Search

Purpose: The radiolabeled gastrin-releasing peptide receptor (GRPR)-targeting antagonist NeoB is a promising radioligand for imaging and therapy of GRPR-expressing malignancies. In the current study, we aimed to discover the target organs of toxicity and the radiotoxic effects to these organs, when repeated dosages of [177Lu]Lu-NeoB are administered to healthy female and male mice. Methods: Animals received either 3 injections, with a 7-day interval, of vehicle (control group 1), 1200 pmol [175Lu]Lu-NeoB (control group 2) or 40 MBq/400 pmol, 80 MBq/800 pmol, and 120 MBq/1200 pmol [177Lu]Lu-NeoB (treatment groups 1, 2, and 3, respectively). At week 5, 19, and 43 after the first injection acute, early, and late organ toxicity, respectively, was determined. For this, histopathological and blood analyses were performed. To correlate the observed toxicity to absorbed dose, we also performed extensive biodistribution and dosimetry studies. Results: The biodistribution study showed the highest absorbed doses in GRPR-expressing pancreas, the liver, and the kidneys (the main organs of excretion). Both control groups and almost all animals of treatment group 1 did not show any treatment-related toxicological effects. Despite the high absorbed doses, no clear microscopic signs of toxicity were found in the pancreas and the liver. Histological analysis indicated kidney damage in the form of hydronephrosis and nephropathy in treatment groups 2 and 3 that were sacrificed at the early and late time point. In the same groups, increased blood urea nitrogen levels were found. Conclusion: In general, repeated administration of [177Lu]Lu-NeoB was tolerated. The most significant radiotoxic effects were found in the kidneys, similar to other clinically applied radioligands. The results of this study underline the potential of [177Lu]Lu-NeoB as a promising option for clinical therapy. [ABSTRACT FROM AUTHOR]

Background: To improve peptide receptor radionuclide therapy (PRRT), we aimed to enhance the expression of somatostatin type-2 receptors (SSTR2) in vitro and in vivo, using valproic acid (VPA). Methods: Human NCI-H69 small-cell lung carcinoma cells were treated with VPA, followed by [111In]In-DOTATATE uptake studies, RT-qPCR and immunohistochemistry analysis. Furthermore, NCI-H69 xenografted mice were treated with VPA or vehicle, followed by [177Lu]Lu-DOTATATE injection. Biodistribution studies were performed, and tissues were collected for further analysis. Results: VPA significantly increased SSTR2 expression in vitro. In animals, a statistically significant increased [177Lu]Lu-DOTATATE tumoral uptake was observed when VPA was administered eight hours before [177Lu]Lu-DOTATATE administration, but increased tumor SSTR2 expression levels were lacking. The animals also presented significantly higher [177Lu]Lu-DOTATATE blood levels, as well as an elevated renal tubular damage score. This suggests that the enhanced tumor uptake was presumably a consequence of the increased radiotracer circulation and the induced kidney damage. Conclusions: VPA increases SSTR2 expression in vitro. In vivo, the observed increase in tumoral [177Lu]Lu-DOTATATE uptake is not caused by SSTR2 upregulation, but rather by other mechanisms, e.g., an increased [177Lu]Lu-DOTATATE circulation time and renal toxicity. However, since both drugs are safely used in humans, the potential of VPA to improve PRRT remains open for investigation. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a light-based anticancer therapy that can induce tumor necrosis and/or apoptosis. Two important factors contributing to the efficacy of PDT are the concentration of the photosensitizer in the tumor tissue and its preferential accumulation in the tumor tissue compared to that in normal tissues. In this study, we investigated the use of optical imaging for monitoring whole-body bio-distribution of the fluorescent (660 nm) photosensitizer Bremachlorin in vivo, in a murine pancreatic ductal adenocarcinoma (PDAC) model. Moreover, we non-invasively, examined the induction of tumor necrosis after PDT treatment using near-infrared fluorescent imaging of the necrosis avid cyanine dye IRDye®-800CW Carboxylate. Using whole-body fluorescence imaging, we observed that Bremachlorin preferentially accumulated in pancreatic tumors. Furthermore, in a longitudinal study we showed that 3 hours after Bremachlorin administration, the fluorescent tumor signal reached its maximum. In addition, the tumor-to-background ratio at all-time points was approximately 1.4. Ex vivo, at 6 hours after Bremachlorin administration, the tumor-to-muscle or -normal pancreas ratio exhibited a greater difference than it did at 24 hours, suggesting that, in terms of efficacy, 6 hours after Bremachlorin administration was an effective time point for PDT treatment of PDAC. In vivo administration of the near infrared fluorescence agent IRDye®-800CW Carboxylate showed that PDT, 6 hours after administration of Bremachlorin, selectively induced necrosis in the tumor tissues, which was subsequently confirmed histologically. In conclusion, by using in vivo fluorescence imaging, we could non-invasively and longitudinally monitor, the whole-body distribution of Bremachlorin. Furthermore, we successfully used IRDye®-800CW Carboxylate, a near-infrared fluorescent necrosis avid agent, to image PDT-induced necrotic cell death as a measure of therapeutic efficacy. This study showed how fluorescence can be applied for optimizing, and assessing the efficacy of, PDT., (© 2024. The Author(s).)

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 [ 18 F]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, [ 111 In]In-eFAP-6 demonstrated a superior affinity and a more rapid, although slightly lower, peak uptake than gold standard [ 111 In]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 [ 177 Lu]Lu-eFAP-6 vs. [ 177 Lu]Lu-FAPI-46. However, tumor retention at 24 h post injection of [ 177 Lu]Lu-eFAP-6 was lower than that of [ 177 Lu]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., (© 2024. The Author(s).)

Aims: The aim of our study was to determine the effect of histone deacetylase (HDAC) inhibitors (HDACis) on somatostatin type-2 receptor (SSTR2) expression and [ 111 In]In-/[ 177 Lu]Lu-DOTA-TATE uptake in vitro and in vivo., Materials and Methods: The human cell lines NCI-H69 (small-cell lung carcinoma) and BON-1 (pancreatic neuroendocrine tumor) were treated with HDACis (i.e. entinostat, mocetinostat (MOC), LMK-235, CI-994 or panobinostat (PAN)), and SSTR2 mRNA expression levels and [ 111 In]In-DOTA-TATE uptake were measured. Furthermore, vehicle- and HDACi-treated NCI-H69 and BON-1 tumor-bearing mice were injected with radiolabeled DOTA-TATE followed by biodistribution studies. Additionally, SSTR2 and HDAC mRNA expression of xenografts, and of NCI-H69, BON-1, NCI-H727 (human pulmonary carcinoid) and GOT1 (human midgut neuroendocrine tumor) cells were determined., Key Findings: HDACi treatment resulted in the desired effects in vitro. However, no significant increase in tumoral DOTA-TATE uptake was observed after HDACi treatment in NCI-H69 tumor-bearing animals, whereas tumoral SSTR2 mRNA and/or protein expression levels were significantly upregulated after treatment with MOC, CI-994 and PAN, i.e. a maximum of 2.1- and 1.3-fold, respectively. Analysis of PAN-treated BON-1 xenografts solely demonstrated increased SSTR2 mRNA expression levels. Comparison of HDACs and SSTR2 expression in BON-1 and NCI-H69 xenografts showed a significantly higher expression of 6/11 HDACs in BON-1 xenografts. Of these HDACs, a significant inverse correlation was found between HDAC3 and SSTR2 expression (Pearson r = -0.92) in the studied cell lines., Significance: To conclude, tumoral uptake levels of radiolabeled DOTA-TATE were not enhanced after HDACi treatment in vivo, but, depending on the applied inhibitor, increased SSTR2 expression levels were observed., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Optimal treatment of cancer requires diagnostic methods to facilitate therapy choice and prevent ineffective treatments. Direct assessment of therapy response in viable tumor specimens could fill this diagnostic gap. Therefore, we designed a microfluidic platform for assessment of patient treatment response using tumor tissue slices under precisely controlled growth conditions. The optimized Cancer-on-Chip (CoC) platform maintained viability and sustained proliferation of breast and prostate tumor slices for 7 days. No major changes in tissue morphology or gene expression patterns were observed within this time frame, suggesting that the CoC system provides a reliable and effective way to probe intrinsic chemotherapeutic sensitivity of tumors. The customized CoC platform accurately predicted cisplatin and apalutamide treatment response in breast and prostate tumor xenograft models, respectively. The culture period for breast cancer could be extended up to 14 days without major changes in tissue morphology and viability. These culture characteristics enable assessment of treatment outcomes and open possibilities for detailed mechanistic studies. SIGNIFICANCE: The Cancer-on-Chip platform with a 6-well plate design incorporating silicon-based microfluidics can enable optimal patient-specific treatment strategies through parallel culture of multiple tumor slices and diagnostic assays using primary tumor material., (©2021 The Authors; Published by the American Association for Cancer Research.)

Background: The phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT pathway is frequently activated during prostate cancer (PCa) progression through loss or mutation of the phosphatase and tensin homolog (PTEN) gene. Following the androgen receptor (AR) pathway, it is the second major driver of PCa growth., Objective: To assess efficacy of novel PI3K/AKT-targeted therapies in PCa models, as a single agent and in combination with androgen deprivation., Design, Setting, and Participants: Twelve human PCa cell lines were tested in vitro for sensitivity to the AKT inhibitor AZD5363 and the PI3K beta/delta inhibitor AZD8186. The combination of AZD5363 and AZD8186 with castration was evaluated in vivo in PTEN-negative versus PTEN-positive patient-derived xenografts. Tumors and plasma were collected for biomarker analysis., Outcome Measurements and Statistical Analysis: In vitro growth inhibition was determined by methylthiazolyldiphenyl-tetrazolium bromide assay. In vivo efficacy was monitored by caliper measurements of subcutaneous tumor volume. PI3K/AKT and AR pathway activity was analyzed by Western blot, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction., Results and Limitations: AZD5363 and AZD8186 inhibited in vitro growth of 10 of 12 and 7 of 12 PCa cell lines, respectively, with increased sensitivity under androgen depletion. In vivo, AZD5363 and AZD8186 as single agents significantly inhibited growth of PTEN-negative PC346C xenografts compared to placebo by 60% and 66%, respectively. Importantly, combination of either agent with castration resulted in long-lasting tumor regression, which persisted after treatment cessation. Expression of AR-target genes kallikrein-related peptidase 3 (KLK3, also known as PSA); transmembrane protease, serine 2 (TMPRSS2); and FK506 binding protein 5 (FKBP5) was upregulated after PI3K/AKT inhibition. Neither compound inhibited tumor growth in the PTEN-positive PC310 model., Conclusions: Combination with hormonal therapy improved efficacy of PI3K/AKT-targeted agents in PTEN-negative PCa models. Upregulation of AR-target genes upon PI3K/AKT inhibition suggests a compensatory crosstalk between the PI3K-AR pathways. These data strongly advocate for further clinical evaluation., Patient Summary: Inactivation of the PTEN gene is a common event promoting prostate cancer (PCa) progression. This preclinical study illustrates the potent anticancer activity of novel PTEN-targeted drugs on PCa models, particularly in combination with hormonal therapy., (Copyright © 2014 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

Unlabelled: Treatment options for metastatic castration-resistant prostate cancer (CRPC) have evolved with the established benefit of the novel androgen receptor (AR)-targeted agents abiraterone and enzalutamide in the prechemotherapy setting. However, concerns regarding cross-resistance between the taxanes docetaxel and cabazitaxel and these AR-targeted agents have arisen, and the optimal drug treatment sequence is unknown. We investigated the in vivo efficacy of docetaxel and cabazitaxel in enzalutamide-resistant CRPC, and mechanisms of cross-resistance between these agents. Castrated mice harboring enzalutamide-resistant tumors and enzalutamide-naïve tumors were treated with docetaxel and cabazitaxel. Tumor growth kinetics, AR nuclear localization, AR-regulated gene expression, Ki67 expression, and serum levels of prostate-specific antigen, docetaxel, and cabazitaxel were analyzed. Docetaxel inhibited tumor growth, AR nuclear localization, and AR-regulated gene expression in enzalutamide-naïve tumors, but did not in enzalutamide-resistant tumors, demonstrating in vivo cross-resistance. By contrast, cabazitaxel remained highly effective in enzalutamide-resistant tumors and demonstrated superior antitumor activity compared to docetaxel, independent of the AR pathway. These findings demonstrate that the AR pathway is able to confer in vivo cross-resistance between enzalutamide and docetaxel, but not cabazitaxel, in CRPC., Patient Summary: We found reduced efficacy of docetaxel, but not cabazitaxel, in enzalutamide-resistant prostate cancer., (Copyright © 2014 European Association of Urology. Published by Elsevier B.V. All rights reserved.)

In human adenoviruses (HAdV), 240 copies of the 14.3-kDa minor capsid protein IX stabilize the capsid. Three N-terminal domains of protein IX form triskelions between hexon capsomers. The C-terminal domains of four protein IX monomers associate near the facet periphery. The precise biological role of protein IX remains enigmatic. Here we show that deletion of the protein IX gene from a HAdV-5 vector enhanced the reporter gene delivery 5 to 25-fold, specifically to Coxsackie and Adenovirus Receptor (CAR)-negative cell lines. Deletion of the protein IX gene also resulted in enhanced activation of peripheral blood mononuclear cells. The mechanism for the enhanced transduction is obscure. No differences in fiber loading, integrin-dependency of transduction, or factor-X binding could be established between protein IX-containing and protein IX-deficient particles. Our data suggest that protein IX can affect the cell tropism of HAdV-5, and may function to dampen the innate immune responses against HAdV particles., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Human prostate cancer (PC) overexpresses the gastrin-releasing peptide receptor (GRPR). Radiolabeled GRPR-targeting analogs of bombesin (BN) have successfully been introduced as potential tracers for visualization and treatment of GRPR-overexpressing tumors. A previous study showed GRPR-mediated binding of radiolabeled BN analogs in androgen-dependent but not in androgen-independent xenografts representing the more advanced stages of PC. We have further investigated the effect of androgen modulation on GRPR-expression in three androgen-dependent human PC-bearing xenografts: PC295, PC310 and PC82 using the androgen-independent PC3-model as a reference. Effects of androgen regulation on GRPR expression were initially studied on tumors obtained from our biorepository of xenograft tissues performing reverse transcriptase polymerase chain reaction (RT-PCR) and autoradiography ((125)I-universal-BN). A prospective biodistribution study ((111)In-MP2653) and subsequent autoradiography ((125)I-GRP and (111)In-MP2248) was than performed in castrated and testosterone resupplemented tumor-bearing mice. For all androgen-dependent xenografts, tumor uptake and binding decreased drastically after 7 days of castration. Resupplementation of testosterone to castrated animals restored GRPR expression extensively. Similar findings were concluded from the initial autoradiography and RT-PCR studies. Results from RT-PCR, for which human specific primers are used, indicate that variations in GRPR expression can be ascribed to mRNA downregulation and not to castration-induced reduction in the epithelial fraction of the xenograft tumor tissue. In conclusion, expression of human GRPR in androgen-dependent PC xenografts is reduced by androgen ablation and is reversed by restoring the hormonal status of the animals. This knowledge suggests that hormonal therapy may affect GRPR expression in PC tissue making GRPR-based imaging and therapy especially suitable for non-hormonally treated PC patients.

Background: Specificity of transgene expression is important for safety during gene therapeutical applications. For prostate cancer, transcriptional targeting has been applied but was hampered by loss of specificity and low activity. We constructed a small chimeric promoter for high and prostate-specific transgene expression from adenoviral vectors., Methods: A chimeric promoter, composed of the prostate-specific antigen (PSA) enhancer and the rat probasin promoter, was cloned into an adenoviral vector and its activity was compared to vectors containing conventional prostate-specific promoters and the constitutive Cytomegalovirus (CMV) promoter in in vitro and in vivo prostate cancer models., Results: The chimeric PSA-probasin promoter was the most active prostate-specific promoter reaching up to 20% of CMV promoter activity while maintaining prostate-specificity., Conclusions: The chimeric PSA-probasin promoter is a small promoter that can be utilized in viral vectors for high prostate-specific transgene expression., (Copyright 2007 Wiley-Liss, Inc.)

TARP (T cell receptor gamma-chain alternate reading frame protein) is a protein that in males is uniquely expressed in prostate epithelial cells and prostate cancer cells. We have previously shown that the transcriptional activity of a chimeric sequence comprising the TARP promoter (TARPp) and the PSA enhancer (PSAe) is strictly controlled by testosterone and highly restricted to cells of prostate origin. Here we report that a chimeric sequence comprising TARPp and the PSMA enhancer (PSMAe) is highly active in testosterone-deprived prostate cancer cells, while a regulatory sequence comprising PSAe, PSMAe, and TARPp (PPT) has high prostate-specific activity both in the presence and in the absence of testosterone. Therefore, the PPT sequence may, in a gene therapy setting, be beneficial to prostate cancer patients that have been treated with androgen withdrawal. A recombinant adenovirus vector with the PPT sequence, shielded from interfering adenoviral sequences by the mouse H19 insulator, yields high and prostate-specific transgene expression both in cell cultures and when prostate cancer, PC-346C, tumors were grown orthotopically in nude mice. Intravenous virus administration reveals both higher activity and higher selectivity for the insulator-shielded PPT sequence than for the immediate-early CMV promoter. Therefore, we believe that an adenovirus with therapeutic gene expression controlled by an insulator-shielded PPT sequence is a promising candidate for gene therapy of prostate cancer., (Copyright The American Society of Gene Therapy)