Continuous Docetaxel Chemotherapy Improves Therapeutic Efficacy in Murine Models of Ovarian Cancer

Peritoneal chemotherapy delivery systems for ovarian cancer treatment: systematic review of animal models

Introduction

Intraperitoneal chemotherapy for ovarian cancer treatment has controversial benefits as most methodologies are associated with significant morbidity. We carried out a systematic review to compare tumor response, measured by tumor weight and volume, between intraperitoneal chemotherapy delivered via drug delivery systems (DDSs) and free intraperitoneal chemotherapy in animal models of ovarian cancer. The secondary aim was to assess the toxicity of DDS-delivered chemotherapy, based on changes in animal body weight.

Methods

Based on PRISMA and SYRCLE guidelines, we identified 38 studies for review, of which 20, were used in the meta-analysis. We evaluated outcome, through tumor volume and tumor weight and, toxicity, through animal weight. Analysis was based on drugs employed and treatment duration.

Results

Most studies were performed on mice. Ovarian cancer cell lines most commonly used to induce xenografts were SKOV3 (19 studies) and A2780 (6 studies). Intraperitoneal device, also known as drug delivery systems (DDS), consisted in nanoparticles, hydrogels, lipid polymer and others. The most commonly used drugs were paclitaxel and cisplatin. Most studies used as the control treatment the same chemotherapy applied free intraperitoneally and tumor response/animal weight were evaluated weekly. There was a small benefit in overall tumor reduction in animals treated with intraperitoneal chemotherapy applied through the slow release device compared with animals treated with intraperitoneal free chemotherapy, as evaluated through tumor weight - results in standardized mean difference. (-1.06; 95% CI: -1.34, -0.78) and tumor volume (-3.72; 95% CI: -4.47, -2.97), a benefit that was seen in most weekly evaluations and for most chemotherapy drugs, such as carboplatin (tumor weight: -5.60; 95% CI: -7.83, -3.37), paclitaxel (tumor weight: -1.18; 95% CI: -1.52, -0.83), and cisplatin (tumor volume: -2.85; 95% CI: -3.66, -2.04) carboplatin (tumor volume: -12.71; 95% CI: -17.35, -8.07); cisplatin (tumor volume: -7.76; 95% CI: -9.88, -5.65); paclitaxel (tumor volume: -2.85; 95% CI: -3.66, -2.04). Regarding animal weight, there was no weight reduction in animals treated with intraperitoneal chemotherapy applied through the slow-release device compared with animals treated with intraperitoneal free chemotherapy. However, significant heterogeneity was observed in some comparisons.

Conclusion

slow-release devices are overall safe and effective in animal models of ovarian cancer. It was not possible to evaluate which one is the most promising device to treat ovarian cancer, because many different types were used to apply chemotherapy intraperitoneally.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021224573.

A Comprehensive Review on Current Treatments and Challenges Involved in the Treatment of Ovarian Cancer

Ovarian cancer (OC) is the second most common gynaecological malignancy. It typically affects females over the age of 50, and since 75% of cases are only discovered at stage III or IV, this is a sign of a poor diagnosis. Despite intraperitoneal chemotherapy's chemosensitivity, most patients relapse and face death. Early detection is difficult, but treatment is also difficult due to the route of administration, resistance to therapy with recurrence, and the need for precise cancer targeting to minimize cytotoxicity and adverse effects. On the other hand, undergoing debulking surgery becomes challenging, and therapy with many chemotherapeutic medications has manifested resistance, a condition known as multidrug resistance (MDR). Although there are other therapeutic options for ovarian cancer, this article solely focuses on co-delivery techniques, which work via diverse pathways to overcome cancer cell resistance. Different pathways contribute to MDR development in ovarian cancer; however, usually, pump and non-pump mechanisms are involved. Striking cancerous cells from several angles is important to defeat MDR. Nanocarriers are known to bypass the drug efflux pump found on cellular membranes to hit the pump mechanism. Nanocarriers aid in the treatment of ovarian cancer by enhancing the delivery of chemotherapeutic drugs to the tumour sites through passive or active targeting, thereby reducing unfavorable side effects on the healthy tissues. Additionally, the enhanced permeability and retention (EPR) mechanism boosts the bioavailability of the tumour site. To address the shortcomings of conventional delivery, the current review attempts to explain the current conventional treatment with special reference to passively and actively targeted drug delivery systems (DDSs) towards specific receptors developed to treat ovarian cancer. In conclusion, tailored nanocarriers would optimize medication delivery into the intracellular compartment before optimizing intra-tumour distribution. Other novel treatment possibilities for ovarian cancer include tumour vaccines, gene therapy, targeting epigenetic alteration, and biologically targeted compounds. These characteristics might enhance the therapeutic efficacy.

Thermosensitive Hydrogels Loaded with Resveratrol Nanoemulsion: Formulation Optimization by Central Composite Design and Evaluation in MCF-7 Human Breast Cancer Cell Lines

The second most common cause of mortality among women is breast cancer. A variety of natural compounds have been demonstrated to be beneficial in the management of various malignancies. Resveratrol is a promising anticancer polyphenolic compound found in grapes, berries, etc. Nevertheless, its low solubility, and hence its low bioavailability, restrict its therapeutic potential. Therefore, in our study, we developed a thermosensitive hydrogel formulation loaded with resveratrol nanoemulsion to enhance its bioavailability. Initially, resveratrol nanoemulsions were formulated and optimized utilizing a central composite-face-centered design. The independent variables for optimization were surfactant level, homogenization speed, and time, while the size and zeta potential were the dependent variables. The optimized nanoemulsion formulation was converted into a sensitive hydrogel using poloxamer 407. Rheological studies proved the formation of gel consistency at physiological temperature. Drug loading efficiency and in vitro drug release from gels were also analyzed. The drug release mechanisms from the gels were assessed using various mathematical models. The effect of the optimized thermosensitive resveratrol nanoemulsion hydrogel on the viability of human breast cancer cells was tested using MCF-7 cancer cell lines. The globule size of the selected formulation was 111.54 ± 4.16 nm, with a zeta potential of 40.96 ± 3.1 mV. Within 6 h, the in vitro release profile demonstrated a release rate of 80%. According to cell line studies, the produced hydrogel of resveratrol nanoemulsion was cytotoxic to breast cancer cells. Overall, the results proved the developed nanoemulsion-loaded thermosensitive hydrogel is a promising platform for the effective delivery of resveratrol for the management of breast cancer.

Targeted Ultrafine Iron Oxide Nanoparticles for Delivery of the Topoisomerase Inhibitor SN38 and Ovarian Cancer Treatment

Ovarian cancer remains a challenge to decrease mortality and improve diagnostic efficiency in gynecological cancers. To develop a delivery system capable of efficient cancer cell targeting and delivering novel efficacious therapeutics, we assembled folic acid (FA) conjugated ultrafine iron oxide nanoparticles (uIONP) with encapsulation of DNA topoisomerase inhibitor SN38, which target ovarian cancer cells with over-expression of folate receptor alpha (FRα) and deliver SN38 to induce apoptosis. The assembled FA-uIONP-SN38 exhibited higher drug loading efficiency than the larger counterparts with core diameters more than 10 nm. The targeting specificity of FA-uIONP-SN38 for SKOV-3 cancer cells was validated, with HEK293 kidney cells and Raw264.7 macrophages as non-targeted cell line control. It was found that more SKOV-3 cancer cells were killed due to apoptosis by FA-uIONP-SN38 at the same SN38 dosages compared with uIONP-SN38 and free SN38, respectively. The delivery of this inhibitor to SKOV-3 cancer cells by FRα-targeted FA-uIONP carrier was enhanced by about 10-folds with less cytotoxicity comparing to the free drug SN38. The developed FA-uIONP-SN38 holds a great potential as a theranostic approach in treating ovarian cancer.

Maintenance Long-Term Multiple Cycles Treatment with Docetaxel in Metastatic Castration-Resistant Prostate Cancer: A Report of Three Cases

Prostate cancer (PCa) is one of the most common types of malignancy, most patients with PCa will eventually progress to metastatic castration-resistant prostate cancer (mCRPC), which has a poor prognosis. Since 2004, chemotherapy has been approved by the FDA as the first-line treatment for mCRPC, and docetaxel-based regimens have been shown to improve both the patients’ symptoms and overall survival (OS). 10 cycles of docetaxel therapy are usually given to patients with mCPRC, but there is still no consensus on the optimal number of treatment cycles. Here, we present three cases of mCRPC patients that received maintenance long-term multiple-cycles docetaxel treatment. We believe that this new treatment strategy may benefit carefully selected mCRPC patients and provide several key advantages such as maximum exposure to drugs, improvements in drug efficacy, and reduce the risk of developing drug resistance.

Pharmaceutical strategies in improving anti-tumour efficacy and safety of intraperitoneal therapy for peritoneal metastasis

Introduction: In selected patients with limited peritoneal metastasis (PM), favorable tumor biology, and a good clinical condition, there is an indication for combination of cytoreductive surgery (CRS) and subsequent intravenous (IV) or intraperitoneal (IP) chemotherapy. Compared with IV injection, IP therapy can achieve a high drug concentration within the peritoneal cavity with low systemic toxicity, however, the clinical application of IP chemotherapy is limited by the related abdominal pain, infection, and intolerance.Areas covered:To improve the anti-tumor efficacy and safety of IP therapy, various pharmaceutical strategies have been developed and show promising potential. This review discusses the specialized modification of traditional drug delivery systems and demonstrates the preparation of customized drug carriers for IP therapy, including chemotherapy and gene therapy. IP therapy has important clinical significance in the treatment of PM using novel anti-tumor agents as well as conventional drugs in new applications.Expert opinion: Although IP therapy exhibits good performance both in mouse models and in patients with PM in clinical trials, its clinical application remains limited due to the serious side effects and low acceptability. Further investigations, including pharmaceutical strategies, are needed to develop potential IP therapy, focusing on the efficacy and safety thereof.

Long-term drug delivery using implantable electrospun woven polymeric nanotextiles

A woven nanotextile implant was developed and optimized for long-term continuous drug delivery for potential oncological applications. Electrospun polydioxanone (PDS) nanoyarns, which are twisted bundles of PDS nanofibres, were loaded with paclitaxel (PTX) and woven into nanotextiles of different packing densities. A mechanistic modeling of in vitro drug release proved that a combination of diffusion and matrix degradation controlled the slow PTX-release from a nanoyarn, emphasizing the role of nanostructure in modulating release kinetics. Woven nanotextiles, through variations in its packing density and thereby architecture, demonstrated tuneable PTX-release. In vivo PTX-release, pharmacokinetics and biodistribution were evaluated in healthy BALB/c mice by suturing the nanotextile to peritoneal wall. The slow and metronomic PTX-release for 60 days from the loosely woven implant was extremely effective in enhancing its residence in peritoneum, in contrast to intraperitoneal injections. Such an implantable matrix offers a novel platform for therapy of solid tumors over prolonged durations.

Metronomic chemotherapy and immunotherapy in cancer treatment

Systemic chemotherapy given at maximum tolerated doses (MTD) has been the mainstay of cancer treatment for more than half a century. In some chemosensitive diseases such as hematologic malignancies and solid tumors, MTD has led to complete remission and even cure. The combination of maintenance therapy and standard MTD also can generate good disease control; however, resistance to chemotherapy and disease metastasis still remain major obstacles to successful cancer treatment in the majority of advanced tumors. Metronomic chemotherapy, defined as frequent administration of chemotherapeutic agents at a non-toxic dose without extended rest periods, was originally designed to overcome drug resistance by shifting the therapeutic target from tumor cells to tumor endothelial cells. Metronomic chemotherapy also exerts anti-tumor effects on the immune system (immunomodulation) and tumor cells. The goal of immunotherapy is to enhance host anti-tumor immunities. Adding immunomodulators such as metronomic chemotherapy to immunotherapy can improve the clinical outcomes in a synergistic manner. Here, we review the anti-tumor mechanisms of metronomic chemotherapy and the preliminary research addressing the combination of immunotherapy and metronomic chemotherapy for cancer treatment in animal models and in clinical setting.

A comparative investigation between paclitaxel nanoparticle- and nanocrystal-loaded thermosensitive PECT hydrogels for peri-tumoural administration

For in situ thermosensitive hydrogels, it is a big challenge to achieve high drug loading, long-term local retention, and effective drug release simultaneously. To address these issues, we combined the strategy of drug nanocrystals (NCs) and thermosensitive hydrogels with higher gel strength. In particular, we developed paclitaxel NC-based hydrogels using PECT, a thermosensitive polymer synthesized by us (PTX-NC-PECT), and a nanoparticle-based system was used as the control (PTX-NP-PECT). First, high levels of PTX could be loaded in both PECT hydrogels. Moreover, in vivo near infrared fluorescence (NIRF) imaging showed that both hydrogel systems were able to maintain the payloads of 1,1-dioctadecyltetramethyl indotricarbocyanine iodide (DiR) at a peri-tumoural site for at least 21 days, much longer than that achieved with the control hydrogel of Pluronic® F127. Furthermore, we observed that PTX-NCs released free PTX more effectively and homogeneously than PTX-NPs in vitro. It was further verified in vivo that the release of DiR from DiR-NC-PECT was more complete than that from DiR-NP-PECT. Finally, PTX-NC-PECT gel demonstrated the strongest anti-tumour efficacy on MCF-7 breast cancer. In conclusion, PTX-NC-PECT hydrogel might be a high-performance thermosensitive hydrogel for local cancer therapy.

Thermosensitive hydrogel system assembled by PTX-loaded copolymer nanoparticles for sustained intraperitoneal chemotherapy of peritoneal carcinomatosis

Intraperitoneal (IP) chemotherapy is a preferable treatment option for peritoneal carcinomatosis of malignancies by delivering chemotherapeutic drugs into the abdominal cavity. A persistent major challenge in IP chemotherapy is the need to provide effective drug concentration in the peritoneal cavity for an extended period of time. In the present work, the thermosensitive hydrogel system (PTX/PECT(gel)) assembled by PTX (paclitaxel)-loaded amphiphilic copolymer (PECT, poly (ε-caprolactone-co-1,4,8-trioxa [4.6]spiro-9-undecanone)-poly(ethylene glycol)-poly (ε-caprolactone-co-1,4,8-trioxa [4.6]spiro-9-undecanone)) nanoparticles was developed for sustained IP chemotherapy of peritoneal carcinomatosis model. Cytotoxicity assay indicated that PECT hydrogel was biocompatible with very low cytotoxicity and PTX/PECT(gel) had enhanced cytotoxicity than free PTX. In vivo toxicity study demonstrated the biocompatibility and biosafety of PECT hydrogel as an IP chemotherapy carrier. The fluorescence imaging method was employed to monitor the intraperitoneal degradation of PECT hydrogel by labeling PECT with rhodamine B. PECT hydrogel with the dose of 200μL showed about 8days' retention time and most of the injected hydrogel was located in the intestine. The anti-tumor efficacy study was carried out in mice bearing CT26 intraperitoneal ascites fluid as colorectal peritoneal carcinomatosis model. The result showed that intraperitoneal administration of PTX/PECT(gel) could effectively suppress growth and metastasis of CT26 peritoneal carcinomatosis in vivo, compared with Taxol® group. The pharmacokinetic studies demonstrated that PTX/PECT(gel) could improve the bioavailability of PTX by being formulated in PECT hydrogel. Overall, sustained drug concentration at peritoneal levels in combination with drug in the form of nanoparticle contributes to the enhanced anti-tumor efficacy. Thus, our results suggested that PTX/PECT(gel) may have great potential applications in IP chemotherapy.

In situ gel-forming dual drug delivery system for synergistic combination therapy of colorectal peritoneal carcinomatosis

A novel local drug delivery system composed of docetaxel loaded micelles and an oxaliplatin loaded hydrogel was fabricated and proved to be potentially useful in the treatment of colorectal peritoneal carcinomatosis.

The impact of sustained and intermittent docetaxel chemotherapy regimens on cognition and neural morphology in healthy mice

RATIONALE

A subset of cancer survivors demonstrates impairments in cognition long after chemotherapy completion. At present, it is unclear whether these changes are due to direct neurotoxic effects of chemotherapy.

OBJECTIVES

This study examined the impact of variable docetaxel (DTX) chemotherapy dosing on brain DTX exposure via analyses of neural morphology and changes in cognition.

METHODS

Male CD-1 mice were treated with DTX either intermittently (8 mg/kg i.p. weekly) or via a sustained delivery system (DTX-PoLigel), which continuously releases DTX. Both groups received total DTX doses of 32 mg/kg. Mice were assessed on the novel object recognition (NOR) task and the Morris water maze (MWM) shortly after treatment.

RESULTS

Post-treatment behavioral testing demonstrated impaired NOR in mice treated with either dosing schedule relative to controls. No differences were observed between groups in MWM training and initial testing, though control mice performed better than chance while DTX-treated mice did not. Appreciable amounts of DTX were found in the brain after both treatment regimens. DTX treatment did not significantly increase levels of apoptosis within the CNS. However, some elevation in neural autophagy was observed following DTX treatment. Analysis of astrocytic activation demonstrated that intermittent DTX treatment resulted in an elevation of GFAP-positive astrocytes for 48 h after administration. Sustained chemotherapy demonstrated prolonged but lower levels of astrocyte activation over 9 days following implantation.

CONCLUSIONS

DTX treatment induced cognitive impairment shortly after treatment. Further, these findings suggest an association between DTX dosing, neurotoxicity, and cognitive effects.

Active targeting using HER-2-affibody-conjugated nanoparticles enabled sensitive and specific imaging of orthotopic HER-2 positive ovarian tumors

Despite advances in cancer diagnosis and treatment, ovarian cancer remains one of the most fatal cancer types. The development of targeted nanoparticle imaging probes and therapeutics offers promising approaches for early detection and effective treatment of ovarian cancer. In this study, HER-2 targeted magnetic iron oxide nanoparticles (IONPs) are developed by conjugating a high affinity and small size HER-2 affibody that is labeled with a unique near infrared dye (NIR-830) to the nanoparticles. Using a clinically relevant orthotopic human ovarian tumor xenograft model, it is shown that HER-2 targeted IONPs are selectively delivered into both primary and disseminated ovarian tumors, enabling non-invasive optical and MR imaging of the tumors as small as 1 mm in the peritoneal cavity. It is determined that HER-2 targeted delivery of the IONPs is essential for specific and sensitive imaging of the HER-2 positive tumor since we are unable to detect the imaging signal in the tumors following systemic delivery of non-targeted IONPs into the mice bearing HER-2 positive SKOV3 tumors. Furthermore, imaging signals and the IONPs are not detected in HER-2 low expressing OVCAR3 tumors after systemic delivery of HER-2 targeted-IONPs. Since HER-2 is expressed in a high percentage of ovarian cancers, the HER-2 targeted dual imaging modality IONPs have potential for the development of novel targeted imaging and therapeutic nanoparticles for ovarian cancer detection, targeted drug delivery, and image-guided therapy and surgery.

Four-arm PEG cross-linked hyaluronic acid hydrogels containing PEGylated apoptotic TRAIL protein for treating pancreatic cancer

Four-arm polyethylene glycol (PEG) cross-linked hyaluronic acid (HA) hydrogels containing PEGylated tumor necrosis factor-related apoptosis-inducing ligand (PEG-TRAIL) were fabricated, and their antitumor effects were evaluated in pancreatic cell (Mia Paca-2)-xenografted mice. HA was conjugated with 4-arm PEG(10k)-amine (a cross-linker) at ratios of 100:1 and 100:2 using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride as a cross-linker, and TRAIL or PEG-TRAIL was incorporated into these HA hydrogels. HA hydrogels at a 100:1 ratio were prepared in good yields (>88%), were moderately stiff, and gradually released PEG-TRAIL over ~14 days in vitro and over ~7 days in vivo (as determined by high-pressure liquid chromatography and infrared imaging). The released PEG-TRAIL was found to have obvious apoptotic activity in Mia Paca-2 cells. PEG-TRAIL HA hydrogels displayed remarkably more antitumor efficacy than TRAIL HA hydrogels in Mia Paca-2 cell-xenografted mice in terms of tumor volumes (size) and weights (453.2mm(3) and 1.03 g vs. 867.5mm(3) and 1.86 g). Furthermore, this improved antitumor efficacy was found to be due to the apoptotic activity of PEG-TRAIL in vivo (determined by a TUNEL assay) despite its substantially lower cytotoxicity than native TRAIL (IC50 values: 71.8 and 202.5 ng ml(-1), respectively). This overall enhanced antitumor effect of PEG-TRAIL HA hydrogels appeared to be due to the increased stability of PEGylated TRAIL in HA hydrogels. These findings indicate that this HA hydrogel system combined with PEG-TRAIL should be considered a potential candidate for the treatment of pancreatic cancer.

Continuous intraperitoneal carboplatin delivery for the treatment of late-stage ovarian cancer

The rate of failure of chemotherapy treatment in ovarian cancer remains high, resulting in a low 5-year survival rate of 20-40% in patients that present with advanced-stage disease. Treatment-free periods between cycles of chemotherapy may contribute to accelerated tumor cell proliferation and decreased treatment response. The elimination of treatment-free breaks has been deemed beneficial in the context of cell-cycle-specific agents. The potential benefit of this approach for non-cell-cycle-specific agents has not yet been elucidated. The present study is the first to address this issue by investigating the impact of continuous versus intermittent intraperitoneal administration of carboplatin over a 14 day period to SCID mice bearing SKOV-3 ovarian cancer xenografts. Immunostaining of tumor sections was employed to quantify tumor proliferation, angiogenesis, and apoptosis using Ki-67, CD-31, caspase-3 (CASP3), and terminal deoxytransferase-mediated dUTP nick-end labeling (TUNEL). Continuous ip administration of carboplatin resulted in greater tumor growth inhibition than intermittent therapy (p < 0.05). Significantly greater tumor cell apoptosis and less cell proliferation and angiogenesis were measured in tumors of mice treated with continuous carboplatin as compared to both intermittent and control groups. These results indicate that continuous local administration may be a promising approach to improve the effectiveness of platinum-based chemotherapy regimens.

Thermosensitive depot-forming injectable phosphatidylcholine blends tailored for localized drug delivery

A thermosensitive depot-forming system was developed for sustained and localized delivery of the anticancer drug, paclitaxel. The formulation is injectable as a melt slightly above the body temperature and forms a solid depot upon cooling to 37°C. The thermosensitive system was prepared by blending various combinations of phosphatidylcholines at specific weight ratios solubilized in laurinaldehyde. Of the blends investigated, distearoyl-phosphatidylcholine (DSPC) and egg-phosphatidylcholine (ePC) were found to be most miscible. A liquid-to-gel phase transition temperature (TC ) of 39°C was observed for the 70:30 (w/w) DSPC-ePC blend and a TC of 38.4°C with the addition of paclitaxel. Blends containing higher concentrations of ePC had a greater degree of swelling and weight loss. Furthermore, microscopy revealed an increase in porosity and erosion as the amount of ePC was increased in blends incubated in biologically relevant media. DSPC-ePC blends provided sustained release of paclitaxel over a 30-day period and the rate of drug release increased as the amount of ePC increased. Overall, the relationships established between the composition and properties of the blend may be employed to tailor the thermosensitive injectable formulation for localized chemotherapy of solid tumors.

Preclinical analysis of resistance and cross-resistance to low-dose metronomic chemotherapy

Low-dose metronomic chemotherapy is an emerging form of chemotherapy with distinct mechanisms of action from conventional chemotherapy (e.g., antiangiogenesis). Although developed to overcome resistance to conventional chemotherapy, metronomic chemotherapy is subject to resistance on its own. However, there is a paucity of information on mechanisms of resistance, on cross-resistance between metronomic regimens using different cytotoxic drugs, and on cross-resistance between metronomic versus conventional chemotherapy, or versus targeted antiangiogenic therapy. Herein we show that PC-3 human prostate cancer xenografts were sensitive to both metronomic cyclophosphamide and metronomic docetaxel, but resistant to metronomic topotecan. Conventional docetaxel was only moderately active in parental PC-3 and in metronomic cyclophosphamide resistant PC-3 tumors. However, in metronomic cyclophosphamide resistant PC-3 tumors combining conventional docetaxel or bolus cyclophosphamide therapy with continued metronomic cyclophosphamide was superior to each treatment alone. Furthermore, bevacizumab had single-agent activity against metronomic cyclophosphamide resistant PC-3 tumors. Microarray analyses identified altered regulation of protein translation as a potential mechanism of resistance to metronomic cyclophosphamide. Our results suggest that sensitivity to metronomic chemotherapy regimens using different cytotoxic drugs not only depends on shared mechanisms of action such as antiangiogenesis, but also on as yet unknown additional antitumor effects that appear to be drug-specific. As clinically observed with targeted antiangiogenic agents, the continued use of metronomic chemotherapy beyond progression may amplify the effects of added second-line therapies or vice versa. However, metronomic chemotherapy is no different from other systemic therapies in that predictive biomarkers will be essential to fully exploit this novel use of conventional chemotherapeutics.

The short and long term effects of docetaxel chemotherapy on rodent object recognition and spatial reference memory

AIMS

Previous animal studies have examined the potential for cytostatic drugs to induce learning and memory deficits in laboratory animals but, to date, there is no pre-clinical evidence that taxanes have the potential to cause cognitive impairment. Therefore our aim was to explore the short- and long-term cognitive effects of different dosing schedules of the taxane docetaxel (DTX) on laboratory rodents.

MAIN METHODS

Healthy male hooded Wistar rats were treated with DTX (6 mg/kg, 10mg/kg) or physiological saline (control), once a week for 3 weeks (Experiment 1) or once only (10mg/kg; Experiment 2). Cognitive function was assessed using the novel object recognition (NOR) task and spatial water maze (WM) task 1 to 3 weeks after treatment and again 4 months after treatment.

KEY FINDINGS

Shortly after DTX treatment, rats perform poorly on NOR regardless of treatment regimen. Treatment with a single injection of 10mg/kg DTX does not appear to induce sustained deficits in object recognition or peripheral neuropathy.

SIGNIFICANCE

Overall these findings show that treatment with the taxane DTX in the absence of cancer and other anti-cancer treatments causes cognitive impairment in healthy rodents.

Docetaxel-loaded thermoresponsive conjugated linoleic acid-incorporated poloxamer hydrogel for the suppression of peritoneal metastasis of gastric cancer

We evaluated the potential of a thermoresponsive hydrogel consisting of conjugated linoleic acid-coupled Pluronic F-127 (Plu-CLA) as a controlled release, intraperitoneal delivery system for docetaxel with the aim of treating peritoneal dissemination of gastric cancer. Previously, we established a peritoneal metastasis model that involves the injection of BALB/c mice with TMK1 human gastric cancer cells. One week after the TMK1 cells were injected, the mice were injected intraperitoneally with docetaxel alone or docetaxel-loaded Plu-CLA. Tumor progression and response to therapy were monitored by micro-positron emission tomography. The total number of peritoneal tumors and the ascites volume were also measured. Compared with docetaxel alone, the combination of docetaxel and Plu-CLA (docetaxel-Plu-CLA) significantly and synergistically reduced tumor cell survival. Docetaxel-Plu-CLA showed excellent anti-tumor activity, inducing apoptosis more potently than docetaxel alone. Docetaxel-Plu-CLA also significantly reduced the number of peritoneal metastatic nodules and increased survival in the peritoneal gastric cancer xenograft model. Our results show that intraperitoneal administration of docetaxel-Plu-CLA synergistically inhibits peritoneal metastasis and prolongs survival in a peritoneal gastric cancer model. Therefore, Plu-CLA is a potential intraperitoneal-route carrier for hydrophobic docetaxel for the effective treatment of peritoneal metastatic gastric cancer.

Concentration- and schedule-dependent effects of chemotherapy on the angiogenic potential and drug sensitivity of vascular endothelial cells

The anti-angiogenic activity of chemotherapy is both dose- and schedule-dependent. While conventional maximum tolerated dose (MTD) chemotherapy exerts only mild and reversible anti-angiogenic effects, low-dose metronomic (LDM) chemotherapy was developed to specifically target tumour angiogenesis. However, the long-term effects of either MTD or LDM chemotherapy on vascular endothelial cells have never been investigated. Here, we demonstrated that repeated exposure to MTD and LDM chemotherapy differentially impact on the angiogenic potential and chemosensitivity of immortalized endothelial cells. Repeated MTD vinblastine treatment of vascular endothelial cells led to an increased proliferation rate and resistance to paclitaxel. In contrast, repeated LDM treatment with vinblastine or etoposide impaired the angiogenic potential of endothelial cells and increased their chemosensitivity. This effect was associated with a significant decrease in βII- and βIII-tubulin expression. Functional analysis using siRNA showed that silencing the expression of βIII-tubulin in endothelial cells significantly decreased their capacity to form vascular structures and increased their sensitivity to the anti-angiogenic and vascular-disrupting effects of chemotherapy, whereas silencing βII-tubulin expression had no effect. Collectively our results show that LDM chemotherapy impairs the angiogenic potential of endothelial cells while increasing their chemosensitivity-an effect at least in part mediated by the down-regulation of βIII-tubulin expression. Furthermore, our study suggests that βIII-tubulin represents an attractive therapeutic target to increase the anti-angiogenic effects of chemotherapy and overall anti-tumour efficacy.

An injectable depot system for sustained intraperitoneal chemotherapy of ovarian cancer results in favorable drug distribution at the whole body, peritoneal and intratumoral levels

The current study characterizes the impact of docetaxel (DTX) distribution on efficacy following sustained intraperitoneal (IP) chemotherapy in murine models of ovarian cancer. A polymer-lipid biodegradable depot (PoLigel) was used to deliver DTX in a sustained manner over 21-days following IP administration. Distribution and efficacy studies were carried out in SCID mice bearing SKOV3 IP solid tumors or C57BL/6 mice with ID8 IP ascites fluid. In addition, a subcutaneous (SC) SKOV3 model was used to determine whether systemic drug levels that result from IP administration of the PoLigel influence antitumor efficacy. Immunostained IP and SC SKOV3 tumor sections were used to study cell death, intratumoral drug distribution and tumor penetration. Sustained concentrations of DTX were observed in plasma, tissue, tumor and ascites over the entire study period. Drug accumulation was several fold greater in tumors and ascites when compared to plasma levels. Sustained chemotherapy resulted in significant reduction in tumor burden and ascites volume. IP tumors showed greater cell death compared to the SC tumors as seen by higher TUNEL and caspase-3 expression. At the intratumoral level, DTX distributed more towards the core of IP tumors compared to the SC tumors. Tumor penetration of drug from nearest blood vessel was 1.5 fold greater in the IP tumors than the SC tumors. Overall, favorable drug distribution at the whole-body, peritoneal and intratumoral levels in combination with local and systemic sustained drug exposure contribute to the high efficacy observed. These results encourage the clinical use of IP sustained chemotherapy for ovarian cancer.

Synthetic modification of carboxymethylcellulose and use thereof to prepare a nanoparticle forming conjugate of docetaxel for enhanced cytotoxicity against cancer cells

A nanoparticle formulation of docetaxel (DTX) was designed to address the strengths and limitations of current taxane delivery systems: PEGylation, high drug conjugation efficiency (>30 wt %), a slow-release mechanism, and a well-defined and stable nanoparticle identity were identified as critical design parameters. The polymer conjugate was synthesized with carboxymethylcellulose (CMC), an established pharmaceutical excipient characterized by a high density of carboxylate groups permitting increased conjugation of a drug. CMC was chemically modified through acetylation to eliminate its gelling properties and to improve solvent solubility, enabling high yield and reproducible conjugation of DTX and poly(ethylene glycol) (PEG). The optimal conjugate formulation (Cellax) contained 37.1 ± 1.5 wt % DTX and 4.7 ± 0.8 wt % PEG, exhibited a low critical aggregation concentration of 0.6 μg/mL, and formed 118-134 nm spherical nanoparticles stable against dilution. Conjugate compositions with a DTX degree of substitution (DS) outside the 12.3-20.8 mol % range failed to form discrete nanoparticles, emphasizing the importance of hydrophobic and hydrophilic balance in molecular design. Cellax nanoparticles released DTX in serum with near zero order kinetics (100% in 3 weeks), was internalized in murine and human cancer cells, and induced significantly higher toxic effects against a panel of tumor cell lines (2- to 40-fold lower IC50 values) compared to free DTX.

Synergistic enhancement of cancer therapy using a combination of docetaxel and photothermal ablation induced by single-walled carbon nanotubes

Background

Single-walled carbon nanotubes (SWNT) are poorly soluble in water, so their applications are limited. Therefore, aqueous solutions of SWNT, designed by noncovalent functionalization and without toxicity, are required for biomedical applications.

Methods

In this study, we conjugated docetaxel with SWNT via π-π accumulation and used a surfactant to functionalize SWNT noncovalently. The SWNT were then conjugated with docetaxel (DTX-SWNT) and linked with NGR (Asn-Gly-Arg) peptide, which targets tumor angiogenesis, to obtain a water-soluble and tumor-targeting SWNT-NGR-DTX drug delivery system.

Results

SWNT-NGR-DTX showed higher efficacy than docetaxel in suppressing tumor growth in a cultured PC3 cell line in vitro and in a murine S180 cancer model. Tumor volumes in the S180 mouse model decreased considerably under near-infrared radiation compared with the control group.

Conclusion

The SWNT-NGR-DTX drug delivery system may be promising for high treatment efficacy with minimal side effects in future cancer therapy.

Anti-MUC1 monoclonal antibody (C595) and docetaxel markedly reduce tumor burden and ascites, and prolong survival in an in vivo ovarian cancer model

MUC1 is associated with cellular transformation and tumorigenicity and is considered as an important tumor-associated antigen (TAA) for cancer therapy. We previously reported that anti-MUC1 monoclonal antibody C595 (MAb C595) plus docetaxel (DTX) increased efficacy of DTX alone and caused cultured human epithelial ovarian cancer (EOC) cells to undergo apoptosis. To further study the mechanisms of this combination-mediated apoptosis, we investigated the effectiveness of this combination therapy in vivo in an intraperitoneal (i.p.) EOC mouse model. OVCAR-3 cells were implanted intraperitoneally in female athymic nude mice and allowed to grow tumor and ascites. Mice were then treated with single MAb C595, DTX, combination test (MAb C595 and DTX), combination control (negative MAb IgG₃ and DTX) or vehicle control i.p for 3 weeks. Treated mice were killed 4 weeks post-treatment. Ascites volume, tumor weight, CA125 levels from ascites and survival of animals were assessed. The expression of MUC1, CD31, Ki-67, TUNEL and apoptotic proteins in tumor xenografts was evaluated by immunohistochemistry. MAb C595 alone inhibited i.p. tumor growth and ascites production in a dose-dependent manner but did not obviously prevent tumor development. However, combination test significantly reduced ascites volume, tumor growth and metastases, CA125 levels in ascites and improved survival of treated mice compared with single agent-treated mice, combination control or vehicle control-treated mice (P<0.05). The data was in a good agreement with that from cultured cells in vitro. The mechanisms behind the observed effects could be through targeting MUC1 antigens, inhibition of tumor angiogenesis, and induction of apoptosis. Our results suggest that this combination approach can effectively reduce tumor burden and ascites, prolong survival of animals through induction of tumor apoptosis and necrosis, and may provide a potential therapy for advanced metastatic EOC.

Core-shell biodegradable nanoassemblies for the passive targeting of docetaxel: features, antiproliferative activity and in vivo toxicity

Amphiphilic block copolymers of poly(ɛ-caprolactone) and poly(ethylene oxide) were assembled in core-shell nanoparticles (NPs) by a melting-sonication technique (MeSo). The entrapment of the poorly water-soluble anticancer drug docetaxel (DTX), nanocarrier cytotoxicity toward different cells and toxicity in mice were investigated. The encapsulation mechanism was rationalized and related to copolymer properties such as crystallinity and drug solubility in the copolymer phase. DTX release from NPs occurred in 2 drug pulses over 30 days. DTX entrapment in NPs strongly decreased haemolysis of erythrocytes in comparison with a commercial DTX formulation. In comparison with free DTX, NPs were both more efficient in inhibiting cell growth of breast and prostate cancer cells and less toxic in experimental animal models. The results of this study indicate that MeSo is an interesting technique for the achievement of peculiar core-shell nanocarriers for the passive targeting and sustained release of poorly water-soluble anticancer drugs.

FROM THE CLINICAL EDITOR

In this study, stealth nanoparticles of PEO/PCL block copolymers for passive targeting of docetaxel to solid tumors were developed using a novel technique. The studied properties of NPs suggest strong potential as anticancer drug-delivery system.

Chemotherapy dosing schedule influences drug resistance development in ovarian cancer

Drug resistance leads to chemotherapy failure and is responsible for the death of a great majority of patients with metastatic, late-stage ovarian cancer. The present study addressed whether changes in the chemotherapy dosing schedule affect the development, further worsening, or circumvention of drug resistance in chemosensitive and chemoresistant ovarian cancer. Severe combined immunodeficient mice bearing HeyA8 and HeyA8-MDR xenografts were treated with docetaxel intermittently (1×/wk or 3×/wk) or continuously for 21 days. Tumor mRNA expression of genes implicated in docetaxel resistance was measured by quantitative real-time-PCR. Analyzed genes included those encoding for the drug efflux transporters mdr1 and mrp7 and for molecules that interfere with or overcome the effects of docetaxel, including β-tubulinIII, actinin4, stathmin1, bcl2, rpn2, thoredoxin, and akt2. In both models, continuous docetaxel resulted in greater antitumor efficacy than 1×/wk or 3×/wk dosing and did not induce upregulation of any analyzed genes. Once weekly dosing caused upregulation of various drug resistance-related genes, especially in chemoresistant xenografts. More frequent, 3×/wk dosing diminished this effect, although levels of various genes were higher than for continuous chemotherapy. Drug efflux transporter expression was further examined by Western blotting, confirming that intermittent, but not continuous, docetaxel induced significant upregulation. Overall, our results show that the presence and length of treatment-free intervals contribute to the development of drug resistance. Elimination of these intervals by continuous dosing resulted in superior antitumor efficacy and prevented drug resistance induction in chemosensitive and chemoresistant disease. These results encourage the clinical implementation of continuous chemotherapy to overcome and/or prevent drug resistance in newly diagnosed and recurrent, refractory ovarian cancer.