HCPT-peptide prodrug with tumor microenvironment -responsive morphology transformable characteristic for boosted bladder tumor chemotherapy

Supramolecular assembly of isomeric SN-38 prodrugs regulated by conjugation sites

Supramolecular polymers (SPs) are an emerging class of drug transporters employed to improve drug therapy. Through the rational design of self-assembling monomers, one can optimize the properties of the resulting supramolecular nanostructures, such as size, shape, surface chemistry, release, and, therefore, biological fates. This study highlights the design of isomeric SN38 prodrugs through the conjugation of hydrophilic oligo(ethylene glycol) (OEG) with hydroxyls at positions 10 and 20 on hydrophobic SN-38. Self-assembling prodrug (SAPD) isomers 10-OEG-SN38 and 20-OEG-SN38 can self-assemble into giant nanotubes and filamentous assemblies, respectively, via aromatic associations that dominate self-assembly. Our study reveales the influence of modification sites on the assembly behavior and ability of the SN38 SAPDs, as well as drug release and subsequent in vitro and in vivo antitumor effects. The SAPD modified at position 20 exhibits stronger π-π interactions among SN38 units, leading to more compact packing and enhanced assembly capability, whereas OEG at position 10 poses steric hindrance for aromatic associations. Importantly, owing to its higher chemical and supramolecular stability, 20-OEG-SN38 outperforms 10-OEG-SN38 and irinotecan, a clinically used prodrug of SN38, in a CT26 tumor model, demonstrating enhanced tumor growth inhibition and prolonged animal survival. This study presents a new strategy of using interactions among drug molecules as dominating features to create supramolecular assemblies. It also brings some insights into creating effective supramolecular drug assemblies via the engineering of self-assembling building blocks, which could contribute to the optimization of design principles for supramolecular drug delivery systems.

Advances in peptide-based drug delivery systems

Drug delivery systems (DDSs) are designed to deliver drugs to their specific targets to minimize their toxic effects and improve their susceptibility to clearance during targeted transport. Peptides have high affinity, low immunogenicity, simple amino acid composition, and adjustable molecular size; therefore, most peptides can be coupled to drugs via linkers to form peptide-drug conjugates (PDCs) and act as active pro-drugs. PDCs are widely thought to be promising DDSs, given their ability to improve drug bio-compatibility and physiological stability. Peptide-based DDSs are often used to deliver therapeutic substances such as anti-cancer drugs and nucleic acid-based drugs, which not only slow the degradation rate of drugs in vivo but also ensure the drug concentration at the targeted site and prolong the half-life of drugs in vivo. This article provides an profile of the advancements and future development in functional peptide-based DDSs both domestically and internationally in recent years, in the expectation of achieving targeted drug delivery incorporating functional peptides and taking full advantage of synergistic effects.

A multifunctional integrated biomimetic spore nanoplatform for successively overcoming oral biological barriers

The biological barriers have seriously restricted the efficacious responses of oral delivery system in diseases treatment. Utilizing a carrier based on the single construction means is hard to overcome these obstacles simultaneously because the complex gastrointestinal tract environment requires carrier to have different or even contradictory properties. Interestingly, spore capsid (SC) integrates many unique biological characteristics, such as high resistance, good stability etc. This fact offers a boundless source of inspiration for the construction of multi-functional oral nanoplatform based on SC without further modification. Herein, we develop a type of biomimetic spore nanoplatform (SC@DS NPs) to successively overcome oral biological barriers. Firstly, doxorubicin (DOX) and sorafenib (SOR) are self-assembled to form carrier-free nanoparticles (DS NPs). Subsequently, SC is effectively separated from probiotic spores and served as a functional vehicle for delivering DS NPs. As expect, SC@DS NPs can efficaciously pass through the rugged stomach environment after oral administration and further be transported to the intestine. Surprisingly, we find that SC@DS NPs exhibit a significant improvement in the aspects of mucus penetration and transepithelial transport, which is related to the protein species of SC. This study demonstrates that SC@DS NPs can efficiently overcome multiple biological barriers and improve the therapeutic effect.

Self-assembled nanoformulations of paclitaxel for enhanced cancer theranostics

Chemotherapy has occupied the critical position in cancer therapy, especially towards the post-operative, advanced, recurrent, and metastatic tumors. Paclitaxel (PTX)-based formulations have been widely used in clinical practice, while the therapeutic effect is far from satisfied due to off-target toxicity and drug resistance. The caseless multi-components make the preparation technology complicated and aggravate the concerns with the excipients-associated toxicity. The self-assembled PTX nanoparticles possess a high drug content and could incorporate various functional molecules for enhancing the therapeutic index. In this work, we summarize the self-assembly strategy for diverse nanodrugs of PTX. Then, the advancement of nanodrugs for tumor therapy, especially emphasis on mono-chemotherapy, combinational therapy, and theranostics, have been outlined. Finally, the challenges and potential improvements have been briefly spotlighted.

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.

Modulating tumor-stromal crosstalk via a redox-responsive nanomedicine for combination tumor therapy

Interaction between carcinoma-associated fibroblasts (CAFs) and tumor cells leads to the invasion and metastasis of breast cancer. Herein, we prepared a redox-responsive chondroitin sulfate (CS)-based nanomedicine, in which hydrophobic cabazitaxel (CTX) was conjugated to the backbone of CS via glutathione (GSH)-sensitive dithiomaleimide (DTM) to form an amphipathic CS-DTM-CTX (CDC) conjugate, and dasatinib (DAS) co-assembled with the CDC conjugate to obtain DAS@CDC. After CD44 receptor-mediated internalization by CAFs, the nanomedicine could reverse CAFs to normal fibroblasts, blocking their crosstalk with tumor cells and reducing synthesis of major tumor extracellular matrix proteins, including collagen and fibronectin. Meanwhile, the nanomedicine internalized by tumor cells could effectively inhibit tumor proliferation and metastasis, leading to shrinkage of the tumor volume and inhibition of lung metastasis in a subcutaneous 4T1 tumor model with low side effects. Collectively, the nanomedicine showed a remarkably synergistic therapy effect against breast cancer by modulating tumor-stromal crosstalk.

Carboxylated paclitaxel prodrug nanofibers for enhanced chemotherapy

The facile availability of nanoformulations with enhanced antitumor performance remains a big challenge. Herein, we synthesize paclitaxel prodrugs with amphiphilic structures and robust assembling ability. Carboxylated paclitaxel prodrugs (PSCB) containing disulfide bonds prefer to form exquisite nanofibers, while phenylcarbinol end capped paclitaxel prodrugs (PSP) assemble into spherical nanoparticles. The transformation of morphology from nanofibers to nanorods can be realized via tuning the content of paclitaxel. Hydrophilic domains of PSCB nanofibers accelerate the cleavage of disulfide bond for rapid drug release in tumor cells, thus exhibiting the enhanced cytotoxicity and antitumor activity. This study provides a crucial insight into the functional design of hydrophobic drugs to improve chemotherapy.

Mitochondrial-Targeted Triphenylphosphonium-Hydroxycamptothecin Conjugate and Its Nano-Formulations for Breast Cancer Therapy: In Vitro and In Vivo Investigation

Mitochondria are involved in various stages of cancer cell diffusion and metastasis. Therefore, targeting tumor mitochondria with antineoplastic medicines to cause mitochondria to initiate apoptosis may be an effective strategy for cancer therapy. Here, in order to enhance the anti-tumor efficacy of the antineoplastic agent hydroxycamptothecin (HCPT), the mitochondrial targeting ligand 4-(carboxybutyl) triphenylphosphine bromide (TPP) was attached to HCPT by an ester linkage. The resultant TPP-HCPT (TH) conjugate could self-assemble into nano-aggregates, with a mean particle size of 203.2 nm and a polydispersity index (PDI) value of 0.312. The TH conjugate could also co-assembly with mPEG₃₀₀₀-PLGA₅₀₀₀ into nanoparticles (TH-NPs), with a mean diameter of 86.41 nm, a PDI value of 0.256 and a zeta potential of -0.125 mV. In contrast to HCPT injections, TH aggregates displayed enhanced cellular uptake, mitochondria-targetability and cytotoxicity against 4T1 cells, while TH-NPs showed even better improvement than TH aggregates. In the in vivo study, TH aggregates displayed higher anti-tumor efficacy in 4T1 tumor-bearing mice than HCPT injections (tumor inhibition rate, 55.71% vs. 69.17%), and TH-NPs displayed more superior anti-tumor effects (tumor inhibition rate, 80.02%). In conclusion, our research demonstrated that the TPP-HCPT conjugate and its nano-formulations, including TH aggregates and TH-NPs, may be a promising mitochondria-targeting anticancer medicine for cancer therapy. As far as we know, this is the first report in which TPP and HCPT have been conjugated directly for this aim.

Tumor-targeting albumin nanoparticles as an efficacious drug delivery system and potential diagnostic tool in non-muscle-invasive bladder cancer therapy

Current intravesical chemotherapy for non-muscle invasive bladder cancer (NMIBC) has limited efficacy due to loss of the instilled agent from urine voiding and the agent's lack of specificity for the tumors. We developed a nanocarrier (txCD47-HNP, ∼100 nm) based on human serum albumin conjugated with a peptide that targets the cluster of differentiation 47 receptor overexpressed on bladder cancer (BC) cells. The IC₅₀ of gemcitabine elaidate (GEM) loaded in the txCD47-HNP was almost an order of magnitude lower than that of free GEM. In a mouse orthotopic BC model, GEM loaded in txCD47-HNP effectively reduced the tumor burden. Tumor cells in BC patients' urine can also be targeted by fluorescence-labeled txCD47-HNP resulting in >83 % of the cells exhibiting fluorescence. Thus, txCD47-HNP can potentially be a theranostic agent in NMIBC management by serving as a targeted drug delivery vehicle as well as an alternative to urine cytology.

Advances in Antitumor Nano-Drug Delivery Systems of 10-Hydroxycamptothecin

10-Hydroxycamptothecin (HCPT) is a natural plant alkaloid from Camptotheca that shows potent antitumor activity by targeting intracellular topoisomerase I. However, factors such as instability of the lactone ring and insolubility in water have limited the clinical application of this drug. In recent years, unprecedented advances in biomedical nanotechnology have facilitated the development of nano drug delivery systems. It has been found that nanomedicine can significantly improve the stability and water solubility of HCPT. NanoMedicines with different diagnostic and therapeutic functions have been developed to significantly improve the anticancer effect of HCPT. In this paper, we collected reports on HCPT nanomedicines against tumors in the past decade. Based on current research advances, we dissected the current status and limitations of HCPT nanomedicines development and looked forward to future research directions.

Advanced Peptide Nanomedicines for Bladder Cancer Theranostics

Cancer is still a global public health problem. Although remarkable success has been achieved in cancer diagnosis and treatment, the high recurrence and mortality rates remain severely threatening to human lives and health. In recent years, peptide nanomedicines with precise selectivity and high biocompatibility have attracted intense attention in biomedical applications. In particular, there has been a significant increase in the exploration of peptides and their derivatives for malignant tumor therapy and diagnosis. Herein, we review the applications of peptides and their derivatives in the diagnosis and treatment of bladder cancer, providing new insights for the design and development of novel peptide nanomedicines for the treatment of bladder cancer in the future.

Recent Advances in Peptides-Based Stimuli-Responsive Materials for Biomedical and Therapeutic Applications: A Review

Smart materials are engineered materials that have one or more properties that are introduced in a controlled fashion by surrounding stimuli. Engineering of biomacromolecules like proteins into a smart material call for meticulous artistry. Peptides have grabbed notable attention as a preferred source for smart materials in the medicinal field, promoted by their versatile chemical and biophysical attributes of biocompatibility, and biodegradability. Recent advances in the synthesis of multifunctional peptides have proliferated their application in diverse domains: agriculture, nanotechnology, medicines, biosensors, therapeutics, and soft robotics. Stimuli such as pH, temperature, light, metal ions, and enzymes have vitalized physicochemical properties of peptides by augmented sensitivity, stability, and selectivity. This review elucidates recent (2018-2021) advances in the design and synthesis of smart materials, from stimuli-responsive peptides followed by their biomedical and therapeutic applications.

Strategies of engineering nanomedicines for tumor retention

The retention of therapeutic agents in solid tumors at sufficient concentration and duration is crucial for their antitumor effects. Given the important contribution of nanomedicines to oncology, we herein summarized two major strategies of nanomedicines for tumor retention, such as transformation- and interactions-mediated strategies. The transformation-mediated retention strategy was achieved by enlarging particle size of nanomedicines or modulating the morphology into fibrous structures, while the interactions-mediated retention strategy was accomplished by modulating nanomedicines to promote their interactions with versatile cells or components in tumors. Moreover, we provide some considerations and perspectives of tumor-retaining nanomedicines for effective cancer therapy.

Recent Advances in Stimuli-Sensitive Amphiphilic Polymer-Paclitaxel Prodrugs

Paclitaxel (PTX) is a broad-spectrum chemotherapy drug employed in the treatment of a variety of tumors. However, the clinical applications of PTX are limited by its poor water solubility. Adjuvants are widely used to overcome this issue. However, these adjuvants often have side effects and poor biodistribution. The smart drug delivery system is a promising strategy for the improvement of solubility, permeability, and stability of drugs, and can promote sustained controlled release, increasing therapeutic efficacy and reducing side effects. Polymeric prodrugs show great advantages for drug delivery due to their high drug loading and stability. There has been some groundbreaking work in the development of PTX-based stimulus-sensitive polymeric prodrug micelles, which is summarized in this study. We consider these in terms of the four main types of stimulus (pH, reduction, enzyme, and reactive oxygen species (ROS)). The design, synthesis, and biomedical applications of stimulus-responsive polymeric prodrugs of PTX are reviewed, and the current research results and future directions of the field are summarized.

Acidity-Activated Charge Conversion of 177Lu-Labeled Nanoagent for the Enhanced Photodynamic Radionuclide Therapy of Cancer

Nanomaterials in combination with radionuclide therapy (RNT) provide new opportunities for cancer treatment. However, nanomaterials with efficient tumor accumulation have been less exploited for effective radionuclide-based therapy. Here, we report glycol chitosan-based nanoparticles (GCP-NPs) with acidic pH-dependent surface charge conversion for efficient radionuclide-based combination therapy. The nanoplatform can change the surface charge of nanoparticles from slight negative to positive in the acidic tumor microenvironment, which facilitates cellular internalization and penetration and thus improves the tumor accumulation efficiency of nanomaterials. Radiolabeling of GCP-NPs with ^99mTc enables in vivo radioactive imaging in the mouse subcutaneous tumor model, showing 8.1-fold enhanced tumor uptake relative to pH-insensitive control nanoparticles (termed as GCOP-NPs). Afterward, therapeutic radioisotope ¹⁷⁷Lu-labeled GCP-NPs (¹⁷⁷Lu-GCP-NPs) that utilize RNT synergistic with photodynamic therapy (PDT) derived from conjugated pyropheophorbide-a within nanoparticles endow superior antitumor efficacy in living cells and tumor-bearing mouse model. More importantly, the combination of RNT and PDT using ¹⁷⁷Lu-GCP-NPs can effectively inhibit lung metastasis and eliminate splenomegaly, which is not possible for individual RNT or PDT. Therefore, this study proposes a facile radionuclide-based combination therapy strategy toward complete cancer remission.