Rachel Blau

Polymeric nanotheranostics for real-time non-invasive optical imaging of breast cancer progression and drug release

Polymeric nanocarriers conjugated with low molecular weight drugs are designed in order to improve their efficacy and toxicity profile. This approach is particularly beneficial for anticancer drugs, where the polymer-drug conjugates selectively accumulate at the tumor site, due to the enhanced permeability and retention (EPR) effect. The conjugated drug is typically inactive, and upon its pH- or enzymatically-triggered release from the carrier, it regains its therapeutic activity. These settings lack information regarding drug-release time, kinetics and location. Thereby, real-time non-invasive intravital monitoring of drug release is required for theranostics (therapy and diagnostics). We present here the design, synthesis and characterization of a theranostic nanomedicine, based on N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer, owing its fluorescence-based monitoring of site-specific drug release to a self-quenched near-infrared fluorescence (NIRF) probe. We designed two HPMA copolymer-based systems that complement to a theranostic nanomedicine. The diagnostic system consists of self-quenched Cy5 (SQ-Cy5) as a reporter probe and the therapeutic system is based on the anticancer agent paclitaxel (PTX). HPMA copolymer-PTX/SQ-Cy5 systems enable site-specific release upon enzymatic degradation in cathepsin B-overexpressing breast cancer cells. The release of the drug occurs concomitantly with the activation of the fluorophore to its Turn-ON state. HPMA copolymer-SQ-Cy5 exhibits preferable body distribution and drug release compared with the free drug and probe when administered to cathepsin B-overexpressing 4T1 murine mammary adenocarcinoma-bearing mice. This approach of co-delivery of two complementary systems serves as a proof-of-concept for real-time deep tissue intravital orthotopic monitoring and may have the potential use in clinical utility as a theranostic nanomedicine.

Synthesis and evaluation of new NIR-fluorescent probes for cathepsin B: ICT versus FRET as a turn-ON mode-of-action

Recent years have seen tremendous progress in the design and study of molecular imaging geared towards biological and biomedical applications. The expression or activity of specific enzymes including proteases can be monitored by cutting edge molecular imaging techniques. Cathepsin B plays key roles in tumor progression via controlled degradation of extracellular matrix. Consequently, this protease has been attracting significant attention in cancer research, and many imaging probes targeting its activity have been developed. Here, we describe the design, synthesis and evaluation of two novel near infrared (NIR) fluorescent probes for detection of cathepsin B activity with different turn-ON mechanisms. One probe is based on an ICT activation mechanism of a donor-two-acceptor π-electron dye system, while the other is based on the FRET mechanism obtained by a fluorescent dye and a quencher. The two probes exhibit significant fluorescent turn-ON response upon cleavage by cathepsin B. The NIR fluorescence of the ICT probe in its OFF state was significantly lower than that of the FRET-based probe. This effect results in a higher signal-to-noise ratio and consequently increased sensitivity and better image contrast.

A Highly Efficient Chemiluminescence Probe for the Detection of Singlet Oxygen in Living Cells

Singlet oxygen is among the reactive oxygen species (ROS) with the shortest life-times in aqueous media because of its extremely high reactivity. Therefore, designing sensors for detection of 1 O2 is perhaps one of the most challenging tasks in the field of molecular probes. Herein, we report a highly selective and sensitive chemiluminescence probe (SOCL-CPP) for the detection of 1 O2 in living cells. The probe reacts with 1 O2 to form a dioxetane that spontaneously decomposes under physiological conditions through a chemiexcitation pathway to emit green light with extraordinary intensity. SOCL-CPP demonstrated promising ability to detect and image intracellular 1 O2 produced by a photosensitizer in HeLa cells during photodynamic therapy (PDT) mode of action. Our findings make SOCL-CPP the most effective known chemiluminescence probe for the detection of 1 O2 . We anticipate that our chemiluminescence probe for 1 O2 imaging would be useful in PDT-related applications and for monitoring 1 O2 endogenously generated by cells in response to different stimuli.

Amphiphilic nanocarrier-induced modulation of PLK1 and miR-34a leads to improved therapeutic response in pancreatic cancer

The heterogeneity of pancreatic ductal adenocarcinoma (PDAC) suggests that successful treatment might rely on simultaneous targeting of multiple genes, which can be achieved by RNA interference-based therapeutic strategies. Here we show a potent combination of microRNA and siRNA delivered by an efficient nanocarrier to PDAC tumors. Using proteomic-microRNA profiles and survival data of PDAC patients from TCGA, we found a novel signature for prolonged survival. Accordingly, we used a microRNA-mimic to increase miR-34a together with siRNA to silence PLK1 oncogene. For in vivo dual-targeting of this combination, we developed a biodegradable amphiphilic polyglutamate amine polymeric nanocarrier (APA). APA-miRNA–siRNA polyplexes systemically administered to orthotopically inoculated PDAC-bearing mice showed no toxicity and accumulated at the tumor, resulting in an enhanced antitumor effect due to inhibition of MYC oncogene, a common target of both miR-34a and PLK1. Taken together, our findings warrant this unique combined polyplex’s potential as a novel nanotherapeutic for PDAC.Treatment of pancreatic ductal adenocarcinoma is still challenging and patients survival has only marginally improved in the last decade. Here the authors produce a PGA-based polymeric nanocarrier for the dual delivery of miR-34a-mimic and PLK1-targeting siRNA resulting in killing of pancreatic cancer cells in vivo.

Integrin-targeted nano-sized polymeric systems for paclitaxel conjugation: a comparative study

Abstract The generation of rationally designed polymer therapeutics via the conjugation of low molecular weight anti-cancer drugs to water-soluble polymeric nanocarriers aims to improve the therapeutic index. Here, we focus on applying polymer therapeutics to target two cell compartments simultaneously – tumour cells and angiogenic endothelial cells. Comparing different polymeric backbones carrying the same therapeutic agent and targeting moiety may shed light on any correlation between the choice of polymer and the anti-cancer activity of the conjugate. Here, we compared three paclitaxel (PTX)-bound conjugates with poly-l-glutamic acid (PGA, 4.9 mol%), 2-hydroxypropylmethacrylamide (HPMA, 1.2 mol%) copolymer, or polyethyleneglycol (PEG, 1:1 conjugate). PGA and HPMA copolymers are multivalent polymers that allow the conjugation of multiple compounds within the same polymer backbone, while PEG is a bivalent commercially available Food and Drug Administration (FDA)-approved polymer. We further conjugated PGA–PTX and PEG–PTX with the integrin αvβ3-targeting moiety RGD (5.5 mol% and 1:1 conjugate, respectively). We based our selection on the overexpression of integrin αvβ3 on angiogenic endothelial cells and several types of cancer cells. Our findings suggest that the polymer structure has major effect on the conjugates activity on different tumour compartments. A multivalent PGA–PTX–E-[c(RGDfK)2] conjugate displayed a stronger inhibitory effect on the endothelial compartment, showing a 50% inhibition of the migration of human umbilical vein endothelial cell cells, while a PTX–PEG–E-[c(RGDfK)2] conjugate possessed enhanced anti-cancer activity on MDA-MB-231 tumour cells (IC50 = 20 nM versus IC50 300 nM for the PGA conjugate).

Emerging Nanomedical Solutions for Angiogenesis Regulation

This special issue on Angiogenesis Regulation in Advanced Drug Delivery Reviews is dedicated to the 10 year memorial of Judah Folkman, who founded the field of angiogenesis research [1]. Angiogenesis is the physiological process by which new blood vessels form from preexisting vessels [2] ; a process that occurs during embryonic development, growth, and wound healing. However, pathological angiogenesis is also a fundamental process involved inmore than 80 diseases including the malignant transformation of tumors, tumor growth, andmetastasis [3,4]. The field of angiogenesis began in the early 1970s when Judah Folkman proposed that tumor growth would be halted if the tumorwere deprived of a blood supply. Fifty years later, Folkmans controversial idea is nowwidely accepted and angiogenesis inhibitors hold great promise for the treatment of cancer and other angiogenesisdependent diseases. This special issue gives the ADDR readers an upto-date comprehensive view on the different aspects of therapeutic and imaging toward diseases with angiogenic etiologies. The following articles in this issue also present the development of new macromoleculesand nanoparticle-based systems to overcome many challenges in identifying and treating angiogenesis-related diseases and their potential applications. Since the approval of bevacizumab as anti-angiogenic therapy in 2004 by the FDA, an array of angiogenesis inhibitors have been developed and approved. However, results were disappointing with regard to their therapeutic efficacy. RNA interference approaches offer the possibility of rational design with high specificity, lacking in many current drug treatments for various diseases including cancer. Gene therapy has become a promising strategy for the treatment of such a disordered state through the introduction of exogenous nucleic acids that express or silence the target agents, thereby engineering neovascularization in both directions. Satchi-Fainaro and her coworkers summarize the advances in the last decade in thefield of angiogenesis-targetedRNA interference approaches, with special emphasis on oncology applications, including experimental evidence and clinical trials data on angiogenesis regulation by RNA interference. Green follows up on this theme showing key factors targeted for therapeutic angiogenesis and antiangiogenesis gene therapy, non-viral nanoparticle-mediated approaches to gene delivery, and recent gene therapy applications in pre-clinical and clinical trials for cancer and other diseases such as ischemia, tissue regeneration, andwet age-relatedmacular degeneration. The evaluation and modulation of the enhanced permeability and retention (EPR) effect in each tumor or metastasis is currently a major issue still limiting the impact and activity of nanomedicines. Kiessling and Lammers describe the different methods used for the alteration of angiogenic vessels to improve drug delivery to tumors. Their review

Molecular Weight-Dependent Activity of Aminated Poly(α)glutamates as siRNA Nanocarriers

RNA interference (RNAi) can contribute immensely to the area of personalized medicine by its ability to target any gene of interest. Nevertheless, its clinical use is limited by lack of efficient delivery systems. Polymer therapeutics can address many of the challenges encountered by the systemic delivery of RNAi, but suffer from inherent drawbacks such as polydispersity and batch to batch heterogeneity. These characteristics may have far-reaching consequences when dealing with therapeutic applications, as both the activity and the toxicity may be dependent on the length of the polymer chain. To investigate the consequences of polymers’ heterogeneity, we have synthesized two batches of aminated poly(α)glutamate polymers (PGAamine), differing in their degree of polymerization, but not in the monomer units or their conjugation. Isothermal titration calorimetry study was conducted to define the binding affinity of these polymers with siRNA. Molecular dynamics simulation revealed that Short PGAamine:siRNA polyplexes exposed a higher amount of amine moieties to the surroundings compared to Long PGAamine. This resulted in a higher zeta potential, leading to faster degradation and diminished gene silencing. Altogether, our study highlights the importance of an adequate physico-chemical characterization to elucidate the structure–function-activity relationship, for further development of tailor-designed RNAi delivery vehicles.