Tuning the efficacy of esterase-activatable prodrug nanoparticles for the treatment of colorectal malignancies

Co-delivery of Plinabulin and Tirapazamine boosts anti-tumor efficacy by simultaneously destroying tumor blood vessels and killing tumor cells

It is imperative to optimize chemotherapy for heightened anti-tumor therapeutic efficacy. Unrestrained tumor cell proliferation and sustained angiogenesis are pivotal for cancer progression. Plinabulin, a vascular disrupting agent, selectively destroys tumor blood vessels. Tirapazamine (TPZ), a hypoxia-activated prodrug, intensifies cytotoxicity in diminishing oxygen levels within tumor cells. Despite completing Phase III clinical trials, both agents exhibited modest treatment efficiency due to dose-limiting toxicity. In this study, we employed methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG-b-PDLLA) to co-deliver Plinabulin and TPZ to the tumor site, concurrently disrupting blood vessels and eliminating tumor cells, addressing both symptoms and the root cause of tumor progression. Plinabulin was converted into a prodrug with esterase response (PSM), and TPZ was synthesized into a hexyl chain-containing derivative (TPZHex) for effective co-delivery. PSM and TPZHex were co-encapsulated with mPEG-b-PDLLA, forming nanodrugs (PT-NPs). At the tumor site, PT-NPs responded to esterase overexpression, releasing Plinabulin, disrupting blood vessels, and causing nutritional and oxygen deficiency. TPZHex was activated in response to increased hypoxia, killing tumor cells. In treating 4T1 tumors, PT-NPs demonstrated enhanced therapeutic efficacy, achieving a 92.9 % tumor suppression rate and a 20 % cure rate. This research presented an innovative strategy to enhance synergistic efficacy and reduce toxicity in combination chemotherapy.

Synergistic Nanomedicine Delivering Topoisomerase I Toxin (SN-38) and Inhibitors of Polynucleotide Kinase 3'-Phosphatase (PNKP) for Enhanced Treatment of Colorectal Cancer

Inhibitors of a DNA repair enzyme known as polynucleotide kinase 3'-phosphatase (PNKP) are expected to show synergistic cytotoxicity in combination with topoisomerase I (TOP1) inhibitors in cancer. In this study, the synergistic cytotoxicity of a novel inhibitor of PNKP, i.e., A83B4C63, with a potent TOP1 inhibitor, i.e., SN-38, against colorectal cancer cells was investigated. Polymeric micelles (PMs) for preferred tumor delivery of A83B4C63, developed through physical encapsulation of this compound in methoxy poly(ethylene oxide)-poly(α-benzyl carboxylate-ε-caprolactone) (mPEO-b-PBCL) micelles, were combined with SN-38 in free or PM form. The PM form of SN-38 was prepared through chemical conjugation of SN-38 to the functional end group of mPEO-b-PBCL and further assembly of mPEO-b-PBCL-SN-38 in water. Moreover, mixed micelles composed of mPEO-b-PBCL and mPEO-b-PBCL-SN-38 were used to co-load A83B4C63 and SN-38 in the same nanoformulation. The loading content (% w/w) of the SN-38 and A83B4C63 to mPEO-b-PBCL in the co-loaded formulation was 7.91 ± 0.66 and 16.13 ± 0.11% (w/w), respectively, compared to 15.67 ± 0.34 (% w/w) and 23.06 ± 0.63 (% w/w) for mPEO-b-PBCL micelles loading individual drugs. Notably, the average diameter of PMs co-encapsulating both SN-38 and A83B4C63 was larger than that of PMs encapsulating either of these compounds alone but still lower than 60 nm. The release of A83B4C63 from PMs co-encapsulating both drugs was 76.36 ± 1.41% within 24 h, which was significantly higher than that of A83B4C63-encapsulated micelles (42.70 ± 0.72%). In contrast, the release of SN-38 from PMs co-encapsulating both drugs was 44.15 ± 2.61% at 24 h, which was significantly lower than that of SN-38-conjugated PMs (74.16 ± 3.65%). Cytotoxicity evaluations by the MTS assay as analyzed by the Combenefit software suggested a clear synergy between PM/A83B4C63 (at a concentration range of 10-40 μM) and free SN-38 (at a concentration range of 0.001-1 μM). The synergistic cytotoxic concentration range for SN-38 was narrowed down to 0.1-1 or 0.01-1 μM when combined with PM/A83B4C63 at 10 or 20-40 μM, respectively. In general, PMs co-encapsulating A83B4C63 and SN-38 at drug concentrations within the synergistic range (10 μM for A83B4C63 and 0.05-1 μM for SN-38) showed slightly less enhancement of SN-38 anticancer activity than a combination of individual micelles, i.e., A83B4C63 PMs + SN-38 PMs at the same molar concentrations. This was attributed to the slower release of SN-38 from the SN-38 and A83B4C63 co-encapsulated PMs compared to PMs only encapsulating SN-38. Cotreatment of cells with TOP1 inhibitors and A83B4C63 formulation enhanced the expression level of γ-HA2X, cleaved PARP, caspase-3, and caspase-7 in most cases. This trend was more consistent and notable for PMs co-encapsulating both A83B4C63 and SN-38. The overall result from the study shows a synergy between PMs of SN-38 and A83B4C63 as a mixture of two PMs for individual drugs or PMs co-encapsulating both drugs.

Nanocarriers address intracellular barriers for efficient drug delivery, overcoming drug resistance, subcellular targeting and controlled release

The cellular barriers are major bottlenecks for bioactive compounds entering into cells to accomplish their biological functions, which limits their biomedical applications. Nanocarriers have demonstrated high potential and benefits for encapsulating bioactive compounds and efficiently delivering them into target cells by overcoming a cascade of intracellular barriers to achieve desirable therapeutic and diagnostic effects. In this review, we introduce the cellular barriers ahead of drug delivery and nanocarriers, as well as summarize recent advances and strategies of nanocarriers for increasing internalization with cells, promoting intracellular trafficking, overcoming drug resistance, targeting subcellular locations and controlled drug release. Lastly, the future perspectives of nanocarriers for intracellular drug delivery are discussed, which mainly focus on potential challenges and future directions. Our review presents an overview of intracellular drug delivery by nanocarriers, which may encourage the future development of nanocarriers for efficient and precision drug delivery into a wide range of cells and subcellular targets.

Nanotherapeutic Heterogeneity: Sources, Effects, and Solutions

Nanomaterials have revolutionized medicine by enabling control over drugs' pharmacokinetics, biodistribution, and biocompatibility. However, most nanotherapeutic batches are highly heterogeneous, meaning they comprise nanoparticles that vary in size, shape, charge, composition, and ligand functionalization. Similarly, individual nanotherapeutics often have heterogeneously distributed components, ligands, and charges. This review discusses nanotherapeutic heterogeneity's sources and effects on experimental readouts and therapeutic efficacy. Among other topics, it demonstrates that heterogeneity exists in nearly all nanotherapeutic types, examines how nanotherapeutic heterogeneity arises, and discusses how heterogeneity impacts nanomaterials' in vitro and in vivo behavior. How nanotherapeutic heterogeneity skews experimental readouts and complicates their optimization and clinical translation is also shown. Lastly, strategies for limiting nanotherapeutic heterogeneity are reviewed and recommendations for developing more reproducible and effective nanotherapeutics provided.

Hindering the unlimited proliferation of tumor cells synergizes with destroying tumor blood vessels for effective cancer treatment

The rational combination of chemotherapy drugs can improve the curative effect of cancer treatment. As two early recognized tumor hallmarks, the limitless replicative potential of tumor cells is essential for the development of their malignant growth state, and sustained angiogenesis is a prerequisite to the rapid growth of tumors. Based on this, we propose a combination therapy that hinders the unlimited proliferation of tumor cells and destroys tumor blood vessels. Herein, 7-ethyl-10-hydroxycamptothecin (SN38), a typical topoisomerase I inhibitor, was bonded to poly(L-glutamic acid) (PLG) to prepare the nanodrug SN38-NPs, which hinders the unlimited proliferation of tumor cells. A poly(L-glutamic acid)-combretastatin A4 conjugate (CA4-NPs), a representative vascular disrupting agent (VDA), was used to selectively disrupt the tumor blood vessels, cutting off the necessary nutrients and oxygen for the proliferation of tumor cells. In the 4T1 tumor model with an initial volume of about 400 mm3, the combined treatment of SN38-NPs and CA4-NPs showed an excellent cancer treatment effect with a tumor suppression rate of 94.3% and a synergistic interaction (Q = 1.25). Our study provides a new combination therapy approach for chemotherapy, with the hope of further improving the curative effect of anti-cancer therapy.

A Guanosine-Derived Antitumor Supramolecular Prodrug

The prodrug strategy for its potential to enhance the pharmacokinetic and/or pharmacodynamic properties of drugs, especially chemotherapeutic agents, has been widely recognized as an important means to improve therapeutic efficiency. Irinotecan's active metabolite, 7-ethyl-10-hydroxycamptothecin (SN38), a borate derivative, was incorporated into a G-quadruplex hydrogel (GB-SN38) by the ingenious and simple approach. Drug release does not depend on carboxylesterase, thus bypassing the side effects caused by ineffective activation, but specifically responds to the ROS-overexpressed tumor microenvironment by oxidative hydrolysis of borate ester that reduces serious systemic toxicity from nonspecific biodistribution of SN38. Comprehensive spectroscopy was used to define the structural and physicochemical characteristics of the drug-loaded hydrogel. The GB-SN38 hydrogel's high level of biosafety and notable tumor-suppressive properties were proven in in vitro and in vivo tests.

Sequence-Responsive Multifunctional Supramolecular Nanomicelles Act on the Regression of TNBC and Its Lung Metastasis via Synergic Pyroptosis-Mediated Immune Activation

Design of effective nanodrugs to modulate the immunosuppression of tumor microenvironment is a desirable approach to boost the clinical tumor-therapeutic effect. Supramolecular nanomicelles PolyMN-TO-8, which are constructed by self-assembling supramolecular host MTX-MPEG2000, guest NPX-2S, and TO-8 through hydrophobic forces, have excellent stability and responsiveness to carboxylesterase and glutathione in turn. In vivo studies validate that PolyMN-TO-8 enable to trigger pyroptosis-mediated immunogenic cell death under laser, avoiding the occurrence of immune dysregulation simultaneously. This therapeutic mode strengthens dendritic cells' maturation and accelerates the infiltration of CD8+ T cells into tumors through moderate activation of pro-inflammatory factors with elimination of immune-escape, ultimately making the tumor inhibition rate as high as 87.44% via synergistic functions of photodynamic therapy, photothermal therapy, chemotherapy, etc. The loss of immune-escape quickens the infiltration of CD8+ T cells into lungs, and further eschews the generation of tumor nodules in it. Chemotherapy, the release of interferon-γ, and immune memory effect also strengthen the defense against metastasis. The generation of O2 catalyzed by PolyMN-TO-8 under laser is indispensable for tumor metastasis inhibition undoubtedly.

Oral liposomal delivery of an activatable budesonide prodrug reduces colitis in experimental mice

Inflammatory bowel disease (IBD) is one of the most common intestinal disorders, with increasing global incidence and prevalence. Numerous therapeutic drugs are available but require intravenous administration and are associated with high toxicity and insufficient patient compliance. Here, an oral liposome that entraps the activatable corticosteroid anti-inflammatory budesonide was developed for efficacious and safe IBD therapy. The prodrug was produced via the ligation of budesonide with linoleic acid linked by a hydrolytic ester bond, which was further constrained into lipid constituents to form colloidal stable nanoliposomes (termed budsomes). Chemical modification with linoleic acid augmented the compatibility and miscibility of the resulting prodrug in lipid bilayers to provide protection from the harsh environment of the gastrointestinal tract, while liposomal nanoformulation enables preferential accumulation to inflamed vasculature. Hence, when delivered orally, budsomes exhibited high stability with low drug release in the stomach in the presence of ultra-acidic pH but released active budesonide after accumulation in inflamed intestinal tissues. Notably, oral administration of budsomes demonstrated favorable anti-colitis effect with only ∼7% mouse body weight loss, whereas at least ∼16% weight loss was observed in other treatment groups. Overall, budsomes exhibited higher therapeutic efficiency than free budesonide treatment and potently induced remission of acute colitis without any adverse side effects. These data suggest a new and reliable approach for improving the efficacy of budesonide. Our in vivo preclinical data demonstrate the safety and increased efficacy of the budsome platform for IBD treatment, further supporting clinical evaluation of this orally efficacious budesonide therapeutic.

Enzymatically Activatable Polymers for Disease Diagnosis and Treatment

The irregular expression or activity of enzymes in the human body leads to various pathological disorders and can therefore be used as an intrinsic trigger for more precise identification of disease foci and controlled release of diagnostics and therapeutics, leading to improved diagnostic accuracy, sensitivity, and therapeutic efficacy while reducing systemic toxicity. Advanced synthesis strategies enable the preparation of polymers with enzymatically activatable skeletons or side chains, while understanding enzymatically responsive mechanisms promotes rational incorporation of activatable units and predictions of the release profile of diagnostics and therapeutics, ultimately leading to promising applications in disease diagnosis and treatment with superior biocompatibility and efficiency. By overcoming the challenges, new opportunities will emerge to inspire researchers to develop more efficient, safer, and clinically reliable enzymatically activatable polymeric carriers as well as prodrugs.

(Nano)platforms in breast cancer therapy: Drug/gene delivery, advanced nanocarriers and immunotherapy

Breast cancer is the most malignant tumor in women, and there is no absolute cure for it. Although treatment modalities including surgery, chemotherapy, and radiotherapy are utilized for breast cancer, it is still a life-threatening disease for humans. Nanomedicine has provided a new opportunity in breast cancer treatment, which is the focus of the current study. The nanocarriers deliver chemotherapeutic agents and natural products, both of which increase cytotoxicity against breast tumor cells and prevent the development of drug resistance. The efficacy of gene therapy is boosted by nanoparticles and the delivery of CRISPR/Cas9, Noncoding RNAs, and RNAi, promoting their potential for gene expression regulation. The drug and gene codelivery by nanoparticles can exert a synergistic impact on breast tumors and enhance cellular uptake via endocytosis. Nanostructures are able to induce photothermal and photodynamic therapy for breast tumor ablation via cell death induction. The nanoparticles can provide tumor microenvironment remodeling and repolarization of macrophages for antitumor immunity. The stimuli-responsive nanocarriers, including pH-, redox-, and light-sensitive, can mediate targeted suppression of breast tumors. Besides, nanoparticles can provide a diagnosis of breast cancer and detect biomarkers. Various kinds of nanoparticles have been employed for breast cancer therapy, including carbon-, lipid-, polymeric- and metal-based nanostructures, which are different in terms of biocompatibility and delivery efficiency.

Thermo-Chemical Resistance to Combination Therapy of Glioma Depends on Cellular Energy Level

Thermal therapy has been widely used in clinical tumor treatment and more recently in combination with chemotherapy, where the key challenge is the treatment resistance. The mechanism at the cellular level underlying the resistance to thermo-chemical combination therapy remains elusive. In this study, we constructed 3D culture models for glioma cells (i.e., 3D glioma spheres) as the model system to recapitulate the native tumor microenvironment and systematically investigated the thermal response of 3D glioma spheres at different hyperthermic temperatures. We found that 3D glioma spheres show high viability under hyperthermia, especially under high hyperthermic temperatures (42 °C). Further study revealed that the main mechanism lies in the high energy level of cells in 3D glioma spheres under hyperthermia, which enables the cells to respond promptly to thermal stimulation and maintain cellular viability by upregulating the chaperon protein Hsp70 and the anti-apoptotic pathway AKT. Besides, we also demonstrated that 3D glioma spheres show strong drug resistance to the thermo-chemical combination therapy. This study provides a new perspective on understanding the thermal response of combination therapy for tumor treatment.

A celastrol-based nanodrug with reduced hepatotoxicity for primary and metastatic cancer treatment

BACKGROUND

Cancer is the world's leading cause of death and a key hindrance to extending life expectancy. Celastrol, a bioactive compound derived from Tripterygium wilfordii, has been shown to have excellent antitumor activity, but its poor solubility and severe organ toxicity side effects have hampered its clinical application.

METHODS

In this study, a self-assembled nanodrug (PLC-NP) was designed to deliver celastrol to tumor sites while efficiently reducing its side effects by conjugating celastrol with the bioactive material LMWH and P-selectin targeting peptide (PSN). Extensive in vitro and in vivo experiments were performed to investigate both therapeutic efficacy and adverse effects. Furthermore, the specific mechanism of the antitumor activity has also been explored.

FINDING

The PLC-NP nanodrugs were spherical in shape, with a mean particle size of 115.83 ± 6.93 nm. PLC-NP was sufficiently stable during blood circulation, with a selective target to P-selectin-highly expressed tumor cells, followed by releasing the containing celastrol under acidic environment and high levels of esterase in tumor cells. Both in vitro and in vivo results confirmed that celastrol's antitumor and anti-metastatic abilities were not attenuated and were actually strengthened after being formed into nanodrugs. More importantly, the organ toxicities of the modified celastrol nanodrug were dramatically reduced. Mechanistic study indicated that the inactivation of PI3K/Akt/mTOR signaling pathway and ROS-mediated mitochondrial dysfunction play critical roles in celastrol-mediated autophagy and apoptosis.

INTERPRETATION

Our findings could offer a potential strategy for the translation of toxic compounds into clinical therapeutic nanomedicine.

FUNDING

See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript.

Reversibly "double locked" hydroxycamptothecin prodrug nanoparticles for targeted chemotherapy of lung cancer

Prodrug assembled nanoparticles integrate the merits of both prodrug and nanoparticle, which significantly improve pharmacokinetic parameters, enhance tumorous accumulation and decrease adverse effects, while they are challenged by disassembly upon dilution in blood, masking the superiority of nanoparticles (NPs). Herein, a reversibly "double locked" hydroxycamptothecin (HCPT) prodrug nanoparticle decorated with cyclic RGD peptide (cRGD) is developed for safe and efficient chemotherapy of orthotopic lung cancer in mice. HCPT prodrug is constructed from acetal (ace)-linked cRGD-PEG-ace-HCPT-ace-acrylate polymer, which is self-assembled into the nanoparticles with "the first lock" of HCPT. Then the nanoparticles undergo the in situ UV-crosslinking of the acrylate residues for constructing "the second lock" of HCPT. The obtained "double locked" nanoparticles (T-DLHN) with simple and well-defined construction are demonstrated to possess extremely high stability against 100-fold dilution and acid-triggered "unlock" including de-crosslinking and liberation of the pristine HCPT. In an orthotopic lung tumor of mouse model, T-DLHN reveals a prolonged circulation time of about 5.0 h, superb lung tumor-homing capacity with tumorous drug uptake of about 7.15%ID/g, resulting in significantly boosted anti-tumor activity and reduced adverse effects. Hence, these nanoparticles utilizing "double lock" and acid-triggered "unlock" strategies represent a unique and promising nanoplatform for safe and efficient drug delivery. STATEMENT OF SIGNIFICANCE: Prodrug assembled nanoparticles have the unique properties of the well-defined structure, systemic stability, improved pharmacokinetics, passive targeting and decreased adverse effects. However, prodrug assembled NPs would disassemble against extensive dilution in the blood circulation when intravenously injected into the body. Herein, we have designed a cRGD-directed reversibly "double-locked" HCPT prodrug nanoparticle (T-DLHN) for safe and efficient chemotherapy of orthotopic A549 human lung tumor xenografts. Upon intravenous injection, T-DLHN can overcome the shortcoming of disassembly against extensive dilution, prolong the circulation time due to the "double locked" configuration and then mediate targeted drug delivery into the tumors. After uptaken into the cells, T-DLHN undergoes concurrent de-crosslinking and liberation of HCPT under acidic condition for enhanced chemotherapeutic efficacy with negligible adverse effects.

Chemically programmed STING-activating nano-liposomal vesicles improve anticancer immunity

The often immune-suppressive tumor microenvironment (TME) may hinder immune evasion and response to checkpoint blockade therapies. Pharmacological activation of the STING pathway does create an immunologically hot TME, however, systemic delivery might lead to undesired off-target inflammatory responses. Here, we generate a small panel of esterase-activatable pro-drugs based on the structure of the non-nucleotide STING agonist MSA-2 that are subsequently stably incorporated into a liposomal vesicle for intravenous administration. The pharmacokinetic properties and immune stimulatory capacity of pro-drugs delivered via liposomes (SAProsomes) are enhanced compared to the free drug form. By performing efficacy screening among the SAProsomes incorporating different pro-drugs in syngeneic mouse tumor models, we find that superior therapeutic performance relies on improved delivery to the desired tumor and lymphoid compartments. The best candidate, SAProsome-3, highly stimulates secretion of inflammatory cytokines and creates a tumoricidal immune landscape. Notably, upon application to breast cancer or melanoma mouse models, SAProsome-3 elicits durable remission of established tumors and postsurgical tumor-free survival while decreasing metastatic burden without significant systemic toxicity. In summary, our work establishes the proof of principle for a better targeted and more efficient and safe STING agonist therapy.

A ROS-response hyaluronic acid-coated/chitosan polymer prodrug for enhanced tumor targeting efficacy of SN38

Ethyl-10-hydroxycamptothecin (SN38) is a camptothecin derivative with significant anti-tumor therapeutic potential, while the clinical application of SN38 was limited by its poor water solubility and low stability. Herein, a core-shell polymer prodrug hyaluronic acid @chitosan-S-SN38 (HA@CS-S-SN38) was designed by CS-S-SN38 as the core and the HA as the shell, which aims to overcome the limitations of the clinical application of SN38, while realizing the high tumor targeting of polymer prodrug and the controllable release of drug in tumor cells. HA@CS-S-SN38 showed the high responsiveness of the tumor microenvironment and the safe stability of blood circulation. Furthermore, HA@CS-S-SN38 exhibited the begin uptake efficiency and favorable apoptosis in the 4T1 cells. More importantly, compared with irinotecan hydrochloride trihydrate (CPT-11), HA@CS-S-SN38 significantly improved the conversion efficiency of the prodrug to SN38, and showed excellent tumor targeting and retention in vivo by combining passive and active targeting strategies. In tumor-bearing mice treatment, HA@CS-S-SN38 showed the perfect anti-tumor effect and therapeutic safety. These results indicated that the polymer prodrug designed by ROS-response/HA-modification strategy is a safe and efficient drug delivery system, which provides a new idea for clinical utilization of SN38 and warrants further evaluation.

A nanotherapeutic strategy that engages cytotoxic and immunosuppressive activities for the treatment of cancer recurrence following organ transplantation

BACKGROUND

Long-term treatment with immunosuppressants is necessary to attenuate allograft rejection following organ transplantation (OT). Consequently, the overall survival of OT recipients with malignancies has been substantially compromised by tumour recurrence. Rapamycin (RAPA) is a clinically approved immunosuppressive agent with antitumour activity that is considered beneficial in preventing posttransplant tumour recurrence. However, the clinical outcome of RAPA is impeded by acquired drug resistance and its poor oral bioavailability.

METHODS

A nanotherapeutic strategy was developed by supramolecular assembly of RAPA into a polymer cytotoxic 7-ethyl-10-hydroxycamptothecin (SN38) prodrug nanoparticle (termed SRNP) for simultaneous codelivery of cytotoxic/immunosuppressive agents. Cell-based experiments were used to evaluate the cytotoxicity of SRNPs against hepatocellular carcinoma (HCC). The therapeutic efficacy of SRNPs was evaluated in multiple preclinical models including an orthotopic HCC mouse model, an orthotopic liver transplantation (OLT) rat model and a clinically relevant cancer-transplant model to examine its antitumour and immunosuppressive activity.

FINDINGS

The combination of SN38 with RAPA resulted in synergetic effects against HCC cells and alleviated RAPA resistance by abrogating Akt/mTOR signalling activation. SRNPs exhibited potent antitumour efficiency in the orthotopic HCC model while substantially prolonging the survival of allografts in the OLT model. In the cancer-transplant model that simultaneously bears tumour xenografts and skin allografts, SRNPs not only effectively inhibited tumour growth but also attenuated allograft damage.

INTERPRETATION

The nanotherapy presented here had enhanced efficacy against tumours and maintained satisfactory immunosuppressive activity and thus has great potential to improve the survival outcomes of patients with a high risk of tumour recurrence following OT.

FUNDING

This work was supported by the National Natural Science Foundation of China (32171368 and 31671019), the Zhejiang Provincial Natural Science Foundation of China (LZ21H180001), the Zhejiang Province Preeminence Youth Fund (LR19H160002), and the Jinan Provincial Laboratory Research Project of Microecological Biomedicine (JNL-2022039c).

Preparation and Cytotoxicity Evaluation of Folic Acid-Modified YF8-OA Self-Assembled Lipid Prodrug Nanoparticles

This study aimed to improve the use of YF8, a matrine derivative obtained through chemical transformation of matrine extracted from Sophora alopecuroides. YF8 has demonstrated improved cytotoxicity compared to matrine, but its hydrophobic nature hinders its application. To overcome this, the lipid prodrug YF8-OA was synthesized by linking oleic acid (OA) to YF8 through an ester bond. Although YF8-OA could self-assemble into unique nanostructures in water, it was not sufficiently stable. To enhance the stability of YF8-OA lipid prodrug nanoparticles (LPs), we employed the strategy of PEGylation using DSPE-mPEG₂₀₀₀ or DSPE-mPEG₂₀₀₀ conjugated with folic acid (FA). This resulted in the formation of uniform spherical nanoparticles with greatly improved stability and a maximum drug load capacity upto 58.63%. Cytotoxicity was evaluated in A549, HeLa, and HepG2 cell lines. The results showed that in HeLa cells, the IC₅₀ value of YF8-OA/LPs with FA-modified PEGylation was significantly lower than that of YF8-OA/LPs modified by PEGylation alone. However, no significant enhancement was observed in A549 and HepG2 cells. In conclusion, the lipid prodrug YF8-OA can form nanoparticles in aqueous solution to address its poor water solubility. Modification with FA resulted in further enhanced cytotoxicity, providing a potential avenue for exerting the antitumor activity of matrine analogs.

Glutathione and Esterase Dual-Responsive Smart Nano-drug Delivery System Capable of Breaking the Redox Balance for Enhanced Tumor Therapy

Conventional chemotherapy usually fails to achieve its intended effect because of the poor water solubility, poor tumor selectivity, and low tumor accumulation of chemotherapy drugs. The systemic toxicity of chemotherapy agents is also a problem that cannot be ignored. It is expected that smart nano-drug delivery systems that are able to respond to tumor microenvironments will provide better therapeutic outcomes with decreased side effects of chemotherapeutics. Nano-drug delivery systems capable of breaking the redox balance can also increase the sensitivity of tumor cells to chemotherapeutics. In this study, using polymer-containing disulfide bonds, ester bonds, and d-α-tocopherol polyethylene glycol succinate (TPGS), which can amplify reactive oxygen species (ROS) in tumor cells, we have successfully prepared a smart glutathione (GSH) and esterase dual-responsive nano-drug delivery system (DTX@PAMBE-SS-TPGS NPs) with the ability to deplete GSH as well as amplify ROS and effectively release an encapsulated chemotherapy drug (DTX) in tumor cells. The potential of DTX@PAMBE-SS-TPGS NPs for enhanced antitumor effects was thoroughly evaluated using in vitro as well as in vivo experiments. Our research offers a promising strategy for maximizing the efficacy of tumor therapy.

Research advances in nanomedicine applied to the systemic treatment of colorectal cancer

The systematic treatment of colorectal cancer (CRC) still has room for improvement. The efficacy of chemotherapy, that of anti-vascular therapy, and that of immunotherapy have been unsatisfactory. In recent years, nanomaterials have been used as carriers to improve the bioavailability of anticancer drugs. For the treatment of colorectal cancer, nanodrugs increase the possibility of more precise targeted delivery. However, the actual benefits may cover more aspects. Nanocarriers can produce synergistic effects with anticancer drugs, including the scavenging of reactive oxygen species and co-delivery of a variety of drugs. Currently, immunotherapy has very limited clinical applications in CRC. Modified nanocarriers can activate the immune microenvironment, which can be used for staging antigen recognition or the immune response. Cancer vaccines based on nanomaterials and modified immune checkpoint inhibitors have shown therapeutic potential in animal models. Considering the direct or indirect relationship between the intestinal microflora and CRC, a variety of nanodrugs that regulate microbial function have been explored as an anticancer strategy, and the special structure of microorganisms can also be used as a basis for improving the delivery of traditional nanoparticles (NPs). This review summarizes recent research performed on nanocarriers in in vivo and in vitro models and the synergistic anticancer effects of nanocarriers, focusing on the interaction between NPs and the body, resulting in enhanced efficacy and immune activation. Furthermore, this review describes the current trend of NPs used in the treatment of CRC.

Macrophage membrane-biomimetic adhesive polycaprolactone nanocamptothecin for improving cancer-targeting efficiency and impairing metastasis

The recent remarkable success and safety of mRNA lipid nanoparticle technology for producing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has stimulated intensive efforts to expand nanoparticle strategies to treat various diseases. Numerous synthetic nanoparticles have been developed for pharmaceutical delivery and cancer treatment. However, only a limited number of nanotherapies have enter clinical trials or are clinically approved. Systemically administered nanotherapies are likely to be sequestered by host mononuclear phagocyte system (MPS), resulting in suboptimal pharmacokinetics and insufficient drug concentrations in tumors. Bioinspired drug-delivery formulations have emerged as an alternative approach to evade the MPS and show potential to improve drug therapeutic efficacy. Here we developed a biodegradable polymer-conjugated camptothecin prodrug encapsulated in the plasma membrane of lipopolysaccharide-stimulated macrophages. Polymer conjugation revived the parent camptothecin agent (e.g., 7-ethyl-10-hydroxy-camptothecin), enabling lipid nanoparticle encapsulation. Furthermore, macrophage membrane cloaking transformed the nonadhesive lipid nanoparticles into bioadhesive nanocamptothecin, increasing the cellular uptake and tumor-tropic effects of this biomimetic therapy. When tested in a preclinical murine model of breast cancer, macrophage-camouflaged nanocamptothecin exhibited a higher level of tumor accumulation than uncoated nanoparticles. Furthermore, intravenous administration of the therapy effectively suppressed tumor growth and the metastatic burden without causing systematic toxicity. Our study describes a combinatorial strategy that uses polymeric prodrug design and cell membrane cloaking to achieve therapeutics with high efficacy and low toxicity. This approach might also be generally applicable to formulate other therapeutic candidates that are not compatible or miscible with biomimetic delivery carriers.

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Macrophage membrane-biomimetic platform was exploited for nanodelivery of polycaprolactone nanocamptothecin.

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Macrophage-camouflaged nanocamptothecin exhibited tumor-tropic effects and increased tumor cell adhesion.

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The nanotherapy effectively suppressed primary tumor growth and the metastatic burden in vivo.

Patient-derived xenograft model in colorectal cancer basic and translational research

Colorectal cancer (CRC) is one of the most popular malignancies globally, with 930 000 deaths in 2020. The evaluation of CRC-related pathogenesis and the discovery of potential therapeutic targets will be meaningful and helpful for improving CRC treatment. With huge efforts made in past decades, the systematic treatment regimens have been applied to improve the prognosis of CRC patients. However, the sensitivity of CRC to chemotherapy and targeted therapy is different from person to person, which is an important cause of treatment failure. The emergence of patient-derived xenograft (PDX) models shows great potential to alleviate the straits. PDX models possess similar genetic and pathological characteristics as the features of primary tumors. Moreover, PDX has the ability to mimic the tumor microenvironment of the original tumor. Thus, the PDX model is an important tool to screen precise drugs for individualized treatment, seek predictive biomarkers for prognosis supervision, and evaluate the unknown mechanism in basic research. This paper reviews the recent advances in constructed methods and applications of the CRC PDX model, aiming to provide new knowledge for CRC basic research and therapeutics.

Programmed pH-responsive core-shell nanoparticles for precisely targeted therapy of ulcerative colitis

pH-Responsive nanotherapeutics were recently developed for the treatment of ulcerative colitis (UC). However, they target the entire colon rather than the UC site, which leads to insufficient accumulation in inflamed colon lesions and causes side effects. Core-shell nanoparticles exhibit unique advantages in improving the precision of targeted delivery. In this study, Eudragit® EPO and L100, two pH-sensitive materials, were coated on nano-sized curcumin to fabricate core-shell nanoparticles. The developed CNs@EPO@L100 exhibited programmed pH-responsive drug release behavior, improved in vitro anti-inflammatory ability, and enhanced accumulation at the site of inflammation in the colon. Furthermore, after oral administration, CNs@EPO@L100 significantly ameliorated the inflammatory symptoms in mice. Taken together, this study provides insights into programmed release through the rational application of pH-sensitive materials and offers strategies for a precisely targeted therapy of UC using core-shell nanoparticles.

Improving cellular uptake and bioavailability of periplocymarin-linoleic acid prodrug by combining PEGylated liposome

Periplocymarin (PPM), a cardiac glycoside isolated from Cortex periplocae, has a strong anti-tumor effect against various cancer cells. However, cardiotoxicity and rapid metabolism hinder its clinical applications. In this study, small molecule prodrug was integrated into PEGylated liposome to improve the efficiency of periplocymarin in vivo. The periplocymarin-linoleic acid (PL) prodrug was constructed by conjugating the linoleic acid with PPM via esterification, which was further facilitated to form PEGylated liposome (PL-Lip) through film dispersion. Compared with PL self-assembling nano-prodrug (PL-SNP), PL-Lip showed better colloid stability, sustained drug release kinetics, and enhanced cellular uptake by tumor cells. Notably, PL-Lip performed better than PPM and PL-SNP in terms of tumor distribution and pharmacokinetics, which include bioavailability and half-life. Altogether, the prodrug PEGylated liposome represents a good strategy and method for long-circulating and tumor-targeting delivery of periplocymarin with enhanced clinical application prospect.

Antihypertension Nanoblockers Increase Intratumoral Perfusion of Sequential Cytotoxic Nanoparticles to Enhance Chemotherapy Efficacy against Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC), one of the worst prognosis types of tumors, is characterized by dense extracellular matrix, which compresses tumor vessels and forms a physical barrier to inhibit therapeutic drug penetration and efficacy. Herein, losartan, an antihypertension agent, is applied as a tumor stroma modulator and developed into a nanosystem. A series of lipophilic losartan prodrugs are constructed by esterification of the hydroxyl group on losartan to fatty acids. Based on the self-assembly ability and hydrodynamic diameter, the losartan-linoleic acid conjugate is selected for further investigation. To improve the stability in vivo, nanoassemblies are refined with PEGylation to form losartan nanoblocker (Los NB), and administered via intravenous injection for experiments. On murine models of pancreatic cancer, Los NB shows a greater ability to remodel the tumor microenvironment than free losartan, including stromal depletion, vessel perfusion increase, and hypoxia relief. Furthermore, Los NB pretreatment remarkably enhances the accumulation and penetration of 7-ethyl-10-hydroxycamptothecin (SN38)-loaded nanodrugs (SN38 NPs) in tumor tissues. Expectedly, overall therapeutic efficacy of SN38 NPs is significantly enhanced after Los NB pretreatment. Since losartan is one of the most commonly used antihypertension agents, this study may provide a potential for clinical transformation in stroma-rich PDAC treatment.

Ultrasound-mediated in vivo biodistribution of coumarin-labeled sorafenib-loaded liposome-based nanotheranostic system

Aim: This study aimed to synthesize folate-conjugated sorafenib-loaded (FCSL) liposomes for theranostic application using ultrasound (US). Materials & methods: US parameter optimization, in vitro release, anticancer effect, in vivo biodistribution, optical imaging and biocompatibility of liposomes were studied. Results: With 84% in vitro release after 4 min of US exposure at 3 MHz (1.2 mechanical index), FCSL liposomes showed lower IC₅₀ (8.70 μM) versus sorafenib (9.34 μM) against HepG2 cells. In vivo biodistribution of FCSL liposomes versus sorafenib after 9 mg/kg injection in the liver (8.63 vs 0.55) > intestine (8.45 vs 1.07) > stomach (5.62 vs 0.57) > kidney (5.46 vs 0.91) showed longer circulation time in plasma and can be tracked in mice. Conclusion: A threefold higher drug concentration in the liver in US-exposed mice makes this a successful nanotheranostic approach.

Advances in polysaccharide-based nano/microcapsules for biomedical applications: A review

Biocompatible and biodegradable polysaccharides are abundant and renewable natural materials. Polysaccharides and their derivatives are developed into various carrier materials for biomedical applications. In particular, advanced polysaccharide-based nano/microcapsules have received extensive attention in biomedical applications due to their good encapsulation ability and tunability. In recent years, polysaccharide-based nano/microcapsules have been widely used in drug carriers, gene carriers, antigen carriers, wound dressings, bioimaging and biosensors. Numerous research results have confirmed the feasibility, safety, and effectiveness of polysaccharide-based nano/microcapsules in the above-mentioned biomedical applications. This review discussed and analyzed the latest research strategies and design considerations for these applications in detail. The preparation methods, application strategies, and design considerations of polysaccharide-based nano/microcapsules are summarized and analyzed, and their challenges and future research prospects in biomedicine are further discussed. It is expected to provide researchers with inspiration and design ideas.

Inhaled Gold Nano-star Carriers for Targeted Delivery of Triple Suicide Gene Therapy and Therapeutic MicroRNAs to Lung Metastases: Development and Validation in a Small Animal Model

Pulmonary metastases pose significant treatment challenges for many cancers, including triple-negative breast cancer (TNBC). We developed and tested a novel suicide gene and therapeutic microRNAs (miRs) combination therapy against lung metastases in vivo in mouse models after intranasal delivery using nontoxic gold nanoparticles (AuNPs) formulated to carry these molecular therapeutics. We used AuNPs coated with chitosan-β-cyclodextrin (CS-CD) and functionalized with a urokinase plasminogen activator (uPA) peptide to carry triple cancer suicide genes (thymidine kinase-p53-nitroreductase: TK-p53-NTR) plus therapeutic miRNAs (antimiR-21, antimiR-10b and miR-100). We synthesized three AuNPs: 20nm nanodots (AuND), and 20nm or 50nm nanostars (AuNS), then surface coated these with CS-CD using a microfluidic-optimized method. We sequentially coated the resulting positively charged AuNP-CS-CD core with synthetic miRNAs followed by TK-p53-NTR via electrostatic interactions, and added uPA peptide through CD-adamantane host-guest chemistry. A comparison of transfection efficiencies for different AuNPs showed that the 50nm AuNS allowed ∼4.16-fold higher gene transfection than other NPs. The intranasal delivery of uPA-AuNS-TK-p53-NTR-microRNAs NPs (pAuNS@TK-p53-NTR-miRs) in mice predominantly accumulated in lungs and facilitated ganciclovir and CB1954 prodrug-mediated gene therapy against TNBC lung metastases. This new nanosystem may serve as an adaptable-across-cancer-type, facile, and clinically scalable platform to allow future inhalational suicide gene-miR combination therapy for patients harboring pulmonary metastases.

Targeting the Mitochondria with Pseudo-Stealthy Nanotaxanes to Impair Mitochondrial Biogenesis for Effective Cancer Treatment

The clinical success of anticancer therapy is usually limited by drug resistance and the metastatic dissemination of cancer cells. Mitochondria are essential generators of cellular energy and play a crucial role in sustaining cell survival and metastatic escape. Selective drug strategies targeting mitochondria are able to rewire mitochondrial metabolism and may provide an alternative paradigm to treat many aggressive cancers with high efficiency and low toxicity. Here, we present a pseudo-stealthy mitochondria-targeted pro-nanotaxane and test it against recurrent and metastatic tumor xenografts. The nanoparticle encapsulates a mitochondria-targetable pro-taxane agent, which can be converted into the chemically unmodified cabazitaxel drug, with further surface cloaking with a low-density lipophilic triphenylphosphonium cation. The resultant nanotaxane could be effectively taken up by cells and consequently specifically localized to the mitochondria. The in situ activated cabazitaxel causes mitochondrial dysfunction and ultimately results in potent cell apoptosis. After intravenous administration to animals, pro-nanotaxane mimics the stealthy behavior of polyethylene glycol-cloaked nanoparticles to provide a long circulation time. The antitumor efficacy of this mitochondria-targeted system was validated in multiple preclinical drug-resistant tumor models. Notably, in a patient-derived metastatic melanoma model that was initially pretreated with cabazitaxel, nanotaxane administration not only produced durable tumor reduction but also substantially suppressed metastatic recurrence. Taken together, these results demonstrate that this combination of a pseudo-stealthy platform with a rationally designed pro-drug is an attractive approach to target mitochondria and enhance drug efficacy.

Oral delivery of camptothecin-loaded multifunctional chitosan-based micelles is effective in reduce colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease with high incidence and mortality worldwide. The efficacy of conventional CRC chemotherapy is hampered by poor drug solubility and bioavailability and suboptimal pharmacokinetic profiles. In this work, camptothecin (CPT), a potent anticancer drug, was loaded into an amphiphilic chitosan modified with PEG and oleic acid, to reduce CRC progression after oral administration. While CPT-loaded micelles presented anticancer activity against HCT116, Caco-2 and HT29 CRC cell lines in vitro, empty micelles demonstrated a safe profile when incubated with human blood cells and colorectal cancer cell lines. In a more complex 3D CRC multicellular spheroid model, CPT-loaded micelles also exhibited a significant effect on the spheroid's metabolic activity and size reduction. Remarkably, in vivo studies performed in a HCT116 xenograft model, showed a significant reduction on the tumor growth during and after treatment with CPT-loaded micelles. Moreover, in a more biological relevant in vivo model of chemically-induced CRC, orally administered CPT-loaded micelles demonstrated a significant reduction on tumor incidence and inflammation signs. The findings here reported indicate that CPT-loaded into chitosan-based micelles, by improving drug solubility, alongside its safety profile for normal tissues, may have a promising role CRC chemotherapy.

Active targeting redox-responsive mannosylated prodrug nanocolloids promote tumor recognition and cell internalization for enhanced colon cancer chemotherapy

Despite the diversified therapeutic approaches for malignant tumors, chemotherapy remains the backbone of current cancer treatment. However, conventional chemotherapeutics was found to be associated with deficient recognition of tumor, low uptake efficiency, insolubility, short circulation, poor biocompatibility and low therapeutic outcomes. Herein, the active targeting redox-responsive mannosylated prodrug nanocolloids (HM NCs) were constructed for enhanced chemotherapy of colon cancer. HM NCs were prepared by the covalent cross-linking of 10-hydroxycamptothecin (HCPT) and mannose (MAN) via a redox-responsive cross-linker containing disulfide bonds, and modified with a moderate amount of polyethylene glycol (PEG). The large amount of mannose contained in HM NCs could actively target overexpressed mannose receptors on the surface of cancer cells and enhance cancer cell internalization through mannose receptor-mediated endocytosis. Owing to the combination of active targeting and the enhanced permeability and retention (EPR) passive targeting, HM NCs could effectively accumulate in tumors and high glutathione (GSH) in tumor microenvironment triggered cleavage of redox-responsive bonds and precise drug release. HM NCs exhibited superior antitumor activity both in vitro and in vivo and appreciably extended the mouse survival rate with good biocompatibility. The innovative HM NCs are expected to be conducive to overcoming the limitations of conventional chemotherapy for colon cancer and providing more choices for future clinical translation. STATEMENT OF SIGNIFICANCE: Despite the enhanced permeability and retention effect, the passive targeting can be interfered with by the complex biologic barriers in the body. In this study, an active targeting system (HM NCs) was constructed by covalent cross-linking of mannose and anticancer drug 10-hydroxycamptothecin via redox-responsive disulfide bonds for enhanced colon cancer chemotherapy. Mannosylation could promote hydrophilia and stability for prolonged blood circulation. Mannose could promote tumor recognition and cell internalization via mannose receptor-mediated endocytosis. High glutathione level could trigger the redox-responsive release of anticancer drugs and further induce cell apoptosis via DNA damage. The HM NCs exhibited superior antitumor activity both in vitro and in vivo and appreciably extended the mouse survival rate with good biocompatibility.

Photo-Enhanced Chemotherapy Performance in Bladder Cancer Treatment via Albumin Coated AIE Aggregates

The implementation of cisplatin-based neoadjuvant chemotherapy (NAC) plays a key role in conjunction with surgical resection in preventing bladder cancer progression and recurrence. However, the significant dose-dependent toxic side effects of NAC are still a major challenge. To solve this problem, we developed a photoenhanced cancer chemotherapy (PECC) strategy based on AIEgen ((E)-3-(2-(2-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)vinyl)-1,1-dimethyl-1H-3λ⁴-benzo[e]indol-3-yl)propane-1-sulfonate), which is abbreviated as BITT. Multifunctional BITT@BSA-DSP nanoparticles (NPs) were employed with an albumin-based nanocarrier decorated with the cisplatin(IV) prodrug and loaded to produce strong near-infrared fluorescence imaging (NIR FLI), and they exhibited good photoenhancement performance via photodynamic therapy (PDT) and photothermal therapy (PTT). In vitro results demonstrated that BITT@BSA-DSP NPs could be efficiently taken up by bladder cancer cells and reduced to release Pt (II) under reductase, ensuring the chemotherapy effect. Furthermore, both in vitro and in vivo evaluation verified that the integration of NIR FL imaging-guided PECC efficiently promoted the sensitivity of bladder cancer to cisplatin chemotherapy with negligible side effects. This work provides a promising strategy to enhance the sensitivity of multiple cancers to chemotherapy drugs and even achieve effective treatments for drug-resistant cancers.

The Alleviation of LPS-Induced Murine Acute Lung Injury by GSH-Mediated PEGylated Artesunate Prodrugs

Acute lung injury (ALI) or its aggravated stage acute respiratory distress syndrome (ARDS) is a common severe clinical syndrome in intensive care unit, may lead to a life-threatening form of respiratory failure, resulting in high mortality up to 30–40% in most studies. Nanotechnology-mediated anti-inflammatory therapy is an emerging novel strategy for the treatment of ALI, has been demonstrated with unique advantages in solving the dilemma of ALI drug therapy. Artesunate (ART), a derivative of artemisinin, has been reported to have anti-inflammatory effects. Therefore, in the present study, we designed and synthesized PEGylated ART prodrugs and assessed whether ART prodrugs could attenuate lipopolysaccharide (LPS) induced ALI in vitro and in vivo. All treatment groups were conditioned with ART prodrugs 1 h before challenge with LPS. Significant increased inflammatory cytokines production and decreased GSH levels were observed in the LPS stimulated mouse macrophage cell line RAW264.7. Lung histopathological changes, lung W/D ratio, MPO activity and total neutrophil counts were increased in the LPS-induced murine model of ALI via nasal administration. However, these results can be reversed to some extent by treatment of ART prodrugs. The effectiveness of mPEG_2k-SS-ART in inhibition of ALI induced by LPS was confirmed. In conclusion, our results demonstrated that the ART prodrugs could attenuate LPS-induced ALI effectively, and mPEG_2k-SS-ART may serve as a novel strategy for treatment of inflammation induced lung injury.

Redox-responsive self-assembled polymeric nanoprodrug for delivery of gemcitabine in B-cell lymphoma therapy

Gemcitabine, as a standard and classic strategy for B-cell lymphoma in the clinic, is limited by its poor pharmacodynamics. Although stimuli-responsive polymeric nanodelivery systems have been widely investigated in the past decade, issues such as complicated procedures, low loading capacity, and uncontrollable release kinetics still hinder their clinical translation. In view of the above considerations, we attempt to construct hyperbranched polyprodrug micelles with considerable drug loading via simple procedures and make use of the particularity of the tumor microenvironment to ensure that the micelles are "inactivated" in normal tissues and "activated" in the tumor microenvironment. Hence, in this work, a redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) with considerable loading capacity (≈ 24.6%) exhibited on-demand and accurate control of gemcitabine release under a simulated tumor microenvironment and thus significantly induced the apoptosis of B-cell lymphoma in vitro. Moreover, in the A20 tumor xenograft murine model, GSP NPs efficiently decreased the expansion of tumor tissues with minimal systemic toxicity. In summary, these redox-responsive and self-assembling GSP NPs with a facile one-pot synthesis procedure may hold great potency in clinical translation for enhanced chemotherapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: A redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) exhibited significant tumor therapeutic effects in vitro and in vivo. The polyprodrug GEM-S-S-PEG prepared in this study shows the great potential of redox-responsive nanodrugs for antitumor activity, which provides a reference value for the optimization of the design of functional polyprodrugs.

An esterase-activatable prodrug formulated liposome strategy: potentiating the anticancer therapeutic efficacy and drug safety

Liposomal nanomedicine represents a common and versatile carrier for the delivery of both lipophilic and hydrophilic drugs. However, the direct formulation of many chemotherapeutics into a liposomal system remains an enormous challenge. Using the topoisomerase I inhibitor 7-ethyl-10-hydroxycamptothecin (SN38) as a model drug, we combined lipophilic prodrug construction with subsequent integration into an exogenous liposomal scaffold to assemble a prodrug-formulated liposome for systemic administration. Reconstructing SN38 with lipid cholesterol via the esterase-activatable bond endows the resulting prodrug with elevated miscibility with liposomal compositions and esterase-responsive drug release in cancerous cells. The systemic administration of the prodrug-based nanoassemblies (Chol-SN38@LP) exhibited preferential accumulation of therapeutic payloads in tumor lesions. Compared to the SN38 clinical counterpart irinotecan, our prodrug-based nanoassemblies with adaptive features showed elevated therapeutic efficacy (∼1.5 times increase of tumor inhibition) in a preclinical A549 lung carcinoma cell-derived mouse model and improved drug tolerability (i.e., alleviated bloody diarrhea and liver damage) in multiple mice models. These results may be ascribed to extended systemic circulation and preferential tumor accumulation of our nanodrugs. Hence, our findings demonstrate that rational engineering of therapeutic nanomedicine is a promising approach for effective and safe delivery of antitumor chemotherapeutics, especially to rescue drug candidates that have failed in clinical trials owing to poor PK properties or severe toxicity in patients.

Combinatorial nanococktails via self-assembling lipid prodrugs for synergistically overcoming drug resistance and effective cancer therapy

Background

Combinatorial systemic chemotherapy is a powerful treatment paradigm against cancer, but it is fraught with problems due to the emergence of chemoresistance and additive systemic toxicity. In addition, coadministration of individual drugs suffers from uncontrollable pharmacokinetics and biodistribution, resulting in suboptimal combination synergy.

Methods

Toward the goal of addressing these unmet medical issues, we describe a unique strategy to integrate multiple structurally disparate drugs into a self-assembling nanococktail platform. Conjugation of a polyunsaturated fatty acid (e.g., linoleic acid) with two chemotherapies generated prodrug entities that were miscible with tunable drug ratios for aqueous self-assembly. In vitro and in vivo assays were performed to investigate the mechanism of combinatorial nanococktails in mitigating chemoresistance and the efficacy of nanotherapy.

Results

The coassembled nanoparticle cocktails were feasibly fabricated and further refined with an amphiphilic matrix to form a systemically injectable and PEGylated nanomedicine with minimal excipients. The drug ratio incorporated into the nanococktails was optimized and carefully examined in lung cancer cells to maximize therapeutic synergy. Mechanistically, subjugated resistance by nanococktail therapy was achieved through the altered cellular uptake pathway and compromised DNA repair via the ATM/Chk2/p53 cascade. In mice harboring cisplatin-resistant lung tumor xenografts, administration of the nanococktail outperformed free drug combinations in terms of antitumor efficacy and drug tolerability.

Conclusion

Overall, our study provides a facile and cost-effective approach for the generation of cytotoxic nanoparticles to synergistically treat chemoresistant cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-022-00249-7.

Interplay Between the Linker and Polymer Molecular Weight of a Self-Assembling Prodrug on the Pharmacokinetics and Therapeutic Efficacy

Poorly water-soluble small hydrophobic compounds can be conjugated to a hydrophilic polymer such as methoxypolyethylene glycol (mPEG) to form amphiphilic prodrugs that can self-assemble into nanoparticles (NPs) with increased aqueous...

Prostate-Specific Membrane Antigen and Esterase Dual Responsive Camptothecin-Oligopeptide Self-Assembled Nanoparticles for Efficient Anticancer Drug Delivery

Background

The clinical utility of camptothecin (CPT) is restricted by poor aqueous solubility, high lipophilicity, active lactone ring instability, and off-targeted toxicities. We report here a prostate-specific membrane antigen (PSMA) and esterase dual responsive self-assembled nanoparticles (CPT-WT-H NPs) for highly efficient CPT delivery and effective cancer therapy.

Methods and Results

In this study, smart self-assembled nanoparticles CPT-WT-H NPs were elaborately designed and synthesized by combing hydrophobic CPT with hydrophilic PSMA-responsive penta-peptide via a cleavable ester bond. This dual responsive nanoparticle with negatively charged surface first respond to the extracellular PSMA and then to the intracellular esterase, achieving a programmable release of CPT at the tumor site and producing the byproducts of biocompatible glutamic acid and aspartic acid. Our data demonstrated that CPT-WT-H NPs exhibited greatly improved water solubility and stability. Results from MTT and flow cytometry showed CPT-WT-H NPs exhibited significantly higher cytotoxicity as well as apoptosis-inducing activity against PSMA-expressing LNCaP-FGC cells than the non-PSMA-expressing cancer cells, showing excellent cytotoxic selectivity. Moreover, the unique nanostructure provided the efficient transportation of CPT to tumor site, which resulted in the effective inhibition of tumor growth and low systemic toxicity in vivo.

Conclusion

CPT-WT-H NPs exhibited excellent in vitro PSMA-response ability and in vivo antitumor activity and safety, holding the promise to become a new and potent anticancer drug. The current research presents a promising strategy for efficient drug delivery.

Redox responsive 7-ethyl-10-hydroxycamptothecin (SN38) lysophospholipid conjugate: synthesis, assembly and anticancer evaluation

7-Ethyl-10-hydroxycamptothecin (SN38), a potent camptothecin derivative specifically targeting DNA topoisomerase I cleavage complexes, has shown great potential in the treatment of solid tumors. Because of its poor solubility and chemical and metabolic stability, the clinical application of SN38 is highly limited. To address these problems, a novel redox-responsive SN38 conjugate based liposomal formulation is developed in this report. First, SN38 was conjugated with lysophospholipid by using a cleavable disulfide bond linker. After that, the conjugate (SN38-SS-PC) was assembled into liposomes by thin film method. Dynamic lightscattering(DLS) characterization indicated that SN38-SS-PC liposomes possessed a narrow size distribution (172.8 ± 10.5 nm) and negative charged zeta potential (-8.9 ± 0.3 mV). The results of storage and physiological stabilities showed that SN38-SS-PC liposomes was stable under different conditions. More importantly, a reduction responsive release of parent drug SN38 was observed in the medium containing glutathione (GSH). In addition, SN38-SS-PC liposomes had a much more rapid cellular uptake behavior against cancer cells. The enhanced anti-cancer efficacy of SN38-SS-PC liposomes was further demonstrated by in vitro cytotoxicity assay against MCF-7 and A549 cells. Under in vivo evaluation in 4 T1 xenograft tumor model, SN38-SS-PC liposomes were observed to have lower systemic toxicity and higher tumor inhibition rate of 53.3% compared with the commercialized SN38 prodrug Irinotecan (Ir). In summary, SN38-SS-PC liposomes could be a promising redox responsive delivery system of SN38 for cancer therapy.

Recent trends in bioresponsive linker technologies of Prodrug-Based Self-Assembling nanomaterials

Prodrugs are designed to improve pharmaceutical properties of potent compounds and represent a central approach in drug development. The success of the prodrug strategy relies on incorporation of a reversible linkage facilitating controlled release of the parent drug. While prodrug approaches enhance pharmacokinetic properties over their parent drug, they still face challenges in absorption, distribution, metabolism, elimination, and toxicity (ADMET). Conjugating a drug to a carrier molecule such as a polymer can create an amphiphile that self-assembles into nanoparticles. These nanoparticles display prolonged blood circulation and passive targeting ability. Furthermore, the drug release can be tailored using a variety of linkers between the parent drug and the carrier molecule. In this review, we introduce the concept of self-assembling prodrugs and summarize different approaches for controlling the drug release with a focus on the linker technology. We also summarize recent clinical trials, discuss the emerging challenges, and provide our perspective on the utility and future potential of this technology.