Intraductally administered pegylated liposomal doxorubicin reduces mammary stem cell function in the mammary gland but in the long term, induces malignant tumors

Tantalum oxide nanoparticles as versatile and high-resolution X-ray contrast agent for intraductal image-guided ablative procedure in rodent models of breast cancer

There are limited options for primary prevention of breast cancer (BC). Experimental procedures to locally prevent BC have shown therapeutic efficacy in animal models. To determine the suitability of FDA-approved iodine-containing and various metal-containing (bismuth, gold, iodine, or tantalum) preclinical nanoparticle-based contrast agents for image-guided intraductal (ID) ablative treatment of BC in rodent models, we performed a prospective longitudinal study to determine the imaging performance, local retention and systemic clearance, safety profile, and compatibility with ablative solution of each contrast agent. At least six abdominal mammary glands (>3 female FVB/JN mice and/or Sprague-Dawley rats, 10-11 weeks of age) were intraductally injected with commercially available contrast agents (Omnipaque® 300, Fenestra® VC, MVivoTM Au, MVivoTM BIS) or in-house synthesized tantalum oxide (TaOx) nanoparticles. Contrast agents were administered at stock concentration or diluted in 70% ethanol (EtOH) and up to 1% ethyl cellulose (EC) as gelling agent to assess their compatibility with our image-guided ablative procedure. Mammary glands were serially imaged by microCT for up to 60 days after ID delivery. Imaging data were analyzed by radiologists and deep learning to measure in vivo signal disappearance of contrast agents. Mammary glands and major organs were ultimately collected for histopathological examination. TaOx-containing solutions provided best imaging performance for nitid visualization of ductal tree immediately after infusion, low outward diffusion (<1 day) and high homogeneity. Of all nanoparticles, TaOx had the highest local clearance rate (46% signal decay as stock and 36% as ablative solution 3 days after ID injection) and exhibited low toxicity. TaOx-containing ablative solution with 1% EC caused same percentage of epithelial cell death (88.62% ± 7.70% vs. 76.38% ± 9.99%, p value = 0.089) with similar minimal collateral damage (21.56 ± 5.28% vs. 21.50% ± 7.14%, p value = 0.98) in mouse and rat mammary glands, respectively. In conclusion, TaOx-nanoparticles are a suitable and versatile contrast agent for intraductal imaging and image-guided ablative procedures in rodent models of BC with translational potential to humans.

Systemic and Local Strategies for Primary Prevention of Breast Cancer

One in eight women will develop breast cancer in the US. For women with moderate (15-20%) to average (12.5%) risk of breast cancer, there are few options available for risk reduction. For high-risk (>20%) women, such as BRCA mutation carriers, primary prevention strategies are limited to evidence-based surgical removal of breasts and/or ovaries and anti-estrogen treatment. Despite their effectiveness in risk reduction, not many high-risk individuals opt for surgical or hormonal interventions due to severe side effects and potentially life-changing outcomes as key deterrents. Thus, better communication about the benefits of existing strategies and the development of new strategies with minimal side effects are needed to offer women adequate risk-reducing interventions. We extensively review and discuss innovative investigational strategies for primary prevention. Most of these investigational strategies are at the pre-clinical stage, but some are already being evaluated in clinical trials and others are expected to lead to first-in-human clinical trials within 5 years. Likely, these strategies would be initially tested in high-risk individuals but may be applicable to lower-risk women, if shown to decrease risk at a similar rate to existing strategies, but with minimal side effects.

Contributions of nanotechnology to the intraductal drug delivery for local treatment and prevention of breast cancer

Breast cancer is a major public health problem, affecting millions of people. It is a very heterogeneous disease, with localized and invasive forms, and treatment generally consists of a combination of surgery and radiotherapy followed by administration of estrogen receptor modulators or aromatase inhibitors. Given its heterogeneity, management strategies that take into consideration the type of disease and biological markers and can provide more personalized and local treatment are required. More recently, the intraductal administration (i.e., into the breast ducts) of drugs has attracted significant attention due to its ability of providing drug distribution through the ductal tree in a minimally invasive manner. Although promising, intraductal administration is not trivial, and difficulties in duct identification and cannulation are important challenges to the further development of this route. New drug delivery strategies such as nanostructured systems can help to achieve the full benefits of the route due to the possibility of prolonging tissue retention, improving targeting and selectivity, increasing cytotoxicity and reducing the frequency of administration. This review aims at discussing the potential benefits and challenges of intraductal administration, focusing on the design and use of nanocarriers as innovative and feasible strategies for local breast cancer therapy and prevention.

X-Ray Visualization of Intraductal Ethanol-Based Ablative Treatment for Prevention of Breast Cancer in Rat Models

There are still a limited number of primary interventions for prevention of breast cancer. For women at a high risk of developing breast cancer, the most effective intervention is prophylactic mastectomy. This is a drastic surgical procedure in which the mammary epithelial cells that can give rise to breast cancer are completely removed along with the surrounding tissue. The goal of this protocol is to demonstrate the feasibility of a minimally invasive intraductal procedure that could become a new primary intervention for breast cancer prevention. This local procedure would preferentially ablate mammary epithelial cells before they can become malignant. Intraductal methods to deliver solutions directly to these epithelial cells in rodent models of breast cancer have been developed at Michigan State University and elsewhere. The rat mammary gland consists of a single ductal tree that has a simpler and more linear architecture compared to the human breast. However, chemically induced rat models of breast cancer offer valuable tools for proof-of-concept studies of new preventive interventions and scalability from mouse models to humans. Here, a procedure for intraductal delivery of an ethanol-based ablative solution containing tantalum oxide nanoparticles as X-ray contrast agent and ethyl cellulose as gelling agent into the rat mammary ductal tree is described. Delivery of aqueous reagents (e.g., cytotoxic compounds, siRNAs, AdCre) by intraductal injection has been described previously in mouse and rat models. This protocol description emphasizes methodological changes and steps that pertain uniquely to delivering an ablative solution, formulation consideration to minimize local and systemic side effects of the ablative solution, and X-ray imaging for in vivo assessment of ductal tree filling. Fluoroscopy and micro-CT techniques enable to determine the success of ablative solution delivery and the extent of ductal tree filling thanks to compatibility with the tantalum-containing contrast agent.

Intraductal Delivery and X-ray Visualization of Ethanol-Based Ablative Solution for Prevention and Local Treatment of Breast Cancer in Mouse Models

Breast cancer is the most prevalent cancer and the second-leading cause of cancer-related death for women in the USA. For high-risk women, prophylactic mastectomy is the most effective primary prevention strategy. Prophylactic mastectomy is an aggressive surgical procedure that completely removes the mammary epithelial cells from which breast cancer arises along with the surrounding tissue. We seek to develop a minimally invasive intraductal procedure as an alternative to prophylactic mastectomy to locally ablate the mammary epithelial cells before they can become malignant. We and others have developed an intraductal delivery procedure to reach and treat these epithelial cells in rodent models of breast cancer. While the mouse mammary gland with a single non-anastomosed ductal tree opening at the nipple has a much less complex and tortuous architecture than the human breast, chemically induced and genetically engineered mouse models of breast cancer are valuable to produce proof-of-concept studies of new preventative strategies. Here, we describe a procedure for intraductal delivery of an ethanol-based ablative solution containing micro-CT/X-ray tantalum-based contrast agent within the mouse mammary ductal tree for the therapeutic purpose of primary prevention of breast cancer. Intraductal delivery of aqueous reagents (e.g., cytotoxic compounds, siRNAs, AdCre) has been previously described in mouse models. Thus, we focus our protocol description on methodological modifications and unique experimental considerations for optimizing delivery of ethanol, for minimizing local and systemic side effects of ethanol administration, and for in vivo visualization of ductal tree filling via micro-CT/fluoroscopy imaging. Visualization of the ductal tree immediately after injection of a contrast-containing solution allows for confirmation of complete filling or unsuccessful outcomes such as underfilling or overfilling. This procedure can be applied for delivery and imaging of other ablative compounds aimed at either preventing tumor formation or locally treating early-stage tumors accessible via the ductal tree.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

Exploring potential formulation strategies for chemoprevention of breast cancer: a localized delivery perspective

This review focuses on the various formulation approaches that have been explored to achieve localized delivery in breast cancer. The rationale behind the necessity of localized drug delivery has been extensively reviewed. The review also emphasizes the various possible routes for achieving localized drug delivery. Particularly, different types of nanoplatforms like lipid-based drug carriers, polymeric particles, hydrogels, drug conjugates and other formulation strategies like microneedles and drug-eluting implants, which have been used to increase tumor retention and subsequently halt tumor progression, have been deliberated here. In addition, the significant challenges that may be encountered in the delivery of anticancer drugs and the aspects that require careful evaluation for effective localized delivery of chemotherapeutic agents have been discussed.

Intraductal administration of N-methyl-N-nitrosourea as a novel rodent mammary tumor model

Background

Chemically induced animal models of breast cancer (BC) using N-methyl-N-nitrosourea (MNU) have been widely used in preclinical research. The conventional approach entails intraperitoneal (i.p) or intravenous injection of a carcinogen, leading to tumor induction at unpredictable locations. This study aimed to establish a modified MNU-induced rat mammary tumor model using intraductal (i.duc) administration and to evaluate its biological behavior, morphology, and response to chemotherapy drugs.

Methods

In a pilot experiment, female Sprague-Dawley (SD) rats were injected with either i.duc MNU or vehicle to test the feasibility of this approach. We explored the appropriate dosage for stable tumor formation in pubescent female SD rats by testing a single i.duc dose of MNU (0.5, 1.0 and 2.0 mg) or vehicle.

Results

An i.duc injection of 20 µL (1 mg/per duct) MNU in the fourth rat mammary gland induced stable carcinomas in situ. Immunohistochemical (IHC) analysis showed positive expression of estrogen receptor (ER), negative expression of human epidermal growth factor receptor 2 (Her-2), and low expression of Ki-67. Histopathology revealed atypical hyperplasia in the mammary gland 4 weeks after carcinogen injection, developing into carcinoma in situ 5-6 weeks after treatment, with loss of α-SMA and calponin expressions during tumor progression. Albumin-bound paclitaxel (nab-PTX) was injected i.duc and intravenously (i.v) 5 weeks after administration of MNU. The tumor growth rate of the nab-PTX i.duc-treated group was lower than in the i.v and control groups. The number of TUNEL-positive apoptotic cells was significantly higher in the nab-PTX i.duc-treated group.

Conclusions

Using i.duc MNU (20 µL, 1 mg) to establish a rat mammary tumor model resulted in a predictable location in the rat mammary gland and exhibited better consistency; i.duc administration of nab-PTX permitted a smaller drug dose, but produced a better drug response, than i.v injection.

Circular RNA Arhgap12 modulates doxorubicin-induced cardiotoxicity by sponging miR-135a-5p

AIM

This study aimed to investigate the regulatory role of differentially-expressed circular RNAs (circRNAs) in mouse cardiomyocytes during doxorubicin (DOX)-induced cardiotoxicity.

MAIN METHODS

Two groups of mice were injected with equal volumes (0.1 mL) of normal saline and DOX. Mouse heart tissue was isolated and digested for total RNA extraction and then subjected to next-generation RNA-sequencing. Expression profiles of circRNAs and circRNA-miRNA-mRNA networks were also constructed. Overall, 48 upregulated and 16 downregulated circRNAs were found to be statistically significant (p < 0.05) in the DOX-injected group. Bioinformatics analysis revealed several potential biological pathways that might be related to apoptosis caused by DOX-induced cardiotoxicity. In addition, using qRT-PCR, we found that a circRNA coded by the Arhgap12 gene, termed circArhgap12, was upregulated in the mouse heart tissue upon DOX intervention. CircArhgap12 enhanced apoptotic cell rate, as assessed using terminal-deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay, and increased reactive oxygen species and malondialdehyde release as well as superoxide dismutase and caspase-3 activation. Using a luciferase reporter assay, we found that circArhgap12 could sponge miR-135a-5p. In rat primary cardiomyocytes, we found that si-circArhgap12 promoted apoptosis and oxidative stress by sponging the miR-135a-5p inhibitor. Using bioinformatics analysis and luciferase reporter assay, we found that miR-135a-5p might have a potential target site for ADCY1 mRNA.

KEY FINDINGS

Our research demonstrated that the expression profile of circRNAs was modified significantly and that circArhgap12 might play a competitive role among endogenous RNAs in mouse cardiomyocytes during DOX-induced cardiotoxicity.

SIGNIFICANCE

Our study may provide a preliminary understanding of DOX-induced cardiotoxicity modulated by circRNA and its competing endogenous RNAs network.

Intraductal Therapy in Breast Cancer: Current Status and Future Prospective

With our improved understanding of the biological behavior of breast cancer, minimally invasive intervention is urgently needed for personalized treatment of early disease. Intraductal therapy is one such minimally invasive approach. With the help of appropriate tools, technologies using the intraductal means of entering the ducts may be used both to diagnose and treat lesions in the mammary duct system with less trauma and at the same time avoid systemic toxicity. Traditional agents such as those targeting pathways, endocrine therapy, immunotherapy, or gene therapy can be used alone or combined with other new technologies, such as nanomaterials, through the intraductal route. Additionally, relevant mammary tumor models in rodents which reflect changes in the tumor microenvironment will help deepen our understanding of their biological behavior and heterogeneity. This article reviews the current status and future prospects of intraductal therapy in breast cancer, with emphasis on ductal carcinoma in situ.

Intraductal fulvestrant for therapy of ERα-positive ductal carcinoma in situ of the breast: a preclinical study

Mammographic screening for breast cancer has led to increased detection of ductal carcinoma in situ (DCIS) and a reappraisal of the necessity of aggressive treatment with their attendant toxicities for a preneoplastic lesion. Fulvestrant, a selective estrogen receptor degrader, is very effective in the treatment of estrogen receptor positive (ER+) breast cancer, but delivery by the painful intramuscular (i.m) route is limiting. We hypothesized that intraductal (i.duc) administration of fulvestrant will provide a direct, safe and effective treatment for DCIS. Mice bearing mammary ductal xenografts of ER+, luciferase-tagged MCF-7 breast cancer cells were administered vehicle or fulvestrant i.m or i.duc. I.duc MCF-7-luc tumors in mice treated with fulvestrant i.duc or i.m grew significantly slower than vehicle control. Whole mount analysis and histopathology showed that i.duc fulvestrant achieved significantly larger cancer-free areas. Western blot analysis showed reduced levels of estrogen receptor alpha (ERα) and its downstream targets, c-Myc and Cyclin D1, and increased levels of ERβ, which is known to inhibit ERα function. Immunohistochemical analysis of tumor sections showed that Ki67 and ERα protein levels decreased by 3-fold, and neoangiogenesis was inhibited by i.duc fulvestrant treatment. I.duc fulvestrant also reduced outgrowth of ERα+, autochthonous N-methyl-N-nitrosourea-induced mammary tumors in rats. Overall, we have shown that i.duc fulvestrant was significantly more effective than, or equivalent in action to i.m fulvestrant in two preclinical models of breast cancer. These studies provide evidence for a novel and safe route for fulvestrant therapy of DCIS and prevention of breast cancer. This preclinical study provides a strong basis for conducting clinical trials for DCIS and early breast cancer.

Breast intraductal nanoformulations for treating ductal carcinoma in situ I: Exploring metal-ion complexation to slow ciclopirox release, enhance mammary persistence and efficacy

INTRODUCTION

Ductal Carcinoma In Situ (DCIS) represents a significant fraction (~20-25%) of all newly diagnosed breast cancer cases and, if left untreated, a significant fraction of patients will progress to invasive disease. Surgery is the only treatment option. Ciclopirox (CPX), an FDA-approved antifungal drug, has exhibited promising antitumor activity by down-regulating the expression of vital antiapoptotic cellular proteins and inhibiting the genetic expression of several oncogenic pathways. In this study, the feasibility of using nanoscale delivery systems to control release and prolong mammary tissue persistence of a lipophilic metal complex of CPX and Zinc (CPXZn) after intraductal administration was investigated.

METHODS

CPX and CPX-Zn nanosuspensions (NSs) were prepared using an evaporative nanoprecipitation-ultra-sonication method. Flash nanoprecipitation was used to prepare PLGA nanoparticles (NPs) loaded with CPXZn. Our established orthotopic DCIS rat model was used to evaluate efficacy. Briefly, two days after 13762 Mat B III cell intraductal inoculation, rats were divided into treatment groups and a single intraductal injection of CPX NS, CPX-Zn NS or CPX-Zn NPs was administered. In the first study arm, the efficacy of CPX NS (1, 3, 5 mg/duct) was evaluated. In the second arm, the in vivo efficacy of CPX NS, CPX-Zn NS and CPX-Zn loaded NPs was evaluated and compared at equivalent CPX doses. The mammary persistence of CPX from CPX NS, CPX-Zn NS, and CPX-Zn PLGA NPs was also assessed.

RESULTS

CPX-Zn complex was successfully synthesized and characterized by several spectral analyses. CPX release was slowed from the CPX-Zn NS and further slowed by incorporating CPX-Zn into PLGA NPs as compared to the CPX NS with release half times following the order: CPX NS < CPX-Zn NS << CPX-Zn NP. Intraductal CPX NS administration was dose and time dependent in suppressing tumor initiation suggesting prolonged mammary exposure may improve efficacy. In the second arm, mammary tissue persistence of CPX followed the rank order CPX NS < CPX-Zn NS << CPX-Zn NP at 6 h and 48 h post-administration. Prolonged mammary CPX exposure was highly correlated to improved efficacy. Prolonged CPX tissue persistence, attributed to slower release from the zinc complex and the PLGA NPs, resulted in a 5-fold dose reduction compared to the CPX NS.

CONCLUSIONS

The current results demonstrate that slowing drug release in the mammary duct after intraductal administration overcomes the rapid ductal clearance of CPX, prolongs mammary tissue persistence, improves efficacy against DCIS lesions in vivo, and requires 5-fold less CPX to achieve equivalent efficacy. The studies also provide a strategic path forward for developing a locally administered drug delivery system for treating DCIS, for which no primary chemotherapy option is available.

Ductal tree ablation by local delivery of ethanol prevents tumor formation in an aggressive mouse model of breast cancer

Background

Prophylactic mastectomy is the most effective intervention to prevent breast cancer. However, this major surgery has life-changing consequences at the physical, emotional, psychological, and social levels. Therefore, only high-risk individuals consider this aggressive procedure, which completely removes the mammary epithelial cells from which breast cancer arises along with surrounding tissue. Here, we seek to develop a minimally invasive procedure as an alternative to prophylactic mastectomy by intraductal (ID) delivery of a cell-killing solution that locally ablates the mammary epithelial cells before they become malignant.

Methods

After ID injection of a 70% ethanol-containing solution in FVB/NJ female animals, ex vivo dual stained whole-mount tissue analysis and in vivo X-ray microcomputed tomography imaging were used to visualize ductal tree filling, and histological and multiplex immunohistochemical assays were used to characterize ablative effects and quantitate the number of intact epithelial cells and stroma. After ID injection of 70% ethanol or other solutions in cancer-prone FVB-Tg-C3(1)-TAg female animals, mammary glands were palpated weekly to establish tumor latency and examined after necropsy to record tumor incidence. Statistical difference in median tumor latency and tumor incidence between experimental groups was analyzed by log-rank test and logistic mixed-effects model, respectively.

Results

We report that ID injection of 70% ethanol effectively ablates the mammary epithelia with limited collateral damage to surrounding stroma and vasculature in the murine ductal tree. ID injection of 70% ethanol into the mammary glands of the C3(1)-TAg multifocal breast cancer model significantly delayed tumor formation (median latency of 150 days in the untreated control group [n = 25] vs. 217 days in the ethanol-treated group [n = 13], p value < 0.0001) and reduced tumor incidence (34% of glands with tumors [85 of 250] in the untreated control group vs. 7.3% of glands with tumor [7 of 95] in the ethanol-treated group, risk ratio = 4.76 [95% CI 1.89 to 11.97, p value < 0.0001]).

Conclusions

This preclinical study demonstrates the feasibility of local ductal tree ablation as a novel strategy for primary prevention of breast cancer. Given the existing clinical uses of ethanol, ethanol-based ablation protocols could be readily implemented in first-in-human clinical trials for high-risk individuals.

Intraductal cisplatin treatment in a BRCA-associated breast cancer mouse model attenuates tumor development but leads to systemic tumors in aged female mice

BRCA deficiency predisposes to the development of invasive breast cancer. In BRCA mutation carriers this risk can increase up to 80%. Currently, bilateral prophylactic mastectomy and prophylactic bilateral salpingo-oophorectomy are the only preventive, albeit radical invasive strategies to prevent breast cancer in BRCA mutation carriers. An alternative non-invasive way to prevent BRCA1-associated breast cancer may be local prophylactic treatment via the nipple.

Using a non-invasive intraductal (ID) preclinical intervention strategy, we explored the use of combined cisplatin and poly (ADP)-ribose polymerase 1 (PARP1) inhibition to prevent the development of hereditary breast cancer. We show that ID cisplatin and PARP-inhibition can successfully ablate mammary epithelial cells, and this approach attenuated tumor onset in a mouse model of Brca1-associated breast cancer from 153 to 239 days. Long-term carcinogenicity studies in 150 syngeneic wild-type mice demonstrated that tumor incidence was increased in the ID treated mammary glands by 6.3% due to systemic exposure to cisplatin. Although this was only evident in aged mice (median age = 649 days), we conclude that ID cisplatin treatment only presents a safe and feasible local prevention option if systemic exposure to the chemotherapy used can be avoided.

Intraductal Delivery to the Rabbit Mammary Gland

Localized intraductal treatments for breast cancer offer potential advantages, including efficient delivery to the tumor and reduced systemic toxicity and adverse effects^{1,2,3,4,5,6,7}. However, several challenges remain before these treatments can be applied more widely. The development and validation of intraductal therapeutics in an appropriate animal model facilitate the development of intraductal therapeutic strategies for patients. While the mouse mammary gland has been widely used as a model system of mammary development and tumorigenesis, the anatomy is distinct from the human gland. A larger animal model, such as the rabbit, may serve as a better model for mammary gland structure and intraductal therapeutic development. In contrast to mice, in which ten ductal trees are spatially distributed along the body axis, each terminating in a separate teat, the rabbit mammary gland more closely resembles the human gland, with multiple overlapping ductal systems that exit through separate openings in one teat. Here, we present minimally invasive methods for the delivery of reagents directly into the rabbit mammary duct and for visualization of the delivery itself with high-resolution ultrasound imaging.

Cancer Stem and Progenitor-Like Cells as Pharmacological Targets in Breast Cancer Treatment

The present review is focused on the current role of neoplastic stem and progenitor-like cells as primary targets in the pharmacotherapy of cancer as well as in the development of new anticancer drugs. We begin by summarizing the main characteristics of these tumor-initiating cells and key concepts that support their participation in therapeutic failure. In particular, we discuss the differences between the major carcinogenesis models (ie, clonal evolution vs cancer stem cell (CSC) model) with emphasis on breast cancer (given its importance to the study of CSCs) and their implications for the development of new treatment strategies. In addition, we describe the main ways to target these cells, including the main signaling pathways that are more activated or altered in CSCs. Finally, we provide a comprehensive compilation of the most recently tested drugs.

Silencing HoxA1 by intraductal injection of siRNA lipidoid nanoparticles prevents mammary tumor progression in mice

With advances in screening, the incidence of detection of premalignant breast lesions has increased in recent decades; however, treatment options remain limited to surveillance or surgical removal by lumpectomy or mastectomy. We hypothesized that disease progression could be blocked by RNA interference (RNAi) therapy and set out to develop a targeted therapeutic delivery strategy. Using computational gene network modeling, we identified HoxA1 as a putative driver of early mammary cancer progression in transgenic C3(1)-SV40TAg mice. Silencing this gene in cultured mouse or human mammary tumor spheroids resulted in increased acinar lumen formation, reduced tumor cell proliferation, and restoration of normal epithelial polarization. When the HoxA1 gene was silenced in vivo via intraductal delivery of nanoparticle-formulated small interfering RNA (siRNA) through the nipple of transgenic mice with early-stage disease, mammary epithelial cell proliferation rates were suppressed, loss of estrogen and progesterone receptor expression was prevented, and tumor incidence was reduced by 75%. This approach that leverages new advances in systems biology and nanotechnology offers a novel noninvasive strategy to block breast cancer progression through targeted silencing of critical genes directly within the mammary epithelium.

Combining the strength of genomics, nanoparticle technology, and direct intraductal delivery for breast cancer treatment

A large number of genes are altered in cancer cells. Often, reversal or inhibition of just one of these alterations leads to death of the cancer cells. Technological advances in multiple areas are necessary to potentiate clinical translation of these findings. In a recent article, Brock and colleagues reported that overexpressed HOXA1 is a critical event in tumor progression in a mouse mammary tumor model. They developed HOXA1-small interfering RNA nanoparticles and achieved effective therapeutic doses by delivering them intraductally through the nipple to the site of the tumor and at the same time circumvented the systemic immune response. This study strengthens the concept of targeting overexpressed genes by using small interfering RNA and bypassing systemic immunity through local intraductal delivery.

Intraductal therapy of ductal carcinoma in situ: a presurgery study

INTRODUCTION

Ductal carcinoma in situ (DCIS) is a noninvasive breast cancer wherein malignant cells are confined within a ductal lobular unit. Although less than half the cases of DCIS will progress to invasive disease, most women are treated aggressively with surgery, radiation, and/or hormone therapy due to the inability to clinically evaluate the extent and location of the disease. Intraductal therapy, in which a drug is administered directly into the mammary duct through the nipple, is a promising approach for treating DCIS, but the feasibility of instilling drug into a diseased duct has not been established.

PATIENTS AND METHODS

Four to 6 weeks before their scheduled surgery, 13 women diagnosed with DCIS were subjected to cannulation of the affected duct. After both the absence of perforation and presence of dye in the duct were confirmed by ductogram, pegylated liposomal doxorubicin was instilled. Histopathologic assessment was performed after surgery to assess the treatment effects.

RESULTS

Of the 13 women enrolled in the study, 6 had their DCIS duct successfully cannulated without perforation and instilled with the drug. The treatment was well tolerated, and no serious adverse events have been reported. Biomarker studies indicated a general decrease in Ki-67 levels but an increase in annexin-1 and 8-hydroxydeoxyguanosine in the lumen of DCIS-containing ducts, which suggests a local response to pegylated liposomal doxorubicin treatment.

CONCLUSIONS

Intraductal therapy offers a nonsurgical strategy to treat DCIS at the site of disease, potentially minimizing the adverse effects of systemic treatment while preventing development of invasive cancer.