Targeted drug delivery via folate receptors in recurrent ovarian cancer: a review

Appraisal of folate functionalized bosutinib cubosomes against hepatic cancer cells: In-vitro, In-silico, and in-vivo pharmacokinetic study

Targeted therapies enhance the efficacy of tumour screening and management while lowering side effects. Multiple tumours, including liver cancer, exhibit elevated levels of folate receptor expression. This research attempted to develop surface-functionalised bosutinib cubosomes against hepatocellular carcinoma. The novelty of this work is the anti-hepatic action of bosutinib (BST) and folic acid-modified bosutinib cubosomes (BSTMF) established through proto-oncogene tyrosine-protein kinase (SrC)/ focal adhesion kinase(FAK), reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and cell cytotoxicity. Later, the in-vivo pharmacokinetics of BSTMF were determined for the first time. The strong affinity of folic acid (FA) for folate receptors allows BSTMF to enter cells via FA receptor-mediated endocytosis. The particle size of the prepared BSTMF was 188.5 ± 2.25 nm, and its zeta potential was -20.19 ± 2.01 mV, an encapsulation efficiency of 90.31 ± 3.15 %, and a drug release rate of 76.70 ± 2.10 % for 48 h. The surface architecture of BSTMF was identified using transmission electron microscopy (TEM) and Atomic force microscopy (AFM). Cell-line studies demonstrated that BSTMF substantially lowered the viability of Hep G2 cells compared to BST and bosutinib-loaded cubosomes (BSTF). BSTMF demonstrated an elevated BST concentration in tumour tissue than in other organs and also displayed superior pharmacokinetics, implying that they hold potential against hepatic cancers. This is the first study to show that BSTMF may be effective against liver cancer by targeting folate receptors and triggering SrC/FAK-dependent apoptotic pathways. Multiple parameters demonstrated that BSTMF enhanced anticancer targeting, therapeutic efficacy, and safety in NDEA-induced hepatocellular carcinoma.

Paradigm Shift: A Comprehensive Review of Ovarian Cancer Management in an Era of Advancements

Ovarian cancer (OC) is the female genital malignancy with the highest lethality. Patients present a poor prognosis mainly due to the late clinical presentation allied with the common acquisition of chemoresistance and a high rate of tumour recurrence. Effective screening, accurate diagnosis, and personalised multidisciplinary treatments are crucial for improving patients' survival and quality of life. This comprehensive narrative review aims to describe the current knowledge on the aetiology, prevention, diagnosis, and treatment of OC, highlighting the latest significant advancements and future directions. Traditionally, OC treatment involves the combination of cytoreductive surgery and platinum-based chemotherapy. Although more therapeutical approaches have been developed, the lack of established predictive biomarkers to guide disease management has led to only marginal improvements in progression-free survival (PFS) while patients face an increasing level of toxicity. Fortunately, because of a better overall understanding of ovarian tumourigenesis and advancements in the disease's (epi)genetic and molecular profiling, a paradigm shift has emerged with the identification of new disease biomarkers and the proposal of targeted therapeutic approaches to postpone disease recurrence and decrease side effects, while increasing patients' survival. Despite this progress, several challenges in disease management, including disease heterogeneity and drug resistance, still need to be overcome.

A year in pharmacology: new drugs approved by the US Food and Drug Administration in 2022

While new drug approvals by the U.S. Food and Drug Administration (FDA) had remained stable or even increased in the first 2 years of the COVID-19 pandemic, the 37 newly approved drugs in 2022 are considerably less than the 53 and 50 new drugs approved in 2020 and 2021, respectively, and less than the rolling 10-year average of 43. As in previous years of this annual review, we assign these new drugs to one of three levels of innovation: first drug against a condition ("first-in-indication"), first drug using a novel molecular mechanism ("first-in-class"), and "next-in-class," i.e., a drug using an already exploited molecular mechanism. We identify two "first-in-indication" (ganaxolon and teplizumab), 20 (54%) "first-in-class," and 17 (46%) "next-in-class" drugs. By treatment area, rare diseases and cancer drugs were once again the most prevalent (partly overlapping) therapeutic areas. Other continuing trends were the use of accelerated regulatory approval pathways and the reliance on biopharmaceuticals (biologics).

Mirvetuximab Soravtansine in Platinum-Resistant Ovarian Cancer

Ovarian cancer is the second leading cause of death from gynecologic malignancies worldwide. Management of platinum-resistant disease is challenging and clinical outcomes with standard chemotherapy are poor. Over the past decades, significant efforts have been made to understand drug resistance and develop strategies to overcome treatment failure. Antibody drug conjugates (ADCs) are a rapidly growing class of oncologic therapeutics, which combine the ability to target tumor-specific antigens with the cytotoxic effects of chemotherapy. Mirvetuximab soravtansine is an ADC comprising an IgG1 monoclonal antibody against the folate receptor alpha (FRα) conjugated to the cytotoxic maytansinoid effector molecule DM4 that has shown promising clinical activity in patients with FR-α-positive ovarian cancer. This review summarizes current evidence of mirvetuximab soravtansine in platinum-resistant ovarian cancer, focusing on clinical activity, toxicity, and future directions.

Nanoparticles as Drug Delivery Systems: A Review of the Implication of Nanoparticles' Physicochemical Properties on Responses in Biological Systems

In the last four decades, nanotechnology has gained momentum with no sign of slowing down. The application of inventions or products from nanotechnology has revolutionised all aspects of everyday life ranging from medical applications to its impact on the food industry. Nanoparticles have made it possible to significantly extend the shelf lives of food product, improve intracellular delivery of hydrophobic drugs and improve the efficacy of specific therapeutics such as anticancer agents. As a consequence, nanotechnology has not only impacted the global standard of living but has also impacted the global economy. In this review, the characteristics of nanoparticles that confers them with suitable and potentially toxic biological effects, as well as their applications in different biological fields and nanoparticle-based drugs and delivery systems in biomedicine including nano-based drugs currently approved by the U.S. Food and Drug Administration (FDA) are discussed. The possible consequence of continuous exposure to nanoparticles due to the increased use of nanotechnology and possible solution is also highlighted.

Design, characterization and evaluation of a new 99mTc-labeled folate derivative with affinity towards folate receptor

Folate receptors (FRs) are known to be over-expressed in several human malignancies and therefore serve as an important target for small radiolabeled folate derivatives for non-invasive imaging of tumor, which is an important tool for future treatment recourse. In the present article, we report the synthesis of a new ^99mTc-labeled radiotracer for the aforementioned application following the well-established ^99mTc-'4+1' chemistry. Formation of the desired [^99mTc]Tc-complex with >95% radiochemical purity was confirmed by radio-HPLC and its structure was ascertained by characterizing a natural rhenium analogue of the said complex. Although the ligand exhibited a weaker affinity towards FRs compared to native folic acid (IC50 8.09 µM vs 29.46 nM), the ^99mTc-labeled complex was found to bind folate receptor-positive KB cells with high specificity (∼90%). Similar studies in a folate receptor negative cell line viz. A549 further corroborated the receptor-specificity of the synthesized complex. In vivo studies in KB tumor xenograft showed moderate uptake of ∼2.6% upto 3 h post-injection with high specificity (∼80%). The favorable features observed warrant further screening of the current design towards achieving an improved molecular probe for the said application.

Multifunctional Nanoparticles as High-Efficient Targeted Hypericin System for Theranostic Melanoma

Biotin, spermine, and folic acid were covalently linked to the F127 copolymer to obtain a new drug delivery system designed for HY-loaded PDT treatment against B₁₆F₁₀ cells. Chemical structures and binders quantification were performed by spectroscopy and spectrophotometric techniques (¹NMR, HABA/Avidin reagent, fluorescamine assay). Critical micelle concentration, critical micelle temperature, size, polydispersity, and zeta potential indicate the hydrophobicity of the binders can influence the physicochemical parameters. Spermine-modified micelles showed fewer changes in their physical and chemical parameters than the F127 micelles without modification. Furthermore, zeta potential measurements suggest an increase in the physical stability of these carrier systems. The phototherapeutic potential was demonstrated using hypericin-loaded formulation against B₁₆F₁₀ cells, which shows that the combination of the binders on F127 copolymer micelles enhances the photosensitizer uptake and potentializes the photodynamic activity.

Folic Acid Enables Targeting Delivery of Lipodiscs by Circumventing IgM-Mediated Opsonization

Folic acid (FA) is one of the most widely utilized small-molecule ligands for cancer targeted drug delivery. Natural IgM was recently found to avidly absorb on the surface of FA-functionalized liposomes (FA-sLip), negatively regulating the in vivo performance by efficiently activating complement. Herein, FA-functionalized lipodiscs (FA-Disc) were constructed to successfully circumvent IgM-mediated opsonization and retained binding activity with folate receptors in vivo. The FA moiety along with the bound IgM was restricted to the highly curved rim of lipodiscs, leading to IgM incapability of presenting the membrane-bound conformation to trigger complement activation. The C1q docking, C3 binding, and C5a release were blocked and accelerated blood clearance phenomenon was mitigated of FA-Disc. FA-Disc retained folate binding activity and could effectively target folate receptor positive tumors in vivo. The present study provides a useful solution to avoid the negative regulation by IgM and achieve FA-enabled targeting by exploring disc-shaped nanocarriers.

Enriching Proteolysis Targeting Chimeras with a Second Modality: When Two Are Better Than One

Proteolysis targeting chimera (PROTAC)-mediated protein degradation has prompted a radical rethink and is at a crucial stage in driving a drug discovery transition. To fully harness the potential of this technology, a growing paradigm toward enriching PROTACs with other therapeutic modalities has been proposed. Could researchers successfully combine two modalities to yield multifunctional PROTACs with an expanded profile? In this Perspective, we try to answer this question. We discuss how this possibility encompasses different approaches, leading to multitarget PROTACs, light-controllable PROTACs, PROTAC conjugates, and macrocycle- and oligonucleotide-based PROTACs. This possibility promises to further enhance PROTAC efficacy and selectivity, minimize side effects, and hit undruggable targets. While PROTACs have reached the clinical investigation stage, additional steps must be taken toward the translational development of multifunctional PROTACs. A deeper and detailed understanding of the most critical challenges is required to fully exploit these opportunities and decisively enrich the PROTAC toolbox.

Electrochemical Cytosensor Based on a Gold Nanostar-Decorated Graphene Oxide Platform for Gastric Cancer Cell Detection

Effectively capturing and sensitively detecting cancer cells are critical to clinical diagnosis and cancer therapy. In this work, we prepared gold nanostar-decorated graphene oxide (GO-AuNSs) nanocomposites using a ultraviolet (UV)-induced strategy, and then modified them with a layer of bio-complex rBSA-FA (coupled reduced bovine serum albumin with folic acid) to generate GO-AuNSs@rBSA-FA nanocomposites. Herein, the application of GO and AuNSs not only strengthened the conductivity of the sensing platform but also guaranteed nanocomposites with biocompatible performance. Moreover, the adopted rBSA-FA layer could effectively enhance the stability and specificity towards gastric cancer cells (MGC-803). According to a systemic construction procedure, a novel electrochemical cytosensor based on GO-AuNSs@rBSA-FA was fabricated for MGC-803 cell detection. With the assistance of cyclic voltammetry (CV) and differential pulse voltammetry (DPV), the cytosensor reached a detection limit of 100 cell/mL in a wide linear range of 3 × 10²~7 × 10⁶ cell/mL towards MGC-803 cells. The good electrochemical characteristics for the cancer cell analysis indicate a promising prospect of this electrochemical cytosensor in clinical cancer diagnosis.

Folic Acid-Modified Fluorescent-Magnetic Nanoparticles for Efficient Isolation and Identification of Circulating Tumor Cells in Ovarian Cancer

Ovarian cancer (OC) is a lethal disease occurring in women worldwide. Due to the lack of obvious clinical symptoms and sensitivity biomarkers, OC patients are often diagnosed in advanced stages and suffer a poor prognosis. Circulating tumor cells (CTCs), released from tumor sites into the peripheral blood, have been recognized as promising biomarkers in cancer prognosis, treatment monitoring, and metastasis diagnosis. However, the number of CTCs in peripheral blood is low, and it is a technical challenge to isolate, enrich, and identify CTCs from the blood samples of patients. This work develops a simple, effective, and inexpensive strategy to capture and identify CTCs from OC blood samples using the folic acid (FA) and antifouling-hydrogel-modified fluorescent-magnetic nanoparticles. The hydrogel showed a good antifouling property against peripheral blood mononuclear cells (PBMCs). The FA was coupled to the hydrogel surface as the targeting molecule for the CTC isolation, held a good capture efficiency for SK-OV-3 cells (95.58%), and successfully isolated 2–12 CTCs from 10 OC patients’ blood samples. The FA-modified fluorescent-magnetic nanoparticles were successfully used for the capture and direct identification of CTCs from the blood samples of OC patients.

Natural Killer Cells: the Missing Link in Effective Treatment for High-Grade Serous Ovarian Carcinoma

OPINION STATEMENT

Ovarian cancer (OC), especially high-grade serous cancer (HGSC), is a highly heterogeneous malignancy with limited options for curative treatment and a high frequency of relapse. Interactions between OC and the immune system may permit immunoediting and immune escape, and current standard of care therapies can influence immune cell infiltration and function within the tumor microenvironment. Natural killer (NK) cells are involved in cancer immunosurveillance and immunoediting and can be activated by therapy, but deliberate approaches to maximize NK cell reactivity for treatment of HGSC are in their infancy. NK cells may be the ideal target for immunotherapy of HGSC. The diverse functions of NK cells, and their established roles in immunosurveillance, make them attractive candidates for more precise and effective HGSC treatment. NK cells' functional capabilities differ because of variation in receptor expression and genetics, with meaningful impacts on their anticancer activity. Studying HGSC:NK cell interactions will define the features that predict the best outcomes for patients with the disease, but the highly diverse nature of HGSC will likely require combination therapies or approaches to simultaneously target multiple, co-existing features of the tumor to avoid tumor escape and relapse. We expect that the ideal therapy will enable NK cell infiltration and activity, reverse immunosuppression within the tumor microenvironment, and enable effector functions against the diverse subpopulations that comprise HGSC.

Folate-mediated targeted PLK1 inhibition therapy for ovarian cancer: A comparative study of molecular inhibitors and siRNA therapeutics

PLK1 is a promising target for clinical treatment of diverse malignancies including ovarian cancer (OC), in which PLK1 over-expression is often correlated with poor prognosis and short survival. PLK1 can be blocked with small molecular inhibitors like volasertib (Vol) or silenced with PLK1-specific siRNA (siPLK1), hence effectively suppressing tumor growth. Surprisingly, despite intensive work on molecular inhibitor and siRNA therapeutics, there is no direct comparison between them reported for targeted tumor therapy. Herein, we employing folate as a ligand and polymersomes as a nanovehicle performed a comparative study on Vol and siPLK1 in inhibiting OC in vitro and in vivo. Folate-targeted polymersomal Vol and siPLK1 (termed as FA-Ps-Vol and FA-Ps-siPLK1, respectively) were both nano-sized and stable, and displayed an optimal FA density of 20% for SKOV-3 cells. Notably, FA-Ps-Vol and FA-Ps-siPLK1 exhibited an IC₅₀ of 193 and 770 nM, respectively, to SKOV-3 cells, indicating a greater potency of Vol than siPLK1. The markedly increased uptake for FA-Ps-Vol and FA-Ps-siPLK1 compared with respective non-targeted controls by SKOV-3 tumor xenografts in mice confirmed that FA mediates strong OC-targeting in vivo. Intriguingly, FA-Ps-Vol while greatly lessening toxic effects of Vol potently repressed tumor growth with a remarkable tumor inhibition rate (TIR) of 97% at 20 mg (i.e. 32.4 µmol) Vol equiv./kg. FA-Ps-siPLK1 achieved effective tumor inhibition (TIR = ca. 87% or 90%) at 2 or 4 mg (i.e. 0.15 or 0.3 µmol) siPLK1 equiv./kg without causing adverse effects. This comparative study highlights that molecular inhibitor has the advantage of easy dose escalation and potent protein inhibition at the expense of certain adverse effects while siRNA therapeutics has low toxicity with moderate protein inhibition in vivo. STATEMENT OF SIGNIFICANCE: PLK1 is a promising target for the development of innovative and specific treatments against diverse malignancies. Interestingly, despite intensive work on molecular inhibitors and siRNA against PLK1, little work has been directed to compare their efficacy in targeted tumor therapy. Here, we employed folate as a ligand and polymersomes as a nanovehicle and have performed a comparative study on volasertib and siPLK1 in inhibiting ovarian cancer in vitro and in vivo. Our data show that the dose of volasertib can be easily escalated to induce prominent antitumor efficacy at the expense of certain adverse effects, while siPLK1 brings about moderate protein inhibition and antitumor therapy without causing toxicity at two-orders-of-magnitude lower dose.

Synergistic effect of folate-conjugated polymers and 5-fluorouracil in the treatment of colon cancer

Background

In recent years, targeted drug delivery strategies have received special attention from the scientific world due to advantages such as more effective therapy and reduction of side effects. The principle of operation is delayed excretion from the bloodstream of the drug delivery system compared to the drug itself, as well as facilitated penetration into diseased cells thanks to the use of ligands recognized by appropriate receptors. Particularly interesting drug carriers are amphiphilic copolymers that form nano-sized micelles with a drug, which can release the drug at a specific place in the body under the influence of appropriate stimuli.

Results

We describe the synthesis of the diblock polymer, poly(2-hydroxyethyl acrylate)-b-poly(N-vinylcaprolactam) using RAFT/MADIX (Reversible Addition-Fragmentation chain Transfer/MAcromolecular Design by Interchange of Xanthate) controlled polymerization affording polymers with good dispersity according to SEC (Size-Exclusion Chromatography). Some post-modifications of the polymer with folic acid were then performed as evidenced by NMR (Nuclear Magnetic Resonance), UV–Vis (UltraViolet–Visible) and FT-IR (Fourier-Transform Infrared) spectroscopy, and TGA (ThermoGravimetric Analysis). The formation of stable micellar systems from polymers with and without the drug, 5-fluorouracil, was confirmed by DLS (Dynamic Light Scattering) and zeta potential measurements, and TEM (Transmission Eelectron Microscopy) imaging. Finally, the cloud point of the polymers was investigated, which turned out to be close to the temperature of the human body. Most importantly, these micellar systems have been explored as a drug delivery system against colon cancer, showing increased cytotoxicity compared to the drug alone. This effect was achieved due to the easier cellular uptake by the interaction of folic acid and its receptors on the surface of cancer cells.

Conclusions

The presented results constitute a solid foundation for the implementation of a nano-sized drug delivery system containing folic acid for practical use in the treatment of drug-resistant cancer, as well as more effective therapy with fewer side effects.

Graphical Abstract

Selenium stimulates the antitumour immunity: Insights to future research

Selenium is an essential trace element for regulating immune functions through redox-regulating activity of selenoproteins (e.g. glutathione peroxidase), protecting immune cells from oxidative stress. However, in cancer, selenium has biological bimodal action depending on the concentration. At nutritional low doses, selenium, depending on its form, may act as an antioxidant, protecting against oxidative stress, supporting cell survival and growth, thus, plays a chemo-preventive role; while, at supra-nutritional higher pharmacological doses, selenium acts as pro-oxidant inducing redox signalling and cell death. To date, many studies have been conducted on the benefits of selenium intake in reducing the risk of cancer incidence at the nutritional level, indicating that likely selenium functions as an immunostimulator, i.e. reversing the immunosuppression in tumour microenvironment towards antitumour immunity by activating immune cells (e.g. M₁ macrophages and CD8⁺ T-lymphocytes) and releasing pro-inflammatory cytokines such as interferon-gamma; whereas, fewer studies have explored the effects of supra-nutritional or pharmacological doses of selenium in cancer immunity. This review, thus, systematically analyses the current knowledge about how selenium stimulates the immune system against cancer and lay the groundwork for future research. Such knowledge can be promising to design combinatorial therapies with Selenium-based compounds and other modalities like immunotherapy to lower the adverse effects and increase the efficacy of treatments.

Selenofolate inhibits the proliferation of IGROV1 cancer cells independently from folate receptor alpha

Cancer is one of the main causes of human mortality worldwide and novel chemotherapeutics are required due to the limitations of conventional cancer therapies. For example, using redox selenium compounds as novel chemotherapeutics seem to be very promising. The objective of this study was to explore if folate could be used as a carrier to deliver a newly synthesised selenium derivative selenofolate into cancer cells. Particularly, the cytotoxic effects of this selenofolate compound were investigated in a variety of cancer cell types including lung, liver, and cervical cancers and specifically IGROV1 cells. Our results showed that selenofolate inhibits the growth of cancer cells in-vitro. However, despite the expectations, folate receptor alpha (FRα) was not involved in the transportation of selenofolate compound into the cells i.e. growth inhibition was independent of FRα, suggesting that multiple transporters (e.g. reduced folate carrier-1) are possibly involved in the delivery and internalisation of folate in IGROV1 cells. Additionally, selenofolate did not exert cell death through apoptosis. Instead, anti-proliferative activity showed to be the main cause of growth inhibition of selenolofate in the IGROV1 cell line. In conclusion, selenofolate inhibits the growth of cancer cells and thus, may be explored further as a potential chemotherapeutic agent.

Advancements in folate receptor targeting for anti-cancer therapy: A small molecule-drug conjugate approach

Targeted delivery combined with controlled release of drugs has a crucial role in future of personalized medicine. The majority of cancer drugs are intended to interfere with one or more cellular events. Anticancer agents can also be toxic to healthy cells, as healthy cells may also need to proliferate and avoid apoptosis. The focus of this review covers the principles, advantages, drawbacks and summarize criteria that must be met for design of small molecule-drug conjugates (SMDCs) to achieve the desired therapeutic potency with minimal toxicity. SMDCs are composed of a targeting ligand, a releasable bridge, a spacer, and a therapeutic payload. We summarize the criteria for the effective design that influences the selection of tumor specific receptor and optimum elements in the design of SMDCs. We also discuss the criteria for selecting the optimal therapeutic drug payload, spacer and linker. The linker chemistries and cleavage strategies are also discussed. Finally, we review the folate receptor targeting SMDCs that are in preclinical development and in clinical trials.

Targeting Strategies for Enhancing Paclitaxel Specificity in Chemotherapy

Paclitaxel (PTX) has been used for cancer treatment for decades and has become one of the most successful chemotherapeutics in the clinic and financially. However, serious problems with its use still exist, owing to its poor solubility and non-selective toxicity. With respect to these issues, recent advances have addressed the water solubility and tumor specificity related to PTX application. Many measures have been proposed to remedy these limitations by enhancing tumor recognition via ligand-receptor-mediated targeting as well as other associated strategies. In this review, we investigated various kinds of ligands that have emerged as PTX tumor-targeting tools. In particular, this article highlights small molecule-, protein-, and aptamer-functionalized conjugates and nanoparticles (NPs), providing a promising approach for PTX-based individualized treatment prospects.

Raltitrexed-Modified Gold and Silver Nanoparticles for Targeted Cancer Therapy: Cytotoxicity Behavior In Vitro on A549 and HCT-116 Human Cancer Cells

Two different raltitrexed gold and silver nanoparticles for the delivery of an antitumoral drug into cancer cells were synthesized and characterized. A cysteine linker was used for the covalent bonding of raltitrexed to the surface of nanoparticles. To evaluate the efficacy of the antifolate-derivative nanoparticles, their cytotoxicity was assayed in vitro with A549 human lung adenocarcinoma and HCT-116 colorectal carcinoma human cells. Modified nanoparticles are a biocompatible material, and administration of silver raltitrexed nanoparticles strongly inhibited the viability of the cancer cells; gold raltitrexed nanoparticles do not show any type of cytotoxic effect. The results suggest that silver raltitrexed nanoparticles could be a potential delivery system for certain cancer cells.

Folic Acid-Targeted MXene Nanoparticles for Doxorubicin Loaded Drug Delivery

MXenes are two-dimensional (2D) materials with a large specific surface area and abundant surface functional groups. A folate receptors-targeted drug carrier was constructed based on the rich surface functional groups and high biocompatibility of MXenes. This drug carrier possesses as high as 69.9 % drug-loading capability and as long as 48 h drug release time. Tumour targeting and a pH-responsive mechanism can make MXene nanoparticles quickly accumulate in tumour sites and slowly release loads. The results showed that DOX was released in a large amount in a PBS solution at pH 4.5. Compared with the naked drug, MXenes-FA-SP@DOX has a higher cell inhibition rate and a longer drug action time at a lower concentration (less than 10 μg mg−1). This drug delivery system exhibited potential applications for the treatment of malignant tumour and this work extends the biomedical applications of MXenes in nanomedicine.

Targeting Strategies for Enhancing Paclitaxel Specificity in Chemotherapy

Paclitaxel (PTX) has been used for cancer treatment for decades and has become one of the most successful chemotherapeutics in the clinic and financially. However, serious problems with its use still exist, owing to its poor solubility and non-selective toxicity. With respect to these issues, recent advances have addressed the water solubility and tumor specificity related to PTX application. Many measures have been proposed to remedy these limitations by enhancing tumor recognition via ligand-receptor-mediated targeting as well as other associated strategies. In this review, we investigated various kinds of ligands that have emerged as PTX tumor-targeting tools. In particular, this article highlights small molecule-, protein-, and aptamer-functionalized conjugates and nanoparticles (NPs), providing a promising approach for PTX-based individualized treatment prospects.

The targeted inhibition of prostate cancer by iron-based nanoparticles based on bioinformatics

Prostate cancer is an epithelial malignant tumor of the prostate, and it is one of the malignant tumors with a high incidence of urogenital system in men. The local treatment of prostate cancer is mainly radical resection and radical radiotherapy, but they are not applicable to advanced prostate cancer. Systemic therapy mainly includes targeted therapy and immunotherapy which could cause many complications, and will affect the prognosis and quality of life of patients. It is urgent to find new treatments for prostate cancer. Bioinformatics offers hope for us to find reliable therapeutic targets. Bioinformatics can use the tumor informations in database and analyze them to screen out the best differentially expressed genes. Using the selected differentially expressed genes as targets, a gene interference plasmid was designed, and the constructed plasmid was used for targeted gene therapy. There are some problems about gene therapy that need to be solved, such as how to transfer genes to target cells is also an important challenge. Due to their large molecular weight and hydrophilic nature, they cannot enter cells through passive diffusion mechanisms. Here we synthesized a DNA carrier used surface modified iron based nanoparticles, and used it to load plasmid including ShRNA which can inhibit the expression of oncogene SLC4A4 selected by bioinformatics’ method. After that we use this iron based nanoparticles/plasmid DNA nanocomposite to treat prostate cancer cells in vitro and in vivo. The target gene SLC4A4 we had selected using bioinformatics had a strong effect on the proliferation of prostate cells; Our nanocomposite could inhibit the expression of SLC4A4 effectively, it had strong inhibitory effects on prostate cancer cells both in vivo and in vitro, and can be used as a potential method for prostate cancer treatment.

Multimodal image-guided folic acid targeted Ag-based quantum dots for the combination of selective methotrexate delivery and photothermal therapy

Multifunctional quantum dots (QDs) with photothermal therapy (PTT) potential loaded with an anticancer drug and labelled with a targeting agent can be highly effective nano-agents for tumour specific, image-guided PTT/chemo combination therapy of cancer. Ag-chalcogenides are promising QDs with good biocompatibility. Ag₂S QDs are popular theranostic agents for imaging in near-infrared with PTT potential. However, theranostic applications of AgInS2 QDs emitting in the visible region and its PTT potential need to be explored. Here, we first present a simple synthesis of small, glutathione (GSH) coated AgInS₂ QDs with peak emission at 634 nm, 21% quantum yield, and excellent long-term stability without an inorganic shell. Ag2S-GSH QDs emitting in the near-infrared region (peak emission = 822 nm) were also produced. Both QDs were tagged with folic acid (FA) and conjugated with methotrexate (MTX). About 3-fold higher internalization of FA-tagged QDs by folate-receptor (FR) overexpressing HeLa cells than HT29 and A549 cells was observed. Delivery of MTX by QD-FA-MTX reduced the IC50 of the drug from 10 μg/mL to 2.5-5 μg/mL. MTX release was triggered at acidic pH, which was further enhanced with local temperature increase created by laser irradiation. Irradiation of AgInS₂-GSH QDs at 640 nm (300 mW) for 10 min, caused about 10 °C temperature increase but did not cause any thermal ablation of cells. On the other hand, Ag₂S-GSH-FA based PTT effectively and selectively killed HeLa cells with 10 min 808 nm laser irradiation via mostly necrosis with an IC₅₀ of 5 μg Ag/mL. Under the same conditions, IC₅₀ of MTX was reduced to 0.21 μg/mL if Ag₂S-GSH-FA.

Folate Modified Long Circulating Nano-Emulsion as a Promising Approach for Improving the Efficiency of Chemotherapy Drugs in Cancer Treatment

PURPOSE

In order to improve the therapeutic efficiency of the chemotherapeutic drug paclitaxel in tumors, a folate-based Paclitaxel nanoemulsion (FNEs) was developed for tumor targeted treatment.

METHODS

In this study, we designed a folate-targeted nanoemulsion (folate/PEG-DSPE/nanoemulsion, FNEs) based on the traditional nanoemulsion using the principle of long-circulation targeting receptor mediated. The nanoemulsion (folate/PEG-DSPE/nanoemulsion, FNEs) was fabricated using high-pressure homogenization with a microfluidizer.

RESULTS

The nanoemulsion (folate/PEG-DSPE/nanoemulsion, FNEs) can improve the delivery efficiency of nanocarriers at the tumor site by virtue of the high expression of folate receptors on the tumor surface. Malvern Nanoseries device and transmission electron microscopy (TEM) analyses showed that the nanoemulsions were spherical with an average diameter of 140 nm. The nanoemulsions can effectively carry paclitaxel (PTX) with an encapsulation rate of about 95%. And in vitro experiments have shown that it can efficiently increase the uptake of PTX in 4 T1 breast cancer cells and FNEs had a targeting capability hundredfold higher than that of PTX-loaded nanoemulsions (PTX-NEs) without folate. In vivo experiments have shown that the pharmacokinetic parameters of FNEs were better than those of other PTX groups and FNEs can significantly enhance circulation time in the body of the subcutaneously implanted 4 T1 breast cancer in mice, increase the accumulation of chemotherapy drugs at tumor sites and effectively inhibit tumor growth with lower system toxicity.

CONCLUSIONS

This study can effectively improve the therapeutic efficiency of chemotherapy drugs for tumors, and provide an useful reference for solving the problem of low efficacy of chemotherapy drugs in clinical treatment of tumors. Graphical Abstract Schematic representation of Folic acid/PEG-DSPE/nano-emulsion (FNEs) specifically target tumor cells and enhanced anti-tumor effects.

Anti-tumor Drug Targets Analysis: Current Insight and Future Prospect

The incidence and mortality of malignant tumors are on the rise, which has become the second leading cause of death in the world. At present, anti-tumor drugs are one of the most common methods for treating cancer. In recent years, with the in-depth study of tumor biology and related disciplines, it has been gradually discovered that the essence of cell carcinogenesis is the infinite proliferation of cells caused by the disorder of cell signal transduction pathways, followed by a major shift in the concept of anti-tumor drugs research and development. The focus of research and development is shifting from traditional cytotoxic drugs to a new generation of anti-tumor drugs targeted at abnormal signaling system targets in tumor cells. In this review, we summarize the targets of anti-tumor drugs and analyse the molecular mechanisms of their effects, which lay a foundation for subsequent treatment, research and development.

Antibody-drug conjugates for ovarian cancer: current clinical development

PURPOSE OF REVIEW

Antibody drug conjugates (ADC) are a novel class of cancer therapeutics, delivering cytotoxic therapy directly to cancer cells, and show promise in the management of platinum-resistant ovarian cancer. Herein we summarize the ADC landscape currently in clinical study.

RECENT FINDINGS

Mirvetuximab Soravtansine, IMGN853, is an ADC targeting the folate receptor alpha (FRα) and has demonstrated promising single agent activity and a favorable toxicity profile in FRα-positive, platinum-resistant, epithelial ovarian cancer (EOC). The antitumor effect is seen primarily in less heavily pretreated EOC patients with moderate-to-high FRα tumor expression. A phase III study, randomizing patients to either IMGN853 or the physician's choice of single-agent chemotherapy has completed accrual. Additional ADC are being evaluated in ovarian cancer including agents that target NaPiB2, Trop2, mesothelin, and MUC16 are in phase 1 clinical trials.

SUMMARY

ADC bind antigens overexpressed on cancer cells and provide site-selective drug delivery, with the goal to increase therapeutic efficacy of cytotoxics while decreasing the off-target toxicity of the payloads. With appropriate antigen selection and adequate, measurable antigen threshold targets, these new agents may provide an improved strategy for overcoming resistance to standard chemotherapy in ovarian cancer.

Nanotechnology based therapeutic application in cancer diagnosis and therapy

Due to the lack of early diagnosis, cancer remains as one of the leading cause of human mortality. Inability to translate research into clinical trials and also inability of chemotherapeutics delivery to targeted tumor sites are major drawbacks in cancer therapeutics. With the emergence of nanomedicine, several nanoprobes (conjugated with targeting ligands and chemotherapeutic drugs) are developed. It can interact with biological system and thus sense and monitor the biological events with high efficiency and accuracy along with therapy application. Nanoparticles like gold and iron oxide are frequently used in the computed tomography and magnetic resonance imaging applications, respectively. Moreover, enzymatic activity of gold and iron oxide nanoparticles enables the visible colorimetric diagnostic of cancer cells, whereas, fluorescence property of quantum dots and upconversion nanoparticles helps in in vivo imaging application. Other than this, drug conjugation with nanoparticles also reduces the systemic toxic effect of chemotherapeutic drugs. Due to their several unique intrinsic properties, nanoparticles itself can also be employed as therapeutics in cancer treatment by photothermal therapy (PTT) and photodynamic therapy (PDT). Thus, the main focus of this review is to emphasize on current progress in diagnostic and therapeutic application of nanoprobes in cancer.

SNORD89 promotes stemness phenotype of ovarian cancer cells by regulating Notch1-c-Myc pathway

Background

Ovarian cancer is the leading cause of death in gynecological cancer. Cancer stem cells (CSCs) contribute to the occurrence, progression and resistance. Small nucleolar RNAs (SnoRNAs), a class of small molecule non-coding RNA, involve in the cancer cell stemness and tumorigenesis.

Methods

In this study, we screened out SNORNAs related to ovarian patient’s prognosis by analyzing the data of 379 cases of ovarian cancer patients in the TCGA database, and analyzed the difference of SNORNAs expression between OVCAR-3 (OV) sphere-forming (OS) cells and OV cells. After overexpression or knockdown SNORD89, the expression of Nanog, CD44, and CD133 was measured by qRT-PCR or flow cytometry analysis in OV, CAOV-3 (CA) and OS cells, respectively. CCK-8 assays, plate clone formation assay and soft agar colony formation assay were carried out to evaluate the changes of cell proliferation and self-renewal ability. Scratch migration assay and trans-well invasion analysis were used for assessing the changes of migration and invasion ability.

Results

High expression of SNORD89 indicates the poor prognosis of ovarian cancer patients and was associated with patients’ age, therapy outcome. SNORD89 highly expressed in ovarian cancer stem cells. The overexpression of SNORD89 resulted in the increased stemness markers, S phase cell cycle, cell proliferation, invasion and migration ability in OV and CA cells. Conversely, these phenomena were reversed after SNORD89 silencing in OS cells. Further, we found that SNORD89 could upregulate c-Myc and Notch1 expression in mRNA and protein levels. SNORD89 deteriorates the prognosis of ovarian cancer patients by regulating Notch1-c-Myc pathway to promote cell stemness and acts as an oncogene in ovarian tumorigenesis. Consequently, SNORD89 can be a novel prognostic biomarker and therapeutic target for ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-2005-1) contains supplementary material, which is available to authorized users.

Humanized Anti-hepatocyte Growth Factor Monoclonal Antibody (YYB-101) Inhibits Ovarian Cancer Progression

Current chemotherapy regimens have certain limitations in improving the survival rates of patients with advanced ovarian cancer. Hepatocyte growth factor (HGF) is important in ovarian cancer cell migration and invasion. This study assessed the effects of YYB-101, a humanized monoclonal anti-HGF antibody, on the growth and metastasis of ovarian cancer cells. YYB-101 suppressed the phosphorylation of the HGF receptor c-MET and inhibited the migration and invasion of SKOV3 and A2780 ovarian cancer cells. Moreover, the combination of YYB-101 and paclitaxel synergistically inhibited tumor growth in an in vivo ovarian cancer mouse xenograft model and significantly increased the overall survival (OS) rate compared with either paclitaxel or YYB-101 alone. Taken together, these findings suggest that YYB-101 has therapeutic potential in ovarian cancer when combined with conventional chemotherapy agents.

β-Cyclodextrin coated and folic acid conjugated magnetic halloysite nanotubes for targeting and isolating of cancer cells

The study developed a simple, effective and inexpensive strategy for capturing, enriching and detecting circulating tumor cells (CTCs) by using folic acid (FA) as the targeting molecule instead of antibodies. This work constructed magnetic halloysite nanotubes (MHNTs) coated with biocompatible β-cyclodextrin (CD), and conjugated to FA via a PEG-Ad linker, to specifically capture the FA receptor (FR)-overexpressing cancer cells. The capture efficiencies of MHNTs@β-CD@Ad-PEG-FA for the Skov3, Hela and A549 cancer cells were 96.3%, 97.0% and 95.6% respectively. In addition, the nanoparticles were able to capture very low numbers of the cancer cells (25-500 cells/mL) from PBS and whole blood, as well as selectively capture the cancer cells over normal HEK 293 T cells. Furthermore, the captured cells were viable and grew normally in vitro, indicating the future potential of downstream analyses. This approach can be adapted for different CTCs, once the tumor-specific surface markers are identified and the efficacy of targeting ligands is established. Taken together, FA-conjugated MHNTs nanoparticles are a highly promising tool for isolating CTCs for the diagnosis and treatment of cancer.

Targeted Delivery of Nanoparticulate Cytochrome C into Glioma Cells Through the Proton-Coupled Folate Transporter

In this study, we identified the proton-coupled folate transporter (PCFT) as a route for targeted delivery of drugs to some gliomas. Using the techniques of confocal imaging, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and small interfering (siRNA) knockdown against the PCFT, we demonstrated that Gl261 and A172 glioma cells, but not U87 and primary cultured astrocytes, express the PCFT, which provides selective internalization of folic acid (FA)-conjugated cytochrome c-containing nanoparticles (FA-Cyt c NPs), followed by cell death. The FA-Cyt c NPs (100 µg/mL), had no cytotoxic effects in astrocytes but caused death in glioma cells, according to their level of expression of PCFT. Whole-cell patch clamp recording revealed FA-induced membrane currents in FA-Cyt c NPs-sensitive gliomas, that were reduced by siRNA PCFT knockdown in a similar manner as by application of FA-Cyt c NPs, indicating that the PCFT is a route for internalization of FA-conjugated NPs in these glioma cells. Analysis of human glioblastoma specimens revealed that at least 25% of glioblastomas express elevated level of either PCFT or folate receptor (FOLR1). We conclude that the PCFT provides a mechanism for targeted delivery of drugs to some gliomas as a starting point for the development of efficient methods for treating gliomas with high expression of PCFT and/or FOLR1.

Is Targeting the Folate Receptor in Ovarian Cancer Coming of Age?

Prognosis for women with epithelial ovarian cancer remains poor. One new molecular target in epithelial ovarian cancer is folate receptor alpha (FRα). This commentary discusses the characteristics that contribute to its attractiveness as a candidate for therapeutic intervention.

Catch and Release Photosensitizers: Combining Dual-Action Ruthenium Complexes with Protease Inactivation for Targeting Invasive Cancers

Dual action agents containing a cysteine protease inhibitor and Ru-based photosensitizer for photodynamic therapy (PDT) were designed, synthesized, and validated in 2D culture and 3D functional imaging assays of triple-negative human breast cancer (TNBC). These combination agents deliver and release Ru-based PDT agents to tumor cells and cause cancer cell death upon irradiation with visible light, while at the same time inactivating cathespin B (CTSB), a cysteine protease strongly associated with invasive and metastatic behavior. In total five Ru-based complexes were synthesized with the formula [Ru(bpy)₂(1)](O₂CCF₃)₂ (3), where bpy = 2,2'-bipyridine and 1 = a bipyridine-based epoxysuccinyl inhibitor; [Ru(tpy)(NN)(2)](PF₆)₂, where tpy = terpiridine, 2 = a pyridine-based epoxysuccinyl inhibitor and NN = 2,2'-bipyridine (4); 6,6'-dimethyl-2,2'-bipyridine (5); benzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (6); and 3,6-dimethylbenzo[ i]dipyrido[3,2- a:2',3'- c]phenazine (7). Compound 3 contains a [Ru(bpy)₃]²⁺ fluorophore and was designed to track the subcellular localization of the conjugates, whereas compounds 4-7 were designed to undergo either photoactivated ligand dissociation and/or singlet oxygen generation. Photochemical studies confirmed that complexes 5 and 7 undergo photoactivated ligand dissociation, whereas 6 and 7 generate singlet oxygen. Inhibitors 1-7 all potently and irreversibly inhibit CTSB. Compounds 4-7 were evaluated against MDA-MB-231 TNBC and MCF-10A breast epithelial cells in 2D and 3D culture for effects on proteolysis and cell viability under dark and light conditions. Collectively, these data reveal that 4-7 potently inhibit dye-quenched (DQ) collagen degradation, whereas only compound 7 causes efficient cell death under light conditions, consistent with its ability to release a Ru(II)-based photosensitizer and to also generate ¹O₂.

FORWARD I: a Phase III study of mirvetuximab soravtansine versus chemotherapy in platinum-resistant ovarian cancer

Mirvetuximab soravtansine, an antibody–drug conjugate that binds with high affinity to folate receptor-α to provide tumor-directed delivery of the potent microtubule-disrupting agent DM4, has emerged as a promising investigational agent for the treatment of ovarian cancer, particularly in the setting of platinum-resistant disease. Here we describe the rationale and design of FORWARD I (NCT02631876), the first randomized, multicenter Phase III study to compare the safety and efficacy of mirvetuximab soravtansine versus investigator's choice of chemotherapy in women with folate receptor-α-positive, platinum-resistant epithelial ovarian, primary peritoneal or fallopian tube cancer. Patients will be randomized in a 2:1 ratio. The primary end point is progression-free survival, and key secondary objectives include comparison of overall response rates, overall survival and duration of response.

Folic Acid-Functionalized Hybrid Photonic Barcodes for Capture and Release of Circulating Tumor Cells

Recovery of circulating tumor cells (CTCs) from cancer patients by an efficient CTCs capture and release method can greatly increase their application in diagnostics and treatment of cancers. In this paper, we presented a folic acid (FA)-functionalized hybrid photonic barcode for capture and release of CTCs. The hybrid photonic barcodes were formed by two nano-ordered parts, poly(ethylene glycol) diacrylate (PEGDA) inverse opal structure for sustaining integrity and methacrylated gelatin (GelMA) gel filler for conjugating FA molecules to mediate cell capture. The nano-ordered structures of the hybrid photonic barcodes not only increased contact area, but also decreased steric hindrance among FA molecules. Thus, the topographic interaction between the barcodes and CTCs was greatly enhanced. In addition, GelMA gel was soft and extracellular matrix (ECM) alike, which was beneficial to decrease impairment to CTCs during the CTCs-barcode interaction as well as preserving their viability. Demonstrated by four CTCs types, Hela (epithelial tissue, folate receptor positive, FR+), A02 (bone marrow, FR+), Raji (lymphoid tissue, FR+), and A549 (epithelial tissue, folate receptor negative, FR-), FR+ CTCs could be captured efficiently with reliability and specificity. The captured cells could be controllably released with high viability just by quick trypsinization. The whole processes were simple and efficient. These features indicated that the FA-functionalized hybrid photonic barcodes were promising for full recovery of CTCs from cancer patients, which was important for diagnosis and treatment of cancer.

Expression of functional folate receptors in multiple myeloma

Receptor-targeted delivery of imaging and therapeutic agents has emerged as an attractive strategy to diagnosis and treat many diseases including cancer. One of the most well-studied receptors for targeted therapies is the folate receptor (FR) family. FR-α and FR-β are present on many cancers with little expression in normal tissues; leading to the testing of at least six folate-targeted drugs in human clinical trials for various cancers. However, the expression of FR in blood cancers has not been fully explored with no reports of FR expression in myelomas. Herein, we report the expression of both FR-α and FR-β on CD138 + plasma cells isolated from patients with multiple myeloma. In addition, all-trans retinoic acid was shown to increase the levels of FR-α and FR-β in two myeloma cell lines. Altogether, this data suggests that folate-targeted therapies for the treatment of multiple myeloma warrants further investigation.