TH1902, a new docetaxel-peptide conjugate for the treatment of sortilin-positive triple-negative breast cancer

Advances in peptide-based drug delivery systems

Drug delivery systems (DDSs) are designed to deliver drugs to their specific targets to minimize their toxic effects and improve their susceptibility to clearance during targeted transport. Peptides have high affinity, low immunogenicity, simple amino acid composition, and adjustable molecular size; therefore, most peptides can be coupled to drugs via linkers to form peptide-drug conjugates (PDCs) and act as active pro-drugs. PDCs are widely thought to be promising DDSs, given their ability to improve drug bio-compatibility and physiological stability. Peptide-based DDSs are often used to deliver therapeutic substances such as anti-cancer drugs and nucleic acid-based drugs, which not only slow the degradation rate of drugs in vivo but also ensure the drug concentration at the targeted site and prolong the half-life of drugs in vivo. This article provides an profile of the advancements and future development in functional peptide-based DDSs both domestically and internationally in recent years, in the expectation of achieving targeted drug delivery incorporating functional peptides and taking full advantage of synergistic effects.

Sudocetaxel Zendusortide (TH1902) triggers the cGAS/STING pathway and potentiates anti-PD-L1 immune-mediated tumor cell killing

The anticancer efficacy of Sudocetaxel Zendusortide (TH1902), a peptide-drug conjugate internalized through a sortilin-mediated process, was assessed in a triple-negative breast cancer-derived MDA-MB-231 immunocompromised xenograft tumor model where complete tumor regression was observed for more than 40 days after the last treatment. Surprisingly, immunohistochemistry analysis revealed high staining of STING, a master regulator in the cancer-immunity cycle. A weekly administration of TH1902 as a single agent in a murine B16-F10 melanoma syngeneic tumor model demonstrated superior tumor growth inhibition than did docetaxel. A net increase in CD45 leukocyte infiltration within TH1902-treated tumors, especially for tumor-infiltrating lymphocytes and tumor-associated macrophages was observed. Increased staining of perforin, granzyme B, and caspase-3 was suggestive of elevated cytotoxic T and natural killer cell activities. Combined TH1902/anti-PD-L1 treatment led to increases in tumor growth inhibition and median animal survival. TH1902 inhibited cell proliferation and triggered apoptosis and senescence in B16-F10 cells in vitro, while inducing several downstream effectors of the cGAS/STING pathway and the expression of MHC-I and PD-L1. This is the first evidence that TH1902 exerts its antitumor activity, in part, through modulation of the immune tumor microenvironment and that the combination of TH1902 with checkpoint inhibitors (anti-PD-L1) could lead to improved clinical outcomes.

Peptide-drug conjugates: A new paradigm for targeted cancer therapy

Peptide-drug conjugates (PDCs) are the new hope for targeted therapy after antibody-drug conjugates (ADCs). Compared with ADCs, the core advantages of PDCs are enhanced tissue penetration, easier chemical synthesis, and lower production costs. Two PDCs have been approved by the US Food and Drug Administration (FDA) for the treatment of cancer. The therapeutic effects of PDCs are remarkable, but PDCs also encounter problems when used as targeted therapeutics, such as poor stability, a short blood circulation time, a long research and development time frame, and a slow clinical development process. Therefore, it is very urgent and important to understand the latest research progress of cancer cells targeting PDC, the solution to its stability problem, the scheme of computer technology to assist its research and development, and the direction of its future development. In this manuscript, based on the structure and function of PDCs, the latest research progress on PDCs from the aspects of cancer cell-targeting peptide (CTP) selection, pharmacokinetic characteristics, stability regulation and so on were systematically reviewed, hoping to highlight the current problems and future development directions of PDCs.

Generation and Characterization of SORT1-Targeted Antibody-Drug Conjugate for the Treatment of SORT1-Positive Breast Tumor

Antibody-drug conjugates (ADCs) have greatly improved the outcomes of advanced breast tumors. However, the treatment of breast tumors with existing ADCs is still hindered by many issues, such as tumor antigen heterogeneity and drug resistance. Therefore, ADCs against new targets would provide options for the treatment of these challenges. Sortilin-1 (SORT1) may be a promising target for ADC as it is upregulated in breast cancer. To evaluate the possibility of SORT1 as an ADC target, a humanized antibody_8D302 with high affinity against SORT1 was generated. Additionally, 8D302 was conjugated with MMAE and DXd to generate two ADCs_8D302-MMAE and 8D302-DXd, respectively. Both 8D302-MMAE and 8D302-DXd showed effective cytotoxicity against SORT1 positive breast tumor cell lines and induced bystander killing. Consequently, 8D302-MMAE showed relatively better anti-tumor activity than 8D302-DXd both in vitro and in vivo, but 8D302-DXd had superior safety profile and pharmacokinetics profile over 8D302-MMAE. Furthermore, SORT1 induced faster internalization and lysosomal trafficking of antibodies and had a higher turnover compared with HER2. Also, 8D302-DXd exhibited superior cell cytotoxicity and tumor suppression over trastuzumab-DXd, a HER2-targeted ADC. We hypothesize that the high turnover of SORT1 enables SORT1-targeted ADC to be a powerful agent for the treatment of SORT1-positive breast tumor.

Molecular, Cellular, and Technical Aspects of Breast Cancer Cell Lines as a Foundational Tool in Cancer Research

Breast cancer comprises about 30% of all new female cancers each year and is the most common malignant cancer in women in the United States. Breast cancer cell lines have been harnessed for many years as a foundation for in vitro analytic studies to understand the use of cancer prevention and therapy. There has yet to be a compilation of works to analyze the pitfalls, novel discoveries, and essential techniques for breast cancer cell line studies in a scientific context. In this article, we review the history of breast cancer cell lines and their origins, as well as analyze the molecular pathways that pharmaceutical drugs apply to breast cancer cell lines in vitro and in vivo. Controversies regarding the origins of certain breast cancer cell lines, the benefits of utilizing Patient-Derived Xenograft (PDX) versus Cell-Derived Xenograft (CDX), and 2D versus 3D cell culturing techniques will be analyzed. Novel outcomes from epigenetic discovery with dietary compound usage are also discussed. This review is intended to create a foundational tool that will aid investigators when choosing a breast cancer cell line to use in multiple expanding areas such as epigenetic discovery, xenograft experimentation, and cancer prevention, among other areas.

Generation of a Novel SORT1×HER2 Bispecific Antibody-Drug Conjugate Targeting HER2-Low-Expression Tumor

Human epidermal growth factor receptor 2 (HER2) is considered an ideal antibody-drug conjugate (ADC) target because the gene is overexpressed in many tumors compared to normal tissues. Multiple anti-HER2 ADCs conjugated with different toxic payloads bring benefits to patients with high HER2 expression. However, HER2-targeted ADC technology needs further optimization to improve its effect for the treatment of patients with low HER2 expression. We hypothesized that bispecific antibody-drug conjugate (bsADC) targeting HER2 and Sortilin-1 (SORT1) would overcome this limitation. SORT1 is a suitable target for pairing with HER2 to generate a bispecific antibody (BsAb) since the gene is co-expressed with HER2 in tumors and possesses rapid internalization. We developed a BsAb (bsSORT1×HER2) that exhibited strong binding and internalization activity on HER2-low-expression tumor cells and facilitated higher HER2 degradation. The bsSORT1×HER2 was further conjugated with DXd to generate a bsADC (bsSORT1×HER2-DXd) that showed strong cytotoxicity on HER2-low-expression tumor cells and antitumor efficacy in an MDA-MB-231 xenograft mice model. These results demonstrated that employment of a SORT1×HER2-targeted bsADC may be promising to improve the antitumor efficacy of HER2-targeted ADC for the treatment of tumors with low HER2 expression.

Recent advances in targeted strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC), a highly aggressive subtype of breast cancer, negatively expresses estrogen receptor, progesterone receptor, and the human epidermal growth factor receptor 2 (HER2). Although chemotherapy is the main form of treatment for patients with TNBC, the effectiveness of chemotherapy for TNBC is still limited. The search for more effective therapies is urgent. Multiple targeted therapeutic strategies have emerged according to the specific molecules and signaling pathways expressed in TNBC. These include PI3K/AKT/mTOR inhibitors, epidermal growth factor receptor inhibitors, Notch inhibitors, poly ADP-ribose polymerase inhibitors, and antibody-drug conjugates. Moreover, immune checkpoint inhibitors, for example, pembrolizumab, atezolizumab, and durvalumab, are widely explored in the clinic. We summarize recent advances in targeted therapy and immunotherapy in TNBC, with the aim of serving as a reference for the development of individualized treatment of patients with TNBC in the future.

Facts and prospects of peptide in targeted therapy and immune regulation against triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. Due to the lack of specific therapeutic targets, treatment options are limited, and the recurrence and metastasis rate is high, the overall survival of patients is poor. However, with the discovery of some new targets and the corresponding immune regulation after targeting these targets, TNBC has a new hope in treatment. The peptide has a simple structure, strong binding affinity, and high stability, and has great potential in targeted therapy and immune regulation against TNBC. This review will discuss how single peptides and peptide combinations target triple-negative breast cancer to exert immunomodulatory effects. Among them, single peptides target specific receptors on TNBC cells, act as decoys to target key ligands in the regulatory pathway, and target TME-related cells. The combinations of peptides work in the form of cancer vaccines, engineered exosomes, microRNAs and other immune-related molecular pathways, immune checkpoint inhibitors, chimeric antigen receptor T cells, and drug-peptide conjugates. This article is mainly dedicated to exploring new treatment methods for TNBC to improve the curative effect and prolong the survival time of patients.

Triple Negative Breast Cancer Treatment Options and Limitations: Future Outlook

Triple negative breast cancer (TNBC) has a negative expression of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptors (HER2). The survival rate for TNBC is generally worse than other breast cancer subtypes. TNBC treatment has made significant advances, but certain limitations remain. Treatment for TNBC can be challenging since the disease has various molecular subtypes. A variety of treatment options are available, such as chemotherapy, immunotherapy, radiotherapy, and surgery. Chemotherapy is the most common of these options. TNBC is generally treated with systemic chemotherapy using drugs such as anthracyclines and taxanes in neoadjuvant or adjuvant settings. Developing resistance to anticancer drugs and off-target toxicity are the primary hindrances to chemotherapeutic solutions for cancer. It is imperative that researchers, clinicians, and pharmaceutical companies work together to develop effective treatment options for TNBC. Several studies have suggested nanotechnology as a potential solution to the problem of suboptimal TNBC treatment. In this review, we summarized possible treatment options for TNBC, including chemotherapy, immunotherapy, targeted therapy, combination therapy, and nanoparticle-based therapy, and some solutions for the treatment of TNBC in the future. Moreover, we gave general information about TNBC in terms of its characteristics and aggressiveness.

Establishment of a prognostic model related to tregs and natural killer cells infiltration in bladder cancer

BACKGROUND

Regulatory T cells (Tregs) and natural killer (NK) cells play an essential role in the development of bladder urothelial carcinoma (BUC).

AIM

To construct a prognosis-related model to judge the prognosis of patients with bladder cancer, meanwhile, predict the sensitivity of patients to chemotherapy and immunotherapy.

METHODS

Bladder cancer information data was obtained from The Cancer Genome Atlas and GSE32894. The CIBERSORT was used to calculate the immune score of each sample. Weighted gene co-expression network analysis was used to find genes that will have the same or similar expression patterns. Subsequently, multivariate cox regression and lasso regression was used to further screen prognosis-related genes. The prrophetic package was used to predict phenotype from gene expression data, drug sensitivity of external cell line and predict clinical data.

RESULTS

The stage and risk scores are independent prognostic factors in patients with BUC. Mutations in FGFR3 lead to an increase in Tregs percolation and affect the prognosis of the tumor, and additionally, EMP1, TCHH and CNTNAP3B in the model are mainly positively correlated with the expression of immune checkpoints, while CMTM8, SORT1 and IQSEC1 are negatively correlated with immune checkpoints and the high-risk group had higher sensitivity to chemotherapy drugs.

CONCLUSION

Prognosis-related models of bladder tumor patients, based on Treg and NK cell percolation in tumor tissue. In addition to judging the prognosis of patients with bladder cancer, it can also predict the sensitivity of patients to chemotherapy and immunotherapy. At the same time, patients were divided into high and low risk groups based on this model, and differences in genetic mutations were found between the high and low risk groups.

The Membrane Protein Sortilin Is a Potential Biomarker and Target for Glioblastoma

Glioblastoma (GBM) is a devastating brain cancer with no effective treatment, and there is an urgent need for developing innovative biomarkers as well as therapeutic targets for better management of the disease. The membrane protein sortilin has recently been shown to participate in tumor cell invasiveness in several cancers, but its involvement and clinical relevance in GBM is unclear. In the present study, we explored the expression of sortilin and its potential as a clinical biomarker and therapeutic target for GBM. Sortilin expression was investigated by immunohistochemistry and digital quantification in a series of 71 clinical cases of invasive GBM vs. 20 non-invasive gliomas. Sortilin was overexpressed in GBM and, importantly, higher expression levels were associated with worse patient survival, pointing to sortilin tissue expression as a potential prognostic biomarker for GBM. Sortilin was also detectable in the plasma of GBM patients by enzyme-linked immunosorbent assay (ELISA), but no differences were observed between sortilin levels in the blood of GBM vs. glioma patients. In vitro, sortilin was detected in 11 brain-cancer-patient-derived cell lines at the anticipated molecular weight of 100 kDa. Interestingly, targeting sortilin with the orally bioavailable small molecule inhibitor AF38469 resulted in decreased GBM invasiveness, but cancer cell proliferation was not affected, showing that sortilin is targetable in GBM. Together, these data suggest the clinical relevance for sortilin in GBM and support further investigation of GBM as a clinical biomarker and therapeutic target.

Current therapeutic approaches and promising perspectives of using bioengineered peptides in fighting chemoresistance in triple-negative breast cancer

Breast cancer is a collation of malignancies that manifest in the mammary glands at the early stages. Among breast cancer subtypes, triple-negative breast cancer (TNBC) shows the most aggressive behavior, with apparent stemness features. Owing to the lack of response to hormone therapy and specific targeted therapies, chemotherapy remains the first line of the TNBC treatment. However, the acquisition of resistance to chemotherapeutic agents increase therapy failure, and promotes cancer recurrence and distant metastasis. Invasive primary tumors are the birthplace of cancer burden, though metastasis is a key attribute of TNBC-associated morbidity and mortality. Targeting the chemoresistant metastases-initiating cells via specific therapeutic agents with affinity to the upregulated molecular targets is a promising step in the TNBC clinical management. Exploring the capacity of peptides as biocompatible entities with the specificity of action, low immunogenicity, and robust efficacy provides a principle for designing peptide-based drugs capable of increasing the efficacy of current chemotherapy agents for selective targeting of the drug-tolerant TNBC cells. Here, we first focus on the resistance mechanisms that TNBC cells acquire to evade the effect of chemotherapeutic agents. Next, the novel therapeutic approaches employing tumor-targeting peptides to exploit the mechanisms of drug resistance in chemorefractory TNBC are described.

Sortilin and hypertension

PURPOSE OF REVIEW

The current review aims to present the latest scientific updates on the role of Sortilin in the pathophysiology of hypertension.

RECENT FINDINGS

The main focus of this systematic overview is on the functional contribution of Sortilin to the pathogenesis of hypertension. Sortilin is a glycoprotein mostly known for its actions as a trafficking molecule directing proteins to specific secretory or endocytic compartments of the cell. Emerging evidence indicates that Sortilin is associated with pathological conditions, including inflammation, arteriosclerosis, dyslipidemia, insulin resistance, and vascular calcification. Most recently, Sortilin has been shown to finely control endothelial function and to drive hypertension by modulating sphingolipid/ceramide homeostasis and by triggering oxidative stress.

SUMMARY

The latest findings linking Sortilin and hypertension that are herein discussed can inspire novel areas of research which could eventually lead to the discovery of new therapeutic strategies in cardiovascular medicine.

Peptide-drug conjugates (PDCs): a novel trend of research and development on targeted therapy, hype or hope?

Peptide-drug conjugates (PDCs) are the next generation of targeted therapeutics drug after antibody-drug conjugates (ADCs), with the core benefits of enhanced cellular permeability and improved drug selectivity. Two drugs are now approved for market by US Food and Drug Administration (FDA), and in the last two years, the pharmaceutical companies have been developing PDCs as targeted therapeutic candidates for cancer, coronavirus disease 2019 (COVID-19), metabolic diseases, and so on. The therapeutic benefits of PDCs are significant, but poor stability, low bioactivity, long research and development time, and slow clinical development process as therapeutic agents of PDC, how can we design PDCs more effectively and what is the future direction of PDCs? This review summarises the components and functions of PDCs for therapeutic, from drug target screening and PDC design improvement strategies to clinical applications to improve the permeability, targeting, and stability of the various components of PDCs. This holds great promise for the future of PDCs, such as bicyclic peptide‒toxin coupling or supramolecular nanostructures for peptide-conjugated drugs. The mode of drug delivery is determined according to the PDC design and current clinical trials are summarised. The way is shown for future PDC development.

Strategies for the drug discovery and development of taxane anticancer therapeutics

INTRODUCTION

Paclitaxel and docetaxel have been extensively used in the clinic over the past three decades. Although the patents of these first-generation taxanes have expired, their clinical applications, particularly new formulations and combination therapies, are under active investigations. Inspired by the notable success of Abraxane and Lipusu, new formulations have been extensively developed. In parallel, to overcome multidrug resistance (MDR) and to eradicate cancer stem cells, immense efforts have been made on the discovery and development of new-generation taxanes with improved potency and superior pharmacological properties.

AREAS COVERED

This review covers (a) natural sources of advanced intermediates used for semi-synthesis of taxane API, (b) new formulations, (c) the major issues of FDA approved taxanes, (d) the design and development of next-generation taxanes, (e) new mechanisms of action, and (f) a variety of taxane-based drug delivery systems.

EXPERT OPINION

As the highly potent next-generation taxanes can eradicate cancer stem cells and overcome MDR, the priority is to develop these compounds as an integral part of cancer therapy, especially for pancreatic, colon and prostate cancers which hardly respond to checkpoint inhibitors. In order to mitigate undesirable side effects, the exploration of effective nanoformulations and tumor-targeted drug delivery systems are essential.

Recent advances in therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer (BC) with a poor prognosis. Current treatment options are limited to surgery, adjuvant chemotherapy and radiotherapy; however, a proportion of patients have missed the surgical window at the time of diagnosis. TNBC is a highly heterogeneous cancer with specific mutations and aberrant activation of signaling pathways. Hence, targeted therapies, such as those targeting DNA repair pathways, androgen receptor signaling pathways, and kinases, represent promising treatment options against TNBC. In addition, immunotherapy has also been demonstrated to improve overall survival and response in TNBC. In this review, we summarize recent key advances in therapeutic strategies based on molecular subtypes in TNBC.

nurP28, a New-to-Nature Zein-Derived Peptide, Enhances the Therapeutic Effect of Docetaxel in Breast Cancer Monolayers and Spheroids

The development of novel cancer therapeutic strategies has garnered increasing interest in cancer research. Among the therapeutic choices, chemosensitizers have shown exciting prospects. Peptides are an attractive alternative among the molecules that may be used as chemosensitizers. We rationally designed a new-to-nature peptide, nurP28, derived from the 22-kDa α-zein protein sequence (entry Q00919_MAIZE). The resultant sequence of the nurP28 peptide after the addition of arginine residues was LALLALLRLRRRATTAFIIP, and we added acetyl and amide groups at the N- and C-terminus, respectively, for capping. We evaluated the cytotoxicity of the nurP28 peptide alone and in combination with docetaxel in fibroblast monolayers and breast cancer monolayers and spheroids. Our results indicated that nurP28 is not cytotoxic to human fibroblasts or cancer cells. Nevertheless, when combined with 1 µM docetaxel, 3 ng/mL nurP28 induced equivalent (in MCF7 monolayers) and higher (in MCF7 spheroids) cytotoxic effects than 10-fold higher doses of docetaxel alone. These findings suggest that nurP28 may act as a chemosensitizer in breast cancer treatment. This study describes the enhancing “anti-cancer” effects of nurP28 in breast cancer 2D and 3D cultures treated with docetaxel. Further studies should explore the mechanisms underlying these effects and assess the clinical potential of our findings using animal models.

The Peptide-Drug Conjugate TH1902: A New Sortilin Receptor-Mediated Cancer Therapeutic against Ovarian and Endometrial Cancers

Sortilin (SORT1) receptor-mediated endocytosis functions were exploited for this new approach for effective and safe treatments of gynecological cancers. Here, high expression of SORT1 was found in >75% of the clinically annotated ovarian and endometrial tumors analyzed by immunohistochemistry. Therefore, the anticancer properties of the peptide-drug conjugate TH1902, a peptide that targets SORT1 and which is linked to docetaxel molecules, were investigated both in vitro using ovarian and endometrial cancer cell cultures and in vivo using xenograft models. In vitro, TH1902 inhibited cell proliferation and triggered higher SORT1-dependent cell apoptosis than unconjugated docetaxel did in ES-2 and SKOV3 ovarian cancer cell lines. The uptake of the Alexa488-TH19P01 peptide from TH1902 was reduced upon siRNA-mediated silencing of SORT1. In vivo, weekly administration of TH1902 showed better tolerability compared to equivalent docetaxel doses and inhibited tumor growth in ovarian and endometrial xenograft mice models. TH1902 as a single agent inhibited ovarian tumor growth more than either of the unconjugated taxanes or carboplatin. Furthermore, TH1902 combination with carboplatin also demonstrated better efficacy when compared to both taxanes-carboplatin combinations. Overall, TH1902 shows better in vivo efficacy, compared to that of docetaxel and even paclitaxel, against SORT1-positive ovarian and endometrial cancers and could be safely combined with carboplatin.

TAMpepK Suppresses Metastasis through the Elimination of M2-Like Tumor-Associated Macrophages in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) accounts for approximately 10–15% of all breast cancer cases and is characterized by high invasiveness, high metastatic potential, relapse proneness, and poor prognosis. M2-like tumor-associated macrophages (TAMs) contribute to tumorigenesis and are promising targets for inhibiting breast cancer metastasis. Therefore, we investigated whether melittin-conjugated pro-apoptotic peptide (TAMpepK) exerts therapeutic effects on breast cancer metastasis by targeting M2-like TAMs. TAMpepK is composed of M2-like TAM binding peptide (TAMpep) and pro-apoptotic peptide d(KLAKLAK)₂ (dKLA). A metastatic mouse model was constructed by injecting 4T1-luc2 cells either orthotopically or via tail vein injection, and tumor burden was quantified using a bioluminescence in vivo imaging system. We found that TAMpepK suppressed lung and lymph node metastases of breast cancer by eliminating M2-like TAMs without affecting the viability of M1-like macrophages and resident macrophages in the orthotopic model. Furthermore, TAMpepK reduced pulmonary seeding and the colonization of tumor cells in the tail vein injection model. The number of CD8⁺ T cells in contact with TAMs was significantly decreased in tumor nodules treated with TAMpepK, resulting in the functional activation of cytotoxic CD8⁺ T cells. Taken together, our findings suggest that TAMpepK could be a novel therapeutic agent for the inhibition of breast cancer metastasis by targeting M2-like TAMs.

Sortilin 1 regulates hepatocellular carcinoma progression by activating the PI3K/AKT signaling

Background

Sortilin 1 (SORT1) has been reported as an oncogene in several human tumors. Nonetheless, the biological functions of SORT1 in hepatocellular carcinoma (HCC) remain poorly understood.

Methods

Western blotting was employed for the determination of protein expression. Hepatocellular carcinoma cell viability, apoptosis, migration, and invasion were measured via CCK-8, flow cytometry, wound healing, and Transwell assays.

Results

Sortilin 1 was upregulated in HCC and closely associated with unsatisfactory outcomes of HCC patients. Furthermore, in vitro and in vivo assays revealed that SORT1 knockdown significantly diminished HCC cell proliferation and metastasis but accelerated HCC cell apoptosis; moreover, SORT1 depletion also restrained the growth of xenografted HCC tumors. Mechanistically, SORT1 activated PI3K/AKT signaling in HCC cells, thereby promoting the malignant behaviors of HCC cells.

Conclusion

This study demonstrated that SORT1 might promote HCC progression by activating PI3K/AKT signaling, indicating that SORT1 might be a promising target and biomarker for HCC treatment and prognosis.

New Peptide-Drug Conjugates for Precise Targeting of SORT1-Mediated Vasculogenic Mimicry in the Tumor Microenvironment of TNBC-Derived MDA-MB-231 Breast and Ovarian ES-2 Clear Cell Carcinoma Cells

Vasculogenic mimicry (VM) is defined as the formation of microvascular channels by genetically deregulated cancer cells and is often associated with high tumor grade and cancer therapy resistance. This microcirculation system, independent of endothelial cells, provides oxygen and nutrients to tumors, and contributes also in part to metastasis. VM has been observed in ovarian cancer and in triple negative breast cancer (TNBC) and shown to correlate with decreased overall cancer patient survival. Thus, strategies designed to inhibit VM may improve cancer patient treatments. In this study, sortilin (SORT1) receptor was detected in in vitro 3D capillary-like structures formed by ES-2 ovarian cancer and MDA-MB-231 TNBC-derived cells when grown on Matrigel. SORT1 gene silencing or antibodies directed against its extracellular domain inhibited capillary-like structure formation. In vitro, VM also correlated with increased gene expression of matrix metalloproteinase-9 (MMP-9) and of the cancer stem cell marker CD133. In vivo ES-2 xenograft model showed PAS⁺/CD31^- VM structures (staining positive for both SORT1 and CD133). TH1904, a Doxorubicin-peptide conjugate that is internalized by SORT1, significantly decreased in vitro VM at low nM concentrations. In contrast, VM was unaffected by unconjugated Doxorubicin or Doxil (liposomal Doxorubicin) up to μM concentrations. TH1902, a Docetaxel-peptide conjugate, altered even more efficiently in vitro VM at pM concentrations. Overall, current data evidence for the first time that 1) SORT1 itself exerts a crucial role in both ES-2 and MDA-MB-231 VM, and that 2) VM in these cancer cell models can be efficiently inhibited by the peptide-drug conjugates TH1902/TH1904. These new findings also indicate that both peptide-drug conjugates, in addition to their reported cytotoxicity, could possibly inhibit VM in SORT1-positive TNBC and ovarian cancer patients.