IntroductionThe incidence of tumour-positive surgical resection margins (TPRMs) after breast-conserving surgery (BCS) remains high, ranging from 10 to 40%. A TPRM, defined as breast cancer cells at the edge of the resected specimen at pathological evaluation, implies residual tumour and necessitates re-resection or boost radiation. To prevent these additional treatments, intraoperative near-infrared (NIR) fluorescence imaging with the topically applied, fluorescently quenched, cathepsin-activatable imaging agent AKRO-6qcICG might be used to detect residual cancer in the surgical cavity and guide additional resection during BCS. Cathepsins are proteolytic enzymes that are upregulated by breast cancer (associated) cells and therefore are suitable targets for tumour imaging. Ex vivo validation studies have shown that topically applied AKRO-6qcICG allows for clear breast cancer visualization and the detection of TPRMs. The proposed phase I/II study in healthy volunteers and breast cancer patients will assess the local and systemic safety of a single, topical dose of AKRO-6qcICG and its feasibility for intraoperative margin assessment during BCS.Methods and analysisA total of six healthy volunteers (Part A) and 16 breast cancer patients (Part B) will be enrolled. In Part A, AKRO-6qcICG will be topically applied randomly on drawn blisters in two doses as will the vehicle compound, and one blister will be untreated functioning as a negative control. Physician and subject will remain blinded. In Part B, a single dose of AKRO-6qcICG will be topically applied in the surgical cavity. The primary objective is, with the occurrence of treatment-emergent (serious) adverse events as primary outcome measure. Secondary outcome measures include local and systemic tolerability parameters such as wound healing, numeric rating scales of pain and pruritus, vital signs, electrocardiogram parameters, clinical laboratory tests and pharmacokinetic parameters. Among the exploratory outcome measures are the diagnostic accuracy of the imaging agent to detect residual tumour in the surgical cavity and the tumour-to-background ratio of the fluorescent signal.Ethics and disseminationThis protocol has been approved by the Medical Ethical Committee Leiden-Den Haag- Delft (METC- LDD). The protocol is registered at EU Clinical Trials Register number 2025-523166-24-00. The results of this study will be reported through peer- reviewed publications and conference presentations.Clinical Trial Registrationhttps://ctis.eu/trial/2025-523166-24-00?from=search

The localization of prostate cancer by ultrasound remains limited by the lack of B-mode conspicuity and the confinement of clinically approved microbubbles (MBs) to the vasculature. This precludes differentiating viable tumor, necrotic tissue, and margin-associated disease. We investigated prostate-specific membrane antigen (PSMA)-targeted lipid-shelled perfluorocarbon nanobubbles (PSMA-NBs) in an orthotopic rabbit model using a clinical contrast-enhanced ultrasound (CEUS) system. We implanted PSMA-positive PC3pip-GFP tumors into the prostates of immunosuppressed New Zealand White rabbits and performed transabdominal imaging with PSMA-NBs, MBs, and Plain-NBs using identical protocols. To address tumor heterogeneity and ultrasound boundary ambiguity, regions of interest were defined from baseline B-mode images and segmented into the tumor core, rim, and a peritumoral area. Pixel-wise parametric and decorrelation time (DT) maps were generated and compared with whole-slide histology (H&E) and, in an exploratory and non-specific analysis, with PSMA IHC. Compared to MBs at the doses used, PSMA-NBs exhibited higher peak intensities in the tumor core and rim (1.60-fold and 1.50-fold, respectively) and improved retention (mean transit time [MTT]: 4.20 to 5.40-fold higher) for up to 10 min in the tumor and peritumoral areas. In an exploratory analysis constrained by cohort size, PSMA-NB kinetics, notably MTT, tracked histology-defined tumor viability, and DT mapping showed spatially heterogeneous retention at the tumor periphery. Compared to Plain-NBs, PSMA-NBs also exhibited improved retention (MTT +21% overall) in the rim and peritumoral areas. This study demonstrates the potential of PSMA-NBs to characterize prostate cancer by molecularly targeted CEUS beyond that achieved with MBs at the doses used.

Indocyanine green (ICG) is the only FDA-approved near-infrared cyanine dye and is widely used in clinical imaging, yet its fluorescence response to physiological environments remains insufficiently understood. Here, we systematically examine how water content, viscosity, and polarity individually influence the absorption, emission, and fluorescence quantum yield (FQY) of ICG. Increasing water content promotes H-aggregation and decreases FQY, while isotope substitution (H2O -> D2O, MeOH -> MeOD) reveals that solvent-mediated vibrational quenching is a major nonradiative pathway. Viscosity-controlled methanol:glycerol mixtures isolate the role of conformational flexibility and show that restricting molecular motion enhances FQY. Across a broad polarity range, ICG displays spectral shifts and a bell-shaped FQY dependence, with maximum FQY at intermediate polarity due to polarity-driven electronic stabilization and modulation of molecular rigidity. Comparison with cellular measurements suggests that intracellular ICG resides in environments that are not fully aqueous and have intermediate polarity and restricted mobility. These results provide a mechanistic basis for interpreting ICG fluorescence in complex biological systems and guiding cyanine dye optimization.

Despite advancements made in treatment options, cancer continues to be one of the leading causes of death worldwide. Photodynamic therapy (PDT) has gained attention as a minimally invasive and highly selective treatment option for cancer. However, challenges due to the hydrophobicity of photosensitizers and their poor tumor selectivity have limited their use in cancer therapy. Recent developments in nanotechnology, particularly the use of gold nanoparticles (AuNPs), help overcome these challenges. AuNPs provide a stable and biocompatible platform to deliver photosensitizers, improving their solubility, stability, and ability to target tumors while reducing side effects. Functionalized AuNPs take advantage of mechanisms like the enhanced permeability and retention (EPR) effect and active targeting, improving reactive oxygen species (ROS) production and overall therapeutic efficacy. This review explores innovations in AuNP-based PDT systems, including ligand-functionalized nanoparticles, bioresponsive coatings, and theranostic approaches that combine imaging with therapy. By delving into important aspects of synthesis, characterization, and functionalization, we show how AuNPs improve the delivery and performance of photosensitizers. For instance, systems functionalized with prostate-specific membrane antigen (PSMA) have shown increased therapeutic precision and efficacy in vivo. These advancements are paving the way for more targeted and safer cancer treatments, establishing AuNP-based PDT as a promising approach for developing highly effective oncological therapies with greater precision and fewer side effects.

Purpose To evaluate the use of prostate-specific membrane antigen-targeted nanobubbles (PSMA-NBs) for contrast-enhanced ultrasound (CEUS) in a rabbit model, aiming to enhance prostate cancer imaging and guide clinical translation. Materials and Methods PSMA-NBs were formulated using lipid encapsulation and PSMA-targeting ligands. Human PSMA-positive PC3pip-GFP cells were injected into the prostates of immunosuppressed rabbits to establish tumors. Tumor growth was monitored via B-mode ultrasound (US) and MRI. CEUS was conducted with PSMA-NBs and commercial microbubbles (MBs). Time-intensity curve (TIC) analysis, parametric mapping, and post-mortem histological correlation were performed. Results PSMA-NBs demonstrated 1.60-fold (p = 0.013) and 1.50-fold (p = 0.016) higher peak signal intensities in the tumor core and rim, respectively, compared to MBs, with significantly longer mean transit times (MTTs) in the core (4.20-fold; p = 0.001) and rim (4.50-fold; p < 0.001). At 10 minutes, PSMA-NBs retained detectable signals in tumor rim (7.0 ± 3.0 a.u.), core (3.0 ± 1.0 a.u.), and surrounding tissues (12.0 ± 5.0 a.u.), unlike MBs. Larger tumors showed prolonged MTTs in the rim (3.70 ± 0.50 min) and surrounding tissues (4.60 ± 0.50 min) compared to the core (2.10 ± 0.40 min, p < 0.001). TIC parameters (MTT, AUCwo) correlated with tumor viability, emphasizing PSMA-NBs’ ability to delineate viable regions. Conclusion PSMA-NBs significantly enhanced prostate cancer imaging, correlating with tumor viability and outperforming MBs. These findings support their potential to improve diagnostic precision and guide targeted therapy in prostate cancer. ### Competing Interest Statement A. Exner is a founding member of Visano Theranostics. The authors report no additional affiliations or financial interests with any entities that could be perceived as having a financial stake or conflict related to the subject matter discussed in this manuscript, beyond those already disclosed. Wallace H. Coulter Foundation, https://ror.org/04cmszv87 National Institutes of Health, R01-EB025741, T32GM007250, F30HL160111 Hospital Israelita Albert Einstein, https://ror.org/04cwrbc27

BACKGROUND:Dogs spontaneously develop prostate carcinoma (PC) and share prostate gland anatomy, physiology, and size to men. Over the last 15 years, we have developed and refined a canine model of focal PC to evaluate therapeutic-diagnostic (theranostic) interventions. A comprehensive description of the pathology and synthesis of the various studies has not been performed. The goal of this manuscript was to describe the canine model tumor pathology within the framework of its methodological development to help guide future translational PC research. METHODS:In published and unpublished studies, we previously inoculated prostate glands of immunosuppressed, intact beagle dogs (n = 56) with a canine PC cell line (Ace-1) transduced with human or canine genes for targeted theranostics. Gross tumor assessment and histology were performed in all cases. Molecular tumor and microenvironmental pathology was investigated using digital image analysis, immunohistochemistry, laser-capture microdissection, and quantitative real-time PCR. RESULTS:The model reliably (85.7% engraftment rate) formed prostatic tumors resembling intermediate and high-grade localized PC, with poorly differentiated morphology, stromal invasion, and peripheral growth. Soft tissue metastasis occurred in 13/48 (27.1%) dogs. Most dogs formed multifocal prostatic tumors with occasional tumors outside the prostate gland. Tumor location influenced growth behavior and the microenvironment. Allografts were histologically classified as intraglandular intraprostatic, invasive intraprostatic, capsular, or extraprostatic. Compared to intraprostatic tumors, capsular/extraprostatic tumors had increased proliferation (Ki-67 index), epithelial-to-mesenchymal transition, and microenvironmental alterations that included increased collagenous stroma, fibroplasia, and reduced immune cell infiltration. CONCLUSIONS:The canine model of PC captured important pathologic features of men undergoing curative-intent therapy alongside model- and species-specific characteristics of interest to researchers. Beyond defining pathology, the results highlighted applications of the canine model in studying the tumor microenvironment and advancing preclinical, anti-cancer strategies in a large animal species.

While PSMA-targeted radioligand therapy (RLT) has shown remarkable efficacy for treating end-stage prostate cancer, the α-emitting RLT often results in severe salivary gland toxicity, limiting its use. Various strategies to mitigate this side effect have been attempted with limited success. Accordingly, this study introduced a new PSMA-targeting ligand with more favorable binding characteristics than the existing ligands. The binding affinity of PSMA-1-DOTA to PSMA was compared with that of PSMA-11 and PSMA I T. Comparison of uptake in the salivary glands, kidneys and PC3pip tumor cells in the xenograft mouse models between [68 Ga]Ga-PSMA-1-DOTA, [68 Ga]Ga-PSMA-11 and [68 Ga]Ga-PSMA I T was conducted with microPET/CT within the same week. The same mouse models were treated with [177Lu]Lu-PSMA-1-DOTA or [177Lu]Lu-PSMA-617. A compassionate use PET imaging study on a patient with metastatic castration-resistant prostate cancer was performed using [68 Ga]Ga-PSMA-1-DOTA. The binding affinity of PSMA-1-DOTA to PSMA was found to be approximately four times greater than other PSMA-targeted ligands. Imaging with microPET/CT revealed significantly lower kidney, uptake and little salivary and lacrimal gland uptake with [68 Ga]Ga-PSMA-1-DOTA compared to other PSMA-radioligands. Preclinical efficacy studies demonstrated that [177Lu]Lu-PSMA-1-DOTA inhibited tumor growth comparable to that with [177Lu]Lu-PSMA-617, suggesting its potential to enhance the therapeutic window of targeted RLT by avoiding damage to the salivary glands. The compassionate use PET imaging confirmed the reduced salivary gland uptake of [68 Ga]Ga-PSMA-1-DOTA in the patient, indicating its potential utility as a targeting agent for RLT with α- or β-emitting radionuclides in patients with PSMA-positive prostate cancer. PSMA-1-DOTA shows reduced uptake in salivary glands while effectively targeting PSMA-expressing tumors, thus potentially avoiding the side effects of xerostomia, and possibly moving PSMA-targeted RLT to a more frontline therapy for prostate cancer rather than the current use as a last resort.

Background: Prostate specific membrane antigen (PSMA)-targeted radioligand therapies represent a highly effective treatment for metastatic prostate cancer. However, high and sustain uptake of PSMA-ligands in the salivary glands led to dose limiting dry mouth (xerostomia), especially with α-emitters. The expression of PSMA and histologic analysis couldn't directly explain the toxicity, suggesting a potential off-target mediator for uptake. In this study, we searched for possible off-target non-PSMA protein(s) in the salivary glands. Methods: A machine-learning based quantitative structure activity relationship (QSAR) model was built for seeking the possible off-target(s). The resulting target candidates from the model prediction were subjected to further analysis for salivary protein expression and structural homology at key regions required for PSMA-ligand binding. Furthermore, cellular binding assays were performed utilizing multiple cell lines with high expression of the candidate proteins and low expression of PSMA. Finally, PSMA knockout (PSMA-/-) mice were scanned by small animal PET/MR using [68Ga]Ga-PSMA-11 for in-vivo validation. Results: The screening of the trained QSAR model did not yield a solid off-target protein, which was corroborated in part by cellular binding assays. Imaging using PSMA-/- mice further demonstrated markedly reduced PSMA-radioligand uptake in the salivary glands. Conclusion: Uptake of the PSMA-targeted radioligands in the salivary glands remains primarily PSMA-mediated. Further investigations are needed to illustrate a seemingly different process of uptake and retention in the salivary glands than that in prostate cancer.

AbstractProstatectomy has been the mainstay treatment for men with localized prostate cancer. Surgery, however, often can result in major side effects, which are caused from damage and removal of nerves and muscles surrounding the prostate. A technology that can help surgeons more precisely identify and remove prostate cancer resulting in a more complete prostatectomy is needed. Prostate-specific membrane antigen (PSMA), a type II membrane antigen highly expressed in prostate cancer, has been an attractive target for imaging and therapy. The objective of this study is to develop low molecular weight PSMA-targeted photodynamic therapy (PDT) agents, which would provide image guidance for prostate tumor resection and allow for subsequent PDT to eliminate unresectable or remaining cancer cells. On the basis of our highly negatively charged, urea-based PSMA ligand PSMA-1, we synthesized two PSMA-targeting PDT conjugates named PSMA-1-Pc413 and PSMA-1-IR700. In in vitro cellular uptake experiments and in vivo animal imaging experiments, the two conjugates demonstrated selective and specific uptake in PSMA-positive PC3pip cells/tumors, but not in PSMA-negative PC3flu cells/tumors. Further in vivo photodynamic treatment proved that the two PSMA-1–PDT conjugates can effectively inhibit PC3pip tumor progression. The two PSMA-1–PDT conjugates reported here may have the potential to aid in the detection and resection of prostate cancers. It may also allow for the identification of unresectable cancer tissue and PDT ablation of such tissue after surgical resection with potentially less damage to surrounding tissues. Mol Cancer Ther; 15(8); 1834–44. ©2016 AACR.

Atomically precise gold nanoclusters (AuNCs) exhibit unique physical and optical properties, making them highly promising for targeted cancer therapy. Their small size enhances cellular uptake, facilitates rapid distribution to tumor tissues, and minimizes accumulation in non-target organs compared to larger gold nanoparticles. AuNCs, particularly Au25, show significant potential in phototherapy, including photothermal (PTT), photodynamic (PDT), and radiation therapies. These therapies benefit with minimal damage to surrounding healthy tissue. AuNCs also demonstrate excellent stability and biocompatibility, crucial for their effective use in clinical applications. Recent advances in the synthesis and functionalization of AuNCs have further improved their therapeutic efficacy, making them versatile agents for enhancing cancer treatment outcomes. Ongoing research aims to better understand their pharmacokinetics, biodistribution, and long-term safety, paving the way for their broader application in advanced cancer therapies.

Lipid-shelled nanobubbles (NBs) can be visualized and activated using noninvasive ultrasound (US) stimulation, leading to significant bioeffects. Prior work demonstrates that active targeting of NBs to prostate-specific membrane antigen (PSMA) overexpressed in prostate cancer (PCa) results in enhanced cellular internalization and prolongs NB retention with persistent, cancer-cell specific acoustic activity. In this work, we hypothesized that tumor-accumulated PSMA-NBs combined with low frequency unfocused therapeutic US (TUS) will lead to selective damage and induce a specific therapeutic effect in PSMA-expressing tumors compared to PSMA-negative tumors. We observed that the internalized NBs and cellular compartments were disrupted after the PSMA-NB + TUS (targeted NB therapy or TNT) application, yet treated cells remained intact and viable. In vivo, PSMA-expressing tumors in mice receiving TNT treatment demonstrated a significantly greater extent of apoptosis (78.4 ± 9.3%, p<0.01) compared to controls. TNT treatment significantly inhibited the PSMA expressing tumor growth and increased median survival time by 103%, p<0.001). A significant reduction in tumor progression compared to untreated control was also seen in an orthotopic rabbit PCa model. Results demonstrate that cavitation of PSMA-NBs internalized via receptor-mediated endocytosis into target PCa cells using unfocused ultrasound results in significant, tumor-specific bioeffects. The effects, while not lethal to PSMA-expressing cancer cells in vitro, result in significant in vivo reduction in tumor progression in two models of PCa. While the mechanism of action of these effects is yet unclear, it is likely related to a locally-induced immune response, opening the door to future investigations in this area.

Purpose Prostate specific membrane antigen (PSMA) has been studied in human breast cancer (BCa) biopsies, however, lack of data on PSMA expression in mouse models impedes development of PSMA-targeted therapies, particularly in improving breast conserving surgery (BCS) margins. This study aimed to validate and characterize the expression of PSMA in murine BCa models, demonstrating that PSMA can be utilized to improve therapies and imaging techniques.Methods Murine triple negative breast cancer 4T1 cells, and human cell lines, MDA-MB-231, MDA-MB-468, implanted into the mammary fat pads of BALB/c mice, were imaged by our PSMA targeted theranostic agent, PSMA-1-Pc413, and tumor to background ratios (TBR) were calculated to validate selective uptake. Immunohistochemistry was used to correlate PSMA expression in relation to CD31, an endothelial cell biomarker highlighting neovasculature. PSMA expression was also quantified by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR).Results Accumulation of PSMA-1-Pc413 was observed in 4T1 primary tumors and associated metastases. Average TBR of 4T1 tumors were calculated to be greater than 1.5-ratio at which tumor tissues can be distinguished from normal structures-at peak accumulation with the signal intensity in 4T1 tumors comparable to that in high PSMA expressing PC3-pip tumors. Extraction of 4T1 tumors and lung metastases followed by RT-PCR analysis and PSMA-CD31 co-staining shows that PSMA is consistently localized on tumor neovasculature with no expression in tumor cells and surrounding normal tissues.Conclusion The selective uptake of PSMA-1-Pc413 in these cancer tissues as well as the characterization and validation of PSMA expression on neovasculature in this syngeneic 4T1 model emphasizes their potential for advancements in targeted therapies and imaging techniques for BCa. PSMA holds great promise as an oncogenic target for BCa and its associated metastases.

PSMA-Targeted Nanobubbles (PSMA-NB) are a promising clinical tool for increasing the accuracy of prostate biopsy in situations where multiparametric magnetic resonance imaging (mpMRI) is not available. PSMA-NB contrast-enhanced ultrasound (CEUS) allows for targeted biopsy, reducing the number of necessary samples and aiding in the reduction of complications associated with prostate biopsy. The significantly longer half-life of PSMA-NB enables more comprehensive evaluation by the physician. Furthermore, PSMA-NB allows for real-time molecular imaging of the prostate, which can greatly aid in the accurate diagnosis and management of prostate cancer. Our goal is to assess experimental PSMA-targeted nanobubbles (PSMA-NB) as a UCA for prostate cancer ultrasound molecular imaging in large animal models. Five sexually mature male New Zealand white rabbits and four male beagles were used in the study. Prostate cancer cells were inoculated into the prostate glands via US-guided injection. Multiparametric magnetic resonance imaging (mpMRI) and NB-based CEUS were performed to evaluate tumor growth. Clinically approved microbubble UCA (MB) was used as a control. The rabbits were imaged with a transabdominal approach (17 MHz), while the dogs were imaged with an 8 MHz transrectal end-fire probe. UCA was injected through peripheral vein access and was imaged for 15 minutes after injection. Time-intensity curves (TICs) were normalized for the baseline signal intensity and peak value, and decorrelation time (DT) and area under the curve (AUC) mapping was performed. At the end of the study, tumors were harvested for histopathology assessment. In the rabbit model, PSMA-NB showed a two times higher signal and longer half-life (contrast signal >10 min) than MB in early-stage tumors (< 75 mm3). PSMA-NB demonstrated slower wash-out on tumors than normal prostate, indicating contrast retention; no difference in wash-out was observed with MB. Differences were preserved in tumors outside the prostate. In the canine model, decorrelation time mapping of PSMA-NB clearly delineated tumor growth zones with high cellular activity confirmed by histopathology. Our study demonstrated that PSMA-NB has the potential to highlight tumor areas within the prostate gland in both rabbit and canine models of prostate cancer. NBs showed contrast retention and slower washout of PSMA-NB, enabling differentiation between tumor interest zones and normal prostate tissue. These findings suggest that PSMA-NB UCA could be a promising tool for prostate cancer diagnosis and treatment.

Prostate cancer is the most prevalent cancer among men in the United States and is a leading cause of cancer-related death. Prostate specific membrane antigen (PSMA) has been established as a biomarker for prostate cancer diagnosis and treatment. This study aimed to develop a novel theranostic agent, PSMA-1-MMAE-Pc413, which integrates a PSMA-targeting ligand, the photosensitizer Pc413, and the microtubular inhibitor monomethyl auristatin E (MMAE) for synergistic therapeutic efficacy. In vitro uptake studies revealed that PSMA-1-MMAE-Pc413 demonstrated selective and specific uptake in PSMA-positive PC3pip cells but not in PSMA-negative PC3flu cells, with the uptake in PC3pip cells being approximately three times higher. In vitro cytotoxicity assays showed that, when exposed to light, PSMA-1-MMAE-Pc413 had a synergistic effect, leading to significantly greater cytotoxicity in PSMA-positive cells (IC50 = 2.2 nM) compared to PSMA-1-Pc413 with light irradiation (IC50 = 164.9 nM) or PSMA-1-MMAE-Pc413 without light irradiation (IC50 = 12.6 nM). In vivo imaging studies further demonstrated the selective uptake of PSMA-1-MMAE-Pc413 in PC3pip tumors. In in vivo studies, PSMA-1-MMAE-Pc413 dramatically improves the therapeutic outcome for prostate cancer by providing a synergistic effect that surpasses the efficacy of each treatment modality alone in PC3pip tumors. These findings suggest that PSMA-1-MMAE-Pc413 has strong potential for clinical application in improving prostate cancer treatment.

Up to 40 % of breast cancer patients have a tumor-positive resection margin (TPRM) - defined as cancer cells at the surface of the resected specimen - after breast-conserving surgery (BCS), necessitating re-resection or boost radiation. To prevent these additional treatments, intraoperative near-infrared (NIR) fluorescence imaging with the topically applied, cathepsin-activatable imaging agent AKRO-6qcICG might be used to detect TPRMs and guide additional resection. Here, to validate its performance, the agent is topically applied to all surfaces of freshly resected breast cancer specimens (n =11 patients) and to 3-5 mm thick tissue slices of the specimens (n = 26 patients). NIR fluorescence images of the resection surfaces and tissue slices are acquired and correlated to final histopathology. AKRO-6qcICG detects TPRMs with a sensitivity, specificity, PVV, and NPV of 100%, 67%, 10%, and 100%, respectively. On the tissue slices, the fluorescence signal has a median tumor-to-background ratio of 1.8. These findings indicate that topically applied AKRO-6qcICG can visualize TPRMs ex vivo with a high sensitivity and NPV, with sufficient contrast to adjacent healthy breast tissue.

Cysteine cathepsins are proteases that play a role in normal cellular physiology and neoplastic transformation. Elevated expression and enzymatic activity of cathepsins in breast cancer (BCa) indicates their potential as a target for tumor imaging. In particular cathepsin B (CTSB), L (CTSL), and S (CTSS) are used as targets for near-infrared (NIR) fluorescence imaging (FI), a technique that allows real-time intraoperative tumor visualization and resection margin assessment. Therefore, this immunohistochemical study explores CTSB, CTSL, and CTSS expression levels in a large breast cancer patient cohort, to investigate in which BCa patients the use of cathepsin-targeted NIR FI may have added value. Protein expression was analyzed in tumor tissue microarrays (TMA) of BCa patients using immunohistochemistry and quantified as a total immunostaining score (TIS), ranging from 0–12. In total, the tissues of 557 BCa patients were included in the TMA. CTSB, CTSL, and CTSS were successfully scored in respectively 340, 373 and 252 tumors. All tumors showed CTSB, CTSL, and/or CTSS expression to some extent (TIS > 0). CTSB, CTSL, and CTSS expression was scored as high (TIS > 6) in respectively 28

BACKGROUND:There is an increasing interest in using preclinical models for development and assessment of medical devices and imaging techniques for prostatic disease care. Still, a comprehensive assessment of the prostate's radiological anatomy in primary preclinical models such as dogs, rabbits, and mice utilizing human anatomy as a reference point remains necessary with no optimal model for each purpose being clearly defined in the literature. Therefore, this study compares the anatomical characteristics of different animal models to the human prostatic gland from the imaging perspective. METHODS:We imaged five Beagle laboratory dogs, five New Zealand White rabbits, and five mice, all sexually mature males, under Institutional Animal Care and Use Committee (IACUC) approval. Ultrasonography (US) was performed using the Vevo® F2 for mice (57 MHz probe). Rabbits and dogs were imaged using the Siemens® Acuson S3000 (17 MHz probe) and endocavitary (8 MHz) probes, respectively. Magnetic resonance imaging (MRI) was also conducted with a 7T scanner in mice and 3T scanner in rabbits and dogs. RESULTS:Canine transrectal US emerged as the optimal method for US imaging, depicting a morphologically similar gland to humans but lacking echoic zonal differentiation. MRI findings in canines indicated a homogeneously structured gland similar to the human peripheral zone on T2-weighted images (T2W) and apparent diffusion coefficient (ADC). In rabbits, US imaging faced challenges due to the pubic symphysis, whereas MRI effectively visualized all structures with the prostate presenting a similar aspect to the human peripheral gland on T2W and ADC maps. Murine prostate assessment revealed poor visualization of the prostate glands in ultrasound due to its small size, while 7T MRI delineated the distinct prostates and its lobes, with the lateral and dorsal prostate resembling the peripheral zone and the anterior prostate the central zone of the human gland. CONCLUSION:Dogs stand out as superior models for advanced preclinical studies in prostatic disease research. However, mice present as a good model for early stage studies and rabbits are a cost-effective alternative and serve as valuable tools in specific research domains when canine research is not feasible.

<p>Detailed overview of 510(k) cleared imaging devices by the FDA.</p>

BackgroundMale dogs can develop spontaneous prostate cancer, which is similar physiologically to human disease. Recently, Tweedle and coworkers have developed an orthotopic canine prostate model allowing implanted tumors and therapeutic agents to be tested in a more translational large animal model. We used the canine model to evaluate prostate-specific membrane antigen (PSMA)-targeted gold nanoparticles as a theranostic approach for fluorescence (FL) imaging and photodynamic therapy (PDT) of early stage prostate cancer. MethodsDogs (four in total) were immunosuppressed with a cyclosporine-based immunosuppressant regimen and their prostate glands were injected with Ace-1-hPSMA cells using transabdominal ultrasound (US) guidance. Intraprostatic tumors grew in 4-5 weeks and were monitored by ultrasound (US). When tumors reached an appropriate size, dogs were injected intravenously (iv) with PSMA-targeted nano agents (AuNPs-Pc158) and underwent surgery 24 h later to expose the prostate tumors for FL imaging and PDT. Ex vivo FL imaging and histopathological studies were performed to confirm PDT efficacy. ResultsAll dogs had tumor growth in the prostate gland as revealed by US. Twenty-four hours after injection of PSMA-targeted nano agents (AuNPs-Pc158), the tumors were imaged using a Curadel FL imaging device. While normal prostate tissue had minimal fluorescent signal, the prostate tumors had significantly increased FL. PDT was activated by irradiating specific fluorescent tumor areas with laser light (672 nm). PDT bleached the FL signal, while fluorescent signals from the other unexposed tumor tissues were unaffected. Histological analysis of tumors and adjacent prostate revealed that PDT damaged the irradiated areas to a depth of 1-2 mms with the presence of necrosis, hemorrhage, secondary inflammation, and occasional focal thrombosis. The nonirradiated areas showed no visible damages by PDT. ConclusionWe have successfully established a PSMA-expressing canine orthotopic prostate tumor model and used the model to evaluate the PSMA-targeted nano agents (AuNPs-Pc158) in the application of FL imaging and PDT. It was demonstrated that the nano agents allowed visualization of the cancer cells and enabled their destruction when they were irradiated with a specific wavelength of light.