Peptide-drug conjugates: A new paradigm for targeted cancer therapy

Peptide-Drug Conjugates as Next-Generation Therapeutics: Exploring the Potential and Clinical Progress

Peptide-drug conjugates (PDCs) have emerged as a next-generation therapeutic platform, combining the target specificity of peptides with the pharmacological potency of small-molecule drugs. As an evolution beyond antibody-drug conjugates (ADCs), PDCs offer distinct advantages, including enhanced cellular permeability, improved drug selectivity, and versatile design flexibility. This review provides a comprehensive analysis of the fundamental components of PDCs, including homing peptide selection, linker engineering, and payload optimization, alongside strategies to address their inherent challenges, such as stability, bioactivity, and clinical translation barriers. Therapeutic applications of PDCs span oncology, infectious diseases, metabolic disorders, and emerging areas like COVID-19, with several conjugates advancing in clinical trials and achieving regulatory milestones. Innovations, including bicyclic peptides, supramolecular architectures, and novel linker technologies, are explored as promising avenues to enhance PDC design. Additionally, this review examines the clinical trajectory of PDCs, emphasizing their therapeutic potential and highlighting ongoing trials that exemplify their efficacy. By addressing limitations and leveraging emerging advancements, PDCs hold immense promise as targeted therapeutics capable of addressing complex disease states and driving progress in precision medicine.

Cholesterol-modified peptide nanomicelles as a promising platform for cancer therapy: A review

Drug resistance, systemic toxicity, low solubility, and rapid clearance are common issues with chemotherapy drugs and other molecules used to treat cancer. The development of new therapeutic compounds and nanotherapy offers a solution to these issues. Therapeutic peptides have attracted great interest among these molecules due to their unique advantages, including low immunogenicity, efficient cellular internalization, deep tissue penetration, and low systemic toxicity. They have shown promise in cancer treatment by inducing apoptosis, necrosis, or cell lysis and promoting immunotherapy. In addition, peptides can deliver a range of cargoes, such as drugs, nucleic acids, imaging agents, and nanoparticles, and can specifically target cancer cells. However, problems such as their short half-life and low solubility limit their therapeutic use. Recent developments have addressed these constraints through structural alterations and nanoparticle formulations. In particular, cholesterol modification makes it possible for peptides to self-assemble into nanomicelles, which enhances their stability, half-life, and cell penetration. In this review, therapeutic peptides are presented as a versatile and successful cancer treatment option. The potential of cholesterol-modified peptide micelles as a reliable drug, nucleic acid, and imaging agent delivery system is also examined.

Zwitterionic Internalizable Peptide-Drug Conjugates: Tumor-Selective Ultrafast Uptake and Transcytosis for Enhanced Antitumor Therapy

Here a novel class of zwitterionic internalizable peptide (ZIP)-drug conjugates is presented. The conjugates incorporate γ-glutamyl-α-aminobutyrylamino-functionalized lysine peptides as the ZIP backbones and disulfide-linked camptothecin (CPT) as the toxic payload. The ZIPs significantly enhance the water solubility of CPT without compromising its cytotoxicity. Cellular uptake profiling shows ultrafast internalization of the conjugates in tumor cells within 5 min. Mechanistic studies reveal that they enter cells via lipid raft-mediated pathways, involving both energy-driven active transport and membrane fluidity-dependent passive uptake. Furthermore, these conjugates exhibit robust transcytosis abilities across dense cell monolayers and tumor spheroids. These characteristics confer prolonged blood circulation, enhanced tumor accumulation, and deep tumor penetration on the conjugates, which result in potent in vivo antitumor activity and minimal systemic toxicity. This study underscores the potential of the conjugates for safer and more effective cancer therapies and presents ZIPs as a new category of molecularly defined delivery tools for biomedical applications.

Concept of Targeted Drug Conjugate and Its Application in Reversing Drug Resistance

Small-molecule targeted drugs have become the mainstream cancer treatment due to their specific therapy. However, drug resistance inevitably happens to cancer patients. Herein, we propose the "targeted drug conjugate (TDC)" concept to design drugs that enhance antitumor activity, reduce toxicity, and reverse resistance. Upon this idea, compounds Lapa-603 and Lapa-604 were obtained by modifying Pt(II) units with Lapatinib's pharmacophore. Research has found that Lapa-604 can potently inhibit the proliferation of the tested cancer cells and reverse multiple cancer cell resistance by targeting the EGFR protein and causing severe DNA damage. More importantly, Lapa-604 presented higher tumor growth inhibitory efficacy than Lapatinib, Cisplatin, or their physical mixtures in both MDA-MB-231 and BT474 xenograft tumor models. Our research has provided promise for the design and development of novel drugs based on the TDC concept that can effectively overcome drug resistance with stronger antitumor activity and lower toxicity than the corresponding combination therapy.

Conformation-sensitive targeting of CD18 depletes M2-like tumor-associated macrophages resulting in inhibition of solid tumor progression

BACKGROUND

Tumor-associated macrophages (TAMs) primarily exist in the M2-like phenotype in the tumor microenvironment (TME). M2-TAMs contribute to tumor progression by establishing an immunosuppressive environment. However, TAM targeting is hindered, mainly owing to a lack of specific biomarkers for M2-TAMs. Previously, we demonstrated that a novel peptide drug conjugate (TB511) consisting of a TAM-binding peptide and the apoptosis-promoting peptide targets M2-TAMs. This was achieved through M2-TAM targeting, although the target mechanism of action remained elusive. Herein, we elucidate the anticancer efficacy of TB511 by identifying new target proteins that preferentially bind to M2-TAMs and clarifying the apoptosis-inducing mechanism in these cells.

METHODS

We investigated the target proteins and binding site of TB511 using LC-MS/MS analyses, surface plasmon resonance and peptide-protein interaction 3D modeling. Activated CD18 expression in M2 TAMs was assessed using Quantibrite PE beads in PBMCs. The anticancer efficacy of TB511 was tested using colorectal cancer (CRC) and non-small cell lung cancer (NSCLC) mouse model. The immunotherapeutic effect of TB511 was investigated through spatial transcriptomics in human pancreatic ductal adenocarcinoma (PDAC) model.

RESULTS

Activated CD18 was highly expressed in human tumor tissues and was significantly higher in M2 TAMs than in other immune cells. TB511 showed high binding affinity to CD18 among the cell membrane proteins of M2 macrophages and appeared to bind to the cysteine-rich domain in the activated form. Moreover, TB511 specifically induced apoptosis in M2 TAMs, but its targeting ability to M2 macrophages was inhibited in CD18 blockade or knockout model. In mouse or humanized mouse models of solid tumors such as CRC, NSCLC, and PDAC, TB511 suppressed tumor growth by targeting M2-TAMs via CD18 and enhancing the presence of CD8+ T cells in the TME.

CONCLUSIONS

Collectively, our findings suggest that activated CD18 holds promise as a novel target protein for cancer therapy, and TB511 shows potential as a therapeutic agent for tumor treatment.

A peptide-based fluorescent bioprobe for EphA2-overexpressing tumor targeting and image-guided surgical resection

Fluorescence-guided surgery (FGS) is an emerging and highly promising surgical technique in clinic. Owing to its real-time and visual characteristics, it assists in achieving clear pictures on lesion site, tumor boundary and degree of metastasis, which will definitely improve surgery accuracy and minimize cancer recurrence as much as possible. Herein, we report a near-infrared fluorescent bioprobe, YK80, which utilizes a modified heptamethine cyanine dye as the fluorophore and a self-assembling peptide targeting Ephrin receptor A2 (EphA2) proteins as the ligand. The design strategy and the synthetic route to YK80 are described, and then optical properties, pharmacokinetics, binding affinity between YK80 and the protein are further investigated. YK80 shows high affinity (KD ≈ 100 nM) with EphA2-expressing cancer cells and excellent targeting ability in mouse models bearing colorectal tumors. Meanwhile, indocyanine green (ICG), the commonly used non-targeted fluorescent contrast agent is employed as the comparison for in vivo experiments. However, ICG owns no such capability towards cancer cells or solid tumors. Thus, YK80 could potentially serve as a targeted contrast agent for image-guided surgery and this successful example will boost the development of medical imaging, surgical methods as well as translational medicine.

Recent Advances in Smart Linkage Strategies for Developing Drug Conjugates for Targeted Delivery

Targeted drug delivery systems effectively solve the problem of off-target toxicity of chemotherapeutic drugs by combining chemotherapeutic drugs with antibodies or peptides, thereby promoting drug targeting to the tumor site and bringing further hope for cancer treatment. The development of stimulus-responsive smart linkage technologies has led to the emergence of drug conjugates. Linkage technologies play a crucial role in the design, synthesis, and in vivo circulation of drug conjugates, as they determine the release of cytotoxic drugs from the conjugates and their subsequent therapeutic efficacy. This article reviews some of the smart linkage strategies used in designing drug conjugates, with a focus on the tumor microenvironment and exogenous stimuli as conditions influencing controlled drug release. This review introduces linker classifications and cleavage mechanisms, discusses modular linkers that promote the efficient synthesis of conjugates, and discusses the differences between linkage strategies. Furthermore, this article focuses on the implementation of self-assembly in drug conjugates, which is currently of great interest. Related concepts are introduced and relevant examples of their applications are provided. Furthermore, a comprehensive discourse is presented on the challenges that may arise in the research and clinical implementation of diverse linkage strategies, along with the associated enhancement measures. Finally, the factors that should be considered when designing linkage strategies for drug conjugates are summarized, offering strategies and ideas for scientists involved in drug conjugate research. It is particularly noteworthy that appropriate linkage strategies allow for the intracellular release of drugs after internalization of the conjugates, thereby maximizing their tumor cell-killing effect.

Advance in peptide-based drug development: delivery platforms, therapeutics and vaccines

The successful approval of peptide-based drugs can be attributed to a collaborative effort across multiple disciplines. The integration of novel drug design and synthesis techniques, display library technology, delivery systems, bioengineering advancements, and artificial intelligence have significantly expedited the development of groundbreaking peptide-based drugs, effectively addressing the obstacles associated with their character, such as the rapid clearance and degradation, necessitating subcutaneous injection leading to increasing patient discomfort, and ultimately advancing translational research efforts. Peptides are presently employed in the management and diagnosis of a diverse array of medical conditions, such as diabetes mellitus, weight loss, oncology, and rare diseases, and are additionally garnering interest in facilitating targeted drug delivery platforms and the advancement of peptide-based vaccines. This paper provides an overview of the present market and clinical trial progress of peptide-based therapeutics, delivery platforms, and vaccines. It examines the key areas of research in peptide-based drug development through a literature analysis and emphasizes the structural modification principles of peptide-based drugs, as well as the recent advancements in screening, design, and delivery technologies. The accelerated advancement in the development of novel peptide-based therapeutics, including peptide-drug complexes, new peptide-based vaccines, and innovative peptide-based diagnostic reagents, has the potential to promote the era of precise customization of disease therapeutic schedule.

Trends in the research and development of peptide drug conjugates: artificial intelligence aided design

Peptide-drug conjugates (PDCs) represent an emerging class of targeted therapeutic agents that consist of small molecular drugs coupled to multifunctional peptides through cleavable or non-cleavable linkers. The principal advantage of PDCs lies in their capacity to deliver drugs to diseased tissues at increased local concentrations, thereby reducing toxicity and mitigating adverse effects by limiting damage to non-diseased tissues. Despite the increasing number of PDCs being developed for various diseases, their advancements remain relatively slow due to several development constraints, which include limited available peptides and linkers, narrow therapeutic applications, and incomplete evaluation and information platforms for PDCs. Marked by the recent Nobel Prize awarded to artificial intelligence (AI) and de novo protein design for "protein design and structure prediction," AI is playing an increasingly important role in drug discovery and development. In this review, we summarize the recent developments and limitations of PDCs, highlights the potential of AI in revolutionizing the design and evaluation of PDC.

Bioorthogonal reaction-mediated photosensitizer-peptide conjugate anchoring on cell membranes for enhanced photodynamic therapy

Photodynamic therapy (PDT), utilizing a photosensitizer (PS) to induce tumor cell death, is an effective modality for cancer treatment. PS-peptide conjugates have recently demonstrated remarkable antitumor potential in preclinical trials. However, the limited cell membrane binding affinity and rapid systemic clearance have hindered their transition to clinical applications. To address these challenges, we investigated whether in vivo covalent chemistry could enhance tumor accumulation and potentiate antitumor efficacy. Specifically, we synthesized a PS-peptide conjugate termed P-DBCO-Ce6, with chlorin e6 (Ce6) and dibenzocyclooctyne (DBCO) conjugated to a negatively charged short peptide. By employing metabolic glycoengineering and bioorthogonal reactions, P-DBCO-Ce6 achieves covalent bonding to the cell membrane, enabling prolonged retention of the PS on the cell surface and the in situ generation of reactive oxygen species (ROS) on cell membranes to kill tumor cells. In vivo studies demonstrated a 3.3-fold increase in tumor accumulation of the PS through bioorthogonal reactions compared to the control group, confirming that click chemistry can effectively enhance PS tumor accumulation. This approach allows for the effective elimination of tumors with a single treatment. The improved efficiency of this strategy provides new insights into the design of PDT systems for potential clinical applications.

Dynamic Visualization of Computer-Aided Peptide Design for Cancer Therapeutics

Purpose

Cancer stands as a significant global public health concern, with traditional therapies potentially yielding severe side effects. Peptide-based cancer therapy is increasingly employed for diseases like cancer due to its advantages of excellent targeting, biocompatibility, and convenient synthesis. With advancements in computer technology and bioinformatics, rational design strategies based on computer technology have been employed to develop more cost-effective and potent anticancer peptides (ACPs). This study aims to explore the current status, hotspots, and future trends in the field of computer-aided design of peptides for cancer treatment through a bibliometric analysis.

Methods

A total of 1547 relevant publications published from 2006 to 2024 were collected from the Web of Science Core Collection. Bibliometric analysis was conducted using tools like CiteSpace, VOSviewer, Bibliometrix, Origin, and an online bibliometric platform.

Results

The research in this field has shown a steady growth trend, with the United States and China making the most significant contributions. Currently, ACP research mainly focuses on cell-penetrating peptides related to drug delivery, which are expected to become future research hotspots. Beyond that, peptide vaccines associated with immunotherapy are also worthy of attention. In addition, molecular dynamics simulation and molecular docking are currently popular research methods. At the same time, deep learning is the emerging keyword, indicating its potential for a more significant impact on future peptide design.

Conclusion

Deep learning technology represents emerging research hotspots with immense potential and promising prospects. As cutting-edge research directions, cellularly penetrating peptides and polypeptide immunotherapy are expected to achieve breakthroughs in cancer treatment. This study provides valuable insights into the computer-aided design of peptides in cancer therapy, contributing significantly to advancing the in-depth research and applications in this area.

Navigating cancer therapy: Harnessing the power of peptide-drug conjugates as precision delivery vehicles

Cancer treatment is a formidable challenge due to the adverse effects associated with non-selective therapies like chemotherapy and radiotherapy. This review article primarily centers on the application of Peptide-Drug Conjugates (PDCs) for delivering cancer treatment. PDCs represent a promising class of precision medicines, harnessing the unique attributes of peptides in conjunction with non-peptide components. The covalent linking of peptides and drugs through specialized connectors characterizes PDCs. These constructs play a pivotal role in delivering drugs directly to tumor sites with high precision. PDCs encompass three pivotal components: a targeting ligand, a cytotoxic ligand, and a carefully chosen linker. The selection of these elements is crucial to maximize the efficiency of PDCs. PDCs offer a multitude of advantages over conventional drug molecules, including enhanced specificity, reduced off-target effects, and an improved therapeutic profile. The peptide component within PDCs can be customized to specifically adhere to disease-specific receptors or biomarkers, facilitating targeted drug delivery and accumulation in afflicted cells or tissues. This targeted approach enables the controlled release of therapeutic payloads at the localized site, resulting in heightened effectiveness and minimized systemic toxicity. Diverse linker strategies are employed to ensure the stable connection between the peptide and non-peptide components, ensuring controlled drug release at the desired location of action. The peptides utilized in these treatments encompass cell-penetrating peptides, peptides designed to target tumor cells, and those aimed at the nucleus of cancer cells. While certain clinical trials have been conducted, and some PDCs are currently in use for cancer treatment, it's essential to acknowledge that PDCs have their limitations, such as low stability in plasma, fast elimination and limited oral bioavailability. Ongoing research endeavors seek to surmount these challenges and further establish PDCs as potent agents for cancer treatment. This review sheds light on recent advancements in the design, delivery, and applications of PDCs, while also highlighting the prevailing challenges and charting a path for future research directions.

Dual-Labeled Small Peptides in Cancer Imaging and Fluorescence-Guided Surgery: Progress and Future Perspectives

Dual-labeled compounds that combine radiolabeling and fluorescence labeling represent a significant advancement in precision oncology. Their clinical implementation enhances patient care and outcomes by leveraging the high sensitivity of radioimaging for tumor detection and taking advantage of fluorescence-based optical visualization for surgical guidance. Non-invasive radioimaging facilitates immediate identification of both primary tumors and metastases, while fluorescence imaging assists in decision-making during surgery by offering a spatial distinction between malignant and non-malignant tissue. These advancements hold promise for enhancing patient outcomes and personalization of cancer treatment. The development of dual-labeled molecular probes targeting various cancer biomarkers is crucial in addressing the heterogeneity inherent in cancer pathology and recent studies had already demonstrated the impact of dual-labeled compounds in surgical decision-making (NCT03699332, NCT03407781). This review focuses on the development and application of small dual-labeled peptides in the imaging and treatment of various cancer types. It summarizes the biomarkers targeted to date, tracing their development from initial discovery to the latest advancements in peptidomimetics. Through comprehensive analysis of recent preclinical and clinical studies, the review demonstrates the potential of these dual-labeled peptides to improve tumor detection, localization, and resection. Additionally, it highlights the evolving landscape of dual-modality imaging, emphasizing its critical role in advancing personalized and effective cancer therapy. This synthesis of current research underscores the promise of dual-labeled peptides in enhancing diagnostic accuracy and therapeutic outcomes in oncology.

Key considerations based on pharmacokinetic/pharmacodynamic in the design of antibody-drug conjugates

Background

Antibody-drug conjugate (ADC) is an anticancer drug that links toxins to specifically targeted antibodies via linkers, offering the advantages of high target specificity and high cytotoxicity. However, complexity of its structural composition poses a greater difficulty for drug design studies.

Objectives

Pharmacokinetic/pharmacodynamic (PK/PD) based consideration of ADCs has increasingly become a hot research topic for optimal drug design in recent years, providing possible ideas for obtaining ADCs with desirable properties.

Methods

From the assessment of the ADC action process based on PK/PD, we introduce the main research strategies of ADCs. In addition, we investigated the strategies to solve the prominent problems of ADC in the clinic in recent years, and summarized and evaluated the specific ways to optimize various problems of ADC based on the PK/PD model from two perspectives of optimizing the structure and properties of the drugs themselves. Through the selection of target antigen, the optimization of the linker, the optimization of novel small molecule toxins as payload, the optimization of ADC, overcoming the multi-drug resistance of ADC, improving the ADC tumor penetration of ADC, surface modification of ADC and surface bystander effect of ADC provide a more comprehensive and accurate framework for designing new ADCs.

Results

We've expounded comprehensively on applying pharmacokinetics or pharmacodynamics while designing ADC to obtain higher efficacy and fewer side effects. From the ADC's PK/PD property while coming into play in vivo and the PK/PD study strategy, to specific ADC optimization methods and recommendations based on PK/PD, it has been study-approved that the PK/PD properties exert a subtle role in the development of ADC, whether in preclinical trials or clinical promotion.

Conclusion

The study of PK/PD unfolds the detailed mechanism of ADC action, making it easier to control related parameters in the process of designing ADC, limited efficacy and inevitable off-target toxicity remain a challenging bottleneck.

Recent advances, strategies, and future perspectives of peptide-based drugs in clinical applications

Peptide-based therapies have attracted considerable interest in the treatment of cancer, diabetes, bacterial infections, and neurodegenerative diseases due to their promising therapeutic properties and enhanced safety profiles. This review provides a comprehensive overview of the major trends in peptide drug discovery and development, emphasizing preclinical strategies aimed at improving peptide stability, specificity, and pharmacokinetic properties. It assesses the current applications and challenges of peptide-based drugs in these diseases, illustrating the pharmaceutical areas where peptide-based drugs demonstrate significant potential. Furthermore, this review analyzes the obstacles that must be overcome in the future, aiming to provide valuable insights and references for the continued advancement of peptide-based drugs.

Synthesis and Investigation of Peptide-Drug Conjugates Comprising Camptothecin and a Human Protein-Derived Cell-Penetrating Peptide

Drug targeting strategies, such as peptide-drug conjugates (PDCs), have arisen to combat the issue of off-target toxicity that is commonly associated with chemotherapeutic small molecule drugs. Here we investigated the ability of PDCs comprising a human protein-derived cell-penetrating peptide-platelet factor 4-derived internalization peptide (PDIP)-as a targeting strategy to improve the selectivity of camptothecin (CPT), a topoisomerase I inhibitor that suffers from off-target toxicity. The intranuclear target of CPT allowed exploration of PDC design features required for optimal potency. A suite of PDCs with various structural characteristics, including alternative conjugation strategies (such as azide-alkyne cycloaddition and disulfide conjugation) and linker types (non-cleavable or cleavable), were synthesized and investigated for their anticancer activity. Membrane permeability and cytotoxicity studies revealed that intact PDIP-CPT PDCs can cross membranes, and that PDCs with disulfide- and protease-cleavable linkers liberated free CPT and killed melanoma cells with nanomolar potency. However, selectivity of the PDIP carrier peptide for melanoma compared to noncancerous epidermal cells was not maintained for the PDCs. This study emphasizes the distinct role of the peptide, linker, and drug for optimal PDC activity and highlights the need to carefully match components when assembling PDCs as targeted therapies.

Peptide Aptamer-Paclitaxel Conjugates for Tumor Targeted Therapy

Background/Objectives: Traditional paclitaxel therapy often results in significant side effects due to its non-specific targeting of cancer cells. Peptide aptamer-paclitaxel conjugates present a promising alternative by covalently attaching paclitaxel to a versatile peptide aptamer via a linker. Compared to antibody-paclitaxel conjugates, peptide aptamer-paclitaxel conjugates offer several advantages, including a smaller size, lower immunogenicity, improved tissue penetration, and easier engineering. Methods: This review provides an in-depth analysis of the multifunctional peptide aptamers in these conjugates, emphasizing their structural features, therapeutic efficacy, and challenges in clinical applications. Results: This analysis highlights the potential of peptide aptamer-paclitaxel conjugates as a novel and effective approach for targeted cancer therapy. By harnessing the unique properties of peptide aptamers, these conjugates demonstrate significant promise in improving drug delivery efficiency while reducing the adverse effects associated with traditional paclitaxel therapy. Conclusions: The incorporation of peptide aptamers into paclitaxel conjugates offers a promising pathway for developing more efficient and targeted cancer therapies. However, further research and clinical studies are essential to fully unlock the therapeutic potential of these innovative conjugates and enhance patient outcomes.

Pentagalloyl Glucose from Bouea macrophylla Suppresses the Epithelial-Mesenchymal Transition and Synergizes the Doxorubicin-Induced Anticancer and Anti-Migration Effects in Triple-Negative Breast Cancer

Background: Triple-negative breast cancer (TNBC) represents an aggressive form of breast cancer with few available therapeutic options. Chemotherapy, particularly with drugs like doxorubicin (DOX), remains the cornerstone of treatment for this challenging subtype. However, the clinical utility of DOX is hampered by adverse effects that escalate with higher doses and drug resistance, underscoring the need for alternative therapies. This study explored the efficacy of pentagalloyl glucose (PGG), a natural polyphenol derived from Bouea macrophylla, in enhancing DOX's anticancer effects and suppressing the epithelial-mesenchymal transition (EMT) in TNBC cells. Methods: This study employed diverse methodologies to assess the effects of PGG and DOX on TNBC cells. MDA-MB231 triple-negative breast cancer cells were used to evaluate cell viability, migration, invasion, apoptosis, mitochondrial membrane potential, and protein expression through techniques including MTT assays, wound healing assays, flow cytometry, Western blotting, and immunofluorescence. Results: Our findings demonstrate that PGG combined with DOX significantly inhibits TNBC cell proliferation, migration, and invasion. PGG enhances DOX-induced apoptosis by disrupting the mitochondrial membrane potential and activating caspase pathways; consequently, the activation of caspase-3 and the cleavage of PARP are increased. Additionally, the study shows that the combination treatment upregulates ERK signaling, further promoting apoptosis. Moreover, PGG reverses DOX-induced EMT by downregulating mesenchymal markers (vimentin and β-catenin) and upregulating epithelial markers (E-cadherin). Furthermore, it effectively inhibits STAT3 phosphorylation, associated with cell survival and migration. Conclusions: These results highlight the potential of PGG as an adjuvant therapy in TNBC treatment. PGG synergizes with DOX, which potentiates its anticancer effects while mitigating adverse reactions.

Novel Cyclic Peptide-Drug Conjugate P6-SN38 Toward Targeted Treatment of EGFR Overexpressed Non-Small Cell Lung Cancer

Background/Objectives: Here, we report on the synthesis and biological evaluation of a novel peptide-drug conjugate, P6-SN38, which consists of the EGFR-specific short cyclic peptide, P6, and the Topo I inhibitor SN38, which is a bioactive metabolite of the anticancer drug irinotecan. Methods: SN38 is attached to the peptide at position 20 of the E ring's tertiary hydroxyl group via a mono-succinate linker. Results: The developed peptide-drug conjugate (PDC) exhibited sub-micromolar anticancer activity on EGFR-positive (EGFR+) cell lines but no effect on EGFR-negative (EGFR-) cells. In vivo studies have shown that this PDC specifically accumulates in EGFR+ non-small cell lung cancer (NSCLC) xenografts and presents superior anticancer activity compared to the EGFR-specific antibody cetuximab (ErbituxTM) and free SN38. The 10 mg/kg dose of P6-SN38 in a side-by-side EGFR+/EGFR- xenograft shows eradication of the EGFR+ tumor with good tolerance, but no inhibition of tumor growth of the EGFR- counterpart. Conclusions: The PDC examined in this study was proven to be highly efficient for NSCLC, broadening its utilization for targeted cancer therapy in EGFR overexpressed cancers.

Emerging roles of long non-coding RNA FOXP4-AS1 in human cancers: From molecular biology to clinical application

Forkhead box P4 antisense RNA 1 (FOXP4-AS1) is a long non-coding RNA (lncRNA) situated on the human chromosome 6p21.1 locus. Previous research has demonstrated that FOXP4-AS1 is dysregulated in various cancers and exhibits a dual purpose as a tumor suppressor or oncogene in specific types of cancer. The levels of FOXP4-AS1 are significantly correlated with clinical features of cancer as well as prognosis. Additionally, FOXP4-AS1 is stimulated by transcription factors ATF3, YY1, PAX5, and SP4. The molecular mechanisms of FOXP4-AS1 in cancer are quite complex. It competitively sponges multiple miRNAs, bidirectionally regulates the levels of host gene FOXP4, activates the PI3K/AKT, Wnt/β-catenin, and ERK/MAPK signaling pathways, and recruits chromatin-modifying enzymes or interacts with other proteins to regulate malignant phenotypes of tumors, including proliferation, invasion, epithelial-mesenchymal transition (EMT), and angiogenesis. In this review, we provide an overview of the latest developments in FOXP4-AS1 oncology research, outlines its molecular regulatory networks in cancer, and discusses its prospective relevance as a cancer therapeutic target as well as a biomarker for prognosis and diagnosis.

Engineering peptide drug therapeutics through chemical conjugation and implication in clinics

The development of peptide drugs has made tremendous progress in the past few decades because of the advancements in modification chemistry and analytical technologies. The novel-designed peptide drugs have been modified through various biochemical methods with improved diagnostic, therapeutic, and drug-delivery strategies. Researchers found it a helping hand to overcome the inherent limitations of peptides and bring continued advancements in their applications. Furthermore, the emergence of peptide-drug conjugates (PDCs)-utilizes target-oriented peptide moieties as a vehicle for cytotoxic payloads via conjugation with cleavable chemical agents, resulting in the key foundation of the new era of targeted peptide drugs. This review summarizes the various classifications of peptide drugs, suitable chemical modification strategies to improve the ADME (adsorption, distribution, metabolism, and excretion) features of peptide drugs, and recent (2015-early 2024) progress/achievements in peptide-based drug delivery systems as well as their fruitful implication in preclinical and clinical studies. Furthermore, we also summarized the brief description of other types of PDCs, including peptide-MOF conjugates and peptide-UCNP conjugates. The principal aim is to provide scattered and diversified knowledge in one place and to help researchers understand the pinching knots in the science of PDC development and progress toward a bright future of novel peptide drugs.

Advancing Ovarian Cancer Therapeutics: The Role of Targeted Drug Delivery Systems

Ovarian cancer (OC) is the most lethal reproductive system cancer and a leading cause of cancer-related death. The high mortality rate and poor prognosis of OC are primarily due to its tendency for extensive abdominal metastasis, late diagnosis in advanced stages, an immunosuppressive tumor microenvironment, significant adverse reactions to first-line chemotherapy, and the development of chemoresistance. Current adjuvant chemotherapies face challenges such as poor targeting, low efficacy, and significant side effects. Targeted drug delivery systems (TDDSs) are designed to deliver drugs precisely to the tumor site to enhance efficacy and minimize side effects. This review highlights recent advancements in the use of TDDSs for OC therapies, including drug conjugate delivery systems, nanoparticle drug delivery systems, and hydrogel drug delivery systems. The focus is on employing TDDS to conduct direct, effective, and safer interventions in OC through methods such as targeted tumor recognition and controlled drug release, either independently or in combination. This review also discusses the prospects and challenges for further development of TDDSs. Undoubtedly, the use of TDDSs shows promise in the battle against OCs.

LAMTOR1 decreased exosomal PD-L1 to enhance immunotherapy efficacy in non-small cell lung cancer

Great progress has been made in utilizing immune checkpoint blockade (ICB) for the treatment of non-small-cell lung cancer (NSCLC). Therapies targeting programmed cell death protein 1 (PD-1) and its ligand PD-L1, expressed on tumor cells, have demonstrated potential in improving patient survival rates. An unresolved issue involves immune suppression induced by exosomal PD-L1 within the tumor microenvironment (TME), particularly regarding CD8+ T cells. Our study unveiled the crucial involvement of LAMTOR1 in suppressing the exosomes of PD-L1 and promoting CD8+ T cell infiltration in NSCLC. Through its interaction with HRS, LAMTOR1 facilitates PD-L1 lysosomal degradation, thereby reducing exosomal PD-L1 release. Notably, the ability of LAMTOR1 to promote PD-L1 lysosomal degradation relies on a specific ubiquitination site and an HRS binding sequence. The findings suggest that employing LAMTOR1 to construct peptides could serve as a promising strategy for bolstering the efficacy of immunotherapy in NSCLC. The discovery and comprehension of how LAMTOR1 inhibits the release of exosomal PD-L1 offer insights into potential therapeutic strategies for improving immunotherapy. It is imperative to conduct further research and clinical trials to investigate the feasibility and efficacy of targeting LAMTOR1 in NSCLC treatment.

Natural-source payloads used in the conjugated drugs architecture for cancer therapy: Recent advances and future directions

Drug conjugates are obtained from tumor-located vectors connected to cytotoxic agents via linkers, which are designed to deliver hyper-toxic payloads directly to targeted cancer cells. These drug conjugates include antibody-drug conjugates (ADCs), peptide-drug conjugates (PDCs), small molecule-drug conjugates (SMDCs), nucleic acid aptamer-drug conjugates (ApDCs), and virus-like drug conjugate (VDCs), which show great therapeutic value in the clinic. Drug conjugates consist of a targeting carrier, a linker, and a payload. Payloads are key therapy components. Cytotoxic molecules and their derivatives derived from natural products are commonly used in the payload portion of conjugates. The ideal payload should have sufficient toxicity, stability, coupling sites, and the ability to be released under specific conditions to kill tumor cells. Microtubule protein inhibitors, DNA damage agents, and RNA inhibitors are common cytotoxic molecules. Among these conjugates, cytotoxic molecules of natural origin are summarized based on their mechanism of action, conformational relationships, and the discovery of new derivatives. This paper also mentions some cytotoxic molecules that have the potential to be payloads. It also summarizes the latest technologies and novel conjugates developed in recent years to overcome the shortcomings of ADCs, PDCs, SMDCs, ApDCs, and VDCs. In addition, this paper summarizes the clinical trials conducted on conjugates of these cytotoxic molecules over the last five years. It provides a reference for designing and developing safer and more efficient conjugates.

Design and synthesis of TH19P01-Camptothecin based hybrid peptides inducing effective anticancer responses on sortilin positive cancer cells

Recently, the sortilin receptor (SORT1) was found to be preferentially over-expressed on the surface of many cancer cells, which makes SORT1 a novel anticancer target. The SORT1 binding proprietary peptide TH19P01 could achieve the SORT1-mediated cancer cell binding and subsequent internalization. Inspired by the peptide-drug conjugate (PDC) strategy, the TH19P01-camptothecin (CPT) conjugates were designed, efficiently synthesized, and evaluated for their anticancer potential in this study. The water solubility, in vitro anticancer activity, time-kill kinetics, cellular uptake, anti-migration activity, and hemolysis effects were systematically estimated. Besides, in order to monitor the release of CPT from conjugates in real-time, the CPT/Dnp-based "turn on" hybrid peptide was designed, which indicted that CPT could be sustainably released from the hybrid peptide in both human serum and cancer cellular environments. Strikingly, compared with free CPT, the water solubility, cellular uptake, and selectivity towards cancer cells of hybrid peptide LYJ-2 have all been significantly enhanced. Moreover, unlike free CPT or TH19P01, LYJ-2 exhibited selective anti-proliferative and anti-migration effects against SORT1-positive MDA-MB-231 cells. Collectively, this study not only established efficient strategies to improve the solubility and anticancer potential of chemotherapeutic agent CPT, but also provided important references for the future development of TH19P01 based PDCs targeting SORT1.

Strategies for Targeting Peptide-Modified Exosomes and Their Applications in the Lungs

Exosomes belong to a subgroup of extracellular vesicles secreted by various cells and are involved in intercellular communication and material transfer. In recent years, exosomes have been used as drug delivery carriers because of their natural origin, high stability, low immunogenicity and high engineering ability. However, achieving targeted drug delivery with exosomes remains challenging. In this paper, a phage display technology was used to screen targeted peptides, and different surface modification strategies of targeted peptide exosomes were reviewed. In addition, the application of peptide-targeted exosomes in pulmonary diseases was also summarised.

New Transferrin Receptor-Targeted Peptide-Doxorubicin Conjugates: Synthesis and In Vitro Antitumor Activity

Poor selectivity to tumor cells is a major drawback in the clinical application of the antitumor drug doxorubicin (DOX). Peptide-drug conjugates (PDCs) constructed by modifying antitumor drugs with peptide ligands that have high affinity to certain overexpressed receptors in tumor cells are increasingly assessed for their possibility of tumor-selective drug delivery. However, peptide ligands composed of natural L-configuration amino acids have the defects of easy enzymatic degradation and insufficient biological stability. In this study, two new PDCs (LT7-SS-DOX and DT7-SS-DOX) were designed and synthesized by conjugating a transferrin receptor (TfR) peptide ligand LT7 (HAIYPRH) and its retro-inverso analog DT7 (hrpyiah), respectively, with DOX via a disulfide bond linker. Both conjugates exhibited targeted antiproliferative effects on TfR overexpressed tumor cells and little toxicity to TfR low-expressed normal cells compared with free DOX. Moreover, the DT7-SS-DOX conjugate possessed higher serum stability, more sustained reduction-triggered drug release characteristics, and stronger in vitro antiproliferative activity as compared to LT7-SS-DOX. In conclusion, the coupling of antitumor drugs with the DT7 peptide ligand can be used as a promising strategy for the further development of stable and efficient PDCs with the potential to facilitate TfR-targeted drug delivery.

Peptide Therapeutics: Unveiling the Potential against Cancer-A Journey through 1989

The United States Food and Drug Administration (FDA) has approved a plethora of peptide-based drugs as effective drugs in cancer therapy. Peptides possess high specificity, permeability, target engagement, and a tolerable safety profile. They exhibit selective binding with cell surface receptors and proteins, functioning as agonists or antagonists. They also serve as imaging agents for diagnostic applications or can serve a dual-purpose as both diagnostic and therapeutic (theragnostic) agents. Therefore, they have been exploited in various forms, including linkers, peptide conjugates, and payloads. In this review, the FDA-approved prostate-specific membrane antigen (PSMA) peptide antagonists, peptide receptor radionuclide therapy (PRRT), somatostatin analogs, antibody-drug conjugates (ADCs), gonadotropin-releasing hormone (GnRH) analogs, and other peptide-based anticancer drugs are analyzed in terms of their chemical structures and properties, therapeutic targets and mechanisms of action, development journey, administration routes, and side effects.