A phase I and pharmacokinetic study of paclitaxel poliglumex and cisplatin in patients with advanced solid tumors

Nano delivery system for paclitaxel: Recent advances in cancer theranostics

Paclitaxel is one of the most effective chemotherapeutic drugs which processes the obvious curative effect for a broad range of cancers including breast, ovarian, lung, and head & neck cancers. Though some novel paclitaxel-loaded formulations have been developed, the clinical application of the paclitaxel is still limited due to its toxicity and solubility issues. Over the past decades, we have seen rapid advances in applying nanocarriers in paclitaxel delivery systems. The nano-drug delivery systems offer unique advantages in enhancing the aqueous solubility, reducing side effects, increasing permeability, prolonging circulation half-life of paclitaxel. In this review, we summarize recent advances in developing novel paclitaxel-loaded nano delivery systems based on nanocarriers. These nanocarriers show great potentials in overcoming the disadvantages of pure paclitaxel and as a result improving the efficacy.

Tumor Microenvironment Regulation and Cancer Targeting Therapy Based on Nanoparticles

Although we have made remarkable achievements in cancer awareness and medical technology, there are still tremendous increases in cancer incidence and mortality. However, most anti-tumor strategies, including immunotherapy, show low efficiency in clinical application. More and more evidence suggest that this low efficacy may be closely related to the immunosuppression of the tumor microenvironment (TME). The TME plays a significant role in tumorigenesis, development, and metastasis. Therefore, it is necessary to regulate the TME during antitumor therapy. Several strategies are developing to regulate the TME as inhibiting tumor angiogenesis, reversing tumor associated macrophage (TAM) phenotype, removing T cell immunosuppression, and so on. Among them, nanotechnology shows great potential for delivering regulators into TME, which further enhance the antitumor therapy efficacy. Properly designed nanomaterials can carry regulators and/or therapeutic agents to eligible locations or cells to trigger specific immune response and further kill tumor cells. Specifically, the designed nanoparticles could not only directly reverse the primary TME immunosuppression, but also induce effective systemic immune response, which would prevent niche formation before metastasis and inhibit tumor recurrence. In this review, we summarized the development of nanoparticles (NPs) for anti-cancer therapy, TME regulation, and tumor metastasis inhibition. We also discussed the prospect and potential of nanocarriers for cancer therapy.

Emerging nanotaxanes for cancer therapy

The clinical application of taxane (including paclitaxel, docetaxel, and cabazitaxel)-based formulations is significantly impeded by their off-target distribution, unsatisfactory release, and acquired resistance/metastasis. Recent decades have witnessed a dramatic progress in the development of high-efficiency, low-toxicity nanotaxanes via the use of novel biomaterials and nanoparticulate drug delivery systems (nano-DDSs). Thus, in this review, the achievements of nanotaxanes-targeted delivery and stimuli-responsive nano-DDSs-in preclinical or clinical trials have been outlined. Then, emerging nanotherapeutics against tumor resistance and metastasis have been overviewed, with a particular emphasis on synergistic therapy strategies (e.g., combination with surgery, chemotherapy, radiotherapy, biotherapy, immunotherapy, gas therapy, phototherapy, and multitherapy). Finally, the latest oral nanotaxanes have been briefly discussed.

Self-assembling prodrug nanotherapeutics for synergistic tumor targeted drug delivery

Self-assembling prodrugs represents a robust and effective nanotherapeutic approach for delivering poorly soluble anticancer drugs. With numerous intrinsic advantages, self-assembling prodrugs possess the maximum drug loading capacity, controlled drug release kinetics, prolonged blood circulation, and preferential tumor accumulation based on the enhanced permeability and retention (EPR) effect. These prodrug conjugates allow for efficient self-assembly into nanodrugs with the potential of encapsulating other therapeutic agents that have different molecular targets, enabling simultaneous temporal-spatial release of drugs for synergistic antitumor efficacy with reduced systemic side effects. The aim of this review is to summarize the recent progress of self-assembling prodrug cancer nanotherapeutics that are made through conjugating therapeutically active agents to Polyethylene glycol, Vitamin E, or drugs with different physicochemical properties via rational design, for synergistic tumor targeted drug delivery.

Statement of Significance

All current FDA-approved nanomedicines use inert biomaterials as drug delivery carriers. These biomaterials lack any therapeutic potential, contributing not only to the cost, but may also elicit severe unfavorable adverse effects. Despite the reduction in toxicity associated with the payload, these nanotherapeutics have been met with limited clinical success, likely due to the monotherapy regimen. The self-assembling prodrug (SAP) has been emerging as a powerful platform for enhancing efficacy through co-delivering other therapeutic modalities with distinct molecular targets. Herein, we opportunely present a comprehensive review article summarizing three unique approaches of making SAP for synergistic drug delivery: pegylation, vitamin E-derivatization, and drug-drug conjugation. These SAPs may inevitably pave the way for developing more efficacious, clinically translatable, combination cancer nanotherapies.

Induction of anti-cancer T cell immunity by in situ vaccination using systemically administered nanomedicines

Patients with inadequate anti-cancer T cell responses experience limited benefit from immune checkpoint inhibitors and other immunotherapies that require T cells. Therefore, treatments that induce de novo anti-cancer T cell immunity are needed. One strategy - referred to as in situ vaccination - is to deliver chemotherapeutic or immunostimulatory drugs into tumors to promote cancer cell death and provide a stimulatory environment for priming T cells against antigens already present in the tumor. However, achieving sufficient drug concentrations in tumors without causing dose-limiting toxicities remains a major challenge. To address this challenge, nanomedicines based on nano-sized carriers ('nanocarriers') of chemotherapeutics and immunostimulants are being developed to improve drug accumulation in tumors following systemic (intravenous) administration. Herein, we present the rationale for using systemically administrable nanomedicines to induce anti-cancer T cell immunity via in situ vaccination and provide an overview of synthetic nanomedicines currently used clinically. We also describe general strategies for improving nanomedicine design to increase tumor uptake, including use of micelle- and star polymer-based nanocarriers. We conclude with perspectives for how nanomedicine properties, host factors and treatment combinations can be leveraged to maximize efficacy.

Threatening cancer with nanoparticle aided combination oncotherapy

Employing combination therapy has become obligatory in cancer cases exhibiting high tumor load, chemoresistant tumor population, and advanced disease stages. Realization of this fact has now led many of the combination oncotherapies to become an integral part of anticancer regimens. Combination oncotherapy may encompass a combination of anticancer agents belonging to a similar therapeutic category or that of different therapeutic categories (e.g. chemotherapy + gene therapy). Differences in the physicochemical properties, pharmacokinetics and biodistribution pattern of different payloads are the major constraints that are faced by combination chemotherapy. Concordant efforts in the field of nanotechnology and oncology have emerged with several approaches to solve the major issues encountered by combination therapy. Unique colloidal behaviors of various types of nanoparticles and differential targeting strategies have accorded an unprecedented ability to optimize combination oncotherapeutic delivery. Nanocarrier based delivery of the various types of payloads such as chemotherapeutic agents and other anticancer therapeutics such as small interfering ribonucleic acid (siRNA), chemosensitizers, radiosensitizers, and antiangiogenic agents have been addressed in the present review. Various nano-delivery systems like liposomes, polymeric nanoparticles, polymerosomes, dendrimers, micelles, lipid based nanoparticles, prodrug based nanocarriers, polymer-drug conjugates, polymer-lipid hybrid nanoparticles, carbon nanotubes, nanosponges, supramolecular nanocarriers and inorganic nanoparticles (gold nanoparticles, silver nanoparticles, magnetic nanoparticles and mesoporous silica based nanoparticles) that have been extensively explored for the formulation of multidrug delivery is an imperative part of discussion in the review. The present review features the outweighing benefits of combination therapy over mono-oncotherapy and discusses several existent nanoformulation strategies that facilitate a successful combination oncotherapy. Several obstacles that may impede in transforming nanotechnology-based combination oncotherapy from bench to bedside, and challenges associated therein have also been discussed in the present review.

Isobavachalcone sensitizes cells to E2-induced paclitaxel resistance by down-regulating CD44 expression in ER+ breast cancer cells

Oestrogen receptor (ER) is expressed in approximately 60%‐70% of human breast cancer. Clinical trials and retrospective analyses have shown that ER‐positive (ER+) tumours are more tolerant to chemotherapeutic drug resistance than ER‐negative (ER−) tumours. In addition, isobavachalcone (IBC) is known as a kind of phytoestrogen with antitumour effect. However, the underlying mechanism of IBC in ER+ breast cancer needs to be elucidated further. Our in vitro experiments showed that IBC could attenuate 17β‐estradiol (E₂)‐induced paclitaxel resistance and that E₂ could stimulate CD44 expression in ER+ breast cancer cells but not in ER− cells. Meanwhile, E₂ could promote ERα expression to render ER+ breast cancer cells resistant to paclitaxel. Furthermore, we established paclitaxel‐resistant breast cancer cell lines and determined the function of ERα in the enhancement of paclitaxel resistance via the regulation of CD44 transcription. IBC down‐regulated ERα and CD44 expression and thus inhibited tumour growth in paclitaxel‐resistant xenograft models. Overall, our data demonstrated for the first time that IBC could decrease CD44 expression level via the ERα pathway and make ER+ breast cancer cells sensitive to paclitaxel treatment.

A hindsight reflection on the clinical studies of poly(l-glutamic acid)-paclitaxel

Chemotherapy for cancer treatment is limited by the excessive toxicity to normal tissues. The design of chemodrug-loaded nanoformulations provides a unique approach to improve the treatment efficacy while minimizing toxicity. Despite the numerous publications of nanomedicine for the last several decades, however, only a small fraction of the developed nanoformulations have entered clinical trials, with even fewer being approved for clinical application. Poly(l-glutamic acid)-paclitaxel (PG-TXL) belongs to the few formulations that reached phase III clinical trials. Unfortunately, the development of PG-TXL stopped in 2016 due to the inability to show significant improvement over current standard care. This review will provide an overview of the preclinical and clinical evaluations of PG-TXL, and discuss lessons to be learned from this ordeal. The precise identification of suitable patients for clinical trial studies, deep understanding of the mechanisms of action, and an effective academic-industry partnership throughout all phases of drug development are important for the successful bench-to-bedside translation of new nanoformulations. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Peptide-Based Structures.

Trimethyl chitosan based conjugates for oral and intravenous delivery of paclitaxel

Paclitaxel (PTX) conjugated trimethyl chitosan (TMC-PTX) and folic acid (FA) modified TMC-PTX (FA-TMC-PTX) were developed as polymer-drug conjugates for oral and intravenous delivery of PTX. As amphiphilic conjugates, TMC-PTX and FA-TMC-PTX containing approximately 11wt% PTX could self-assemble into spherical nanoparticles with average sizes of 170 and 187nm, respectively. The conjugates presented a sustained release of PTX and the release rate was positively correlated with the pH value of medium ranging from 1.2 to 7.4. TMC-PTX and FA-TMC-PTX possessed enhanced mucoadhesion compared with trimethyl chitosan, and promoted ex vivo intestinal transport of PTX in comparison to PTX solution by 15.5 and 18.8 folds, respectively. Hemolysis assessment confirmed the safety of TMC-PTX and FA-TMC-PTX, and FA modification alleviated protein adsorption of the conjugates. Prolonged blood retention and increased PTX accumulation in the tumor were achieved for orally and intravenously administered conjugates. In H22 tumor-bearing mice, TMC-PTX delivered via oral or intravenous route showed superior tumor retardation and survival rate compared with intravenously injected PTX, and FA-TMC-PTX further enhanced the antitumor efficacy. Overall, the trimethyl chitosan based drug conjugates may have potential applications as a promising candidate for cancer therapy.

STATEMENT OF SIGNIFICANCE

In the current study, PTX conjugated trimethyl chitosan (TMC-PTX) and folic acid (FA) modified TMC-PTX (FA-TMC-PTX) were developed as the polymer-drug conjugates for oral and intravenous delivery of PTX. By exploiting advantages with respect to improved solubility of drugs, controlled release behavior of covalently linked drugs, and enhanced targeting effect towards tumors, improved tumor growth inhibition efficacy and prolonged survival time were achieved for TMC-PTX as compared with free PTX, and FA modification further enhanced the in vivo antitumor efficacy. Overall, the self-assembled nanoplatform of trimethyl chitosan based drug conjugates may have potential applications as a promising candidate for tumor therapy via different administration routes.

Investigational nanomedicines in 2016: a review of nanotherapeutics currently undergoing clinical trials

Nanomedicine is a relatively new field that is rapidly evolving. Formulation of drugs on the nanoscale imparts many physical and biological advantages. Such advantages can in turn translate into improved therapeutic efficacy and reduced toxicity. While approximately 50 nanotherapeutics have already entered clinical practice, a greater number of drugs are undergoing clinical investigation for a variety of indications. This review aims to examine all the nanoformulations that are currently undergoing clinical investigation and their outlook for ultimate clinical translation. WIREs Nanomed Nanobiotechnol 2017, 9:e1416. doi: 10.1002/wnan.1416 For further resources related to this article, please visit the WIREs website.

Phase 2 trial of paclitaxel polyglumex with capecitabine for metastatic breast cancer

BACKGROUND

Capecitabine and paclitaxel are established effective treatments, alone and combined with other cytotoxic and targeted agents, for metastatic breast cancer (MBC). Paclitaxel polyglumex (a macromolecular conjugate of paclitaxel bound to poly-L-glutamic acid) has potential advantages over conventional paclitaxel, including little alopecia, short infusion time with no premedication, enhanced tumor permeability/retention effect, and improved tolerability. We therefore examined tolerability and efficacy of paclitaxel polyglumex with capecitabine in patients with MBC.

PATIENTS AND METHODS

This was a single-stage phase 2 study, with interim analysis conducted with endpoints of tumor response, adverse events (toxicities), time to progression, and overall survival. The main eligibility criteria were: age >18 years, no prior MBC chemotherapy, Eastern Cooperative Oncology Group performance score <2, disease measurable by RECIST criteria, no HER2 overexpression or amplification, no brain metastases or peripheral sensory neuropathy. Treatment consisted of paclitaxel polyglumex (135 mg/m) by intravenous infusion on day 1+capecitabine (825 mg/m) orally twice daily on days 1 to 14, repeated on a 3-week cycle. Forty-one evaluable patients were required to test the null hypothesis that the complete and partial tumor response rate (CR+PR) was at the most 40% against the alternative of at least 60%. Paclitaxel polyglumex+capecitabine would be considered promising in this population if ≥21 responses were observed among first 41 evaluable patients.

RESULTS

Forty-eight patients were enrolled between April 2006 and April 2007; all patients were evaluable. The median number of treatment cycles administered was 6. Eighteen patients [38%; 95% confidence interval (CI), 24%-53%] had a confirmed tumor response (2 CR, 16 PR) by RECIST criteria. Fifteen (38%; 95% CI, 23%-53%) responses occurred in first 41 patients, falling short of prespecified goal of 21 responses. Median duration of tumor response was 13.2 months. Three of the responders were progression free at last follow-up with a median follow-up of 43 months. Median progression-free survival was 5.1 months (95% CI, 4.0-7.6 mo). Six-month progression-free survival was 42% (95% CI, 30%-58%). Median dose level administered was paclitaxel polyglumex (135 mg/m) and capecitabine (825 mg/m) for cycles 1 to 7. Most common severe (grade 3/4) toxicities (at least possibly related to study drug) were: leukopenia 9 (19%), neutropenia 8 (17%), neurosensory 4 (8%), skin reaction-hand/foot 4 (8%), and dyspnea 2 (4%). Forty-six percent (22/47) of patients experienced grade ≥3 toxicity and 8% (4/48) experienced grade ≥4 toxicity. No alopecia was reported.

CONCLUSIONS

Although the trial failed to reach goal of 21 confirmed tumor responses among the first 41 evaluable patients, paclitaxel polyglumex and capecitabine is well tolerated and effective in MBC.

Polymeric micelles: nanocarriers for cancer-targeted drug delivery

Polymeric micelles represent an effective delivery system for poorly water-soluble anticancer drugs. With small size (10-100 nm) and hydrophilic shell of PEG, polymeric micelles exhibit prolonged circulation time in the blood and enhanced tumor accumulation. In this review, the importance of rational design was highlighted by summarizing the recent progress on the development of micellar formulations. Emphasis is placed on the new strategies to enhance the drug/carrier interaction for improved drug-loading capacity. In addition, the micelle-forming drug-polymer conjugates are also discussed which have both drug-loading function and antitumor activity.

Drug delivery design for intravenous route with integrated physicochemistry, pharmacokinetics and pharmacodynamics: illustration with the case of taxane therapeutics

This review is aimed at combining the published data on taxane formulations into a generalized Drug Delivery approach, starting from the physicochemistry and assessing its relationships with the pharmacokinetics, the biodistribution and the pharmacodynamics. Owing to the number and variety of taxane formulation designs, we considered this class of cytotoxic anticancer agents of particular interest to illustrate the concepts attached to this approach. According to the history of taxane development, we propose a classification as (i) "surfactant-based formulations" first generation, (ii) "surfactant-free formulations" second generation and (iii) "modulated pharmacokinetics drug delivery systems" third generation. Since our objective was to make the link between (i) the physicochemistry of the drug and carrier and (ii) the efficacy and safety of the drug in preclinical animal models and (iii) in human, we focused on the drug delivery technologies that were tested in clinic.

Efficient simultaneous tumor targeting delivery of all-trans retinoid acid and Paclitaxel based on hyaluronic acid-based multifunctional nanocarrier

An amphiphilic hyaluronic acid (HA)-g-all-trans retinoid acid (HRA) conjugate was successfully developed as a tumor-targeting nanocarrier for potentially synergistic combination chemotherapy of all-trans retinoid acid (ATRA) and paclitaxel (PTX). The HRA conjugate was synthesized by an imine reaction between HA-COOH and ATRA-NH2. PTX-loaded HRA nanoparticles possessed a high loading capacity, nanoscale particle sizes, and good biocompatible characteristics. Cell viability assays indicated that PTX-loaded HRA nanoparticles exhibited concentration- and time-dependent cytotoxicity. Moreover, they displayed obvious superiority in inducing the apoptosis of tumor cells. Cellular uptake analysis suggested that HRA nanoparticles could be efficiently taken up by cells via endocytic pathway and transport into the nucleus, contributing to HA receptor-mediated endocytosis and ATRA-induced nuclear translocation, respectively. Moreover, in vivo imaging analysis indicated that the accumulation of DiR-loaded HRA nanoparticles in tumor was increased obviously after intravenous administration as compared to free DiR solution, which confirmed that the HRA nanoparticles could assist the drugs targeting to the tumor. Furthermore, PTX-loaded HRA nanoparticles exhibited greater tumor growth inhibition effect in vivo with reducing the toxicity. Therefore, HRA nanoparticles can be considered as a promising targeted codelivery system for combination cancer chemotherapy.

Nucleic acid therapeutics: concepts for targeted delivery to solid tumors

Solid tumors form a heterogeneous group of diseases, although common features such as hyperproliferation, overexpression of certain growth factor receptors and deregulated vessel formation including leaky vasculature give the opportunity to target macromolecular drug and nucleic acid carriers to tumor tissue. Similar to other macromolecular drugs, nucleic acid carriers have to be designed to enable tumor targeting after systemic injection. Chemical modification of nucleic acids makes them resistant towards enzymatic degradation. Cationic lipids or polycations condense nucleic acids into small, virus-like structures and the surface modification with hydrophilic polymers allows passive accumulation in tumor tissue; tumor cell binding ligands allow cellular targeting. To avoid toxic side effects, biodegradable and biocompatible carriers were designed. The design of thermoresponsive gene carriers allowed their selective tumor accumulation by locoregional hyperthermia. As a therapeutic concept, tumor-specific delivery of antitumoral RNA was realized in an orthotopic brain tumor model. The combination of gene- and radio-therapy enabled selective accumulation of radionuclides in tumors and boosted antitumoral effects. Hence, combining a smart delivery concept for nucleic acids with a suitable therapeutic strategy will allow successful treatment of otherwise incurable malignant diseases.

Nanotechnology-based combinational drug delivery: an emerging approach for cancer therapy

Combination therapy for the treatment of cancer is becoming more popular because it generates synergistic anticancer effects, reduces individual drug-related toxicity and suppresses multi-drug resistance through different mechanisms of action. In recent years, nanotechnology-based combination drug delivery to tumor tissues has emerged as an effective strategy by overcoming many biological, biophysical and biomedical barriers that the body stages against successful delivery of anticancer drugs. The sustained, controlled and targeted delivery of chemotherapeutic drugs in a combination approach enhanced therapeutic anticancer effects with reduced drug-associated side effects. In this article, we have reviewed the scope of various nanotechnology-based combination drug delivery approaches and also summarized the current perspective and challenges facing the successful treatment of cancer.

Combination drug delivery approaches in metastatic breast cancer

Disseminated metastatic breast cancer needs aggressive treatment due to its reduced response to anticancer treatment and hence low survival and quality of life. Although in theory a combination drug therapy has advantages over single-agent therapy, no appreciable survival enhancement is generally reported whereas increased toxicity is frequently seen in combination treatment especially in chemotherapy. Currently used combination treatments in metastatic breast cancer will be discussed with their challenges leading to the introduction of novel combination anticancer drug delivery systems that aim to overcome these challenges. Widely studied drug delivery systems such as liposomes, dendrimers, polymeric nanoparticles, and water-soluble polymers can concurrently carry multiple anticancer drugs in one platform. These carriers can provide improved target specificity achieved by passive and/or active targeting mechanisms.

Nanoscale delivery systems for multiple drug combinations in cancer

Although drug-delivery systems have been developed to improve drug biodistribution and efficiency in cancer therapy, some limitations still hinder successful drug targeting and delivery. Multiple drugs in combination seems a promising strategy for cancer therapy. It enables drugs to be delivered to multiple targets and exhibits the additive or synergistic effects of drugs. Physiological barriers are known to be the main obstacles of insufficient drug efficacy and delivery in tumors, but they are likely to be potential targets in combination therapy as well. This article discusses some general considerations for optimizing multiply drug delivery, including drug-release profiles and loading strategies.

Eribulin mesylate, a novel microtubule inhibitor in the treatment of breast cancer

BACKGROUND

Microtubule-targeted agents are one of the most common classes of chemotherapeutic drug for the treatment of breast cancer. Limitations of current microtubule-targeted agents such as primary or secondary resistance of cancer cells and side effects like neuropathy prompted the discovery and introduction of newer more effective drugs. This review aims to provide a summary of the novel halichondrin B analog eribulin mesylate (E7389) and illustrate where it is placed in the treatment arena versus other agents that are approved or are currently in various stages of clinical development.

METHODS

Preclinical and clinical trial (phases I-III) data for eribulin were obtained from scientific journals and meeting abstracts, posters, and oral presentations. The use of current and other emerging microtubule inhibiting agents in breast cancer was also surveyed and briefly reviewed.

RESULTS

Eribulin mesylate at a dose of 1.4 mg/m(2) given on days 1 and 8 of a 21-day cycle increased overall survival in patients with metastatic breast cancer (MBC). Neutropenia, fatigue, alopecia, nausea and anemia were common adverse events (AEs) associated with eribulin in clinical studies. A low incidence of peripheral neuropathy was also associated with eribulin in clinical studies (21-26%). Other emerging microtubule targeted agents, such as vinflunine and larotaxel, also reported efficacy in patients with MBC who had received prior chemotherapy, with grade 3/4 neutropenia being the most common AEs for both agents.

CONCLUSIONS

Eribulin mesylate offers clinical activity in advanced breast cancer through improved overall survival, its favorable side-effect profile and convenience of preparation and administration.

Combination therapy: opportunities and challenges for polymer-drug conjugates as anticancer nanomedicines

The discovery of new molecular targets and the subsequent development of novel anticancer agents are opening new possibilities for drug combination therapy as anticancer treatment. Polymer-drug conjugates are well established for the delivery of a single therapeutic agent, but only in very recent years their use has been extended to the delivery of multi-agent therapy. These early studies revealed the therapeutic potential of this application but raised new challenges (namely, drug loading and drugs ratio, characterisation, and development of suitable carriers) that need to be addressed for a successful optimisation of the system towards clinical applications.