Novel micelles based on amphiphilic branched PEG as carriers for fenretinide

Topical transdermal chemoprevention of breast cancer: where will nanomedical approaches deliver us?

Despite the high incidence of breast cancer, there are few pharmacological prevention strategies for the high-risk population and those that are available have low adherence. Strategies that deliver drugs directly to the breasts may increase drug local concentrations, improving efficacy, safety and acceptance. The skin of the breast has been proposed as an administration route for local transdermal therapy, which may improve drug levels in the mammary tissue, due to both deep local penetration and percutaneous absorption. In this review, we discuss the application of nanotechnology-based strategies for the delivery of well established and new agents as well as drug repurposing using the topical transdermal route to improve the outcomes of preventive therapy for breast cancer.

Microencapsulation of amorphous solid dispersions of fenretinide enhances drug solubility and release from PLGA in vitro and in vivo

The purpose of this study was to develop solid dispersions of fenretinide(4HPR), incorporate them into poly(lactic-co-glycolic)(PLGA) millicylindrical implants, and evaluate the resulting implants in vitro and in vivo for future applications in oral cancer chemoprevention. Due to the extreme hydrophobicity of 4HPR, 4HPR-polyvinylpyrrolidone (PVP) amorphous solid dispersions(ASDs) were prepared for solubility enhancement. The optimal PVP-4HPR ratio of 9/1(w/w) provided a 50-fold solubility enhancement in aqueous media, which was sustained over 1 week. PVP-4HPR ASD particles were loaded into PLGA millicylinders and drug release was evaluated in vitro in PBST and in vivo by recovery from subcutaneous injection in rats. While initial formulations of PLGA PVP-4HPR millicylinders only released 10% 4HPR in vitro after 28 days, addition of the plasticizer triethyl-o-acetyl-citrate(TEAC) into PVP-4HPR ASDs resulted in a 5.6-fold total increase in drug release. Remarkably, the TEAC-PVP-4HPR PLGA implants demonstrated slow, continuous, and nearly complete release over 1 month in vivo compared to a 25% release for our previously reported formulation incorporating solubilizers and pore-forming agents. Hence, a combination of PLGA plasticizer and ASD formation provides an avenue for long-term controlled release in vivo for the exceptionally difficult drug to formulate, 4HPR, and a suitable formulation for future evaluation in rodent models of oral cancer.

Fenretinide-polyethylene glycol (PEG) conjugate with improved solubility enhanced cytotoxicity to cancer cell and potent in vivo efficacy

Fenretinide (4-HPR), a synthetic retinoid, has shown its antitumor activity in many tumor types with low cytotoxicity to normal cells and high clinical safety. However, the low water solubility limits its further biological applications. To increase solubility, 4-HPR was conjugated with methoxy polyethylene glycol carboxylic acid (mPEG_2K-COOH) by an ester linkage between the phenol hydroxyl of 4-HPR and the carboxyl of mPEG_2K-COOH. The 4-HPR-PEG_2K conjugate micelles had mean size of 76.70 ± 1.248 nm with a narrow distribution and a low critical micelle concentration. In vitro cytotoxicity studies showed the micelles have higher cytotoxicity to A2780s and MCF-7 cells. Its IC₅₀ was 4.7 and 4.1-fold lower than the free 4-HPR, respectively. Importantly, in vivo pharmacokinetic studies, the AUC of 4-HPR was found to be 2.3-fold higher in 4-HPR-PEG_2K micelles compared to free 4-HPR. And the 4-HPR-PEG_2K micelles had higher antitumor activity. Meanwhile, the histopathology analysis exhibited that the micellar treatment decreased the viability of A2780s cells and increased the level of induced apoptosis. Therefore, the enhanced activity of 4-HPR by the method of conjugation with mPEG_2K-COOH could hopefully provide new insights into the matter of ovarian cancer and breast cancer treatment.

A Cationic Nanomicellar Complex of the Quaternary Amphiphilic Amine RC16+ with Fenretinide as a New Multitasking System for Antitumor Therapy

OBJECTIVES

This study investigated the antitumor effect of a new nanomicellar complex obtained by combining the antitumor agent fenretinide with a quaternary amphiphilic amine RC16+ also endowed with antitumor activity.

METHODS

The complex (Fen-RC16+) strongly improved the aqueous solubility of fenretinide (from 1,71 ± 0.08 µg/ml, pure fenretinide to 1500 ± 164 µg /ml, Fen-RC16+ complex) and provided a cytotoxic effect on SH-SY5Y neuroblastoma cell lines resulting from the intrinsic activity of both the complex components. Moreover, the mean size of the nanomicellar complex (ranging from 20 ± 1.97 nm to 40 ± 3.05 nm) was suitable for accumulation to the tumor site by the enhanced permeability and retention effect and the positive charge provided by the quaternary RC16+ induced adsorption of the complex on the tumor cell surface improving the intracellular concentration of fenretinide.

RESULTS

All these characteristics made the Fen-RC16+ complex a multitasking system for antitumor therapy.

CONCLUSION

Indeed its in vivo activity, evaluated on SH-SY5Y xenografts, was strong, and the tumor growth did not resume after the treatment withdrawal.

[Nanoparticle Formation and Delivery of Poorly Water-soluble Drugs by Hydrophobized Polymers]

When a hydrophobic group is introduced into a water-soluble polymer, self-assembly with the hydrophobic group as nucleus occurs in water. In the 1990s, many researchers focused on this phenomenon and various self-aggregates were prepared. Among them, a block copolymer consisting of a hydrophilic chain and a hydrophobic chain is associated in water, producing polymer micelles with the hydrophilic chain oriented in the outer shell and the hydrophobic chain as core. Meanwhile, many studies were conducted to create polymer self-associates by introducing hydrophobic groups into water-soluble polymers. In this review, the author describes hydrophobized polymers with polysaccharides and synthetic polymers that are frequently used as pharmaceutical raw materials. In addition are outlined the usefulness of hydrophobized polymers as carriers with the function of encapsulating and solubilizing poorly water-soluble drugs, along with the results of our research.

A Novel Nanomicellar Combination of Fenretinide and Lenalidomide Shows Marked Antitumor Activity in a Neuroblastoma Xenograft Model

Purpose

Currently >50% of high-risk neuroblastoma (NB) patients, despite intensive therapy and initial partial or complete response, develop recurrent NB due to the persistence of minimal residual disease (MRD) that is resistant to conventional antitumor drugs. Indeed, their low therapeutic index prevents drug-dose escalation and protracted administration schedules, as would be required for MRD treatment. Thus, more effective and less toxic therapies are urgently needed for the management of MRD. To address this aim, we evaluated a new combination of fenretinide and lenalidomide, both endowed with antitumor activity and low-toxicity profiles. New nanomicelles were prepared as carriers for this combination to maximize bioavailability and accumulation at the tumor site because of the enhanced permeability and retention (EPR) effect.

Experimental design

New nanomicelles containing the fenretinide–lenalidomide combination (FLnMs) were prepared by a one-step method, providing high drug encapsulation and micelle dimensions suitable for tumor accumulation. Their administration to mice bearing human NB xenografts allowed us to evaluate their efficacy in comparison with the nanomicelles containing fenretinide alone (FnMs).

Results

Treatment by FLnMs significantly decreased the tumor growth of NB xenografts. FLnMs were more active than FnMs despite comparable fenretinide concentrations in tumors, and lenalidomide alone did not show cytotoxic activity in vitro against NB cells. The tumor mass at the end of treatment with FLnMs was predominantly necrotic, with a decreased Ki-67 proliferation index.

Conclusion

FLnMs provided superior antitumor efficacy in NB xenografts compared to FnMs. The enhanced efficacy of the combination was likely due to the antiangiogenic effect of lenalidomide added to the cytotoxic effect of fenretinide. This new nanomicellar combination is characterized by a low-toxicity profile and offers a novel therapeutic option for the treatment of high-risk tumors where the persistence of MRD requires repeated administrations of therapeutic agents over long periods of time to avoid recurrent disease.

Transient phase behavior of an elastomeric biomaterial applied to abdominal laparotomy closure

Secure closure of the fascial layers after entry into the peritoneal cavity is crucial to prevent incisional hernia, yet appropriate purchase of the tissue can be challenging due to the proximity of the underlying protuberant bowel which may become punctured by the surgical needle or strangulated by the suture itself. Devices currently employed to provide visceral protection during abdominal closure, such as the metal malleable retractor and Glassman Visceral Retainer, are unable to provide complete protection as they must be removed prior to complete closure. A puncture resistant, biocompatible, and degradable matrix that can be left in place without need for removal would facilitate rapid and safe abdominal closure. We describe a novel elastomer (CC-DHA) that undergoes a rapid but controlled solid-to-liquid phase transition through the application of a destabilized carbonate cross-linked network. The elastomer is comprised of a polycarbonate cross-linked network of dihydroxyacetone, glycerol ethoxylate, and tri(ethylene glycol). The ketone functionality of the dihydroxyacetone facilitates hydrolytic cleavage of the carbonate linkages resulting in a rapidly degrading barrier that can be left in situ to facilitate abdominal fascial closure. Using a murine laparotomy model we demonstrated rapid dissolution and metabolism of the elastomer without evidence of toxicity or intraabdominal scarring. Furthermore, needle puncture and mechanical properties demonstrated the material to be both compliant and sufficiently puncture resistant. These unique characteristics make the biomaterial extraordinarily useful as a physical barrier to prevent inadvertent bowel injury during fascial closure, with the potential for wider application across a variety of medical and surgical applications.

STATEMENT OF SIGNIFICANCE

Fascial closure after abdominal surgery requires delicate maneuvers to prevent incisional hernia while minimizing risk for inadvertent bowel injury. We describe a novel biocompatible and biodegradable polycarbonate elastomer (CC-DHA) comprised of dihydroxyacetone, glycerol ethoxylate, and tri(ethylene glycol), for use as a rapidly degrading protective visceral barrier to aid in abdominal closure. Rapid polymer dissolution and metabolism was demonstrated using a murine laparotomy model without evidence of toxicity or intraabdominal scarring. Furthermore, mechanical studies showed the material to be sufficiently puncture resistant and compliant. Overall, this new biomaterial is extraordinary useful as a physical barrier to prevent inadvertent bowel injury during fascial closure, with the potential for wider application across a variety of medical and surgical applications.

Lipid nano-bubble combined with ultrasound for anti-keloids therapy

Keloids were characterized by excessive growth of fibrous tissues, and shared several pathological characteristics with cancer. They did put physical and emotional stress on patients in that keloids could badly change appearance of patients. N-(4-hydroxyphenyl) retinamide (4HPR) showed cytotoxic activity on a wide variety of invasive-growth cells. Our work was aim to prepare N-(4-hydroxyphenyl) retinamide-loaded lipid microbubbles (4HPR-LM) combined with ultrasound for anti-keloid therapy. 4HPR-loaded liposomes (4HPR-L) were first prepared by film evaporation method, and then 4HPR-LM were manufactured by mixing 4HPR-L and perfluoropentane (PFP) with ultrasonic cavitation method. The mean particle size and entrapment efficiency 4HPR-LM were 113 nm and 95%, respectively. The anti-keloids activity of 4HPR-LM was assessed with BALB/c nude mice bearing subcutaneous xenograft keloids model. 4HPR-LM, combined with ultrasound, could significantly induce apoptosis of keloid fibroblasts in vitro and inhibited growth of keloids in vivo. Thus, 4HPR-LM could be considered as a promising agent for anti-keloids therapy.

Preparation and Evaluation of a Novel Class of Amphiphilic Amines as Antitumor Agents and Nanocarriers for Bioactive Molecules

Purpose

We describe a novel class of antitumor amphiphilic amines (RCn) based on a tricyclic amine hydrophilic head and a hydrophobic linear alkyl tail of variable length.

Methods

We tested the lead compound, RC16, for cytotoxicity and mechanism of cell death in several cancer cell lines, anti tumor efficacy in mouse tumor models, and ability to encapsulate chemotherapy drugs.

Results

These compounds displayed strong cytotoxic activity against cell lines derived from both pediatric and adult cancers. The IC50 of the lead compound, RC16, for normal cells including human keratinocytes, human fibroblasts and human umbilical vein endothelial cells was tenfold higher than for tumor cells. RC16 exhibited significant antitumor effects in vivo using several human xenografts and a metastatic model of murine neuroblastoma by both intravenous and oral administration routes. The amphiphilic character of RC16 triggered a spontaneous molecular self-assembling in water with formation of micelles allowing complexation of Doxorubicin, Etoposide and Paclitaxel. These micelles significantly improved the in vitro antitumor activity of these drugs as the enhancement of their aqueous solubility also improved their biologic availability.

Conclusions

RC16 and related amphiphilic amines may be useful as a novel cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1007/s11095-016-1999-9) contains supplementary material, which is available to authorized users.

Targeting tumor microenvironment with PEG-based amphiphilic nanoparticles to overcome chemoresistance

Multidrug resistance is one of the biggest obstacles in the treatment of cancer. Recent research studies highlight that tumor microenvironment plays a predominant role in tumor cell proliferation, metastasis, and drug resistance. Hence, targeting the tumor microenvironment provides a novel strategy for the evolution of cancer nanomedicine. The blooming knowledge about the tumor microenvironment merging with the design of PEG-based amphiphilic nanoparticles can provide an effective and promising platform to address the multidrug resistant tumor cells. This review describes the characteristic features of tumor microenvironment and their targeting mechanisms with the aid of PEG-based amphiphilic nanoparticles for the development of newer drug delivery systems to overcome multidrug resistance in cancer cells.

FROM THE CLINICAL EDITOR

Cancer is a leading cause of death worldwide. Many cancers develop multidrug resistance towards chemotherapeutic agents with time and strategies are urgently needed to combat against this. In this review article, the authors discuss the current capabilities of using nanomedicine to target the tumor microenvironments, which would provide new insight to the development of novel delivery systems for the future.

Branched Polymer-Drug Conjugates for Multivalent Blockade of Angiotensin II Receptors

The use of angiotensin receptor blockers (ARBs) for treatment of ocular diseases associated with neovascularizations, such as proliferative diabetic retinopathy, shows tremendous promise but is presently limited due to short intravitreal half-life. Conjugation of ARB molecules to branched polymers could vastly augment their therapeutic efficacy. EXP3174, a potent non-peptide ARB, was conjugated to branched poly(ethylene glycol) (PEG) and poly(amido amine) (PAMAM) dendrimers: 7.8 ligand molecules were tethered to each 40 kDa PEG molecule whereas 16.7 ligand molecules were linked to each PAMAM generation 5 dendrimer. The multivalent PEG and PAMAM conjugates blocked AT1R signaling with an IC50 of 224 and 36.3 nM, respectively. The 6-fold higher affinity of the multivalent ligand-conjugated PAMAM dendrimers was due to their unique microarchitecture and ability to suppress polymer-drug interactions. Remarkably, both polymer-drug conjugates exhibited no cytotoxicity, in stark contrast to plain PAMAM dendrimers. With sufficiently long vitreous half-lives, both synthesized polymer-ARB conjugates have the potential to pave a new path for the therapy of ocular diseases accompanied by retinal neovascularizations.

Anti-tumor activity of fenretinide complexed with human serum albumin in lung cancer xenograft mouse model

Sufficient knowledge regarding cellular and molecular basis of lung cancer progression and metastasis would help in the development of novel and effective strategies for the treatment of lung cancer. 4HPR is a synthetic retinoid with potential anti-tumor activity but is still limited because of its poor bioavailability. The use of albumin as a complexing agent for a hydrophobic drug is expected to improve the water solubility and consequently their bioavailability.This study investigated the antitumor activity of a novel complex between albumin and 4-HPR in a mouse model of human lung cancer and focuses on role and mechanism of Cav-1 mainly involved in regulating cancer and Acsvl3 mainly connected with tumor growth.

Their expressions were assayed by immunohistochemistry and qRT-PCR, to demonstrate the reduction of the tumor growth following the drug treatment. Our results showed a high antitumor activity of 4HPR-HSA by reduction of the volume of tumor mass and the presence of a high level of apoptotic cell by TUNEL assay. The downregulation of Cav-1 and Acsvl3 suggested a reduction of tumor growth.

In conclusion, we demonstrated the great potential of 4HPR-HSA in the treatment of lung cancer. More data about the mechanism of drug delivery the 4HPR-HSA are necessary.

Albumin nanocapsules containing fenretinide: pre-clinical evaluation of cytotoxic activity in experimental models of human non-small cell lung cancer

The present study deals with the preparation of albumin nanocapsules containing fenretinide and their evaluation in experimental models of human non-small cell lung cancer. These nanocapsules showed enhanced antitumor activity with respect to free fenretinide due to the solubilization effect of albumin on the hydrophobic drug, known to improve bioavailability. The high expression of caveolin-1 on the A549 cell surface further enhanced the antitumor activity of the nanoencapsulated fenretinide. Caveolin-1 favored albumin uptake and improved the efficacy of the fenretinide-loaded albumin nanocapsules, especially in 3-D cultures where the densely packed 3-D structures impaired drug diffusibility and severely reduced the activity of the free drug. The efficacy of the fenretinide albumin nanocapsules was further confirmed in tumor xenograft models of A549 by the significant delay in tumor progression observed with respect to control after intravenous administration of the novel formulation.

FROM THE CLINICAL EDITOR

This study describes the preparation of fenretinide containing albumin nanocapsules and their evaluation in experimental models of non-small cell lung cancer, showing enhanced antitumor activity compared to free fenretinide.

Nanocarrier-mediated targeting of tumor and tumor vascular cells improves uptake and penetration of drugs into neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor in children, accounting for about 8% of childhood cancers. Despite aggressive treatment, patients suffering from high-risk NB have very poor 5-year overall survival rate, due to relapsed and/or treatment-resistant tumors. A further increase in therapeutic dose intensity is not feasible, because it will lead to prohibitive short-term and long-term toxicities. New approaches with targeted therapies may improve efficacy and decrease toxicity. The use of drug delivery systems allows site specific delivery of higher payload of active agents associated with lower systemic toxicity compared to the use of conventional (“free”) drugs. The possibility of imparting selectivity to the carriers to the cancer foci through the use of a targeting moiety (e.g., a peptide or an antibody) further enhances drug efficacy and safety. We have recently developed two strategies for increasing local concentration of anti-cancer agents, such as CpG-containing oligonucleotides, small interfering RNAs, and chemotherapeutics in NB. For doing that, we have used the monoclonal antibody anti-disialoganglioside (GD₂), able to specifically recognize the NB tumor and the peptides containing NGR and CPRECES motifs, that selectively bind to the aminopeptidase N-expressing endothelial and the aminopeptidase A-expressing perivascular tumor cells, respectively. The review will focus on the use of tumor- and tumor vasculature-targeted nanocarriers to improve tumor targeting, uptake, and penetration of drugs in preclinical models of human NB.

Enhanced anti-tumor and anti-angiogenic efficacy of a novel liposomal fenretinide on human neuroblastoma

Neuroblastoma is an embryonal tumor originating from the simpatico-adrenal lineage of the neural crest. It approximately accounts for about 15% of all pediatric oncology deaths. Despite advances in multimodal therapy, metastatic neuroblastoma tumors at diagnosis remain a clinical challenge. Retinoids are a class of compounds known to induce both terminal differentiation and apoptosis/necrosis of neuroblastoma cells. Among them, fenretinide (HPR) has been considered one of the most promising anti-tumor agent but it is partially efficacious due to both poor aqueous solubility and rapid metabolism. Here, we have developed a novel HPR formulation, by which the drug was encapsulated into sterically stabilized nanoliposomes (NL[HPR]) according to the Reverse Phase Evaporation method. This procedure led to a higher structural integrity of liposomes in organic fluids for a longer period of time, in comparison with our previous liposomal formulation developed by the film method. Moreover, NL[HPR] were further coupled with NGR peptides for targeting the tumor endothelial cell marker, aminopeptidase N (NGR-NL[HPR]). Orthotopically xenografted neuroblastoma-bearing mice treated with NGR-NL[HPR] lived statistically longer than mice untreated or treated with free HPR (NGR-NL[HPR] vs both control and HPR: P<0.0001). Also, NL[HPR] resulted in a statistically improved survival (NL[HPR] vs both control and HPR: P<0.001) but to a less extent if compared with that obtained with NGR-NL[HPR] (NGR-NL[HPR] vs NL[HPR]: P<0.01). Staining of tumor sections with antibodies specific for neuroblastoma and for either pericytes or endothelial cells evidenced that HPR reduced neuroblastoma growth through both anti-tumor and anti-angiogenic effects, mainly when delivered by NGR-NL[HPR]. Indeed, in this group of mice a marked reduction of tumor progression, of intra-tumoral vessel counts and VEGF expression, together with a marked down-modulation of matrix metalloproteinases MMP2 and MMP9, was observed. In conclusion, the use of this novel targeted delivery system for the apoptotic and antiangiogenic drug, fenretinide, could be considered as an adjuvant tool in the future treatment of neuroblastoma patients.