatment baseline PCNA protein concentration in a cancer patient who has achieved remission; collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter; isolating exosomes from each sample using standardized protocols; measuring PCNA protein concentrations using enzy me-linked immunosorbent assay; calculating fold-change relative to the post-treatment baseline; and diagnosing cancer recurrence when PCNA protein concentration increases by 2-fold or more above the post-treatment baseline.

90. A method for cancer recurrence surveillance, comprising: establishing post-treatment baseline PCNA mRNA levels in a cancer patient who has achieved remission; collecting plasma samples at regular surveillance intervals; isolating exosomes and extracting RNA using standardized methods; measuring PCNA mRNA levels using quantitative polymerase chain reaction; calculating percentage changes relative to baseline levels; and diagnosing cancer recurrence when PCNA mRNA levels increase by 2-fold or more above the post-treatment baseline.

91. A method for detecting cancer in a subject, the method comprising the steps of: a) obtaining a biological fluid sample from the subject: b) isolating exosomes from the biological fluid sample by ultracentrifugation at 120,000 x g for 2 hours; c) lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X- 100 in phosphate-buffered saline; d) detecting proliferating cell nuclear antigen (PCNA) in the lysed exosomes by performing an enzyme-linked immunosorbent assay using anti-PCNA antibodies immobilized on a solid surface; e) measuring an optical density’ signal generated by an enzyme-substrate reaction to determine a concentration of exosomal PCNA in ng / mL;1) comparing the measured concentration to a reference concentration of 97.81 ng / mL; and g) identifying the subject as having cancer when the measured concentration exceeds the reference concentration.

92. The method according to claim 91, wherein the biological fluid sample is selected from the group consisting of serum, plasma, urine, saliva, sputum, pleural effusion, ascites, cerebrospinal fluid, lymph fluid, and synovial fluid.

93. The method according to claim 91 or 92. wherein step b) further comprises: centrifuging the biological fluid sample at 300 x g for 10 minutes to remove cells; filtering the supernatant through a 0.45 pm membrane; and washing the exosome pellet with phosphate-buffered saline followed by recentrifugation at 120,000 x g for 2 hours.

94. The method according to any one of claims 91 to 93, wherein the enzyme- linked immunosorbent assay in step d) comprises: incubating the lysed exosomes with monoclonal anti-PCNA capture antibodies for 45 minutes at 37°C; washing with phosphate-buffered saline containing 0.05% Tween-20; incubating with biotin-conjugated anti-PCNA detection antibodies for 30 minutes at 37°C; adding streptavidin-horseradish peroxidase conjugate for 30 minutes; and developing colour with tetramethylbenzidine substrate.

95. The method according to any one of claims 91 to 94, further comprising thestep of: determining a tissue of origin of the cancer by isolating tissue-specific exosome populations using magnetic beads conjugated to tissue-specific antibodies selected from the group consisting of anti-ASGPRl antibodies for liver-derived exosomes and anti-GPA33 antibodies for colorectal-derived exosomes.

96. A method for monitoring cancer treatment response in a subject, the method comprising the steps of: a) obtaining a first serum sample from the subject before treatment initiation; b) obtaining a second serum sample from the subject after a predetermined treatment period; c) isolating exosomes from each serum sample using precipitation with polyethylene glycol-based reagent followed by centrifugation at 3,000 x g for 10 minutes; d) lysing the isolated exosomes with 0.4% Triton X-100; e) measuring PCNA concentrations in both samples using enzyme-linked immunosorbent assay; f) calculating a percentage change in PCNA concentration between the first and second samples; and g) determining treatment response when the PCNA concentration decreases by at least 25%.

97. The method according to claim 96. wherein the predetermined treatment period is 4 weeks, and the method further comprises: obtaining additional serum samples at 8-week intervals during treatment; measuring PCNA concentrations in each sample; and generating a temporal profile of PCNA levels to assess ongoing treatment response.

98. A method for early cancer detection screening in a population, the method comprising the steps of: a) collecting serum samples from a plurality of asymptomatic individuals; b) processing each serum sample by centrifugation at 2,000 x g for 10 minutes to remove cellular debris; c) isolating exosomes using ExoQuick precipitation reagent according to manufacturer specifications; d) lysing exosomes with detergent solution containing 0.4% Triton X-100; e) quantifying PCNA protein using sandwich enzyme-linked immunosorbent assay with anti-PCNA antibodies;f) measuring absorbance at 450 nm using a microplate reader; g) converting absorbance values to PCNA concentrations using a standard curve; h) classifying individuals with PCNA concentrations above 97.81 ng / mL as high-risk for cancer; and i) recommending further diagnostic evaluation for high-risk individuals.

99. A method for detecting multiple cancer types simultaneously, the method comprising the steps of: a) obtaining a serum sample from a subject; b) dividing the sample into aliquots for parallel processing; c) isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33. surfactant protein B, and prostate-specific membrane antigen; d) measuring PCNA concentrations in each tissue-specific exosome population using enzy me-linked immunosorbent assay; e) comparing measured concentrations to tissue-specific reference values comprising12 ng / mL for ASGPR1 -positive exosomes, 15 ng / mL for GPA33-positive exosomes.13 ng / mL for surfactant protein B-positive exosomes, and 10 ng / mL for prostatespecific membrane antigen-positive exosomes; and f) identifying cancer type and location based on which tissue-specific exosome population exhibits elevated PCNA levels.

100. A method for cancer recurrence surveillance, the method comprising the steps of: a) establishing a post-treatment baseline PCNA concentration in a cancer patient who has achieved remission; b) collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter; c) isolating exosomes from each sample using ultracentrifugation at 120,000 x g; d) measuring PCNA concentrations using standardized enzyme-linked immunosorbent assay; e) calculating fold-change relative to the post-treatment baseline; and1) detecting cancer recurrence when PCNA concentration increases by 2-fold or more above the post-treatment baseline.

101. A method for detecting cancer in a subject, comprising: obtaining a biological fluid sample from the subject;isolating exosomes from the biological fluid sample using ultracentrifugation at 120,000 x g for 2 hours; lysing the isolated exosomes with a detergent solution comprising 0.4% Triton X-100 in phosphate-buffered saline; detecting proliferating cell nuclear antigen (PCNA) in the lysed exosomes using an enzyme-linked immunosorbent assay with anti-PCNA antibodies; measuring optical density to determine exosomal PCNA concentration in ng / mL; comparing the measured concentration to a reference concentration of 97.81 ng / mL; and determining the subject has cancer when the measured concentration exceeds the reference concentration.

102. The method of claim 101, wherein the biological fluid sample is serum obtained by venipuncture and centrifugation of whole blood at 1,500 x g for 10 minutes.

103. The method of claim 101, wherein isolating exosomes further comprises: centrifuging the biological fluid sample at 300 x g for 10 minutes to remove cells; filtering the supernatant through a 0.45 pm membrane filter; and washing the exosome pellet with phosphate-buffered saline followed by recentrifugation at 120,000 x g for 2 hours.

104. The method of claim 101, wherein the enzyme-linked immunosorbent assay comprises: coating microplate wells with monoclonal anti-PCNA capture antibodies; incubating lysed exosomes in the coated wells for 45 minutes at 37°C; washing with phosphate-buffered saline containing 0.05% Tween-20; adding biotin-conjugated anti-PCNA detection antibodies for 30 minutes at 37°C; adding streptavidin-horseradish peroxidase conjugate for 30 minutes; and developing color with tetramethylbenzidine substrate solution.

105. The method of claim 101, further comprising: isolating liver-specific exosomes using magnetic beads conjugated to anti-ASGPRl antibodies; measuring PCNA concentration in the liver-specific exosomes; and identifying liver cancer when PCNA concentration in liver-specific exosomes exceeds 12 ng / mL.

106. A method for monitoring cancer treatment response, comprising: obtaining a first serum sample from a cancer patient before treatment;obtaining a second serum sample from the patient after 4 weeks of treatment; isolating exosomes from each sample using polyethylene glycol precipitation followed by centrifugation at 3,000 * g for 10 minutes; lysing exosomes with 0.4% Triton X-100 solution; measuring PCNA concentrations using enzyme-linked immunosorbent assay; calculating percentage change in PCNA concentration between samples; and determining positive treatment response when PCNA concentration decreases by at least 25%.

107. The method of claim 106, further comprising: collecting additional serum samples at 8-week intervals during treatment; measuring PCNA concentrations in each sample; and generating a temporal profile to monitor ongoing treatment response.

108. A method for cancer screening in asymptomatic populations, comprising: collecting serum samples from multiple asymptomatic individuals; centrifuging each sample at 2,000 g for 10 minutes to remove cellular debris; isolating exosomes using commercial precipitation reagents; lysing exosomes with detergent solution containing 0.4% Triton X-100; quantifying PCNA using sandwich enzyme-linked immunosorbent assay; measuring absorbance at 450 nm wavelength; converting absorbance to PCNA concentrations using standard curves; identifying individuals with PCNA concentrations above 97.81 ng / mL as high cancer risk; and recommending diagnostic follow-up for high-risk individuals.

109. A method for simultaneous detection of multiple cancer types, comprising: obtaining a serum sample from a subject; dividing the sample into separate aliquots; isolating tissue-specific exosome populations using magnetic immunoprecipitation with antibodies against ASGPR1, GPA33, and surfactant protein B; measuring PCNA concentrations in each tissue-specific population using enzyme- linked immunosorbent assay; comparing concentrations to tissue-specific thresholds of 12 ng / mL for ASGPR1- positive exosomes, 15 ng / mL for GPA33-positive exosomes, and 13 ng / mL for surfactant protein B-positive exosomes; and identifying cancer type based on which tissue-specific population shows elevatedPCNA levels.

110. A method for cancer recurrence surveillance, comprising: establishing baseline PCNA concentration in a cancer patient after successful treatment; collecting serum samples at 3-month intervals for the first year and 6-month intervals thereafter; isolating exosomes using standardized ultracentrifugation protocols; measuring PCNA concentrations using validated enzyme-linked immunosorbent assay; calculating fold-change relative to baseline concentration; and detecting cancer recurrence when PCNA concentration increases 2-fold or more above baseline levels.

111. A method for diagnosing cancer, comprising:(a) isolating exosomes from a human biological fluid sample via immunoaffmity capture using at least one pan-exosome marker antibody;(b) quantifying PCNA protein levels in said exosomes using a chemiluminescent immunoassay;(c) comparing the quantified PCNA levels to a reference threshold of 5.0 ng / mL; and(d) diagnosing the patient with cancer if PCNA levels exceed said threshold, wherein said diagnosis triggers administration of an anti-cancer drug.

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