The fibroblast activation protein alpha as a biomarker of pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a rare, chronic, and progressive interstitial lung disease with an average survival of approximately 3 years. The evolution of IPF is unpredictable, with some patients presenting a relatively stable condition with limited progression over time, whereas others deteriorate rapidly. In addition to IPF, other interstitial lung diseases can lead to pulmonary fibrosis, and up to a third have a progressive phenotype with the same prognosis as IPF. Clinical, biological, and radiological risk factors of progression were identified, but no specific biomarkers of fibrogenesis are currently available. A recent interest in the fibroblast activation protein alpha (FAPα) has emerged. FAPα is a transmembrane serine protease with extracellular activity. It can also be found in a soluble form, also named anti-plasmin cleaving enzyme (APCE). FAPα is specifically expressed by activated fibroblasts, and quinoline-based specific inhibitors (FAPI) were developed, allowing us to visualize its distribution in vivo by imaging techniques. In this review, we discuss the use of FAPα as a useful biomarker for the progression of lung fibrosis, by both its assessment in human fluids and/or its detection by imaging techniques and immunohistochemistry.

Tubular adenoma at the hepatico-jejunal anastomosis in familial adenomatous polyposis (FAP) following pancreaticoduodenectomy: challenges in adenoma surveillance and management.

Upper gastrointestinal tumors, including ampullary adenomas, occur frequently in patients with familial adenomatous polyposis (FAP). Guidelines recommend upper gastrointestinal endoscopy in FAP for surveillance of gastric and duodenal adenomas. However, adenomas can rarely arise from biliary epithelium in patients with FAP. Here, we describe a case of tubular adenoma at the hepatico-jejunal anastomosis with intraductal extension in a patient with FAP and previous pancreaticoduodenectomy. This report illustrates a unique case and emphasizes the need for data on postoperative surveillance in patients with FAP, particularly following pancreaticoduodenectomy.

Large-scale application of ClinGen-InSiGHT APC-specific ACMG/AMP variant classification criteria leads to substantial reduction in VUS.

Pathogenic constitutional APC variants underlie familial adenomatous polyposis, the most common hereditary gastrointestinal polyposis syndrome. To improve variant classification and resolve the interpretative challenges of variants of uncertain significance (VUSs), APC-specific variant classification criteria were developed by the ClinGen-InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP) based on the criteria of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP). A streamlined algorithm using the APC-specific criteria was developed and applied to assess all APC variants in ClinVar and the International Society for Gastrointestinal Hereditary Tumours (InSiGHT) international reference APC Leiden Open Variation Database (LOVD) variant database, which included a total of 10,228 unique APC variants. Among the ClinVar and LOVD variants with an initial classification of (likely) benign or (likely) pathogenic, 94% and 96% remained in their original categories, respectively. In contrast, 41% ClinVar and 61% LOVD VUSs were reclassified into clinically meaningful classes, the vast majority as (likely) benign. The total number of VUSs was reduced by 37%. In 24 out of 37 (65%) promising APC variants that remained VUS despite evidence for pathogenicity, a data-mining-driven work-up allowed their reclassification as (likely) pathogenic. These results demonstrated that the application of APC-specific criteria substantially reduced the number of VUSs in ClinVar and LOVD. The study also demonstrated the feasibility of a systematic approach to variant classification in large datasets, which might serve as a generalizable model for other gene- or disease-specific variant interpretation initiatives. It also allowed for the prioritization of VUSs that will benefit from in-depth evidence collection. This subset of APC variants was approved by the VCEP and made publicly available through ClinVar and LOVD for widespread clinical use.

Preclinical evaluation and first-in-human study of [18F]AlF-FAP-NUR for PET imaging cancer-associated fibroblasts.

BACKGROUND: Fibroblast activation protein (FAP) has gained attention as a promising molecular target with potential utility for cancer diagnosis and therapy. [68Ga]Ga-labeled FAP-targeting peptides have been successfully applied to positron emission tomography (PET) imaging of various tumor types. To meet the applicable demand for peptide-based FAP tracers with high patient throughput, we herein report the radiosynthesis, preclinical evaluation, and the first-in-human imaging of a novel [18F]F-labeled FAP-targeting peptide. RESULTS: [18F]AlF-FAP-NUR was automatedly prepared within 45 min with a non-decay corrected radiochemical yield of 18.73 ± 4.25% (n = 3). Compared to [68Ga]Ga-FAP-2286, the [18F]F-labeled peptide demonstrated more rapid, higher levels of cellular uptake and internalization, and lower levels of cellular efflux in HT1080-FAP cells. Micro-PET imaging and biodistribution studies conducted on xenograft mice models revealed a similar distribution pattern between the two tracers. However, [18F]AlF-FAP-NUR demonstrated significantly higher tumor-specific uptake resulting in improved Tumor-Background Ratios (TBRs). In the patients, a significant accumulation of [18F]AlF-FAP-NUR was found in the primary tumor. High uptake of the tracer within the bladder indicated that its major route of excretion was through urine. CONCLUSIONS: Based on the physical imaging properties and longer half-life of [18F]F, [18F]AlF-FAP-NUR exhibited promising characteristics such as enhanced tumor-specific accumulation and elevated TBRs, which made it a viable candidate for further clinical investigation. TRIAL REGISTRATION: www.Chictr.org.cn , ChiCTR2300076976 Retrospectively registered 25 October 2023. at, URL: https://www.chictr.org.cn/showproj.html?proj=206753 .

Optimizing the Therapeutic Index of sdAb-Based Radiopharmaceuticals Using Pretargeting.

Single-domain antibodies (sdAbs) demonstrate favorable pharmacokinetic profiles for molecular imaging applications. However, their renal excretion and retention are obstacles for applications in targeted radionuclide therapy (TRT). Methods: Using a click-chemistry-based pretargeting approach, we aimed to reduce kidney retention of a fibroblast activation protein α (FAP)-targeted sdAb, 4AH29, for 177Lu-TRT. Key pretargeting parameters (sdAb-injected mass and lag time) were optimized in healthy mice and U87MG (FAP+) xenografts. A TRT study in a pancreatic ductal adenocarcinoma (PDAC) patient-derived xenograft (PDX) model was performed as a pilot study for sdAb-based pretargeting applications. Results: Modification of 4AH29 with trans-cyclooctene (TCO) moieties did not modify the sdAb pharmacokinetic profile. A 200-µg injected mass of 4AH29-TCO and an 8-h lag time for the injection of [177Lu]Lu-DOTA-PEG7-tetrazine resulted in the highest kidney therapeutic index (2.0 ± 0.4), which was 5-fold higher than that of [177Lu]Lu-DOTA-4AH29 (0.4 ± 0.1). FAP expression in the tumor microenvironment was validated in a PDAC PDX model with both immunohistochemistry and PET/CT imaging. Mice treated with the pretargeting high-activity approach (4AH29-TCO + [177Lu]Lu-DOTA-PEG7-tetrazine; 3 × 88 MBq, 1 injection per week for 3 wk) demonstrated prolonged survival compared with the vehicle control and conventionally treated ([177Lu]Lu-DOTA-4AH29; 3 × 37 MBq, 1 injection per week for 3 wk) mice. Mesangial expansion was reported in 7 of 10 mice in the conventional cohort, suggesting treatment-related kidney morphologic changes, but was not observed in the pretargeting cohort. Conclusion: This study validates pretargeting to mitigate sdAbs' kidney retention with no observation of morphologic changes on therapy regimen at early time points. Clinical translation of click-chemistry-based pre-TRT is warranted on the basis of its ability to alleviate toxicities related to biovectors' intrinsic pharmacokinetic profiles. The absence of representative animal models with extensive stroma and high FAP expression on cancer-associated fibroblasts led to a low mean tumor-absorbed dose even with high injected activity and consequently to modest survival benefit in this PDAC PDX.

DAB2 + macrophages support FAP + fibroblasts in shaping tumor barrier and inducing poor clinical outcomes in liver cancer.

Background: Cancer-associated fibroblasts (CAFs) are the key components of the immune barrier in liver cancer. Therefore, gaining a deeper understanding of the heterogeneity and intercellular communication of CAFs holds utmost importance in boosting immunotherapy effectiveness and improving clinical outcomes. Methods: A comprehensive analysis by combing single-cell, bulk, and spatial transcriptome profiling with multiplexed immunofluorescence was conducted to unravel the complexities of CAFs in liver cancer. Results: Through an integrated approach involving 235 liver cancer scRNA-seq samples encompassing over 1.2 million cells, we found that CAFs were particularly increased in hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). FAP + fibroblasts were identified as the dominant subtype of CAFs, and which were mainly involved in extracellular matrix organization and angiogenesis. These CAFs were enriched in the tumor boundary of HCC, but diffusely scattered within ICC. The DAB2 + and SPP1 + tumor-associated macrophages (TAMs) reinforce the function of FAP + CAFs through signals such as TGF-ß, PDGF, and ADM. Notably, the interaction between DAB2 + TAMs and FAP + CAFs promoted the formation of immune barrier and correlated with poorer patient survival, non-response to immunotherapy in HCC. High FAP and DAB2 immunohistochemical scores predicted shorter survival and higher serum AFP concentration in a local clinical cohort of 90 HCC patients. Furthermore, this communication pattern might be applicable to other solid malignancies as well. Conclusions: The interaction between DAB2 + TAMs and FAP + CAFs appears crucial in shaping the immune barrier. Strategies aimed at disrupting this communication or inhibiting the functions of FAP + CAFs could potentially enhance immunotherapy effectiveness and improve clinical outcomes.

Enzymatic activity of fibroblast activation protein-α is essential for TGF-ß1-induced fibroblastic differentiation of human periodontal ligament cells.

Human periodontal ligament cells (hPDLCs) contain multipotent postnatal stem cells that can differentiate into PDL fibroblasts, osteoblasts, and cementoblasts. Interaction between the extracellular environment and stem cells is an important factor for differentiation into other progenitor cells. To identify cell surface molecules that induce PDL fibroblastic differentiation, we developed a series of monoclonal antibodies against membrane/ECM molecules. One of these antibodies, an anti-PDL25 antibody, recognizes approximately a 100 kDa protein, and this antigenic molecule accumulates in the periodontal ligament region of tooth roots. By mass spectrometric analysis, we found that the antigenic molecule recognized by the anti-PDL25 antibody is fibroblast activation protein α (FAPα). The expression level of FAPα/PDL25 increased in TGF-ß1-induced PDL fibroblasts, and this protein was localized in the cell boundaries and elongated processes of the fibroblastic cells. Ectopic expression of FAPα induced fibroblastic differentiation. In contrast, expression of representative markers for PDL differentiation was decreased by knock down and antibody blocking of FAPα/PDL25. Inhibition of dipeptidyl peptidase activity by a potent FAPα inhibitor dramatically inhibited PDL fibroblastic marker expression but did not affect in cell proliferation and migration.

Facial Artery Perforator Flap for Perioral and Perinasal Oncologic Defect Reconstruction: Surgical Technique and Postoperative Outcomes.

INTRODUCTION: Facial artery perforator (FAP) flap is a versatile and reliable one-step facial reconstruction technique. However, its full potential remains underutilized due to a lack of clear guidelines and rigorous technique requirements. This study report the use of FAP flaps in our centre for the management of perioral and nasal oncologic defects, focusing on surgical technique performed and post-operative management. METHODS: We conducted a retrospective review of all patients who underwent reconstruction with a perioral or perinasal FAP flap only following tumor resection over a 4-year period (n = 29). Parameters measured included flap survival, complication rates, surgical technique performed, and the need for touch-up procedures. Patients were grouped based on age, defect size, and location and outcomes were compared across these groups. RESULTS: The mean histological tumor defect area was 331 mm2. During at least 6 months of follow-up, no local recurrence was observed. Twenty-seven (93.1%) flaps survived completely. Major postsurgical complications occurred in seven (23.8%) patients, including complete flap necrosis (1), partial flap necrosis (1), flap collapse (1), venous congestion (1), wound dehiscence (1), and local infection (2). A higher complication rate was associated with nose tip defects (80.0% vs. 12.5%, p = 0.007). Touch-up procedures were more frequently required for reconstructions involving the nasal sidewall and dorsum (53.8% vs. 13.3%, p = 0.04). CONCLUSION: Based on our experience, the FAP flap is highly effective for the reconstruction of the upper lip, nasolabial fold, and certain oncologic nasal defects. However, specific defect locations, such as the nose tip, may be associated with higher complication rates, necessitating careful patient selection and surgical planning.

Evaluation of Fibroblast Activation Protein Expression Using 68Ga-FAPI46 PET in Hypertension-Induced Tissue Changes.

Chronic hypertension leads to injury and fibrosis in major organs. Fibroblast activation protein (FAP) is one of key molecules in tissue fibrosis, and 68Ga-labeled FAP inhibitor-46 (FAPI46) PET is a recently developed method for evaluating FAP. The aim of this study was to evaluate FAP expression and fibrosis in a hypertension model and to test the feasibility of 68Ga-FAPI46 PET in hypertension. Methods: Hypertension was induced in mice by angiotensin II infusion for 4 wk. 68Ga-FAPI46 biodistribution studies and PET scanning were conducted at 1, 2, and 4 wk after hypertension modeling, and uptake in the major organs was measured. The FAP expression and fibrosis formation of the heart and kidney tissues were analyzed and compared with 68Ga-FAPI46 uptake. Subgroups of the hypertension model underwent angiotensin receptor blocker administration and high-dose FAPI46 blocking, for comparison. As a preliminary human study, 68Ga-FAPI46 PET images of lung cancer patients were analyzed and compared between hypertension and control groups. Results: Uptake of 68Ga-FAPI46 in the heart and kidneys was significantly higher in the hypertension group than in the sham group as early as week 1 and decreased after week 2. The uptake was specifically blocked in the high-dose blocking study. Immunohistochemistry also revealed FAP expression in both heart and kidney tissues. However, overt fibrosis was observed in the heart, whereas it was absent from the kidneys. The angiotensin receptor blocker-treated group showed lower uptake in the heart and kidneys than did the hypertension group. In the pilot human study, renal uptake of 68Ga-FAPI46 significantly differed between the hypertension and control groups. Conclusion: In hypertension, FAP expression is increased in the heart and kidneys from the early phases and decreases over time. FAP expression appears to represent fibrosis activity preceding or underlying fibrotic tissue formation. 68Ga-FAPI46 PET has potential as an effective imaging method for evaluating FAP expression in progressive fibrosis by hypertension.

[68Ga]Ga-FAP-2286-Synthesis, Quality Control and Comparison with [18F]FDG PET/CT in a Patient with Suspected Cholangiocellular Carcinoma.

[68Ga]Ga-FAP-2286 is a new peptide-based radiopharmaceutical for positron-emission tomography (PET) that targets fibroblast activation protein (FAP). This article describes in detail the automated synthesis of [68Ga]Ga-FAP-2286 using a commercially available synthesis tool that includes quality control for routine clinical applications. The synthesis was performed using a Scintomics GRP-3V module and a GMP grade 68Ge/68Ga generator. A minor alteration for transferring the eluate to the module was established, eliminating the need for new method programming. Five batches of [68Ga]Ga-FAP-2286 were tested to validate the synthesis. A stability analysis was conducted up to 3 h after production to determine the shelf-life of the finished product. The automated synthesis on the Scintomics GRP-3V synthesis module was found to be compliant with all quality control requirements. The shelf-life of the product was set to 2 h post-production based on the stability study. A patient suffering from cholangiocellular carcinoma that could not be clearly detected by conventional imaging, including a [18F]FDG-PET/CT, highlights the potential use of [68Ga]Ga-FAP-PET/CT.

211At radiolabeled APBA-FAPI for enhanced targeted-alpha therapy of glioma.

Fibroblast activation protein-α (FAPα) is highly expressed in tumor-associated cells and has become one of the most attractive targeting sites in cancer diagnosis and therapy. To ameliorate the rapid metabolism of FAPα inhibitor (FAPI), here, a multifunctional binding agent was introduced to simultaneously achieve 211At radiolabeling and tumor retention prolongation of corresponding radiolabeled drug. 211At-APBA-FAPI was successfully synthesized by conjugating 211At with the designed FAPI carrier in satisfactory radiochemical yield (>60 %). 211At-APBA-FAPI exhibited excellent in vitro stability, significant tumor affinity and specific killing effect on FAPα-positive U87MG cells. Molecular docking reveals that FAPI decorated with albumin binder can bind with FAPα protein via multiple intermolecular interactions with a considerable binding energy of -9.66 kcal/mol 211At-APBA-FAPI exhibits good targeting in murine xenograft models, showing obviously longer tumor retention than previously-reported radioastatinated compound. As a result, 211At-APBA-FAPI presents pronounced therapeutic effect with ignorable normal organs/tissues biotoxicity. All these indicate that introducing a multifunctional binding agent can effectively enhance the availability of FAPI for 211At conjugation and tumoricidal effect, providing vital hints for the translation of targeted-alpha therapy based on radiolabeled FAPI derivatives.

The comparative utility of FAPI-based PET radiotracers over [18F]FDG in the assessment of malignancies.

Fibroblast activation protein (FAP) is a type II transmembrane serine protease overexpressed in cancer-associated fibroblasts (CAFs) and has been associated with poor prognosis. PET/CT imaging with radiolabeled FAP inhibitors (FAPI) is currently being studied for various malignancies. This review identifies the uses and limitations of FAPI PET/CT in malignancies and compares the advantages and disadvantages of FAPI and 18F-fluorodeoxyglucose ([18F]FDG). Due to high uptake, rapid clearance from the circulation, and limited uptake in normal tissue, FAPI tumor-to-background contrast ratios are equivalent to or better than [18F]FDG in most applications. In several settings, FAPI has shown greater uptake specificity than [18F]FDG and improved sensitivity in detecting lymph node, bone, and visceral tissue metastases. Therefore, FAPI PET/CT may be complementary in distinguishing pathological lesions with conventional imaging, determining the primary site of malignancy, improving tumor staging, and detecting disease recurrence, especially in patients with inconclusive [18F]FDG PET/CT findings. Nevertheless, FAPI has limitations, including certain settings with non-specific uptake, modified uptake with age and menopause status, challenges with clinical access, and limited clinical evidence.

Developmental regulation of dermal adipose tissue by BCL11b.

The distinct anatomic environment in which adipose tissues arise during organogenesis is a principle determinant of their adult expansion capacity. Metabolic disease results from a deficiency in hyperplastic adipose expansion within the dermal/subcutaneous depot; thus, understanding the embryonic origins of dermal adipose is imperative. Using single-cell transcriptomics throughout murine embryogenesis, we characterized cell populations, including Bcl11b + cells, that regulate the development of dermal white adipose tissue (dWAT). We discovered that BCL11b expression modulates the Wnt signaling microenvironment to enable adipogenic differentiation in the dermal compartment. Subcutaneous and visceral adipose arises from a distinct population of Nefl + cells during embryonic organogenesis, whereas Pi16 + /Dpp4 + fibroadipogenic progenitors support obesity-stimulated hypertrophic expansion in the adult. Together, these results highlight the unique regulatory pathways used by anatomically distinct adipose depots, with important implications for human metabolic disease.

BrfA functions as a bacterial enhancer-binding protein to regulate functional amyloid Fap-dependent biofilm formation in Pseudomonas fluorescens by sensing cyclic diguanosine monophosphate.

The functional amyloid of Pseudomonas (Fap) is essential for the formation of macrocolony biofilms, pellicles, and solid surface-associated (SSA) biofilms of Pseudomonas fluorescens PF07, an isolate from refrigerated marine fish. However, limited information on the expression regulation of fap genes is available. Herein, we found that a novel bacterial enhancer-binding protein (bEBP), BrfA, regulated Fap-dependent biofilm formation by directly sensing cyclic diguanosine monophosphate (c-di-GMP). Our in vivo data showed that the REC domain deletion of BrfA promoted fap gene expression and biofilm formation, and c-di-GMP positively regulated the transcription of fapA in a BrfA-dependent manner. In in vitro experiments, we found that the ATPase activity of BrfA was inhibited by the REC domain and was activated by c-di-GMP. BrfA and the sigma factor RpoN bound to the upstream region of fapA, and the binding ability of BrfA was not affected by either deletion of the REC domain or c-di-GMP. BrfA specifically bound to the three enhancer sites upstream of the fapA promoter, which contain the consensus sequence CA-(N4)-TGA(A/T)ACACC. In vivo experiments using a lacZ fusion reporter indicated that all three BrfA enhancer sites were essential for the activation of fapA transcription. Overall, these findings reveal that BrfA is a new type of c-di-GMP-responsive transcription factor that directly controls the transcription of Fap biosynthesis genes in P. fluorescens. Fap functional amyloids and BrfA-type transcription factors are widespread in Pseudomonas species. The novel insights into the c-di-GMP- and BrfA-dependent expression regulation of fap provided by this work will contribute to the development of antibiofilm strategies.

FAP-Targeted Nanoparticle-based Imaging in Cancer: A Systematic Review.

Background: Fibroblast Activation Protein (FAP)-targeted nanoparticles (NPs) are designed to accumulate in cancerous stroma. These NPs hold promise for imaging applications in cancer therapy. Objective: This systematic review aimed to comprehensively explore the use of FAP-targeting NPs for cancer diagnosis through different imaging modalities. Material and Methods: This systematic review followed the framework proposed by O'Malley and Arksey. Peer-reviewed studies were searched in the Scopus, Science Direct, PubMed, and Google Scholar databases. Eligible studies were selected, and data were extracted to investigate the FAP-targeting NPs in imaging. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was also utilized to present the results. Results: Five studies met the specified inclusion criteria and were finally selected for analysis. The extracted data was classified into two categories: general and specific data. The general group indicated that most studies have been conducted in Mexico and have increased since 2022, and the specific group showed that colorectal cancer and Nude mice have received the most research attention. Furthermore, FAP-targeted NPs have demonstrated superior diagnostic imaging capabilities, even compared to specific methods for each cancer type. Also, they have been safe, with no toxicity. Conclusion: FAP-targeted NPs using different ligands, such as Fibroblast Activation Protein Inhibitor (FAPI), can accurately detect tumors and metastases, and outperform specific cancer peptides like PSMA in cancer diagnosis. They are also non-toxic and do not cause radiation damage to tissues. Therefore, FAP-targeted NPs have the potential to serve as a viable alternative to FAP-targeted radionuclides for cancer diagnosis.

Fibroblast activation protein constitutes a novel target of chimeric antigen receptor T-cell therapy in solid tumors.

With recent advances in tumor immunotherapy, chimeric antigen receptor T (CAR-T) cell therapy has achieved unprecedented success in several hematologic tumors, significantly improving patient prognosis. However, in solid tumors, the efficacy of CAR-T cell therapy is limited because of high antigen uncertainty and the extremely restrictive tumor microenvironment (TME). This challenge has led to the exploration of new targets, among which fibroblast activation protein (FAP) has gained attention for its relatively stable and specific expression in the TME of various solid tumors, making it a potential new target for CAR-T cell therapy. This study comprehensively analyzed the biological characteristics of FAP and discussed its potential application in CAR-T cell therapy, including the theoretical basis, and preclinical and clinical research progress of targeting FAP with CAR-T cell therapy for solid tumor treatment. The challenges and future optimization directions of this treatment strategy were also explored, providing new perspectives and strategies for CAR-T cell therapy in solid tumors.

Comparison of 68Ga-FAP-2286 and 18F-FDG PET/CT in the diagnosis of advanced lung cancer.

Purpose: The 68Ga/177Lu-FAP-2286 is a newly developed tumor imaging agent that shows potential for visualizing and treating tumor stroma. The objective of this research was to evaluate the effectiveness of 68Ga-FAP-2286 PET/CT and 18F-FDG PET/CT in diagnosing advanced lung cancer. Methods: In this prospective study, patients with lung cancer who underwent 68Ga-FAP-2286 and 18F-FDG PET/CT examinations between September 2022 and June 2023 were analyzed. Lesion uptake was converted to SUVmax. A paired T-test was used to compare the SUVmax, and the number of positive lesions detected by the two methods was recorded. Results: In total, 31 participants (median age: 56 years) were assessed. The uptake of 68Ga-FAP-2286 was significantly higher than that of 18F-FDG in primary lesions (9.90 ± 5.61 vs. 6.09 ± 2.84, respectively, P < 0.001), lymph nodes (7.95 ± 2.75 vs. 5.55 ± 1.59, respectively, P=0.01), and bone metastases (7.74 ± 3.72 vs. 5.66 ± 3.55, respectively, P=0.04). Furthermore, the detection sensitivity of lymph nodes using 68Ga-FAP-2286 PET/CT was superior to that with 18F-FDG PET/CT [100% (137/137) vs. 78.8% (108/137), respectively], as well as for bone metastases [100% (384/384) vs. 68.5% (263/384), respectively]. However, the detection sensitivity for primary tumors using both modalities was comparable [100% (13/13) for both]. Conclusion: Compared to 18F-FDG PET/CT, 68Ga-FAP-2286 PET/CT demonstrated better lesion detection capabilities for lung cancer, particularly in lymph nodes and bone metastases, providing compelling imaging evidence for the efficacy of 177Lu-FAP-2286 treatment.

Investigating the effect of Fusobacterium nucleatum on the aggressive behavior of cancer-associated fibroblasts in colorectal cancer.

Fusobacterium nucleatum, (F. nucleatum) as a known factor in inducing oncogenic, invasive, and inflammatory responses, can lead to an increase in the incidence and progression of colorectal cancer (CRC). Cancer-associated fibroblasts (CAF) are also one of the key components of the tumor microenvironment (TME), which lead to resistance to treatment, metastasis, and disease recurrence with their markers, secretions, and functions. This study aimed to investigate the effect of F. nucleatum on the invasive phenotype and function of fibroblast cells isolated from normal and cancerous colorectal tissue. F. nucleatum bacteria were isolated from deep periodontal pockets and confirmed by various tests. CAF cells from tumor tissue and normal fibroblasts (NF) from a distance of 10 cm of tumor tissue were isolated from 5 patients by the explant method and were exposed to secretions and ghosts of F. nucleatum. The expression level of two markers, fibroblast activation protein (FAP), and α-smooth muscle actin (α-SMA), and the amount of production of two cytokines TGF-ß and IL-6 from fibroblast cells were measured by flow cytometry and ELISA test, respectively before and after exposure to different bacterial components. The expression of the FAP marker was significantly higher in CAF cells compared to NF cells (P < 0.05). Also, the expression of IL-6 in CAF cells was higher than that of NF cells. In investigating the effect of bacterial components on the function of fibroblastic cells, after comparing the amount of IL-6 produced between the normal tissue of each patient and his tumoral tissue under 4 treated conditions, it was found that the amount of IL-6 production from the CAF cells of patients in the control group, treated with heat-killed ghosts and treated with paraformaldehyde-fixed ghosts had a significant increase compared to NF cells (P < 0.05). Due to the significant increase in FAP marker expression in fibroblast cells of tumor tissue compared to normal tissue, it seems that FAP can be used as a very good therapeutic marker, especially in patients with high levels of CAF cells. Various components of F. nucleatum could affect fibroblast cells differentially and at least part of the effect of this bacterium in the TME is mediated by CAF cells.

In vitro and in vivo analyses of eFAP: a novel FAP-targeting small molecule for radionuclide theranostics and other oncological interventions.

BACKGROUND: Fibroblast activation protein (FAP), a transmembrane serine protease overexpressed by cancer-associated fibroblasts in the tumor stroma, is an interesting biomarker for targeted radionuclide theranostics. FAP-targeting radiotracers have demonstrated to be superior to [18F]FDG PET/CT in various solid cancers. However, these radiotracers have suboptimal tumor retention for targeted radionuclide therapy (TRT). We aimed to develop a novel FAP-targeting pharmacophore with improved pharmacokinetics by introducing a substitution at the 8-position of (4-quinolinoyl)-glycyl-2-cyanopyrrolidine, which allows for conjugation of a chelator, dye, or other payloads. RESULTS: Here we showed the synthesis of DOTA-conjugated eFAP-6 and sulfo-Cyanine5-conjugated eFAP-7. After chemical characterization, the uptake and specificity of both tracers were determined on FAP-expressing cells. In vitro, [111In]In-eFAP-6 demonstrated a superior affinity and a more rapid, although slightly lower, peak uptake than gold standard [111In]In-FAPI-46. Confocal microscopy demonstrated a quick FAP-mediated internalization of eFAP-7. Studies with HT1080-huFAP xenografted mice confirmed a more rapid uptake of [177Lu]Lu-eFAP-6 vs. [177Lu]Lu-FAPI-46. However, tumor retention at 24 h post injection of [177Lu]Lu-eFAP-6 was lower than that of [177Lu]Lu-FAPI-46, hereby currently limiting its use for TRT. CONCLUSION: The superior affinity and faster tumor accumulation of eFAP-6 over FAPI-46 makes it a suitable compound for radionuclide imaging. After further optimization, the eFAP series has great potential for various oncological interventions, including fluorescent-guided surgery and effective targeted radionuclide theranostics.