MCT4 and CD147 colocalize with MMP14 in invadopodia and support matrix degradation and invasion by breast cancer cells.

Expression levels of the lactate-H+ cotransporter MCT4 (also known as SLC16A3) and its chaperone CD147 (also known as basigin) are upregulated in breast cancers, correlating with decreased patient survival. Here, we test the hypothesis that MCT4 and CD147 favor breast cancer invasion through interdependent effects on extracellular matrix (ECM) degradation. MCT4 and CD147 expression and membrane localization were found to be strongly reciprocally interdependent in MDA-MB-231 breast cancer cells. Overexpression of MCT4 and/or CD147 increased, and their knockdown decreased, migration, invasion and the degradation of fluorescently labeled gelatin. Overexpression of both proteins led to increases in gelatin degradation and appearance of the matrix metalloproteinase (MMP)-generated collagen-I cleavage product reC1M, and these increases were greater than those observed upon overexpression of each protein alone, suggesting a concerted role in ECM degradation. MCT4 and CD147 colocalized with invadopodia markers at the plasma membrane. They also colocalized with MMP14 and the lysosomal marker LAMP1, as well as partially with the autophagosome marker LC3, in F-actin-decorated intracellular vesicles. We conclude that MCT4 and CD147 reciprocally regulate each other and interdependently support migration and invasiveness of MDA-MB-231 breast cancer cells. Mechanistically, this involves MCT4-CD147-dependent stimulation of ECM degradation and specifically of MMP-mediated collagen-I degradation. We suggest that the MCT4-CD147 complex is co-delivered to invadopodia with MMP14.

The collagen landscape in cancer: profiling collagens in tumors and in circulation reveals novel markers of cancer-associated fibroblast subtypes.

Cancer-associated fibroblasts (CAFs) deposit and remodel collagens in the tumor stroma, impacting cancer progression and efficacy of interventions. CAFs are the focus of new therapeutics with the aim of normalizing the tumor microenvironment. To do this, a better understanding of CAF heterogeneity and collagen composition in cancer is needed. In this study, we sought to profile the expression of collagens at multiple levels with the goal of identifying cancer biomarkers. We investigated the collagen expression pattern in various cell types and CAF subtypes in a publicly available single-cell RNA sequencing (RNA-seq) dataset of pancreatic ductal adenocarcinoma. Next, we investigated the collagen expression profile in tumor samples across cancer types from The Cancer Genome Atlas (TCGA) database and evaluated if specific patterns of collagen expression were associated with prognosis. Finally, we profiled circulating collagen peptides using a panel of immunoassays to measure collagen fragments in the serum of cancer patients. We found that pancreatic stellate cells and fibroblasts were the primary producers of collagens in the pancreas. COL1A1, COL3A1, COL5A1, COL6A1 were expressed in all CAF subtypes, whereas COL8A1, COL10A1, COL11A1, COL12A1 were specific to myofibroblast CAFs (myCAF) and COL14A1 specific to inflammatory CAFs (iCAF). In TCGA database, myCAF collagens COL10A1 and COL11A1 were elevated across solid tumor types, and multiple associations between high expression and worse survival were found. Finally, circulating collagen biomarkers were elevated in the serum of patients with cancer relative to healthy controls with COL11A1 (myCAF) having the best diagnostic accuracy of the markers measured. In conclusion, CAFs express a noncanonical collagen profile with specific collagen subtypes associated with iCAFs and myCAFs in PDAC. These collagens are deregulated at the cellular, tumor, and systemic levels across different solid tumors and associate with survival. These findings could lead to new discoveries such as novel biomarkers and therapeutic targets. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Blood-based tumor fibrosis markers as diagnostic and prognostic biomarkers in patients with biliary tract cancer.

Biliary tract cancer (BTC) is characterized by a desmoplastic extracellular matrix (ECM). We tested the diagnostic and prognostic use of seven circulating biomarkers of ECM remodeling: pro-peptides of type III collagen (PRO-C3), VI (PRO-C6) and XI (PRO-C11), matrix metalloprotease (MMP) degraded type III collagen (C3M) and type IV collagen (C4M) fragments, granzyme B degraded type IV collagen fragments (C4G) and MMP degraded and citrullinated vimentin (VICM) a marker of macrophage activation. The study included 269 patients with all stages of BTC and 49 patients with benign biliary tract diseases. Serum samples from BTC patients were collected before surgery, or before first- or second-line chemotherapy. C3M, C4M, PRO-C3, PRO-C6, PRO-C11 and VICM levels were elevated in patients with BTC compared to patients with benign disease. Receiver operating characteristics curve analyses identified PRO-C3 (area under curve [AUC] = 0.87) as the ECM marker with the best diagnostic performance. The ECM biomarkers correlated with inflammation biomarkers (C-reactive protein [CRP], interleukin-6 [IL-6] and YKL-40) but not with CA19-9. To investigate prognostic performance, patients were split into three cohorts (first-line, second-line and surgery). Elevated ECM biomarker levels were associated with short overall survival (OS), but only pretreatment PRO-C3 and PRO-C6 were associated with OS in both the first-line and second-line settings when adjusting for CA19-9, performance status and stage in a multivariate Cox-regression analyses. Our results indicate that collagen remodeling is increased in patients with BTC and associated with survival. The collagen pro-peptides (PRO-C3 and PRO-C6) could be used as novel biomarkers in these patients.

Levels of type XVII collagen (BP180) ectodomain are elevated in circulation from patients with multiple cancer types and is prognostic for patients with metastatic colorectal cancer.

BACKGROUND: Collagens are the major components of the extracellular matrix (ECM) and are known to contribute to tumor progression and metastasis. There are 28 different types of collagens each with unique functions in maintaining tissue structure and function. Type XVII collagen (BP180) is a type II transmembrane protein that provides stable adhesion between epithelial cells and the underlying basement membrane. Aberrant expression and ectodomain shedding of type XVII collagen have been associated with epithelial damage, tumor invasiveness, and metastasis in multiple tumor types and may consequently be used as a potential (non-invasive) biomarker in cancer and treatment target. METHOD: An ELISA targeting the type XVII collagen ectodomain (PRO-C17) was developed for use in serum. PRO-C17 was measured in a cohort of patients with 11 different cancer types (n = 214) and compared to healthy controls (n = 23) (cohort 1). Based on the findings from cohort 1, PRO-C17 and its association with survival was explored in patients with metastatic colorectal cancer (mCRC) treated with bevacizumab in combination with chemotherapy (n = 212) (cohort 2). RESULTS: PRO-C17 was robust and specific towards the ectodomain of type XVII collagen. In cohort 1, PRO-C17 levels were elevated (p < 0.05) in serum from patients with CRC, kidney, ovarian, bladder, breast, and head and neck cancer compared to healthy controls. PRO-C17 was especially good at discriminating between CRC patients and healthy controls with an AUROC of 0.904. In cohort 2, patients with mCRC and high levels (tertile 3) of PRO-C17 had shorter overall survival (OS) with a median OS of 390 days compared to 539 days for patients with low levels of PRO-C17. When evaluated by multivariate Cox regression analysis, high PRO-C17 was predictive for poor OS independent of risk factors and the tumor fibrosis biomarker PRO-C3. CONCLUSION: PRO-C17 measures the ectodomain of type XVII collagen in serum and is a promising non-invasive biomarker that can aid in understanding tumor heterogeneity as well as elaborate on the role of collagen XVII in tumor progression. Moreover, the findings in the study proposes PRO-C17 as novel biomarker of epithelial damage in specific cancer types including CRC.

Fibrotic activity quantified in serum by measurements of type III collagen pro-peptides can be used for prognosis across different solid tumor types.

Due to activation of fibroblast into cancer-associated fibroblasts, there is often an increased deposition of extracellular matrix and fibrillar collagens, e.g. type III collagen, in the tumor microenvironment (TME) that leads to tumor fibrosis (desmoplasia). Tumor fibrosis is closely associated with treatment response and poor prognosis for patients with solid tumors. To assure that the best possible treatment option is provided for patients, there is medical need for identifying patients with high (or low) fibrotic activity in the TME. Measuring unique collagen fragments such as the pro-peptides released into the bloodstream during fibrillar collagen deposition in the TME can provide a non-invasive measure of the fibrotic activity. Based on data from 8 previously published cohorts, this review provides insight into the prognostic value of quantifying tumor fibrosis by measuring the pro-peptide of type III collagen in serum of a total of 1692 patients with different solid tumor types and discusses the importance of tumor fibrosis for understanding prognosis and for potentially guiding future drug development efforts that aim at overcoming the poor outcome associated with a fibrotic TME.

Autoreactivity against Denatured Type III Collagen Is Significantly Decreased in Serum from Patients with Cancer Compared to Healthy Controls.

Autoantibodies have the potential as cancer biomarkers as they may associate with the outcome and immune-related adverse events (irAEs) following immunotherapy. Cancer and other fibroinflammatory diseases, such as rheumatoid arthritis (RA), are associated with excessive collagen turnover leading to collagen triple helix unfolding and denaturation with exposure of immunodominant epitopes. In this study, we aimed to investigate the role of autoreactivity against denatured collagen in cancer. A technically robust assay to quantify autoantibodies against denatured type III collagen products (anti-dCol3) was developed and then measured in pretreatment serum from 223 cancer patients and 33 age-matched controls. Moreover, the association between anti-dCol3 levels and type III collagen degradation (C3M) and formation (PRO-C3) was investigated. Anti-dCol3 levels were significantly lower in patients with bladder (p = 0.0007), breast (p = 0.0002), colorectal (p < 0.0001), head and neck (p = 0.0005), kidney (p = 0.005), liver (p = 0.030), lung (p = 0.0004), melanoma (p < 0.0001), ovarian (p < 0.0001), pancreatic (p < 0.0001), prostate (p < 0.0001), and stomach cancers (p < 0.0001) compared to controls. High anti-dCol3 levels were associated with type III collagen degradation (C3M, p = 0.0002) but not type III collagen formation (PRO-C3, p = 0.26). Cancer patients with different solid tumor types have downregulated levels of circulating autoantibodies against denatured type III collagen compared to controls, suggesting that autoreactivity against unhealthy type III collagen may be important for tumor control and eradication. This autoimmunity biomarker may have the potential for studying the close relationship between autoimmunity and cancer.

In Contrast to Anti-CCP, MMP-Degraded and Citrullinated Vimentin (VICM) Is Both a Diagnostic and a Treatment Response Biomarker.

Protein citrullination and degradation by matrix metalloproteinases (MMP) plays a central role in the pathology of rheumatoid arthritis (RA). Autoantibodies are known to target citrullinated vimentin. The aim of this study was to investigate the relationship between the blood levels of MMP-degraded and citrullinated vimentin (VICM), as compared with the levels of MMP-degraded and non-citrullinated vimentin (VIM), and the standard anti-CCP biomarker in RA patients undergoing treatment. Thus, VIM, VICM and anti-CCP were quantified by ELISA in serum samples from baseline and week 8 of patients (n = 257) with RA, treated with either tocilizumab (8 mg/kg), methotrexate (7.5−15 mg/kg) or a placebo and compared with a reference cohort (n = 64). The three biomarkers were elevated in RA serum compared with the reference cohort: medians were 1.7 vs. 0.8 ng/mL (p < 0.05) for VIM; 7.5 vs. 0.7 ng/mL (p < 0.0001) for VICM; 57 vs. 4 RU/mL (p < 0.001) for anti-CCP. VICM was decreased in response to tocilizumab (2.9-fold, p < 0.0001) and to methotrexate (1.5-fold, p < 0.05) compared with the placebo, while anti-CCP was not. Serum VIM was also modulated by both drugs, although to a lesser degree. A high baseline level of VICM was predictive of a low disease activity response at week 8. In conclusion, VICM can differentiate between RA and healthy donors in a similar manner to anti-CCP; furthermore, VICM is also a pharmacodynamic marker.

Type XX Collagen Is Elevated in Circulation of Patients with Solid Tumors.

In the tumor microenvironment, the extracellular matrix (ECM) has been recognized as an important part of cancer development. The dominant ECM proteins are the 28 types of collagens, each with a unique function in tissue architecture. Type XX collagen, however, is poorly characterized, and little is known about its involvement in cancer. We developed an ELISA quantifying type XX collagen, named PRO-C20, using a monoclonal antibody raised against the C-terminus. PRO-C20 and PRO-C1, an ELISA targeting the N-terminal pro-peptide of type I collagen, was measured in sera of 219 patients with various solid cancer types and compared to sera levels of 33 healthy controls. PRO-C20 was subsequently measured in a separate cohort comprising 36 patients with pancreatic ductal adenocarcinoma (PDAC) and compared to 20 healthy controls and 11 patients with chronic pancreatitis. PRO-C20 was significantly elevated in all cancers tested: bladder, breast, colorectal, head and neck, kidney, lung, melanoma, ovarian, pancreatic, prostate, and stomach cancer (p < 0.01−p < 0.0001). PRO-C1 was only elevated in patients with ovarian cancer. PRO-C20 could discriminate between patients and healthy controls with AUROC values ranging from 0.76 to 0.92. Elevated levels were confirmed in a separate cohort of patients with PDAC (p < 0.0001). High PRO-C20 levels (above 2.57 nM) were predictive of poor survival after adjusting for the presence of metastasis, age, and sex (HR: 4.25, 95% CI: 1.52−11.9, p-value: 0.006). Circulating type XX collagen is elevated in sera of patients with various types of cancer and has prognostic value in PDAC. If validated, PRO-C20 may be a novel biomarker for patients with solid tumors and can help understand the ECM biology of cancer.

Noninvasive prognostic biomarker potential of quantifying the propeptides of Type XI collagen alpha-1 chain (PRO-C11) in patients with pancreatic ductal adenocarcinoma.

Type XI collagen has been associated with tumor fibrosis and aggressiveness in patients with pancreatic ductal adenocarcinoma (PDAC). The propeptide on Type XI collagen is released into the circulation after proteolytic processing at either amino acid 253 or 511. This allows for a noninvasive biomarker approach to quantify Type XI collagen production. We developed two ELISA-based biomarkers, targeting the two enzymatic cleavage sites (PRO-C11-253 and PRO-C11-511). In a discovery cohort including serum from patients with PDAC (n = 39, Stages 1-4), chronic pancreatitis (CP, n = 12) and healthy controls (n = 20), PRO-C11-511, but not PRO-C11-253, was significantly upregulated in patients with PDAC and CP compared to healthy controls. Furthermore, PRO-C11-511 levels >75th percentile were associated with poor overall survival (OS) (HR, 95% CI: 3.40, 1.48-7.83). The PRO-C11-511 biomarker potential was validated in serum from 686 patients with PDAC. Again, high levels of PRO-C11-511 (>75th percentile) were associated with poor OS (HR, 95% CI: 1.68, 1.40-2.02). Furthermore, PRO-C11-511 remained significant after adjusting for clinical risk factors (HR, 95% CI: 1.50, 1.22-1.86). In conclusion, quantifying serum levels of Type XI collagen with PRO-C11-511 predicts poor OS in patients with PDAC. This supports that Type XI collagen is important for PDAC biology and that PRO-C11-511 has prognostic noninvasive biomarker potential for patients with PDAC.

Blood-based extracellular matrix biomarkers as predictors of survival in patients with metastatic pancreatic ductal adenocarcinoma receiving pegvorhyaluronidase alfa.

BACKGROUND: Extensive extracellular matrix (ECM) remodeling is a hallmark of metastatic pancreatic ductal adenocarcinoma (mPDA). We investigated fragments of collagen types III (C3M, PRO-C3), VI (PRO-C6), and VIII (C8-C), and versican (VCANM) in plasma as biomarkers for predicting progression-free survival (PFS) and overall survival (OS) in patients with mPDA treated with pegvorhyaluronidase alfa, a biologic that degrades the ECM component hyaluronan (HA), in a randomized phase 2 study (HALO109-202). METHODS: HALO109-202 comprised a discovery cohort (Stage 1, n = 94) and a validation cohort (Stage 2, n = 95). Plasma ECM biomarkers were analyzed by ELISAs. Univariate Cox regression analysis and Kaplan-Meier plots evaluated predictive associations between biomarkers, PFS and OS in patients treated with pegvorhyaluronidase alfa plus nab-paclitaxel/gemcitabine (PAG) versus nab-paclitaxel/gemcitabine (AG) alone. RESULTS: PFS was improved with PAG vs. AG in Stage 1 patients with high C3M/PRO-C3 ratio (median cut-off): median PFS (mPFS) 8.0 vs. 5.3 months, P = 0.031; HR = 0.40; 95% CI 0.17-0.92). High C3M/PRO-C3 ratio was validated in Stage 2 patients by predicting a PFS benefit of PAG vs. AG (mPFS: 8.8 vs. 3.4 months, P = 0.046; HR = 0.46; 95% CI 0.21-0.98). OS was also improved in patients with high C3M/PRO-C3 ratio treated with PAG vs. AG (mOS 13.8 vs 8.5 months, P = 0.009; HR = 0.35; 95% CI 0.16-0.77). Interestingly, high C3M/PRO-C3 ratio predicted for a PFS benefit to PAG vs. AG both in patients with HA-low tumors (HR = 0.36; 95% CI 0.17-0.79) and HA-high tumors (HR = 0.20; 95% CI 0.06-0.69). CONCLUSIONS: The C3M/PRO-C3 ratio measuring type III collagen turnover in plasma has potential as a blood-based predictive biomarker in patients with mPDA and provides additional value to a HA biopsy when applied for patient selection. TRIAL REGISTRATION: NCT01839487. Registered 25 April 2016.

A Human Cellular Model for Colorectal Anastomotic Repair: The Effect of Localization and Transforming Growth Factor-ß1 Treatment on Collagen Deposition and Biomarkers.

Anastomotic leakage (AL) is a devastating complication after colorectal surgery, possibly due to the loss of stabilizing collagen fibers in the submucosa. Our aim was to assess the formation of collagen in the colon versus the rectum with or without transforming growth factor (TGF)-ß1 exposure in a human cellular model of colorectal repair. Primary fibroblasts were isolated by an explant procedure from clinically resected tissue rings during anastomosis construction in 19 consecutive colorectal patients who underwent laparoscopy. The cells, identified as fibroblasts by morphologic characteristics and flow cytometry analysis (CD90+), were cultured for 8 days and in 12 patients in the presence of 1 ng/mL TGF-ß1. Total collagen deposition was measured colorimetrically after Sirius red staining of fixed cell layers, and type I, III, and VI collagen biosynthesis and degradation were specifically determined by the biomarkers PINP, PRO-C3, PRO-C6, and C3M in conditioned media by competitive enzyme-linked immunosorbent assays. Total collagen deposition by fibroblasts from the colon and rectum did not significantly differ. TGF-ß1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-ß1 treatment increased COL1A1 and ACTA2 (encoding α-smooth muscle actin), and decreased COL6A1 and MMP2 mRNA levels in colorectal fibroblasts. In conclusion, we found no effect of anatomic localization on collagen production by fibroblasts derived from the large intestine. TGF-ß1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.

Clinical value of serum hyaluronan and propeptide of type III collagen in patients with pancreatic cancer.

Hyaluronan (HA) and collagen are highly expressed in pancreatic cancer (PC) stroma. HA and collagen accumulation increase tumor interstitial fluid pressure, compromising blood flow and drug penetration. The aim of this biomarker study was to determine the clinical utility of serum HA and the propeptide of type III collagen (PRO-C3) in patients with PC. A cohort from the Danish BIOPAC study (NCT03311776) including patients with histologically confirmed pancreatic ductal adenocarcinoma (n = 809), ampullary carcinoma (n = 44), distal biliary tract cancer (n = 31), chronic pancreatitis (n = 15), intraductal papillary mucinous neoplasm (n = 41), duodenal adenoma (n = 7) and no cancer (n = 25). Healthy controls were available for serum HA (n = 141) and PRO-C3 (n = 8). The main outcome was overall survival (OS) of patients with PC in relation to pretreatment serum HA and PRO-C3 levels. Patients with PC had higher baseline serum HA and PRO-C3 than healthy subjects and patients with benign conditions. Pretreatment serum baseline HA and PRO-C3 in patients with PC were associated with poorer survival and PRO-C3 remained prognostic also after adjusting for age, performance status, stage, the presence of liver and peritoneum metastasis, and CA19-9. Detection of HA and PRO-C3 may be useful in differentiating between malignant and benign pancreatic conditions. Serum HA and PRO-C3 were prognostic for OS in patients with PC.

Multinutrient Supplementation Increases Collagen Synthesis during Early Wound Repair in a Randomized Controlled Trial in Patients with Inguinal Hernia.

BACKGROUND: Inguinal hernia disease is associated with an imbalanced collagen metabolism. Surgical stress has a negative impact on nutrients important for collagen synthesis. OBJECTIVE: We hypothesized that supplementation with a combination of nutrients would enhance collagen biosynthesis in inguinal hernia disease patients when undergoing hernia repair. METHODS: In this exploratory randomized controlled trial, 21 men (age: 55.2 ± 2.8 y; BMI: 25.0 ± 0.7 kg/m2) scheduled for Lichtenstein inguinal hernia repair were assigned to multinutrient supplementation (n = 10; multinutrient group) or no multinutrient supplementation (n = 11; control group). The multinutrient group received 14 g l-arginine, 14 g l-glutamine, 1250 mg vitamin C, and 55 mg zinc daily starting 14 d before surgery and ending 14 d after surgery. The multinutrient and control groups received high-quality protein to ensure a daily intake of 1.5 g protein/kg. Collagen biosynthesis was measured by the biomarkers type I procollagen propeptide (CICP), type III procollagen propeptide (PRO-C3), and type V procollagen propeptide (PRO-C5) in the sera on days -14, 0, and 1, and in the wound fluids on postoperative days 1 and 2. Compliance was recorded after the 28-d intervention period. RESULTS: Serum PRO-C5 concentrations decreased (P < 0.05) postoperatively in the control but not the multinutrient group. Neither CICP nor PRO-C3 serum concentrations differed significantly between the 2 groups. In wound fluid, the CICP concentrations increased (P < 0.05) from days 1 to 2 in the multinutrient group and were 49% higher (P = 0.10) than those in the control group on day 2. Wound fluid concentrations PRO-C3 and PRO-C5 showed no significant time or group differences. The 28-d compliance was similar (P = 0.27) in the 2 groups. CONCLUSION: Oral supplementation with arginine, glutamine, vitamin C, and zinc augment collagen synthesis during the first 2 d after inguinal hernia repair. This trial was registered at clinicaltrials.gov as NCT03221686.

High turnover of extracellular matrix reflected by specific protein fragments measured in serum is associated with poor outcomes in two metastatic breast cancer cohorts.

Increased extracellular matrix (ECM) formation and matrix metalloprotease (MMP)-mediated ECM degradation are parts of tumorgenesis and generates collagen fragments that are released into circulation. We evaluated the association of specific collagen fragments measured in serum with outcomes in two independent metastatic breast cancer (MBC) cohorts. ELISAs were used to measure C1M (MMP-generated type I collagen fragment), C3M (MMP-generated type III collagen fragment), C4M (MMP-generated type IV collagen fragment), and PRO-C3 (pro-peptide of type III collagen) in pretreatment serum from a phase 3 randomized clinical trial of second-line hormone therapy (HR+, n = 148), and a first-line trastuzumab-treated cohort (HER2+, n = 55). All sites of metastases were included. The collagen fragments were evaluated by Cox-regression analysis for their association with time-to-progression (TTP) and overall survival (OS). In the HR+ cohort, higher C1M and C3M levels (75th percentile cut-off) were associated with shorter TTP; all fragments were associated with shorter OS. In the HER2+ cohort, higher levels of all fragments were associated with shorter TTP; higher PRO-C3 was associated with shorter OS. In multivariate analysis of the HR+ trial for OS, higher levels of all fragments were significant for reduced OS when added separately (C1M HR = 2.1, p < 0.001; C3M HR = 1.8, p = 0.028; C4M HR = 1.8, p = 0.018; PRO-C3 HR = 1.8, p = 0.017); none other clinical covariates were significant. In conclusion, collagen fragments quantified in pretreatment serum was associated with shorter TTP and OS in two independent MBC cohorts receiving systemic therapy. If validated, quantification of ECM remodeling in serum has potential as prognostic and/or predictive biomarkers in MBC.

Quantification of altered tissue turnover in a liquid biopsy: a proposed precision medicine tool to assess chronic inflammation and desmoplasia associated with a pro-cancerous niche and response to immuno-therapeutic anti-tumor modalities.

Immuno-therapy has begun to revolutionize cancer treatment. However, despite the significant progress achieved in regard to the duration of clinical benefits, a substantial number of patients do not respond to these therapies. To improve the outcome of patients receiving immuno-therapy, there is a need for novel biomarkers that can predict and monitor treatment. Tumor microenvironment alterations, more specifically the state of chronic inflammation and desmoplasia (tumor fibrosis), are important factors to consider in this context. Here, we discuss the potential for quantification of altered tissue turnover in a liquid biopsy as a proposed precision medicine tool to assess chronic inflammation and desmoplasia in the immuno-oncology (IO) setting. We highlight the need for novel non-invasive biomarkers in IO and the importance of addressing tumor microenvironment alterations. We focus on desmoplasia and extracellular matrix (ECM) remodeling, and how the composition of the ECM defines T-cell permissiveness in the tumor microenvironment and opens up the possibility for associated liquid biopsy biomarkers. Moreover, we address the importance of the assessment of chronic inflammation, primarily macrophage activity, in a liquid biopsy.

Serological assessment of neutrophil elastase activity on elastin during lung ECM remodeling.

BACKGROUND: During the pathological destruction of lung tissue, neutrophil elastase (NE) degrades elastin, one of the major constituents of lung parenchyma. However there are no non-invasive methods to quantify NE degradation of elastin. We selected specific elastin fragments generated by NE for antibody generation and developed an ELISA assay (EL-NE) for the quantification of NE-degraded elastin. METHODS: Monoclonal antibodies were developed against 10 NE-specific cleavage sites on elastin. One EL-NE assay was tested for analyte stability, linearity and intra- and inter-assay variation. The NE specificity was demonstrated using elastin cleaved in vitro with matrix metalloproteinases (MMPs), cathepsin G (CatG), NE and intact elastin. Clinical relevance was assessed by measuring levels of NE-generated elastin fragments in serum of patients diagnosed with idiopathic pulmonary fibrosis (IPF, n = 10) or lung cancer (n = 40). RESULTS: Analyte recovery of EL-NE for human serum was between 85% and 104%, the analyte was stable for four freeze/thaw cycles and after 24 h storage at 4°C. EL-NE was specific for NE-degraded elastin. Levels of NE-generated elastin fragments for elastin incubated in the presence of NE were 900% to 4700% higher than those seen with CatG or MMP incubation or in intact elastin. Serum levels of NE-generated elastin fragments were significantly increased in patients with IPF (137%, p = 0.002) and in patients with lung cancer (510%, p < 0.001) compared with age- and sex-matched controls. CONCLUSIONS: The EL-NE assay was specific for NE-degraded elastin. The EL-NE assay was able to specifically quantify NE-degraded elastin in serum. Serum levels of NE-degraded elastin might be used to detect excessive lung tissue degradation in lung cancer and IPF.

Type IX Collagen Turnover Is Altered in Patients with Solid Tumors.

The fibrotic tumor microenvironment, characterized by its intricate extracellular matrix (ECM), consists of many collagens with diverse functions and unexplored biomarker potential. Type IX collagen is a member of the low-abundance collagen family known as the fibril-associated collagen with interrupted triple helices (FACITs) and is found mostly in cartilage. Its role in the tumor microenvironment remains unexplored. To investigate the biomarker potential of a type IX collagen in cancer, an immuno-assay was developed (PRO-C9) and technical assay performance was evaluated for the assessment of serum. PRO-C9 levels were measured in serum samples from 259 patients with various solid tumor types compared to serum levels from 73 healthy controls. PRO-C9 levels were significantly elevated in patients with solid tumors including bladder, breast, colorectal, gastric, head and neck, lung, melanoma, ovarian, pancreatic, and renal compared to levels in healthy controls (p < 0.05-p < 0.0001). PRO-C9 could discriminate between patients with cancer and healthy controls, with the area under the receiver operating characteristic values ranging from 0.58 to 0.86 (p < 0.3-p < 0.0001), indicating potential diagnostic utility. This study suggests that type IX collagen turnover is altered in patients with solid tumors and demonstrates the feasibility of using PRO-C9 as a non-invasive serum-based biomarker with relevance in multiple cancer types. Furthermore, these results underscore the potential utility of PRO-C9 to better elucidate the biology of FACITs in cancers.

Fibroblast Activation Protein (FAP)-Mediated Cleavage of Type III Collagen Reveals Serum Biomarker Potential in Non-Small Cell Lung Cancer and Spondyloarthritis.

Fibroblast activation protein (FAP) is a known promoter of tumor development and is associated with poor clinical outcome for various cancer types. Being specifically expressed in pathological conditions including multiple types of fibrosis and cancers, FAP is an optimal target for diagnostics and treatment. Treatment strategies utilizing the unique proteolytic activity of FAP are emerging, thus emphasizing the importance of biomarkers to directly assess FAP activity. FAP is a type II transmembrane serine protease that has been shown to cleave collagens and other ECM components. In this study, we developed an ELISA assay (C3F) targeting a circulating type III collagen fragment derived from FAP cleavage to reflect FAP activity. We demonstrated that C3F was specific to the neoepitope of the cleavage site and that the fragment was generated through FAP cleavage of type III collagen. We measured C3F in serum from a cohort of patients with non-small cell lung cancer (NSCLC) (n = 109) matched to healthy subjects (n = 42) and a cohort of patients with spondyloarthritis (SpA) (n = 17) matched to healthy subjects (n = 19). We found that C3F was significantly elevated in patients with NSCLC and in patients with SpA compared to healthy controls (p < 0.0001 and p = 0.0015, respectively). These findings suggest that C3F is a promising non-invasive biomarker reflecting FAP activity, which may aid in understanding tumor heterogeneity and potentially FAP-targeted therapies.

Extracellular matrix specific protein fingerprints measured in serum can separate pancreatic cancer patients from healthy controls.

BACKGROUND: Pancreatic cancer (PC) is an aggressive disease with an urgent need for biomarkers. Hallmarks of PC include increased collagen deposition (desmoplasia) and increased matrix metalloproteinase (MMP) activity. The aim of this study was to investigate whether protein fingerprints of specific MMP-generated collagen fragments differentiate PC patients from healthy controls when measured in serum. METHODS: The levels of biomarkers reflecting MMP-mediated degradation of type I (C1M), type III (C3M) and type IV (C4M, C4M12a1) collagen were assessed in serum samples from PC patients (n = 15) and healthy controls (n = 33) using well-characterized and validated competitive ELISAs. RESULTS: The MMP-generated collagen fragments were significantly elevated in serum from PC patients as compared to controls. The diagnostic power of C1M, C3M, C4M and C4M12 were ≥83% (p < 0.001) and when combining all biomarkers 99% (p < 0.0001). CONCLUSIONS: A panel of serum biomarkers reflecting altered MMP-mediated collagen turnover is able to differentiate PC patients from healthy controls. These markers may increase the understanding of mode of action of the disease and, if validated in larger clinical studies, provide an improved and additional tool in the PC setting.

Bringing cancer serological diagnosis to a new level: focusing on HER2, protein ectodomain shedding and neoepitope technology.

Cancer is a heterogeneous disease and consequently an exact diagnosis is as important as the actual therapy. Therefore, identification of novel diagnostic biomarker targets is urgently needed. Physiological and pathological changes are reflected by post-translational modifications of proteins. Each post-translational modification (e.g., proteolytic cleavage) is the result of a specific local process and may produce disease-specific neoepitopes. Neoepitopes have been successfully used as biomarkers in many diseases, and may also serve as promising tools in the development of future diagnostic assays within oncology. By specifically targeting neoepitopes, more information regarding disease-type and -state may be obtained and future research into neoepitopes will provide important and novel means for the diagnosis, prognosis and treatment efficacy in cancer. In this paper, we focus on protein ectodomain shedding and the generation of neoepitopes as future noninvasive (serological) cancer biomarkers. We use the protein ectodomain shedding of the human epidermal growth factor receptor 2, which is associated with breast cancer, as an example. We assess the current status of measuring human epidermal growth factor receptor 2 and discuss how this potentially could be improved. Furthermore, we expand the discussion to include examples of other cancer associated proteins.