BACKGROUND:Pre-clinical in vivo characterization is a necessary step in the translation of novel radiotherapeutic interventions to clinical application. In vivo irradiations using a radioactive source like Ir-192 are challenging due to steep dose gradients and absence of universally available applicators that do not require physical contact or interstitial insertion. PURPOSE:To develop a novel external beam radiotherapy (EBRT) jig for accurate and reproducible radiotherapy treatments delivered using an Ir-192 source for in vivo studies. METHODS:An irradiation jig was constructed as a flat treatment bed and upright 6 cm diameter semi-circle with eight peripheral catheter positions encompassing the lateral side of a mouse. A CT scan was acquired of the jig along with a silicone phantom of a mouse with flank tumor. The scan was imported into Oncentra® for planning using 500 cGy prescribed to the tumor and calculated using TG43 and collapsed cone. EBT4 film and OSLD measurements verified dose distributions in the axial and coronal directions along with the entrance and exit dose to the tumor. Monte Carlo simulations using TOPAS™ were used to observe the 3D dose distribution within the tumor itself. Five female immunodeficient mice inoculated with HEC-1A cervical cancer tumors were irradiated and monitored for 3 weeks for tumor growth, body weight, and signs of toxicity. RESULTS:Dosimetry measurements agreed within 2%-15% of the tumor's entrance and exit dose as reported by Oncentra® using both computational formalisms. Monte Carlo simulations confirmed a uniform dose distribution within the tumor of ± 10%. Compared to unirradiated mice, a significant reduction in tumor growth post-irradiation was observed in all irradiated mice with no observable signs of toxicity. CONCLUSION:We have successfully developed an EBRT platform for in vivo irradiations with an Ir-192 source. The platform can be adapted for various tumor and sample sizes and other radioactive sources.

The development of safe and effective anticancer drugs remains a significant challenge for the scientific community. A broad range of chemotherapeutic agents has been extensively evaluated for their efficacy across various patient populations. Among them, epirubicin has exhibited strong anti-cancer potential across different tumor models. In this study, epirubicin-loaded bovine serum albumin nanoparticles (EPI@BSA) were prepared using the desolvation method to explore their potential in lung cancer therapy. Physicochemical characterization confirmed that the nanoparticles were spherical and highly monodispersed. Cytotoxicity testing on the A549 cell line revealed enhanced cell death with the nanoparticle formulation compared to that with the free drug. Furthermore, semi-quantitative RT-PCR analysis indicated that the nanoparticles effectively induced apoptosis. These findings support the potential of a protein-based biodegradable carrier system to enhance the therapeutic efficacy of epirubicin in cancer treatment.

Nanomedicine offers powerful opportunities for targeted drug delivery and cancer therapy, yet clinical translation remains limited by the complex and dynamic interactions of nanoparticles within biological systems. This review integrates current evidence on how nanoparticle size, shape, and surface properties govern cellular uptake and processing, systemic biodistribution, immune interactions, and therapeutic performance across in vitro, ex vivo, and in vivo models. By comparatively analyzing findings across two-dimensional, three-dimensional, xenograft, and immunocompetent tumor models, this review identifies model-dependent determinants of nanoparticle performance that influence translational outcomes. Foundational studies in two-dimensional monolayers established relationships between physicochemical attributes, endocytic pathways, vesicular trafficking, and exocytosis. Three-dimensional spheroids introduce extracellular matrix density and cellular packing constraints that limit nanoparticle movement and alter uptake trends observed in monolayers. In vivo, xenograft models emphasize the influence of vascular permeability and stromal architecture but often overestimate delivery due to exaggerated enhanced permeability and retention effects and the lack of adaptive immunity. Immunocompetent tumor models capture complement activation, opsonization, macrophage-mediated clearance, dynamic protein corona evolution, and cytokine-driven vascular changes. These immune-mediated processes reshape biodistribution patterns and often diminish ligand-mediated targeting benefits. They operate alongside systemic factors such as renal and hepatosplenic filtration, biotransformation, and species-specific differences in vascular structure and immune composition, influencing nanoparticle pharmacokinetics and therapeutic response. Together, these findings underscore that successful nanomedicine design requires integrating material engineering with an understanding of immune surveillance, vascular biology, tumor microenvironment heterogeneity, and whole-body transport dynamics. Future progress will depend on developing nanoparticles that maintain functional stability in immune-intact hosts, minimize premature clearance, and achieve sustained intratumoral delivery. These advances must be supported by predictive, physiologically relevant models that bridge gaps between in vitro results, preclinical outcomes, and clinical translation.

BACKGROUND:Associated normal tissue toxicity from current radiotherapy (RT) treatments limits effective dose escalation in the tumor to achieve nominal treatment results. Gold nanoparticles (GNPs) as radiosensitizing agents to locally increase photoelectron production have gained interest as a safe and viable method to improve therapeutic results. Among many other factors, the dose rate of the incident radiation has been shown to affect the radiosensitizing properties of GNPs significantly. PURPOSE:To evaluate GNP-induced radiosensitization during variable dose rate delivery from the decay of a high dose rate brachytherapy 192-Ir source and a clinical 6MV linear accelerator (LINAC). METHODS:HEC-1A endometrial cancer cells were seeded into 35mm petri dishes with or without 10µg/mL with spherical 11nm GNPs functionalized with polyethylene glycol and integrin binding domain RGD to improve intracellular uptake. Variable dose rate delivery from the 192-Ir source was achieved at two source strengths of 37.95 mGy m2/h and 18.97 mGy m2/h, corresponding to dose rates of 1.1 and 0.55Gy/min, respectively. For 6MV irradiations, dose rate variability was controlled by adjusting the distance to the target from 91cm to 129cm, yielding identical dose rates of 1.1 and 0.55Gy/min, respectively. Cellular viability was measured using a clonogenic assay after irradiations between 0 and 8Gy, and a DNA double-strand break assay after 2Gy irradiations. RESULTS:GNP-induced radiosensitization was significantly greater with higher dose rates than lower. Clonogenic loss with GNPs was increased from 1.00 to 1.19 (p < 0.001) with higher dose rates from 192-Ir source and from 1.03 to 1.16 (p < 0.001) with higher dose rate LINAC irradiations. DNA damage increase from GNPs was not significant at lower dose rates for both 192-Ir (p > 0.05) and LINAC (p > 0.05) irradiations; however, DNA damage was significantly increased at higher dose rates (192-Ir: p < 0.01; 6MV: p < 0.05). CONCLUSIONS:We have successfully demonstrated in vitro that clinically plausible GNP concentrations can induce variable radiosensitization based on the administered dose rate from both 192-Ir and LINAC irradiations. This work demands future research into the clinical translation of GNPs into high-dose-rate environments.

Despite promising achievements of gold nanoparticles (GNPs) as either drug delivery vehicles or radiosensitizing agents in vitro, their clinical application remains limited. A major consideration for their translation to the clinic is optimizing their accumulation in malignant tissue while limiting their sequestration and toxicity in healthy organs. Achieving optimal tumor accumulation in vivo of GNPs requires extensive consideration of their functionalization and route of administration. Surface modifications with integrin binding domain RGD and polyethylene glycol (PEG) are both common practices to improve the blood circulation of GNPs and preferential tumor accumulation. However, the route of administration and functionalization strategy could significantly affect their biodistribution due to the presence of phagocytic elements of the host that recognize the RGD motif. In our study, we systematically evaluate the biodistribution of GNPs after intravenous (i.v.) or intratumoral (i.t.) injections and surface modification with PEG and RGD. After i.v. injections, RGD surface-functionalized GNPs had poor blood circulation time and demonstrated a 91% reduction in tumor accumulation relative to PEGylation alone, indicating significant recognition of the RGD motif by phagocytosing elements. In contrast, i.t. injections of RGD-functionalized GNPs showed increased tumor retention compared to PEGylation alone and reduced GNP accumulation in phagocytosing organs compared to i.v. injections. Our results highlight the importance of optimizing targeting moieties of GNPs when administered through either i.v. or i.t. routes and warrant further investigations into alternative surface ligands to improve their delivery and retention in tumors.

Cancer treatments are limited by poor tumor specificity and toxicity. We tested a radiosensitizing approach using PEG/RGD-functionalized gold nanoparticles (GNPs), a lipid-nanoparticle–encapsulated docetaxel prodrug (LNPDTX–P), and external-beam radiotherapy (RT). In MIA PaCa-2 xenografts, intravenous GNPs (2 mg/kg) and LNPDTX–P (6 mg/kg) were given before 5 Gy RT. Both LNPDTX–P + RT and GNPs + LNPDTX–P + RT reduced tumor volume by ~40% and significantly prolonged survival versus RT alone (p < 0.001). Adding GNPs did not enhance efficacy, indicating LNPDTX–P was the main driver under this regimen. These results demonstrate nanocarrier-enabled radiosensitization in vivo and support further studies toward clinical translation.

The success of nanoparticle-based cancer therapeutics relies on their efficient tumor uptake and retention. Given this, improving nanoparticle localization in tumors is paramount to maximize their therapeutic potential. A common approach to achieve this is to functionalize nanoparticles with active targeting moieties that bind to specific tumor-associated receptors. Among these, arginine-glycine-aspartic acid (RGD) peptides have shown a potential to promote tumor accumulation by targeting the ανβ3 integrin receptor, a receptor commonly overexpressed by tumors owing to its role in promoting angiogenesis, metastasis and proliferation. Yet, its efficacy is commonly assessed using immunocompromised mice models. While useful, these models do not accurately account for immune-related interactions, which could lead to an overestimation of targeting efficacy. In our study, we investigated the efficacy of RGD peptides to improve the tumor accumulation of PEGylated gold nanoparticles (GNPs) using an immunocompetent mouse model. While RGD functionalization increased GNP uptake in cancer cells in vitro, it significantly reduced tumor accumulation in vivo due to enhanced off-target clearance by the mononuclear phagocyte system, with elevated accumulation in the spleen and liver. These findings highlight that RGD functionalization can promote immune-driven clearance in vivo, despite improving GNP uptake in cancer cells in vitro, emphasizing the importance of assessing targeting strategies in immunocompetent models for more physiologically relevant assessments.

This research underscores the potential of combining nanotechnology with conventional therapies in cancer treatment, particularly for challenging cases like pancreatic cancer. We aimed to enhance pancreatic cancer treatment by investigating the synergistic effects of gold nanoparticles (GNPs) and docetaxel (DTX) as potential radiosensitizers in radiotherapy (RT) both in vitro and in vivo, utilizing a MIA PaCa-2 monoculture spheroid model and NRG mice subcutaneously implanted with MIA PaCa-2 cells, respectively. Spheroids were treated with GNPs (7.5 μg/mL), DTX (100 nM), and 2 Gy of RT using a 6 MV linear accelerator. In parallel, mice received treatments of GNPs (2 mg/kg), DTX (6 mg/kg), and 5 Gy of RT (6 MV linear accelerator). In vitro results showed that though RT and DTX reduced spheroid size and increased DNA DSBs, the triple combination of DTX/RT/GNPs led to a significant 48% (p = 0.05) decrease in spheroid size and a 45% (p = 0.05) increase in DNA DSBs. In vivo results showed a 20% (p = 0.05) reduction in tumor growth 20 days post-treatment with (GNPs/RT/DTX) and an increase in mice median survival. The triple combination exhibited a synergistic effect, enhancing anticancer efficacy beyond individual treatments, and thus could be employed to improve radiotherapy and potentially reduce adverse effects.

Radiotherapy is an essential component of the treatment regimens for many cancer patients. Despite recent technological advancements to improve dose delivery techniques, the dose escalation required to enhance tumor control is limited due to the inevitable toxicity to the surrounding healthy tissue. Therefore, the local enhancement of dosing in tumor sites can provide the necessary means to improve the treatment modality. In recent years, the emergence of nanotechnology has facilitated a unique opportunity to increase the efficacy of radiotherapy treatment. The application of high-atomic-number (Z) nanoparticles (NPs) can augment the effects of radiotherapy by increasing the sensitivity of cells to radiation. High-Z NPs can inherently act as radiosensitizers as well as serve as targeted delivery vehicles for radiosensitizing agents. In this work, the therapeutic benefits of high-Z NPs as radiosensitizers, such as their tumor-targeting capabilities and their mechanisms of sensitization, are discussed. Preclinical data supporting their application in radiotherapy treatment as well as the status of their clinical translation will be presented.

Cancer is defined as the uncontrolled proliferation of heterogeneous cell cultures in the body that develop abnormalities and mutations, leading to their resistance to many forms of treatment. Left untreated, these abnormal cell growths can lead to detrimental and even fatal complications for patients. Radiation therapy is involved in around 50% of cancer treatment workflows; however, it presents significant recurrence rates and normal tissue toxicity, given the inevitable deposition of the dose to the surrounding healthy tissue. Chemotherapy is another treatment modality with excessive normal tissue toxicity that significantly affects patients’ quality of life. To improve the therapeutic efficacy of radiotherapy and chemotherapy, multiple conjunctive modalities have been proposed, which include the targeting of components of the tumour microenvironment inhibiting tumour spread and anti-therapeutic pathways, increasing the oxygen content within the tumour to revert the hypoxic nature of the malignancy, improving the local dose deposition with metal nanoparticles, and the restriction of the cell cycle within radiosensitive phases. The tumour microenvironment is largely responsible for inhibiting nanoparticle capture within the tumour itself and improving resistance to various forms of cancer therapy. In this review, we discuss the current literature surrounding the administration of molecular and nanoparticle therapeutics, their pharmacokinetics, and contrasting mechanisms of action. The review aims to demonstrate the advancements in the field of conjugated nanomaterials and radiotherapeutics targeting, inhibiting, or bypassing the tumour microenvironment to promote further research that can improve treatment outcomes and toxicity rates.

Despite promising preclinical research on nanoparticle-based strategies for improving cancer therapeutics, their clinical translation remains limited. The efficacy of these strategies often depends on the efficient delivery of nanoparticles to the tumor environment, making accurate representations of their biodistribution paramount in evaluating their potential. However, many studies commonly employ immunodeficient animal models to assess their therapeutic efficacy. While useful, these models do not accurately depict nanoparticle interactions with the immune system, which could lead to results being overstated due to the misrepresentation of their biodistribution. In our study, we demonstrate that immunocompetent mouse models exhibit significant alterations to the biodistribution of gold nanoparticles compared to conventional immunodeficient mouse models. The presence of a fully functional murine immune system was found to significantly increase the accumulation of gold nanoparticles in phagocytosing organs, consequently decreasing the concentration in tumors up to 95%, highlighting the importance of employing syngeneic tumor models to better predict clinical performance. Furthermore, we show that the concurrent administration of the chemotherapeutic agent docetaxel can assist in remediating this decrease by significantly enhancing gold nanoparticle accumulation in syngeneic tumors, demonstrating its potential as a combinatorial approach with nanoparticle-based cancer therapeutics. Based on our results, this elicits further investigation on the interactions of immune cells with gold nanoparticles and surface ligands used in our study to fully optimize their delivery to tumors.

Pancreatic cancer stands among the deadliest forms of cancer, and the existing treatments fall short of providing adequate efficacy. Novel and more effective treatment approaches are urgently required to address this critical medical challenge. In this study, we aimed to evaluate the anti-cancer efficacy of gold nanoparticles (GNPs) in combination with radiotherapy (RT). A 3D pancreatic cancer co-culture spheroid model of MIA PaCa-2 cancer cells and patient-derived cancer-associated fibroblasts (CAF-98) was used. The spheroids were treated with GNPs (7.5 μg/mL) and 2 Gy of RT. The spheroids' cell viability was assessed through the CellTiter-Glo 3D assay, and an immunofluorescence assay was used to assess the DNA DSBs via the expression of the DNA damage marker 53BP1. Co-culture samples showed a 10.8% (p < 0.05) increase in proliferation and a 13.0% (p < 0.05) decrease in DNA DSB when compared to monoculture samples, However, they displayed a 175% (p < 0.001) increase in GNPs uptake when compared to monoculture spheroids. Using GNPs/RT, we were able to show a significant reduction of 6.2% (p < 0.05) in spheroid size and an increase of 14.3% (p < 0.05) in DNA DSB damage in co-culture samples. The combination of GNPs with RT demonstrated remarkable radiosensitization effects, representing a promising approach to enhance cancer treatment efficacy. These effects were particularly noteworthy in the more treatment-resistant co-culture spheroid model.

BackgroundRadiotherapy (RT) is an essential component in the treatment regimens for many cancer patients. However, the dose escalation required to improve curative results is hindered due to the normal tissue toxicity that is induced. The introduction of radiosensitizers to RT treatment is an avenue that is currently being explored to overcome this issue. By introducing radiosensitizers into tumor sites, it is possible to preferentially enhance the local dose deposited. Gold nanoparticles (GNPs) are a potential candidate that have shown great promise in increasing the radiosensitivity of cancer cells through an enhancement in DNA damage. Furthermore, docetaxel (DTX) is a chemotherapeutic agent that arrests cells in the G2/M phase of the cell cycle, the phase most sensitive to radiation damage. We hypothesized that by incorporating DTX to GNP-enhanced radiotherapy treatment, we could further improve the radiosensitization experienced by cancer cells. To assess this strategy, we analyzed the radiotherapeutic effects on monolayer cell cultures in vitro, as well as on a mice prostate xenograft model in vivo while using clinically feasible concentrations for both GNPs and DTX.ResultsThe introduction of DTX to GNP-enhanced radiotherapy further increased the radiotherapeutic effects experienced by cancer cells. A 38% increase in DNA double-strand breaks was observed with the combination of GNP/DTX vs GNP alone after a dose of 2 Gy was administered. In vivo results displayed significant reduction in tumor growth over a 30-day observation period with the treatment of GNP/DTX/RT when compared to GNP/RT after a single 5 Gy dose was given to mice. The treatment strategy also resulted in 100% mice survival, which was not observed for other treatment conditions.ConclusionsIncorporating DTX to work in unison with GNPs and RT can increase the efficacy of RT treatment. Our study suggests that the treatment strategy could improve tumor control through local dose enhancement. As the concentrations used in this study are clinically feasible, there is potential for this strategy to be translated into clinical settings.

Many cancer therapeutics are tested in vitro using only tumour cells. However, the tumour promoting effect of cancer associated fibroblasts (CAFs) within the tumour microenvironment (TME) is thought to reduce cancer therapeutics' efficacy. We have chosen pancreatic ductal adenocarcinoma (PDAC) as our tumor model. Our goal is to create a co-culture of CAFs and tumour cells to model the interaction between cancer and stromal cells in the TME and allow for better testing of therapeutic combinations. To test the proposed co-culture model, a gold nanoparticle (GNP) mediated-radiation response was used. Cells were grown in co-culture with different ratios of CAFs to cancer cells. MIA PaCa-2 was used as our PDAC cancer cell line. Co-cultured cells were treated with 2 Gy of radiation following GNP incubation. DNA damage and cell proliferation were examined to assess the combined effect of radiation and GNPs. Cancer cells in co-culture exhibited up to a 23% decrease in DNA double strand breaks (DSB) and up to a 35% increase in proliferation compared to monocultures. GNP/Radiotherapy (RT) induced up to a 25% increase in DNA DSBs and up to a 15% decrease in proliferation compared to RT alone in both monocultured and co-cultured cells. The observed resistance in the co-culture system may be attributed to the role of CAFs in supporting cancer cells. Moreover, we were able to reduce the activity of CAFs using GNPs during radiation treatment. Indeed, CAFs internalize a significantly higher number of GNPs, which may have led to the reduction in their activity. One reason experimental therapeutics fail in clinical trials relates to limitations in the pre-clinical models that lack a true representation of the TME. We have demonstrated a co-culture platform to test GNP/RT in a clinically relevant environment.

Abstract Background Much in vitro research on the applicability of gold nanoparticles (GNPs) in cancer treatment has been focused on two-dimensional (2D) monolayer models. To improve this, we explored the effect of the combination of GNPs and docetaxel (DTX) with radiotherapy (RT) in a more complex three-dimensional (3D) spheroid that can better mimic a real tumour microenvironment. Methods Two cell lines, prostate cancer LNCaP and cervical cancer HeLa, were grown in monolayer and spheroids. Cells were dosed with GNPs at a concentration of 10 $$\mathrm{\mu g}/\mathrm{mL}$$ μ g / mL and with DTX at a dose that inhibited growth-rate by 50%. Samples were irradiated 24 h after drug dosing with 2 Gy, 5 Gy, or 10 Gy using a 6 MV beam. Monolayer cells had the DNA double-strand breaks (DSBs) probed 24 h post-radiation, and cell proliferation observed over 7 days. Spheroid proliferation was monitored over 14 days along with spheroid volume measurements. Results In DTX and GNP-treated monolayer samples, there is decreased survival after irradiation with 5 and 10 Gy of 16–24% and an increase in DSBs of 91.6–109.9%, compared to DTX. In spheroids, GNPs decreased the surviving cells by 10.54–15.61% compared to control, while GNPs and DTX decreased survival by 20.9–31.04%. There is reduced spheroid volume 14 days after treatment with the triple combination. Conclusions Combining GNPs and DTX leads to a synergistic radiosensitization effect in spheroids, which can better mimic the tumour microenvironment. Testing treatment modalities with spheroids and RT may allow a quicker translation to the clinic.

By 2040, the number of new cancer cases per year is expected to rise to 29.5 million and the number of cancer-related deaths to 16.4 million.Approximately 50 percent of all cancer patients can benefit from radiotherapy (RT).Although an increasing number of patients survive at least five years past their cancer diagnosis, cancer continues to be the leading cause of death worldwide.RT is an essential element of curative treatment of many cancers including breast, prostate, cervix, head and neck, lung, and brain.For prostate cancer, radiotherapy dose-escalation is known to improve disease control, but can also increase late normal tissue toxicity.Despite advancements in treatment planning & delivery we are now approaching the limit of RT dose that can be safely delivered to patients, creating a clear need for novel methods to enhance radiotherapy effects to further improve the survival, while reducing side effects.Enhancing targeted delivery of radiotherapy (RT) has tremendous potential to maximize the effect of dose given to the tumor and reduce the dose given to normal tissue.One of the current strategies to preferentially increase tumor radiation dose effect is to add a radiosensitizer to RT, which has improved survival for those with cancers.Dr. Chithrani uses gold nanoparticles in combination with other radiation sensitizing agents to optimize current radiotherapy.In this talk, she will discuss the promising outcomes of such novel strategies to overcome current challenges imposed by the tumour and its microenvironment.

The objective of this study was to assess the anticancer effectiveness of gold nanoparticles (GNPs) and lipid-encapsulated docetaxel prodrug (LNPDTX-P) with radiotherapy (RT). The study utilized a co-culture spheroid model comprising MIA PaCa-2 cancer cells and patient-derived cancer-associated fibroblasts (CAF-98) to mimic pancreatic cancer conditions. The spheroids underwent treatment with GNPs (7.5 μg/mL), LNPDTX-P (99 nM of DTX pro-drug), and 2 Gy of RT. Cell viability of the spheroids was evaluated using the CellTiter-Glo 3D assay. At the same time, DNA double-strand breaks (DSBs) were assessed by examining the expression of the DNA damage marker 53BP1 through an immunofluorescence assay. Alt-hough GNPs/RT and RT/LNPDTX-P showed a reduction in spheroid size and an apparent in-crease in DNA DSB damage, the combination of the two nanoparticles, GNPs, and LNPDTX-P, with RT, significantly enhanced the anticancer efficacy, resulting in a 28% decrease in spheroid size and an estimated 39% increase in DNA DSB. The combination of GNPs and LNPDTX-P with RT showed a synergetic effect due to their radiosensitizing properties, improving the ther-apeutic efficacy of each treatment modality alone. This triple modality offers a hopeful strategy to enhance cancer treatment efficacy while reducing adverse effects.

One of the major issues in current radiotherapy (RT) is the associated normal tissue toxicity. Enhancement of the RT effect with novel radiosensitizers can address this need. In this study, gold nanoparticles (GNPs) and bleomycin (BLM) were used as a unique combination of radiosensitizers. GNPs offer a two-fold promise as a delivery vehicle for BLM and as a radiosensitizing agent. In this study, GNPs were functionalized and complexed with BLM using a gold-thiol bond (denoted GNP-BLM). Our results show that there was a 40% and 10% decrease in cell growth with GNP-BLM vs. free BLM for the MIA PaCa-2 and PC-3 cell lines, respectively. Testing the GNP-BLM platform with RT showed an 84% and 13% reduction in cell growth in MIA PaCa-2 cells treated with GNP-BLM and GNPs, respectively. Similar results were seen with PC-3 cells. The efficacy of this approach was verified by mapping DNA double-strand breaks (DSBs) as well. Therefore, this proposed incorporation of nanomedicine with RT is promising in achieving a significantly higher therapeutic ratio which is necessary to make a paradigm change to the current clinical approach.