Professor Ruth Duncan: a pioneer in the field of polymer therapeutics

This special issue of the Journal of Drug Targeting marks the past, and the continuing contribution of Ruth Duncan to the field of drug delivery, more specifically the branch termed ‘Polymer Therapeutics’. The three of us have witnessed, for more than 20 years, Ruth’s never-ending enthusiasm and persistence in many different interdisciplinary arenas under this banner, and the immense scientific contribution to the field of drug delivery this vision (and tenacity) has generated. It has been a pleasure for us to edit this special issue, which pays tribute to her outstanding achievements within the context of the Journal of Drug Targeting’s Lifetime Achievement Award for 2017

HPMA copolymer-phospholipase C and dextrin-phospholipase A2 as model triggers for polymer enzyme liposome therapy (PELT)

‘Polymer Enzyme Liposome Therapy’ (PELT) is a two-step anticancer approach in which a liposomal drug and polymer-phospholipase conjugate are administered sequentially to target the tumour interstitium by the enhanced permeability and retention effect, and trigger rapid, local, drug release. To date, however, the concept has only been described theoretically. We synthesised two polymer conjugates of phospholipase C (PLC) and A2 (PLA2) and evaluated their ability to trigger anthracycline release from the clinically used liposomes, Caelyx® and DaunoXome®. N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer–PLC and a dextrin-PLA2 were synthesised and their enzymatic activity characterised. Doxorubicin release from polyethyleneglycol-coated (PEGylated) Caelyx® was relatively slow (<20%, 60 min), whereas daunomycin was rapidly released from non-PEGylated DaunoXome® (∼87%) by both enzymes. Incubation with dextrin–PLA2 triggered significantly less daunomycin release than HPMA copolymer-PLC, but when dextrin-PLA2 was pre-incubated with α-amylase, the rate of daunomycin release increased. DaunoXome®’s diameter increased in the presence of PLA2, while Caelyx®’s diameter was unaffected by free or conjugated PLA2. Dextrin–PLA2 potentiated the cytotoxicity of DaunoXome® to MCF-7 cells to a greater extent than free PLA2, while combining dextrin–PLA2 with Caelyx® resulted in antagonism, even in the presence of α-amylase, presumably due to steric hindrance by PEG. Our findings suggest that in vivo studies to evaluate PELT combinations should be further evaluated

Two-step polymer- and liposome- enzyme prodrug therapies for cancer: PDEPT and PELT concepts and future perspectives

Polymer-directed enzyme prodrug therapy (PDEPT) and polymer enzyme liposome therapy (PELT) are two-step therapies developed to provide anticancer drugs site-selective intratumoral accumulation and release. Nanomedicines, such as polymer-drug conjugates and liposomal drugs, accumulate in the tumor site due to extravasation-dependent mechanism (enhanced permeability and retention – EPR – effect), and further need to cross the cellular membrane and release their payload in the intracellular compartment. The subsequent administration of a polymer-enzyme conjugate able to accumulate in the tumor tissue and to trigger the extracellular release of the active drug showed promising preclinical results. The development of polymer-enzyme, polymer-drug conjugates and liposomal drugs had undergone a vast advancement over the past decades. Several examples of enzyme mimics for in vivo therapy can be found in the literature. Moreover, polymer therapeutics often present an enzyme-sensitive mechanism of drug release. These nanomedicines can thus be optimal substrates for PDEPT and this review aims to provide new insights and stimuli toward the future perspectives of this promising combination

Molecular weight-dependent activity of aminated poly(&#945;)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&rsquo; heterogeneity, we have synthesized two batches of aminated poly(&alpha;)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&ndash;function-activity relationship, for further development of tailor-designed RNAi delivery vehicles

6′′‐Thioether Tobramycin Analogues: Towards Selective Targeting of Bacterial Membranes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91322/1/ange_201200761_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/91322/2/5750_ftp.pd

Targeting Angiogenesis-Dependent Calcified Neoplasms Using Combined Polymer Therapeutics

There is an immense clinical need for novel therapeutics for the treatment of angiogenesis-dependent calcified neoplasms such as osteosarcomas and bone metastases. We developed a new therapeutic strategy to target bone metastases and calcified neoplasms using combined polymer-bound angiogenesis inhibitors. Using an advanced "living polymerization" technique, the reversible addition-fragmentation chain transfer (RAFT), we conjugated the aminobisphosphonate alendronate (ALN), and the potent anti-angiogenic agent TNP-470 with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer through a Glycine-Glycine-Proline-Norleucine linker, cleaved by cathepsin K, a cysteine protease overexpressed at resorption sites in bone tissues. In this approach, dual targeting is achieved. Passive accumulation is possible due to the increase in molecular weight following polymer conjugation of the drugs, thus extravasating from the tumor leaky vessels and not from normal healthy vessels. Active targeting to the calcified tissues is achieved by ALN's affinity to bone mineral.The anti-angiogenic and antitumor potency of HPMA copolymer-ALN-TNP-470 conjugate was evaluated both in vitro and in vivo. We show that free and conjugated ALN-TNP-470 have synergistic anti-angiogenic and antitumor activity by inhibiting proliferation, migration and capillary-like tube formation of endothelial and human osteosarcoma cells in vitro. Evaluation of anti-angiogenic, antitumor activity and body distribution of HPMA copolymer-ALN-TNP-470 conjugate was performed on severe combined immunodeficiency (SCID) male mice inoculated with mCherry-labeled MG-63-Ras human osteosarcoma and by modified Miles permeability assay. Our targeted bi-specific conjugate reduced VEGF-induced vascular hyperpermeability by 92% and remarkably inhibited osteosarcoma growth in mice by 96%.This is the first report to describe a new concept of a narrowly-dispersed combined polymer therapeutic designed to target both tumor and endothelial compartments of bone metastases and calcified neoplasms at a single administration. This new approach of co-delivery of two synergistic drugs may have clinical utility as a potential therapy for angiogenesis-dependent cancers such as osteosarcoma and bone metastases

Inflammatory Activation of Astrocytes Facilitates Melanoma Brain Tropism via the CXCL10-CXCR3 Signaling Axis

Melanoma is the deadliest skin cancer due to its high rate of metastasis, frequently to the brain. Brain metastases are incurable; therefore, understanding melanoma brain metastasis is of great clinical importance. We used a mouse model of spontaneous melanoma brain metastasis to study the interactions of melanomas with the brain microenvironment. We find that CXCL10 is upregulated in metastasis-associated astrocytes in mice and humans and is functionally important for the chemoattraction of melanoma cells. Moreover, CXCR3, the receptor for CXCL10, is upregulated in brain-tropic melanoma cells. Targeting melanoma expression of CXCR3 by nanoparticle-mediated siRNA delivery or by shRNA transduction inhibits melanoma cell migration and attenuates brain metastasis in vivo. These findings suggest that the instigation of pro-inflammatory signaling in astrocytes is hijacked by brain-metastasizing tumor cells to promote their metastatic capacity and that the CXCL10-CXCR3 axis may be a potential therapeutic target for the prevention of melanoma brain metastasis

Therapeutic targeting of PD-1/PD-L1 blockade by novel small-molecule inhibitors recruits cytotoxic T cells into solid tumor microenvironment

© Author(s) (or their employer(s)) 2022.This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See http://creativecommons.org/licenses/by-nc/4.0/.Background: Inhibiting programmed cell death protein 1 (PD-1) or PD-ligand 1 (PD-L1) has shown exciting clinical outcomes in diverse human cancers. So far, only monoclonal antibodies are approved as PD-1/PD-L1 inhibitors. While significant clinical outcomes are observed on patients who respond to these therapeutics, a large proportion of the patients do not benefit from the currently available immune checkpoint inhibitors, which strongly emphasize the importance of developing new immunotherapeutic agents. Methods: In this study, we followed a transdisciplinary approach to discover novel small molecules that can modulate PD-1/PD-L1 interaction. To that end, we employed in silico analyses combined with in vitro, ex vivo, and in vivo experimental studies to assess the ability of novel compounds to modulate PD-1/PD-L1 interaction and enhance T-cell function. Results: Accordingly, in this study we report the identification of novel small molecules, which like anti-PD-L1/PD-1 antibodies, can stimulate human adaptive immune responses. Unlike these biological compounds, our newly-identified small molecules enabled an extensive infiltration of T lymphocytes into three-dimensional solid tumor models, and the recruitment of cytotoxic T lymphocytes to the tumor microenvironment in vivo, unveiling a unique potential to transform cancer immunotherapy. Conclusions: We identified a new promising family of small-molecule candidates that regulate the PD-L1/PD-1 signaling pathway, promoting an extensive infiltration of effector CD8 T cells to the tumor microenvironment.C and RCA are supported by the Fundação para a Ciência e a Tecnologia, Ministério da Ciência, Tecnologia e Ensino Superior (FCT-MCTES) (PhD grants PD/BD/128238/2016 (RCA) and SFRH/BD/131969/2017 (BC)). The authors thank the funding received from the European Structural & Investment Funds through the COMPETE Programme and from National Funds through FCT under the Programme grant LISBOA-01-0145-FEDER016405 - SAICTPAC/0019/2015 (HF and RCG). HFF and RCA received additional support from FCT-MCTES (UIDB/04138/2020, PTDC/BTM-SAL/4350/2021 and UTAPEXPL/NPN/0041/2021; EXPL/MED-QUI/1316/2021, respectively). The MultiNano@MBM project was supported by The Israeli Ministry of Health, and FCTMCTES, under the frame of EuroNanoMed-II (ENMed/0051/2016; HF and RS-F). HF and RS-F thank the generous financial support from ‘La Caixa’ Foundation under the framework of the Healthcare Research call 2019 (NanoPanther; LCF/PR/HR19/52160021), as well as CaixaImpulse (Co-Vax; LCF/TR/CD20/52700005). MP thanks the financial support from Liga Portuguesa Contra o Cancro – Nucleo Regional do Sul and ‘iNOVA4Health – UIDB/04462/2020’, a program financially supported by Fundação para a Ciência e Tecnologia/Ministério da Educação e Ciência. RS-F thanks the following funding agencies for their generous support: the European Research Council (ERC) Advanced Grant Agreement No. (835227)–3DBrainStrom, ERC PoC Grant Agreement no. 862580 – 3DCanPredict, The Israel Science Foundation (Grant No. 1969/18), The Melanoma Research Alliance (MRA Established Investigator Award n°615808), the Israel Cancer Research Fund (ICRF) Professorship award (n° PROF-18-682), and the Morris Kahn Foundation.info:eu-repo/semantics/publishedVersio

Macrophage-Induced Lymphangiogenesis and Metastasis following Paclitaxel Chemotherapy Is Regulated by VEGFR3

While chemotherapy strongly restricts or reverses tumor growth, the response of host tissue to therapy can counteract its anti-tumor activity by promoting tumor re-growth and/or metastases, thus limiting therapeutic efficacy. Here, we show that vascular endothelial growth factor receptor 3 (VEGFR3)-expressing macrophages infiltrating chemotherapy-treated tumors play a significant role in metastasis. They do so in part by inducing lymphangiogenesis as a result of cathepsin release, leading to VEGF-C upregulation by heparanase. We found that macrophages from chemotherapy-treated mice are sufficient to trigger lymphatic vessel activity and structure in naive tumors in a VEGFR3-dependent manner. Blocking VEGF-C/VEGFR3 axis inhibits the activity of chemotherapy-educated macrophages, leading to reduced lymphangiogenesis in treated tumors. Overall, our results suggest that disrupting the VEGF-C/VEGFR3 axis not only directly inhibits lymphangiogenesis but also blocks the pro-metastatic activity of macrophages in chemotherapy-treated mice