Therapeutic efficacy of combined PEGylated liposomal doxorubicin and radiofrequency ablation: Comparing single and combined therapy in young and old mice

Mechanisms and Barriers in Nanomedicine: Progress in the Field and Future Directions

In recent years, steady progress has been made in synthesizing and characterizing engineered nanoparticles, resulting in several approved drugs and multiple promising candidates in clinical trials. Regulatory agencies such as the Food and Drug Administration and the European Medicines Agency released important guidance documents facilitating nanoparticle-based drug product development, particularly in the context of liposomes and lipid-based carriers. Even with the progress achieved, it is clear that many barriers must still be overcome to accelerate translation into the clinic. At the recent conference workshop "Mechanisms and Barriers in Nanomedicine" in May 2023 in Colorado, U.S.A., leading experts discussed the formulation, physiological, immunological, regulatory, clinical, and educational barriers. This position paper invites open, unrestricted, nonproprietary discussion among senior faculty, young investigators, and students to trigger ideas and concepts to move the field forward.

The Emerging Landscape for Combating Resistance Associated with Energy-Based Therapies via Nanomedicine

Cancer represents a serious disease with significant implications for public health, imposing substantial economic burden and negative societal consequences. Compared to conventional cancer treatments, such as surgery and chemotherapy, energy-based therapies (ET) based on athermal and thermal ablation provide distinct advantages, including minimally invasive procedures and rapid postoperative recovery. Nevertheless, due to the complex pathophysiology of many solid tumors, the therapeutic effectiveness of ET is often limited. Nanotechnology offers unique opportunities by enabling facile material designs, tunable physicochemical properties, and excellent biocompatibility, thereby further augmenting the outcomes of ET. Numerous nanomaterials have demonstrated the ability to overcome intrinsic therapeutic resistance associated with ET, leading to improved antitumor responses. This comprehensive review systematically summarizes the underlying mechanisms of ET-associated resistance (ETR) and highlights representative applications of nanoplatforms used to mitigate ETR. Overall, this review emphasizes the recent advances in the field and presents a detailed account of novel nanomaterial designs in combating ETR, along with efforts aimed at facilitating their clinical translation.

Targeted co-delivery of resiquimod and a SIRPα variant by liposomes to activate macrophage immune responses for tumor immunotherapy

Tumor-associated macrophages (TAMs) are the major immune cells infiltrating the tumor microenvironment (TME) and typically exhibit an immunosuppressive M2-like phenotype, which facilitates tumor growth and promotes resistance to immunotherapy. Additionally, tumor cells tend to express high levels of CD47, a "don't eat me" signal, that obstructs macrophage phagocytosis. Consequently, re-educating TAMs in combination with CD47 blockage is promising to trigger intense macrophage immune responses against tumors. As a toll-like receptor 7/8 agonist, resiquimod (R848) possesses the capacity to re-educate TAMs from M2 type to M1 type. We found that intratumoral administration of R848 synergistically improved the antitumor immunotherapeutic effect of CV1 protein (a SIRPα variant with high antagonism to CD47). However, the poor bioavailability and potential toxicity of this combo strategy remain a challenge. Here, a TAMs-targeted liposome (named: R-LS/M/CV1) co-delivering R848 and CV1 protein was constructed via decorating mannose on the liposomal surface. R-LS/M/CV1 exhibited high abilities of targeting, re-education and pro-phagocytosis of tumor cells to M2 macrophages in vitro. Intratumoral administration of R-LS/M/CV1 remarkedly eliminated tumor burden in the MC38 tumor model via repolarization of TAMs to M1 type, pro-phagocytosis of TAMs against tumors, and recruitment of tumor-infiltrating T cells. More encouragingly, due to the double targeting to TAMs and tumor cells of mannose and CV1 protein, R-LS/M/CV1 effectively accumulated at the tumor site, thereby not only remarkedly inhibiting tumors, but also exerting no hematological and histopathological toxicity when administered systemically. Our integrated strategy based on re-educating TAMs and CD47 blockade provides a promising approach to trigger macrophage immune responses against tumors for immunotherapy.

Modification of Extracellular Vesicle Surfaces: An Approach for Targeted Drug Delivery

Extracellular vesicles (EVs) are a promising drug delivery vehicle candidate because of their natural origin and intrinsic function of transporting various molecules between different cells. Several advantages of the EV delivery platform include enhanced permeability and retention effect, efficient interaction with recipient cells, the ability to traverse biological barriers, high biocompatibility, high biodegradability, and low immunogenicity. Furthermore, EV membranes share approximately similar structures and contents to the cell membrane, which allows surface modification of EVs, an approach to enable specific targeting. Enhanced drug accumulation in intended sites and reduced adverse effects of chemotherapeutic drugs are the most prominent effects of targeted drug delivery. In order to improve the targeting ability of EVs, chemical modification and genetic engineering are the most adopted methods to date. Diverse chemical methods are employed to decorate EV surfaces with various ligands such as aptamers, carbohydrates, peptides, vitamins, and antibodies. In this review, we introduce the biogenesis, content, and cellular pathway of natural EVs and further discuss the genetic modification of EVs, and its challenges. Furthermore, we provide a comprehensive deliberation on the various chemical modification methods for improved drug delivery, which are directly related to increasing the therapeutic index.

Sialic acid-mediated photochemotherapy enhances infiltration of CD8+ T cells from tumor-draining lymph nodes into tumors of immunosenescent mice

Immunoscenescence plays a key role in the initiation and development of tumors. Furthermore, immunoscenescence also impacts drug delivery and cancer therapeutic efficacy. To reduce the impact of immunosenescence on anti-tumor therapy, this experimental plan aimed to use neutrophils with tumor tropism properties to deliver sialic acid (SA)-modified liposomes into the tumor, kill tumor cells via SA-mediated photochemotherapy, enhance infiltration of neutrophils into the tumor, induce immunogenic death of tumor cells with chemotherapy, enhance infiltration of CD8⁺ T cells into the tumor-draining lymph nodes and tumors of immunosenescent mice, and achieve SA-mediated photochemotherapy. We found that CD8⁺ T cell and neutrophil levels in 16-month-old mice were significantly lower than those in 2- and 8-month-old mice; 16-month-old mice exhibited immunosenescence. The anti-tumor efficacy of SA-mediated non-photochemotherapy declined in 16-month-old mice, and tumors recurred after scabbing. SA-mediated photochemotherapy enhanced tumor infiltration by CD8⁺ T cells and neutrophils, induced crusting and regression of tumors in 8-month-old mice, inhibited metastasis and recurrence of tumors and eliminated the immunosenescence-induced decline in antitumor therapeutic efficacy in 16-month-old mice via the light-heat-chemical-immunity conversion.

The Fate of Sialic Acid and PEG Modified Epirubicin Liposomes in Aged versus Young Cells and Tumor Mice Models

In preclinical studies of young mice, nanoparticles showed excellent anti-tumor therapeutic effects by harnessing Peripheral Blood Monocytes (PBMs) and evading the immune system. However, the changes of age will inevitably affect PBMs and the immune system, and there is a serious lack of relevant research. Sialic acid (SA)-octadecylamine (ODA) was synthesized, and SA- or polyethylene glycol (PEG)-modified epirubicin (EPI) liposomes (EPI-SL and EPI-PL, respectively) were prepared to explore differences in antitumor treatment using 8-month-old and 8-week-old Kunming mice. Based on presented data, 8-month-old mice had more PBMs in peripheral blood than 8-week-old mice, and age differences resulted in different anti-tumor treatment effects following EPI-SL and EPI-PL treatment. Following EPI-PL administration, the tumor volume was significantly smaller in 8-week-old mice than in 8-month-old mice (* p < 0.05). Eight-month-old mice treated with EPI-SL (8M-SL) presented no damage to healthy tissue, with a 100% survival rate, and 50% mice in 8M-SL showed ‘shedding’ of tumor tissues from the growth site. Accordingly, 8-month-old mice treated with EPI-SL achieved the best therapeutic effect at different ages and with different liposomes. EPI-SL could improve the antitumor effect of 8-week-old and 8-month-old mice.

PEGylated Liposomes Remotely Loaded with the Combination of Doxorubicin, Quinine, and Indocyanine Green Enable Successful Treatment of Multidrug-Resistant Tumors

Multidrug resistance (MDR) of cancer cells remains a major obstacle to favorable outcomes of treatment with many drugs, including doxorubicin. Most of the clinical trials failed to demonstrate the benefit of the drug efflux transporter P-glycoprotein (P-gp) inhibitors to circumvent P-gp-mediated drug resistance in vivo. The present study explored the therapeutic potential of combined treatment with liposomal doxorubicin, P-gp inhibitor quinine, and the photodynamic therapy (PDT) using indocyanine green (ICG) in the adenocarcinoma drug-resistant tumor model. Liposomes were actively co-remotely loaded with doxorubicin and quinine, and ICG was passively adsorbed. The liposomes were characterized by differential scanning calorimetry (DSC) and cryogenic transmission microscopy (Cryo-TEM). We found that quinine impaired the crystalline structure of doxorubicin. In vitro, treatment with single agents themselves was insufficient to inhibit the growth of HT-29 MDR1 cells. However, pegylated liposomal doxorubicin and quinine (PLDQ) significantly diminished HT-29 MDR1 cell survival. Furthermore, survival inhibition intensified by the addition of ICG to the PLDQ (ICG + PLDQ). In vivo, ICG + PLDQ significantly decreased tumor growth when combined with tumor irradiation with NIR light (** p < 0.01). ICG + PLDQ + irradiation was superior to single treatments or combinational treatments without irradiation. These findings suggest that ICG + PLDQ can overcome P-gp-mediated MDR in cancer cells.

Nanomedicine in Oncocardiology: Contribution and Perspectives of Preclinical Studies

Cancer and cardiovascular diseases are the leading causes of death and morbidity worldwide. Strikingly, cardiovascular disorders are more common and more severe in cancer patients than in the general population, increasing incidence rates. In this context, it is vital to consider the anticancer efficacy of a treatment and the devastating heart complications it could potentially cause. Oncocardiology has emerged as a promising medical and scientific field addressing these aspects from different angles. Interestingly, nanomedicine appears to have great promise in reducing the cardiotoxicity of anticancer drugs, maintaining or even enhancing their efficacy. Several studies have shown the benefits of nanocarriers, although with some flaws when considering the concept of oncocardiology. Herein, we discuss how preclinical studies should be designed as closely as possible to clinical protocols, considering various parameters intrinsic to the animal models used and the experimental protocols. The sex and age of the animals, the size and location of the tumors, the doses of the nanoformulations administered, and the acute vs. the long-term effects of treatments are essential aspects. We also discuss the perspectives offered by non-invasive imaging techniques to simultaneously assess both the anticancer effects of treatment and its potential impact on the heart. The overall objective is to accelerate the development and validation of nanoformulations through high-quality preclinical studies reproducing the clinical conditions.

Correlation between mouse age and human age in anti-tumor research: Significance and method establishment

Age is closely related with the occurrence and development of tumors, and with treatment outcomes. To improve the accuracy and rigor of preclinical studies, and to enhance consistency between the preclinical research and the clinical reality, the age of experimental animals used in preclinical studies is important. The mouse genome is 99% identical to the human genome, and mice have similar patterns with respect to organs and systemic physiology. Thus, mice have been the most widely used animals in anti-tumor research. However, most mice used in such studies are 6 to 8 weeks old, ignoring the fact that different tumors may often occur in various periods, with a particular tendency to occur in later stages of life. The great difference in age limits the success rate of clinical transformation. Therefore, it is very important to choose mice of suitable age for preclinical studies and to correlate ages of human and mice. Only a few related studies have been reported and there is a lack of consistency in the findings. This review points out that age is one of the important factors in anti-tumor research, and establishes a new method for calculating the age correlation between humans and mice. The equations obtained from the method can help researchers conveniently determine suitable aged mouse for their research, which will improve the rigor of their experimental results. Furthermore, this method can be used beyond anti-tumor research, in studies on other diseases that use mouse as an animal model.

A Nanodrug Consisting Of Doxorubicin And Exosome Derived From Mesenchymal Stem Cells For Osteosarcoma Treatment In Vitro

Purpose

The primary goal of the present study was to develop the nano-drug consisting of doxorubicin and exosome derived from mesenchymal stem cells, and to explore its effect on osteosarcoma in vitro.

Methods

The exosomes were isolated from bone marrow MSCs (BM-MSCs) by an Exosome Isolation Kit. The exosome-loaded doxorubicin (Exo-Dox) was prepared by mixing exosome with Dox-HCl, desalinizing with triethylamine and then dialyzing against PBS overnight. The nanoparticle tracking analysis (NTA) and transmission electron microscope (TEM) were used to characterize of the exosome and Exo-Dox. The cytotoxicity of Exo-Dox was determined by CCK-8 assay. Further, the cellular uptake of different drugs was analyzed using inverted fluorescence microscope and flow cytometry.

Results

The typical exosome structures can be observed by TEM. After loading with doxorubicin, its size is larger than free exosome. Compared with the free Dox, the prepared Exo-Dox showed enhanced cellular uptake efficiency and anti-tumor effect in osteosarcoma MG63 cell line but low cytotoxicity in myocardial H9C2 cell line.

Conclusion

The prepared Exo-Dox could be used as an excellent chemotherapeutic drug for treatment of osteosarcoma in vitro. Considering the tumor-homing feature of BM-MSCs, the Exo-Dox may be a good candidate for targeted osteosarcoma treatment in future study.

Nanomedicines for Pediatric Cancers

Chemotherapy protocols for childhood cancers are still problematic due to the high toxicity associated with chemotherapeutic agents and incorrect dosing regimens extrapolated from adults. Nanotechnology has demonstrated significant ability to reduce toxicity of anticancer compounds. Improvement in the therapeutic index of cytostatic drugs makes this strategy an alternative to common chemotherapy in adults. However, the lack of nanomedicines specifically for pediatric cancer care raises a medical conundrum. This review highlights the current state and progress of nanomedicine in pediatric cancer and discusses the real clinical challenges and opportunities.

A systematic investigation of the maximum tolerated dose of cytotoxic chemotherapy with and without supportive care in mice

Background

Cytotoxic chemotherapeutics form the cornerstone of systemic treatment of many cancers. Patients are dosed at maximum tolerated dose (MTD), which is carefully determined in phase I studies. In contrast, in murine studies, dosages are often based on customary practice or small pilot studies, which often are not well documented. Consequently, research groups need to replicate experiments, resulting in an excess use of animals and highly variable dosages across the literature. In addition, while patients often receive supportive treatments in order to allow dose escalation, mice do not. These issues could affect experimental results and hence clinical translation.

Methods

To address this, we determined the single-dose MTD in BALB/c and C57BL/6 mice for a range of chemotherapeutics covering the canonical classes, with clinical score and weight as endpoints.

Results

We found that there was some variation in MTDs between strains and the tolerability of repeated cycles of chemotherapy at MTD was drug-dependent. We also demonstrate that dexamethasone reduces chemotherapy-induced weight loss in mice.

Conclusion

These data form a resource for future studies using chemotherapy in mice, increasing comparability between studies, reducing the number of mice needed for dose optimisation experiments and potentially improving translation to the clinic.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3677-7) contains supplementary material, which is available to authorized users.