Antibody-Drug Conjugates: The New Frontier of Chemotherapy

Synthesis of novel pyrrolobenzodiazepine (PBD) C1-substituted monomers and dimers with DNA-binding activity and cytotoxicity

The pyrrolobenzodiazepines (PBDs) represent a major class of sequence-selective DNA-alkylating molecules, one example of which, in its dimeric DNA-cross-linking form, is employed as the payload in the anticancer Antibody Drug Conjugate (ADC) loncastuximab tesirine-lpyl. To date, PBD analogues have been produced with substituents at every position of the tricyclic skeleton except the C1-position. We report here the first synthesis of a C1-subsitituted PBD monomer and dimer, both of which possess DNA-binding activity and cytotoxicity in a cancer cell line.

A Comprehensive Review About the Use of Monoclonal Antibodies in Cancer Therapy

Monoclonal antibodies (mAbs) targeting various pathways in cancer therapy play crucial roles in enhancing the immune system's ability to recognise and eliminate tumour cells. These therapies are designed to either block inhibitory immune checkpoint pathways or to target specific tumour cell markers for direct destruction. Additionally, mAbs can modulate the tumour microenvironment, enhance antibody-dependent cellular cytotoxicity, and inhibit angiogenesis, further amplifying their therapeutic impact. Below is a summary of monoclonal antibodies targeting key pathways, along with their indications and mechanisms of action, which are reviewed based on therapeutic mechanisms.

Progress in the discovery and development of anticancer agents from marine cyanobacteria

Covering 2010-April 2024There have been tremendous new discoveries and developments since 2010 in anticancer research based on marine cyanobacteria. Marine cyanobacteria are prolific sources of anticancer natural products, including the tubulin agents dolastatins 10 and 15 which were originally isolated from a mollusk that feeds on cyanobacteria. Decades of research have culminated in the approval of six antibody-drug conjugates (ADCs) and many ongoing clinical trials. Antibody conjugation has been enabling for several natural products, particularly cyanobacterial cytotoxins. Targeting tubulin dynamics has been a major strategy, leading to the discovery of the gatorbulin scaffold, acting on a new pharmacological site. Cyanobacterial compounds with different mechanisms of action (MOA), targeting novel or validated targets in a range of organelles, also show promise as anticancer agents. Important advances include the development of compounds with novel MOA, including apratoxin and coibamide A analogues, modulating cotranslational translocation at the level of Sec61 in the endoplasmic reticulum, largazole and santacruzamate A targeting class I histone deacetylases, and proteasome inhibitors based on carmaphycins, resembling the approved drug carfilzomib. The pipeline extends with SERCA inhibitors, mitochondrial cytotoxins and membrane-targeting agents, which have not yet advanced clinically since the biology is less understood and selectivity concerns remain to be addressed. In addition, efforts have also focused on the identification of chemosensitizing and antimetastatic agents. The review covers the state of current knowledge of marine cyanobacteria as anticancer agents with a focus on the mechanism, target identification and potential for drug development. We highlight the importance of solving the supply problem through chemical synthesis as well as illuminating the biological activity and in-depth mechanistic studies to increase the value of cyanobacterial natural products to catalyze their development.

Clinical significance of the tumor microenvironment on immune tolerance in gastric cancer

In the realm of oncology, the tumor microenvironment (TME)-comprising extracellular matrix components, immune cells, fibroblasts, and endothelial cells-plays a pivotal role in tumorigenesis, progression, and response to therapeutic interventions. Initially, the TME exhibits tumor-suppressive properties that can inhibit malignant transformation. However, as the tumor progresses, various factors induce immune tolerance, resulting in TME behaving in a state that promotes tumor growth and metastasis in later stages. This state of immunosuppression is crucial as it enables TME to change from a role of killing tumor cells to a role of promoting tumor progression. Gastric cancer is a common malignant tumor of the gastrointestinal tract with an alarmingly high mortality rate. While chemotherapy has historically been the cornerstone of treatment, its efficacy in prolonging survival remains limited. The emergence of immunotherapy has opened new therapeutic pathways, yet the challenge of immune tolerance driven by the gastric cancer microenvironment complicates these efforts. This review aims to elucidate the intricate role of the TME in mediating immune tolerance in gastric cancer and to spotlight innovative strategies and clinical trials designed to enhance the efficacy of immunotherapeutic approaches. By providing a comprehensive theoretical framework, this review seeks to advance the understanding and application of immunotherapy in the treatment of gastric cancer, ultimately contributing to improved patient outcomes.

Drug-Linker Constructs Bearing Unique Dual-Mechanism Tubulin Binding Payloads Tethered through Cleavable and Non-Cleavable Linkers

Antibody-drug conjugates (ADCs) have advanced as a mainstay among the most promising cancer therapeutics, offering enhanced antigen targeting and encompassing wide diversity in their linker and payload components. Small-molecule inhibitors of tubulin polymerization have found success as payloads in FDA approved ADCs and represent further promise in next-generation, pre-clinical and developmental ADCs. Unique dual-mechanism payloads (previously designed and synthesized in our laboratories) function as both potent antiproliferative agents and promising vascular disrupting agents capable of imparting selective and effective damage to tumor-associated microvessels. These payloads have been incorporated into a variety of drug-linker constructs utilizing the clinically relevant cathepsin B cleavable Val-Cit dipeptide linker, employed within several FDA approved ADCs, along with other non-cleavable constructs. Various synthetic strategies were evaluated to prepare these drug-linker constructs. Aniline-based payloads were incorporated utilizing the Val-Cit dipeptide linker similar to FDA approved ADCs such as Adcetris® (brentuximab vedotin). An additional self-immolative group, previously described in the literature for related model systems, was employed to tether the phenolic payloads. A variety of drug-linker constructs (with each bearing a unique dual mechanism payload) were synthesized and evaluated biologically for their enzyme-mediated release of payload and inhibition of tubulin polymerization. Following deactivation of the highly electrophilic maleimido terminus as its corresponding N-acetyl cysteine (NAC) derivative, the most promising construct (NAC-4) demonstrated approximately 90% release of an aniline-functionalized payload (1) upon treatment with cathepsins B or L over 90 minutes. Building on these promising results, future studies will examine the conjugation of drug-linker construct 4 to selected antibodies and engineered proteins and evaluate the biological activity of the resultant antibody-drug conjugates (ADCs).

Ligand-binding assays validated for quantitative bioanalysis of a novel antibody-drug conjugate in monkey serum and related application in a nonclinical study

BACKGROUND

Antibody-drug conjugates (ADCs) are an emerging class of targeted therapeutics and are receiving growing attention in the pharmaceutical field. Here we aimed to validate two ligand binding assays for the quantitation of GQ1001, an ADC made of Trastuzumab site-specifically conjugated with DM1, in cynomolgus monkey serum, and then apply the validated assays to a nonclinical study.

METHODS

The quantitative methods for conjugated GQ1001 and total GQ1001 were validated against regulatory guidance documents on bioanalytical method validation under a Good Laboratory Practice (GLP)-compliant environment. The validated assays were applied to a single-dose pharmacokinetic (PK) study of GQ1001 conducted in cynomolgus monkeys.

RESULTS

Both intra- and inter-assay precision and accuracy met the priori-defined acceptance criteria. Neither matrix effect nor hemolysis effect were observed, and the impact of specific interferents on the assays was evaluated. Dilution linearity was good with the expected dilution factors and no hook effect till up to 20.2 mg/mL of GQ1001 was noted. Besides, the stability of the ADC in monkey serum was found to be sufficient to cover the time required for sample storage and analysis. Furthermore, the assays demonstrated good parallelism determined with a study sample and good reproducibility acquired by incurred sample reanalysis (ISR). Using the validated assays, we obtained serum concentrations for the conjugated GQ1001 and the total GQ1001 in the single-dose PK study, and thereafter, evaluated their exposures over the dosing period.

CONCLUSIONS

All tested performance parameters of the assays met the validation acceptance criteria, which supported the application of the two assays in the nonclinical PK study and allowed the evaluation of the related PK parameters for GQ1001.

Unlocking Natural Potential: Antibody-Drug Conjugates With Naturally Derived Payloads for Cancer Therapy

Natural compound-derived chemotherapies remain central to cancer treatment, however, they often cause off-target side effects that negatively impact patients' quality of life. In contrast, antibody-drug conjugates (ADCs) combine cytotoxic payloads with antibodies to specifically target cancer cells. Most approved and clinically investigated ADCs utilize naturally derived payloads, while those with conventional synthetic molecular payloads remain limited. This review focuses on approved ADCs that enhance the efficacy of naturally derived payloads by linking them with antibodies. We provide an overview of the core components of ADCs, their working mechanisms, and FDA-approved ADCs featuring naturally derived payloads, such as calicheamicin, camptothecin, dolastatin 10, maytansine, pyrrolbenzodiazepine (PBD), and the immunotoxin Pseudomonas exotoxin A. This review also explores recent clinical advancements aimed at broadening the therapeutic potential of ADCs, their applicability in treating heterogeneously composed tumors and their potential use beyond oncology. Additionally, this review highlights naturally derived payloads that are currently being clinically investigated but have not yet received approval. By summarizing the current landscape, this review provides insights into promising avenues for exploration and contributes to the refinement of treatment protocols for improved patient outcomes.

Maytansinoids in cancer therapy: advancements in antibody-drug conjugates and nanotechnology-enhanced drug delivery systems

Cancer remains the second leading cause of death globally, driving the need for innovative therapies. Among natural compounds, maytansinoids have shown significant promise, contributing to nearly 25% of recently approved anticancer drugs. Despite their potential, early clinical trials faced challenges due to severe side effects, prompting advancements in delivery systems such as antibody-maytansinoid conjugates (AMCs). This review highlights the anticancer activity of maytansinoids, with a focus on AMCs designed to target cancer cells specifically. Preclinical and clinical studies show that AMCs, including FDA-approved drugs like Kadcyla and Elahere, effectively inhibit tumor growth while reducing systemic toxicity. Key developments include improved synthesis methods, linker chemistry and payload design. Ongoing research aims to enhance the safety and efficacy of AMCs, integrate nanotechnology for drug delivery, and identify novel therapeutic targets. These advancements hold potential to transform maytansinoid-based cancer treatments in the future.

Nanoparticle innovations in targeted cancer therapy: advancements in antibody-drug conjugates

Antibody-drug conjugates (ADCs) have emerged as a promising strategy in targeted cancer therapy, enabling the precise delivery of cytotoxic agents to tumor sites while minimizing systemic toxicity. However, traditional ADCs face significant limitations, including restricted drug loading capacity, where an optimal drug-to-antibody ratio (DAR) is crucial; low DARs may lead to insufficient potency, while high DARs can cause rapid clearance and increased toxicity. Additionally, ADCs often suffer from instability in circulation due to the potential for premature release of cytotoxic agents, resulting in off-target effects and reduced therapeutic efficacy. Furthermore, their large size can impede adequate penetration into solid tumors, particularly in heterogeneous environments with varying antigen expressions. This review explores the innovative use of nanoparticles as carriers for ADCs, which offers a multifaceted approach to enhance therapeutic efficacy. By leveraging the unique properties of nanoparticles, such as their small size and ability to exploit the enhanced permeability and retention (EPR) effect, researchers can improve drug stability, prolong circulation time, and achieve more effective tumor targeting. Recent studies demonstrate that nanoparticle-encapsulated ADCs can significantly enhance treatment outcomes while reducing off-target effects, as evidenced by improved targeting capabilities and reduced toxicity in preclinical models. Despite the promising advancements, challenges remain, including potential nanoparticle toxicity and manufacturing complexities. This review aims to provide a comprehensive overview of the current research on nanoparticle-encapsulated ADCs. It highlights their potential to transform cancer treatment and offers insights into future directions for optimizing these advanced therapeutic strategies.

Pursuing theranostics: a multimodal architecture approach

Theranostics is a field of nuclear medicine which uses the same targeting vector and chelating system for both a diagnostic and therapeutic radionuclide, allowing for uniformity in imaging and treatment. This growing field requires the development of more flexible chelate systems that permit novel targeting strategies. Toward this end, a multimodal architecture has been realized, making use of a phosphazene-based core and click chemistry to achieve a flexible and customizable scaffold. The six arm phosphazene-based core can scaffold six DTPA chelating motifs or a mixed set of 3 : 3 DTPA : DFO chelates resulting in two multimodal compounds, pDbDt and pDbDtDf, respectively. Terbium complexes displayed strong luminescence, supporting that the structures act as an organic antenna for luminescence. Metal displacement titration studies confirmed the desired structures as well as the capability for heterometallic labeling of the structures. These structures were found to have high thermal and biological stability in vitro. Radiolabeling of each compound resulted in high molar activity labeling of each compound: 169 MBq nmol-1: [161Tb]Tb-pDbDt, 170 MBq nmol-1: [89Zr]Zr-pDbDtDf, and the mixed radiolabeling illustrated chelation of both radionuclides in a 1 : 1 ratio. This multimodal architecture is promising as a heterometallic structure for coupling of both a diagnostic and a therapeutic radionuclide with a highly customizable core structure.

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.

Molecular Matchmakers: Bioconjugation Techniques Enhance Prodrug Potency for Immunotherapy

Cancer patients suffer greatly from the severe off-target side effects of small molecule drugs, chemotherapy, and radiotherapy─therapies that offer little protection following remission. Engineered immunotherapies─including cytokines, immune checkpoint blockade, monoclonal antibodies, and CAR-T cells─provide better targeting and future tumor growth prevention. Still, issues such as ineffective activation, immunogenicity, and off-target effects remain primary concerns. "Prodrug" therapies─classified as therapies administered as inactive and then selectively activated to control the time and area of release─hold significant promise in overcoming these concerns. Bioconjugation techniques (e.g., natural linker conjugation, bioorthogonal reactions, and noncanonical amino acid incorporation) enable the rapid and homogeneous synthesis of prodrugs and offer selective loading of immunotherapeutic agents to carrier molecules and protecting groups to prevent off-target effects after administration. Several prodrug activation mechanisms have been highlighted for cancer therapeutics, including endogenous activation by hypoxic or acidic conditions common in tumors, exogenous activation by targeted bioorthogonal cleavage, or stimuli-responsive light activation, and dual-stimuli activation, which adds specificity by combining these mechanisms. This review will explore modern prodrug conjugation and activation options, focusing on how these strategies can enhance immunotherapy responses and improve patient outcomes. We will also discuss the implications of computational methodology for therapy design and recommend procedures to determine how and where to conjugate carrier systems and "prodrug" groups onto therapeutic agents to enhance the safety and control of these delivery platforms.

A novel life for antitumor combretastatins: Recent developments of hybrids, prodrugs, combination therapies, and antibody-drug conjugates

Since their discovery from natural sources, the potent cytotoxic effects of combretastatins were widely studied for the application in antitumor therapy. However, major pharmacokinetic issues as low water solubility and chemical instability of the double bond configuration prevented their use in therapy. A lot of efforts have been directed towards the search of novel strategies, allowing a safer use of combretastatins as anticancer agents. This review analyses the recent landscape in combretastatin research, characterized by the identification of hybrids, prodrugs, and novel combination treatments. Interestingly, the potent cytotoxic agent combretastatin A4 (CA4) was recently proposed as payload in the construction of novel antibody-drug conjugates (ADCs), allowing an efficient targeting of the cytotoxic agent to specific tumors.

Discovery of a highly specific radiolabeled antibody targeting B-cell maturation antigen: Applications in PET imaging of multiple myeloma

PURPOSE

Multiple myeloma (MM) is characterized by the uncontrolled proliferation of monoclonal plasma cells (PC) in the bone marrow (BM). B-cell maturation antigen (BCMA) is predominantly expressed in malignant plasma cells, and associated with the proliferation, survival, and progression of various myeloma cells. Given these important roles, BCMA emerges as an ideal target antigen for MM therapy. However, effective stratification of patients who may benefit from targeted BCMA therapy and real-time monitoring the therapeutic efficacy poses significant clinical challenge. This study aims to develop a BCMA targeted diagnostic modality, and preliminarily explore its potential value in the radio-immunotherapy of MM.

EXPERIMENTAL DESIGN

Using zirconium-89 (89Zr, t1/2 = 78.4 h) for labeling the BCMA-specific antibody, the BCMA-targeting PET tracer [89Zr]Zr-DFO-BCMAh230430 was prepared. The EC50 values of BCMAh230430 and DFO-BCMAh230430 were determined by ELISA assay. BCMA expression was assessed in four different tumor cell lines (MM.1S, RPMI 8226, BxPC-3, and KYSE520) through Western blot and flow cytometry. In vitro binding affinity was determined by cell uptake studies of [89Zr]Zr-DFO-BCMAh230430 in these tumor cell lines. For in vivo evaluation, PET imaging and ex vivo biodistribution studies were conducted in tumor-bearing mice to evaluate imaging performance and systemic distribution of [89Zr]Zr-DFO-BCMAh230430. Immunochemistry analysis was performed to detect BCMA expression in tumor tissues, confirming the specificity of our probe. Furthermore, we explored the anti-tumor efficacy of Lutetium-177 labeled BCMA antibody, [177Lu]Lu-DTPA-BCMAh230430, in tumor bearing-mice to validate its radioimmunotherapy potential.

RESULTS

The radiolabeling of [89Zr]Zr-DFO-BCMAh230430 and [177Lu]Lu-DTPA-BCMAh230430 showed satisfactory radiocharacteristics, with a radiochemical purity exceeding 99%. ELISA assay results revealed closely aligned EC50 values for BCMAh230430 and DFO-BCMAh230430, which are 57 pM and 67 pM, respectively. Western blot and flow cytometry analyses confirmed the highest BCMA expression level. Cell uptake data indicated that MM.1S cells had a total cellular uptake (the sum of internalization and surface binding) of 38.3% ± 1.53% for [89Zr]Zr-DFO-BCMAh230430 at 12 h. PET imaging of [89Zr]Zr-DFO-BCMAh230430 displayed radioactive uptake of 7.71 ± 0.67%ID/g in MM.1S tumors and 4.13 ± 1.21%ID/g in KYSE520 tumors at 168 h post-injection (n = 4) (P < 0.05), consistent with ex vivo biodistribution studies. Immunohistochemical analysis of tumor tissues confirmed higher BCMA expression in MM.1S tumors xenograft compared to KYSE520 tumors. Notably, [177Lu]Lu-DTPA-BCMAh230430 showed some anti-tumor efficacy, evidenced by slowed tumor growth. Furthermore, no significant difference in body weight was observed in MM.1S tumor-bearing mice over 14 days of administration with or without [177Lu]Lu-DTPA-BCMAh230430.

CONCLUSIONS

Our study has successfully validated the essential role of [89Zr]Zr-DFO-BCMAh230430 in non-invasively monitoring BCMA status in MM tumors, showing favorable tumor uptake and specific binding affinity to MM tumors. Furthermore, our research revealed, as a proof-of-concept, the effectiveness of [177Lu]Lu-DTPA-BCMAh230430 in radioimmunotherapy for MM tumors. In conclusion, we present a novel BCMA antibody-based radiotheranostic modality that holds promise for achieving efficient and precise MM diagnostic and therapy.

The journey of antibody-drug conjugates for revolutionizing cancer therapy: A review

Antibody-drug conjugates (ADCs) represent a powerful class of targeted cancer therapies that harness the specificity of monoclonal antibodies to deliver cytotoxic payloads directly to tumor cells, minimizing off-target effects. This review explores the advancements in ADC technologies, focusing on advancing next-generation ADCs with novel payloads, conjugation strategies, and enhanced pharmacokinetic profiles. In particular, we highlight innovative payloads, including microtubule inhibitors, spliceosome modulators, and RNA polymerase inhibitors, that offer new mechanisms of cytotoxicity beyond traditional apoptosis induction. Additionally, the introduction of sophisticated conjugation techniques, such as site-specific conjugation using engineered cysteines, enzymatic methods, and integration of non-natural amino acids, has greatly improved the homogeneity, efficacy, and safety of ADCs. Furthermore, the review delves into the mechanistic insights into ADC action, detailing the intracellular pathways that facilitate drug release and cell death, and discussing the significance of bioconjugation methods in optimizing drug-antibody ratios (DARs). The establishment of comprehensive databases like ADCdb, which catalog vital pharmacological and biological data for ADCs, is also explored as a critical resource for advancing ADC research and clinical application. Finally, the clinical landscape of ADCs is examined, with a focus on the evolution of FDA-approved ADCs, such as Gemtuzumab Ozogamicin and Trastuzumab Emtansine, as well as emerging candidates in ongoing trials. As ADCs continue to evolve, their potential to revolutionize cancer therapy remains immense, offering new hope for more effective and personalized treatment options. ADCs also offer a significant advancement in targeted cancer therapy by merging the specificity of monoclonal antibodies with cytotoxic potency of chemotherapeutic agents. Hence, this dual mechanism intensifies tumor selectivity while minimizing systemic toxicity, paving the way for more effective and safer cancer treatments.

Immunoconjugates as an Efficient Platform for Drug Delivery: A Resurgence of Natural Products in Targeted Antitumor Therapy

The present review provides a detailed and comprehensive discussion on antibody-drug conjugates (ADCs) as an evolving new modality in the current therapeutic landscape of malignant diseases. The principle concepts of targeted delivery of highly toxic agents forsaken as stand-alone drugs are examined in detail, along with the biochemical and technological tools for their successful implementation. An extensive analysis of ADCs' major components is conducted in parallel with their function and impact on the stability, efficacy, safety, and resistance profiles of the immunoconjugates. The scope of the article covers the major classes of currently validated natural compounds used as payloads, with an emphasis on their structural and mechanistic features, natural origin, and distribution. Future perspectives in ADCs' design are thoroughly explored, addressing their inherent or emerging challenges and limitations. The survey also provides a comprehensive overview of the molecular rationale for active tumor targeting of ADC-based platforms, exploring the cellular biology and clinical relevance of validated tumor markers used as a "homing" mechanism in both hematological and solid tumor malignancies.

Ocular adverse events associated with antibody-drug conjugates for cancer: evidence and management strategies

Antibody-drug conjugates (ADCs) are a fast-growing class of cancer drugs designed to selectively deliver cytotoxic payloads through antibody binding to cancer cells with high expression of the target antigen, thus reducing systemic exposure and minimizing off-target effects. However, ADCs are associated with various ocular adverse events (AEs) that may impact treatment administration and patient outcomes. In this review, we provide a summary of ocular AEs associated with approved and investigational ADCs, recommendations for the mitigation and management of ocular AEs, current guidelines and expert opinions, and recommendations for clinical practice. A literature search was performed, using PubMed and Google Scholar, for English-language articles published between January 1985 and January 2023 to identify studies reporting ocular AEs associated with ADC use. Search terms included generic and investigational names of all identified ADCs, and further searches were performed to identify strategies for managing ADC-associated ocular AEs. ADC-associated ocular AEs include symptoms such as blurred vision and foreign-body sensation and signs such as corneal fluorescein staining, corneal pseudomicrocysts, and conjunctivitis. Reported management strategies include ADC dose modification (eg, dose delay or reduction), cool compresses, artificial tears, topical vasoconstrictors, and topical steroids. Although ADC dose modification appears to be beneficial, the preventive and/or therapeutic benefits of the remaining interventions are unclear. Although the exact mechanisms are not fully understood, most ADC-associated ocular AEs are reversible with dose delay or dose reduction. Management of ocular AEs requires a multidisciplinary approach to minimize treatment discontinuation and optimize clinical outcomes.

Antibody drug conjugates in the clinic

Antibody-drug conjugates (ADCs), chemotherapeutic agents conjugated to an antibody to enhance their targeted delivery to tumors, represent a significant advancement in cancer therapy. ADCs combine the precise targeting capabilities of antibodies and the potent cell-killing effects of chemotherapy, allowing for enhanced cytotoxicity to tumors while minimizing damage to healthy tissues. Here, we provide an overview of the current clinical landscape of ADCs, highlighting 11 U.S. Food and Drug Administration (FDA)-approved products and discussing over 500 active clinical trials investigating newer ADCs. We also discuss some key challenges associated with the clinical translation of ADCs and highlight emerging strategies to overcome these hurdles. Our discussions will provide useful guidelines for the future development of safer and more effective ADCs for a broader range of indications.

Understanding the chemistry & pharmacology of antibody-drug conjugates in triple-negative breast cancer with special reference to exatecan derivatives

In the spectrum of breast malignancies, triple-negative breast cancer is the most widely spreading subtype of breast cancer due to a low availability of therapeutic remedies. Recently, antibody-drug conjugates dramatically resolved the landscape for the treatment of triple-negative breast cancer. This review mainly focuses on the chemistry, structure, mechanism of action, and role of antibody-drug conjugates in triple-negative breast cancer. Datopotecan Deruxtecan (Dato-DXd) is a new-generation ADC showing encouraging results for TNBC. In this review, we have also emphasized TROP-2-directed Datopotamab deruxtecan ADCs to treat triple-negative breast cancer, its synthesis, mechanism of action, pharmacokinetics, pharmacodynamics, adverse events, and their ongoing clinical trials.

Monoclonal antibodies: From magic bullet to precision weapon

Monoclonal antibodies (mAbs) are used to prevent, detect, and treat a broad spectrum of non-communicable and communicable diseases. Over the past few years, the market for mAbs has grown exponentially with an expected compound annual growth rate (CAGR) of 11.07% from 2024 (237.64 billion USD estimated at the end of 2023) to 2033 (679.03 billion USD expected by the end of 2033). Ever since the advent of hybridoma technology introduced in 1975, antibody-based therapeutics were realized using murine antibodies which further progressed into humanized and fully human antibodies, reducing the risk of immunogenicity. Some benefits of using mAbs over conventional drugs include a drastic reduction in the chances of adverse reactions, interactions between drugs, and targeting specific proteins. While antibodies are very efficient, their higher production costs impede the process of commercialization. However, their cost factor has been improved by developing biosimilar antibodies as affordable versions of therapeutic antibodies. Along with the recent advancements and innovations in antibody engineering have helped and will furtherly help to design bio-better antibodies with improved efficacy than the conventional ones. These novel mAb-based therapeutics are set to revolutionize existing drug therapies targeting a wide spectrum of diseases, thereby meeting several unmet medical needs. This review provides comprehensive insights into the current fundamental landscape of mAbs development and applications and the key factors influencing the future projections, advancement, and incorporation of such promising immunotherapeutic candidates as a confrontation approach against a wide list of diseases, with a rationalistic mentioning of any limitations facing this field.

Assessment of mirvetuximab soravtansine immunogenicity in patients with folate receptor alpha-positive ovarian cancer

Aim: The aim of this research was to evaluate the immunogenicity of mirvetuximab soravtansine (MIRV), an antibody-drug conjugate in patients with folate receptor alpha-positive ovarian cancer across four clinical studies.Materials & methods: An assay was developed and validated for the detection of antidrug antibodies (ADAs) against MIRV. A cell-based method was also developed and validated for the detection of neutralizing anti-MIRV antibodies (NAbs). Both ADAs and NAbs were assessed across four clinical studies in 734 patients.Results: Across studies, MIRV demonstrated low immunogenicity with 7.8% of patients with treatment-emergent ADAs, 7.2% with treatment-unaffected ADAs, and 0.5% with treatment-enhanced ADAs. MIRV trough concentrations were comparable in ADA-negative and ADA-positive individuals. Limited data suggest that MIRV ADAs may be associated with decreased efficacy. Due to the very limited number of NAb-positive individuals, no conclusions could be drawn on the effect of NAb on efficacy.Conclusion: Both the validation tests and the data from the MIRV clinical studies demonstrated that these assays were suitable and reliable for the detection of MIRV ADAs and NAbs. These validated assays will continue to be used to monitor MIRV immunogenicity in future clinical trials.

Antibody-drug conjugates for targeted cancer therapy: Recent advances in potential payloads

Antibody-drug conjugates (ADCs) represent a promising cancer therapy modality which specifically delivers highly toxic payloads to cancer cells through antigen-specific monoclonal antibodies (mAbs). To date, 15 ADCs have been approved and more than 100 ADC candidates have advanced to clinical trials for the treatment of various cancers. Among these ADCs, microtubule-targeting and DNA-damaging agents are at the forefront of payload development. However, several challenges including toxicity and drug resistance limit the potential of this modality. To tackle these issues, multiple innovative payloads such as immunomodulators and proteolysis targeting chimeras (PROTACs) are incorporated into ADCs to enable multimodal cancer therapy. In this review, we describe the mechanism of ADCs, highlight the importance of ADC payloads and summarize recent progresses of conventional and unconventional ADC payloads, trying to provide an insight into payload diversification as a key step in future ADC development.

Expanding the repertoire of Antibody Drug Conjugate (ADC) targets with improved tumor selectivity and range of potent payloads through in-silico analysis

Antibody-Drug Conjugates (ADCs) have emerged as a promising class of targeted cancer therapeutics. Further refinements are essential to unlock their full potential, which is currently limited by a lack of validated targets and payloads. Essential aspects of developing effective ADCs involve the identification of surface antigens, ideally distinguishing target tumor cells from healthy types, uniformly expressed, accompanied by a high potency payload capable of selective targeting. In this study, we integrated transcriptomics, proteomics, immunohistochemistry and cell surface membrane datasets from Human Protein Atlas, Xenabrowser and Gene Expression Omnibus utilizing Lantern Pharma's proprietary AI platform Response Algorithm for Drug positioning and Rescue (RADR®). We used this in combination with evidence based filtering to identify ADC targets with improved tumor selectivity. Our analysis identified a set of 82 targets and a total of 290 target indication combinations for effective tumor targeting. We evaluated the impact of tumor mutations on target expression levels by querying 416 genes in the TCGA mutation database against 22 tumor subtypes. Additionally, we assembled a catalog of compounds to identify potential payloads using the NCI-Developmental Therapeutics Program. Our payload mining strategy classified 729 compounds into three subclasses based on GI50 values spanning from pM to 10 nM range, in combination with sensitivity patterns across 9 different cancer indications. Our results identified a diverse range of both targets and payloads, that can serve to facilitate multiple choices for precise ADC targeting. We propose an initial approach to identify suitable target-indication-payload combinations, serving as a valuable starting point for development of future ADC candidates.

B7 homolog 3 in pancreatic cancer

Despite advances in cancer treatment, pancreatic cancer (PC) remains a disease with high mortality rates and poor survival outcomes. The B7 homolog 3 (B7-H3) checkpoint molecule is overexpressed among many malignant tumors, including PC, with low or absent expression in healthy tissues. By modulating various immunological and nonimmunological molecular mechanisms, B7-H3 may influence the progression of PC. However, the impact of B7-H3 on the survival of patients with PC remains a subject of debate. Still, most available scientific data recognize this molecule as a suppressive factor to antitumor immunity in PC. Furthermore, it has been demonstrated that B7-H3 stimulates the migration, invasion, and metastasis of PC cells, and enhances resistance to chemotherapy. In preclinical models of PC, B7-H3-targeting monoclonal antibodies have exerted profound antitumor effects by increasing natural killer cell-mediated antibody-dependent cellular cytotoxicity and delivering radioisotopes and cytotoxic drugs to the tumor site. Finally, PC treatment with B7-H3-targeting antibody-drug conjugates and chimeric antigen receptor T cells is being tested in clinical studies. This review provides a comprehensive analysis of all PC-related studies in the context of B7-H3 and points to deficiencies in the current data that should be overcome by future research.

Novel therapeutic agents in clinical trials: emerging approaches in cancer therapy

Novel therapeutic agents in clinical trials offer a paradigm shift in the approach to battling this prevalent and destructive disease, and the area of cancer therapy is on the precipice of a trans formative revolution. Despite the importance of tried-and-true cancer treatments like surgery, radiation, and chemotherapy, the disease continues to evolve and adapt, making new, more potent methods necessary. The field of cancer therapy is currently witnessing the emergence of a wide range of innovative approaches. Immunotherapy, including checkpoint inhibitors, CAR-T cell treatment, and cancer vaccines, utilizes the host's immune system to selectively target and eradicate malignant cells while minimizing harm to normal tissue. The development of targeted medicines like kinase inhibitors and monoclonal antibodies has allowed for more targeted and less harmful approaches to treating cancer. With the help of genomics and molecular profiling, "precision medicine" customizes therapies to each patient's unique genetic makeup to maximize therapeutic efficacy while minimizing unwanted side effects. Epigenetic therapies, metabolic interventions, radio-pharmaceuticals, and an increasing emphasis on combination therapy with synergistic effects further broaden the therapeutic landscape. Multiple-stage clinical trials are essential for determining the safety and efficacy of these novel drugs, allowing patients to gain access to novel treatments while also furthering scientific understanding. The future of cancer therapy is rife with promise, as the integration of artificial intelligence and big data has the potential to revolutionize early detection and prevention. Collaboration among researchers, and healthcare providers, and the active involvement of patients remain the bedrock of the ongoing battle against cancer. In conclusion, the dynamic and evolving landscape of cancer therapy provides hope for improved treatment outcomes, emphasizing a patient-centered, data-driven, and ethically grounded approach as we collectively strive towards a cancer-free world.

Cancer immunotherapy and its facilitation by nanomedicine

Cancer immunotherapy has sparked a wave of cancer research, driven by recent successful proof-of-concept clinical trials. However, barriers are emerging during its rapid development, including broad adverse effects, a lack of reliable biomarkers, tumor relapses, and drug resistance. Integration of nanomedicine may ameliorate current cancer immunotherapy. Ultra-large surface-to-volume ratio, extremely small size, and easy modification surface of nanoparticles enable them to selectively detect cells and kill cancer cells in vivo. Exciting synergistic applications of the two approaches have emerged in treating various cancers at the intersection of cancer immunotherapy and cancer nanomedicine, indicating the potential that the combination of these two therapeutic modalities can lead to new paradigms in the treatment of cancer. This review discusses the status of current immunotherapy and explores the possible opportunities that the nanomedicine platform can make cancer immunotherapy more powerful and precise by synergizing the two approaches.

Single-Domain Antibodies as Antibody-Drug Conjugates: From Promise to Practice-A Systematic Review

BACKGROUND

Antibody-drug conjugates (ADCs) represent potent cancer therapies that deliver highly toxic drugs to tumor cells precisely, thus allowing for targeted treatment and significantly reducing off-target effects. Despite their effectiveness, ADCs can face limitations due to acquired resistance and potential side effects.

OBJECTIVES

This study focuses on advances in various ADC components to improve both the efficacy and safety of these agents, and includes the analysis of several novel ADC formats. This work assesses whether the unique features of VHHs-such as their small size, enhanced tissue penetration, stability, and cost-effectiveness-make them a viable alternative to conventional antibodies for ADCs and reviews their current status in ADC development.

METHODS

Following PRISMA guidelines, this study focused on VHHs as components of ADCs, examining advancements and prospects from 1 January 2014 to 30 June 2024. Searches were conducted in PubMed, Cochrane Library, ScienceDirect and LILACS using specific terms related to ADCs and single-domain antibodies. Retrieved articles were rigorously evaluated, excluding duplicates and non-qualifying studies. The selected peer-reviewed articles were analyzed for quality and synthesized to highlight advancements, methods, payloads, and future directions in ADC research.

RESULTS

VHHs offer significant advantages for drug conjugation over conventional antibodies due to their smaller size and structure, which enhance tissue penetration and enable access to previously inaccessible epitopes. Their superior stability, solubility, and manufacturability facilitate cost-effective production and expand the range of targetable antigens. Additionally, some VHHs can naturally cross the blood-brain barrier or be easily modified to favor their penetration, making them promising for targeting brain tumors and metastases. Although no VHH-drug conjugates (nADC or nanoADC) are currently in the clinical arena, preclinical studies have explored various conjugation methods and linkers.

CONCLUSIONS

While ADCs are transforming cancer treatment, their unique mechanisms and associated toxicities challenge traditional views on bioavailability and vary with different tumor types. Severe toxicities, often linked to compound instability, off-target effects, and nonspecific blood cell interactions, highlight the need for better understanding. Conversely, the rapid distribution, tumor penetration, and clearance of VHHs could be advantageous, potentially reducing toxicity by minimizing prolonged exposure. These attributes make single-domain antibodies strong candidates for the next generation of ADCs, potentially enhancing both efficacy and safety.

Kinetic models towards an enhanced understanding of diverse ADC conjugation reactions

The conjugation reaction is the central step in the manufacturing process of antibody-drug conjugates (ADCs). This reaction generates a heterogeneous and complex mixture of differently conjugated sub-species depending on the chosen conjugation chemistry. The parametrization of the conjugation reaction through mechanistic kinetic models offers a chance to enhance valuable reaction knowledge and ensure process robustness. This study introduces a versatile modeling framework for the conjugation reaction of cysteine-conjugated ADC modalities-site-specific and interchain disulfide conjugation. Various conjugation kinetics involving different maleimide-functionalized payloads were performed, while controlled gradual payload feeding was employed to decelerate the conjugation, facilitating a more detailed investigation of the reaction mechanism. The kinetic data were analyzed with a reducing reversed phase (RP) chromatography method, that can readily be implemented for the accurate characterization of ADCs with diverse drug-to-antibody ratios, providing the conjugation trajectories of the single chains of the monoclonal antibody (mAb). Possible kinetic models for the conjugation mechanism were then developed and selected based on multiple criteria. When calibrating the established model to kinetics involving different payloads, conjugation rates were determined to be payload-specific. Further conclusions regarding the kinetic comparability across the two modalities could also be derived. One calibrated model was used for an exemplary in silico screening of the initial concentrations offering valuable insights for profound understanding of the conjugation process in ADC development.

Antibody-Drug Conjugates in Urothelial Cancer: From Scientific Rationale to Clinical Development

Antibody-drug conjugates (ADCs) have been a significant advancement in cancer therapy, particularly for urothelial cancer (UC). These innovative treatments, originally developed for hematological malignancies, use target-specific monoclonal antibodies linked to potent cytotoxic agents. This rational drug design efficiently delivers cancer cell-killing agents to cells expressing specific surface proteins, which are abundant in UC owing to their high antigen expression. UC is an ideal candidate for ADC therapy, as it enhances on-target efficacy while mitigating systemic toxicity. In recent years, considerable progress has been made in understanding the biology and mechanisms of tumor progression in UC. However, despite the introduction of immune checkpoint inhibitors, advanced UC is characterized by rapid progression and poor survival rates. Targeted therapies that have been developed include the anti-nectin 4 ADC enfortumab vedotin and the fibroblast growth factor receptor inhibitor erdafitinib. Enfortumab vedotin has shown efficacy in prospective studies in patients with advanced UC, alone and in combination with pembrolizumab. The anti-Trop-2 ADC sacituzumab govitecan has also demonstrated effectiveness in single-armed studies. This review highlights the mechanism of action of ADCs, their application in mono- and combination therapies, primary mechanisms of resistance, and future perspectives for their clinical use in UC treatment. ADCs have proven to be an increasingly vital component of the therapeutic landscape for urothelial carcinoma, filling a gap in the treatment of this progressive disease.

Antibody-Drug Conjugates-Evolution and Perspectives

Antineoplastic therapy is one of the main research themes of this century. Modern approaches have been implemented to target and heighten the effect of cytostatic drugs on tumors and diminish their general/unspecific toxicity. In this context, antibody-drug conjugates (ADCs) represent a promising and successful strategy. The aim of this review was to assess different aspects regarding ADCs. They were presented from a chemical and a pharmacological perspective and aspects like structure, conjugation and development particularities alongside effects, clinical trials, safety issues and perspectives and challenges for future use of these drugs were discussed. Representative examples include but are not limited to the following main structural components of ADCs: monoclonal antibodies (trastuzumab, brentuximab), linkers (pH-sensitive, reduction-sensitive, peptide-based, phosphate-based, and others), and payloads (doxorubicin, emtansine, ravtansine, calicheamicin). Regarding pharmacotherapy success, the high effectiveness expectation associated with ADC treatment is supported by the large number of ongoing clinical trials. Major aspects such as development strategies are first discussed, advantages and disadvantages, safety and efficacy, offering a retrospective insight on the subject. The second part of the review is prospective, focusing on various plans to overcome the previously identified difficulties.

Precision Medicine in Rheumatic Diseases: Unlocking the Potential of Antibody-Drug Conjugates

In the era of precision medicine, antibody-drug conjugates (ADCs) have emerged as a cutting-edge therapeutic strategy. These innovative compounds combine the precision of monoclonal antibodies with the potent cell-killing or immune-modulating abilities of attached drug payloads. This unique strategy not only reduces off-target toxicity but also enhances the therapeutic effectiveness of drugs. Beyond their well established role in oncology, ADCs are now showing promising potential in addressing the unmet needs in the therapeutics of rheumatic diseases. Rheumatic diseases, a diverse group of chronic autoimmune diseases with varying etiologies, clinical presentations, and prognoses, often demand prolonged pharmacological interventions, creating a pressing need for novel, efficient, and low-risk treatment options. ADCs, with their ability to precisely target the immune components, have emerged as a novel therapeutic strategy in this context. This review will provide an overview of the core components and mechanisms behind ADCs, a summary of the latest clinical trials of ADCs for the treatment of rheumatic diseases, and a discussion of the challenges and future prospects faced by the development of next-generation ADCs. SIGNIFICANCE STATEMENT: There is a lack of efficient and low-risk targeted therapeutics for rheumatic diseases. Antibody-drug conjugates, a class of cutting-edge therapeutic drugs, have emerged as a promising targeted therapeutic strategy for rheumatic disease. Although there is limited literature summarizing the progress of antibody-drug conjugates in the field of rheumatic disease, updating the advancements in this area provides novel insights into the development of novel antirheumatic drugs.

Transforming toxins into treatments: the revolutionary role of α-amanitin in cancer therapy

Amanita phalloides is the primary species responsible for fatal mushroom poisoning, as its main toxin, α-amanitin, irreversibly and potently inhibits eukaryotic RNA polymerase II (RNAP II), leading to cell death. There is no specific antidote for α-amanitin, which hinders its clinical application. However, with the advancement of precision medicine in oncology, including the development of antibody-drug conjugates (ADCs), the potential value of various toxic small molecules has been explored. These ADCs ingeniously combine the targeting precision of antibodies with the cytotoxicity of small-molecule payloads to precisely kill tumor cells. We searched PubMed for studies in this area using these MeSH terms "Amanitins, Alpha-Amanitin, Therapeutic use, Immunotherapy, Immunoconjugates, Antibodies" and did not limit the time interval. Recent studies have conducted preclinical experiments on ADCs based on α-amanitin, showing promising therapeutic effects and good tolerance in primates. The current challenges include the not fully understood toxicological mechanism of α-amanitin and the lack of clinical studies to evaluate the therapeutic efficacy of ADCs developed based on α-amanitin. In this article, we will discuss the role and therapeutic efficacy of α-amanitin as an effective payload in ADCs for the treatment of various cancers, providing background information for the research and application strategies of current and future drugs.

An Antibody-Drug Conjugate for Multiple Myeloma Prepared by Multi-Arm Linkers

First-line treatment of multiple myeloma, a prevalent blood cancer lacking a cure, using anti-CD38 daratumumab antibody and lenalidomide is often inadequate due to relapse and severe side effects. To enhance drug safety and efficacy, an antibody-drug conjugate, TE-1146, comprising six lenalidomide drug molecules site-specifically conjugated to a reconfigured daratumumab to deliver cytotoxic lenalidomide to tumor cells is developed. TE-1146 is prepared using the HighDAR platform, which employs i) a maleimide-containing "multi-arm linker" to conjugate multiple drug molecules creating a drug bundle, and ii) a designed peptide with a Zn2+-binding cysteine at the C-termini of a reconfigured daratumumab for site-specific drug bundle conjugation. It is shown that TE-1146 remains intact and effectively enters CD38-expressing tumor cells, releasing lenalidomide, leading to enhanced cell-killing effects compared to lenalidomide/daratumumab alone or their combination. This reveals the remarkable potency of lenalidomide once internalized by myeloma cells. TE-1146 precisely delivers lenalidomide to target CD38-overexpressing tumor cells. In contrast, lenalidomide without daratumumab cannot easily enter cells, whereas daratumumab without lenalidomide relies on Fc-dependent effector functions to kill tumor cells.

Development and validation of bioanalytical methods to support clinical study of disitamab vedotin

Disitamab vedotin (RC48), a humanized anti-HER2 antibody conjugated with monomethyl auristatin E (MMAE), is the first antibody-drug conjugate in China with an approved biological license application. A bioanalytical method was established for three analytes (total antibody, conjugate antibody and free payload) to help characterize their pharmacokinetic behavior in clinical settings. The bioanalytical methods were validated according to M10 guidance. Electrochemiluminescence assay methods were used for the quantitative measurement of total antibody and conjugated antibody in human serum. A LC-MS/MS method was used to quantify the concentration of MMAE in human serum. The method had high specificity and sensitivity with a quantitative range of 19.531-1250.000 ng/ml (total antibody), 39.063-5000.000 ng/ml (conjugated antibody) and 0.04-10.0 ng/ml (MMAE), respectively.

Recent Technological and Intellectual Property Trends in Antibody-Drug Conjugate Research

Antibody-drug conjugate (ADC) therapy, an advanced therapeutic technology comprising antibodies, chemical linkers, and cytotoxic payloads, addresses the limitations of traditional chemotherapy. This study explores key elements of ADC therapy, focusing on antibody development, linker design, and cytotoxic payload delivery. The global rise in cancer incidence has driven increased investment in anticancer agents, resulting in significant growth in the ADC therapy market. Over the past two decades, notable progress has been made, with approvals for 14 ADC treatments targeting various cancers by 2022. Diverse ADC therapies for hematologic malignancies and solid tumors have emerged, with numerous candidates currently undergoing clinical trials. Recent years have seen a noteworthy increase in ADC therapy clinical trials, marked by the initiation of numerous new therapies in 2022. Research and development, coupled with patent applications, have intensified, notably from major companies like Pfizer Inc. (New York, NY, USA), AbbVie Pharmaceuticals Inc. (USA), Regeneron Pharmaceuticals Inc. (Tarrytown, NY, USA), and Seagen Inc. (Bothell, WA, USA). While ADC therapy holds great promise in anticancer treatment, challenges persist, including premature payload release and immune-related side effects. Ongoing research and innovation are crucial for advancing ADC therapy. Future developments may include novel conjugation methods, stable linker designs, efficient payload delivery technologies, and integration with nanotechnology, driving the evolution of ADC therapy in anticancer treatment.

An Anti-CD7 Antibody-Drug Conjugate Target Showing Potent Antitumor Activity for T-Lymphoblastic Leukemia (T-ALL)

Acute T-lymphoblastic leukemia (T-ALL) is a type of leukemia that can occur in both pediatric and adult populations. Compared to acute B-cell lymphoblastic leukemia (B-ALL), patients with T-cell T-ALL have a poorer therapeutic efficacy. In this study, a novel anti-CD7 antibody-drug conjugate (ADC, J87-Dxd) was successfully generated and used for T-ALL treatment. Firstly, to obtain anti-CD7 mAbs, we expressed and purified the CD7 protein extracellular domain. Utilizing hybridoma technology, we obtained three anti-CD7 mAbs (J87, G73 and A15) with a high affinity for CD7. Both the results of immunofluorescence and Biacore assay indicated that J87 (KD = 1.54 × 10-10 M) had the highest affinity among the three anti-CD7 mAbs. In addition, an internalization assay showed the internalization level of J87 to be higher than that of the other two mAbs. Next, we successfully generated the anti-CD7 ADC (J87-Dxd) by conjugating DXd to J87 via a cleavable maleimide-GGFG peptide linker. J87-Dxd also possessed the ability to recognize and bind CD7. Using J87-Dxd to treat T-ALL cells (Jurkat and CCRF-CEM), we observed that J87-Dxd bound to CD7 was internalized into T-ALL cells. Moreover, J87-Dxd treatment significantly induced the apoptosis of Jurkat and CCRF-CEM cells. The IC50 (half-maximal inhibitory concentration) value of J87-Dxd against CCRF-CEM obtained by CCK-8 assay was 6.3 nM. Finally, to assess the antitumor efficacy of a J87-Dxd in vivo, we established T-ALL mouse models and treated mice with J87-Dxd or J87. The results showed that on day 24 after tumor inoculation, all mice treated with J87 or PBS died, whereas the survival rate of mice treated with J87-Dxd was 80%. H&E staining showed no significant organic changes in the heart, liver, spleen, lungs and kidneys of all mice. In summary, we demonstrated that the novel anti-CD7 ADC (J87-Dxd) had a potent and selective effect against CD7-expressing T-All cells both in vitro and in vivo, and could thus be expected to be further developed as a new drug for the treatment of T-ALL or other CD7-expression tumors.

Antibody-drug conjugates in cancer therapy: innovations, challenges, and future directions

The emergence of antibody-drug conjugates (ADCs) as a potential therapeutic avenue in cancer treatment has garnered significant attention. By combining the selective specificity of monoclonal antibodies with the cytotoxicity of drug molecules, ADCs aim to increase the therapeutic index, selectively targeting cancer cells while minimizing systemic toxicity. Various ADCs have been licensed for clinical usage, with ongoing research paving the way for additional options. However, the manufacture of ADCs faces several challenges. These include identifying suitable target antigens, enhancing antibodies, linkers, and payloads, and managing resistance mechanisms and side effects. This review focuses on the strategies to overcome these hurdles, such as site-specific conjugation techniques, novel antibody formats, and combination therapy. Our focus lies on current advancements in antibody engineering, linker technology, and cytotoxic payloads while addressing the challenges associated with ADC development. Furthermore, we explore the future potential of personalized medicine, leveraging individual patients' molecular profiles, to propel ADC treatments forward. As our understanding of the molecular mechanisms driving cancer progression continues to expand, we anticipate the development of new ADCs that offer more effective and personalized therapeutic options for cancer patients.

Metabolite characterisation of the peptide-drug conjugate LN005 in liver S9s by UHPLC-Orbitrap-HRMS

LN005 is a peptide-drug conjugate (PDC) targeting glucose-regulated protein 78 (GRP78) to treat several types of cancer, such as breast, colon, and prostate cancer.As a new drug modality, understanding its metabolism and elimination pathways will help us to have a whole picture of it. Currently, there are no metabolic studies on LN005; therefore, this study aimed to investigate the metabolism of LN005, clarify its metabolic profile in the liver S9s of different species, and identify the major metabolic pathways and differences between species.The incubation samples were measured by ultra-high performance liquid chromatography combined with orbitrap tandem mass spectrometry (UHPLC-Orbitrap-HRMS).The results showed that LN005 was metabolised by liver S9s, and four metabolites were identified. The main metabolic pathway of LN005 in liver S9s was oxidative deamination to ketone or hydrolysis. Similar metabolic profiles were observed in mouse, rat, dog, monkey, and human liver S9s, indicating no differences between these four animal species and humans.This study provides information for the structural modification and optimisation of LN005 and affords a reference for subsequent animal experiments and human metabolism of other PDCs.

A narrative review of antibody-drug conjugates in EGFR-mutated non-small cell lung cancer

In the past 15 years, non-small cell lung cancer (NSCLC) treatment has changed with the discovery of mutations and the development of new targeted therapies and immune checkpoint inhibitors. Epidermal growth factor receptor (EGFR) was the first mutation in NSCLC to have a drug that was FDA-approved in 2013. Osimertinib, a third-generation tyrosine kinase inhibitor, is approved as first-line therapy for advanced NSCLC and in the adjuvant setting for Stage IB-IIIA resected NSCLC. However, resistance to osimertinib is inevitably an issue, and thus patterns of resistance to EGFR-mutated NSCLC have been studied, including MET amplification, EGFR C797X-acquired mutation, human epidermal growth factor 2 (HER2) amplification, and transformation to small cell and squamous cell lung cancer. Current management for EGFR-mutated NSCLC upon progression of EGFR TKI is limited at this time to chemotherapy and radiation therapy, sometimes in combination with the continuation of osimertinib. Antibody-drug conjugates (ADCs) are made up of a monoclonal antibody linked to a cytotoxic drug and are an increasingly popular class of drug being studied in NSCLC. Trastuzumab deruxtecan has received accelerated FDA approval in HER2-mutated NSCLC. ADCs offer a possible solution to finding a new treatment that could bypass the intracellular resistance mechanism. In this review article, we summarize the mechanism of ADCs and investigational ADCs for EGFR-mutated NSCLC, which include targets to MET amplification, HER3, Trop2, and EGFR, along with other ADC targets being investigated in NSCLC, and discuss future directions that may arise with ADCs in EGFR-mutated NSCLC.

Research progress on the immune microenvironment and immunotherapy in gastric cancer

The tumor microenvironment, particularly the immune microenvironment, plays an indispensable role in the malignant progression and metastasis of gastric cancer (GC). As our understanding of the GC microenvironment continues to evolve, we are gaining deeper insights into the biological mechanisms at the single-cell level. This, in turn, has offered fresh perspectives on GC therapy. Encouragingly, there are various monotherapy and combination therapies in use, such as immune checkpoint inhibitors, adoptive cell transfer therapy, chimeric antigen receptor T cell therapy, antibody-drug conjugates, and cancer vaccines. In this paper, we review the current research progress regarding the GC microenvironment and summarize promising immunotherapy research and targeted therapies.

Current Knowledge about the Peritumoral Microenvironment in Glioblastoma

Glioblastoma is a deadly disease, with a mean overall survival of less than 2 years from diagnosis. Recurrence after gross total surgical resection and adjuvant chemo-radiotherapy almost invariably occurs within the so-called peritumoral brain zone (PBZ). The aim of this narrative review is to summarize the most relevant findings about the biological characteristics of the PBZ currently available in the medical literature. The PBZ presents several peculiar biological characteristics. The cellular landscape of this area is different from that of healthy brain tissue and is characterized by a mixture of cell types, including tumor cells (seen in about 30% of cases), angiogenesis-related endothelial cells, reactive astrocytes, glioma-associated microglia/macrophages (GAMs) with anti-inflammatory polarization, tumor-infiltrating lymphocytes (TILs) with an "exhausted" phenotype, and glioma-associated stromal cells (GASCs). From a genomic and transcriptomic point of view, compared with the tumor core and healthy brain tissue, the PBZ presents a "half-way" pattern with upregulation of genes related to angiogenesis, the extracellular matrix, and cellular senescence and with stemness features and downregulation in tumor suppressor genes. This review illustrates that the PBZ is a transition zone with a pre-malignant microenvironment that constitutes the base for GBM progression/recurrence. Understanding of the PBZ could be relevant to developing more effective treatments to prevent GBM development and recurrence.

DG-Affinity: predicting antigen-antibody affinity with language models from sequences

BACKGROUND

Antibody-mediated immune responses play a crucial role in the immune defense of human body. The evolution of bioengineering has led the progress of antibody-derived drugs, showing promising efficacy in cancer and autoimmune disease therapy. A critical step of this development process is obtaining the affinity between antibodies and their binding antigens.

RESULTS

In this study, we introduce a novel sequence-based antigen-antibody affinity prediction method, named DG-Affinity. DG-Affinity uses deep neural networks to efficiently and accurately predict the affinity between antibodies and antigens from sequences, without the need for structural information. The sequences of both the antigen and the antibody are first transformed into embedding vectors by two pre-trained language models, then these embeddings are concatenated into an ConvNeXt framework with a regression task. The results demonstrate the superiority of DG-Affinity over the existing structure-based prediction methods and the sequence-based tools, achieving a Pearson's correlation of over 0.65 on an independent test dataset.

CONCLUSIONS

Compared to the baseline methods, DG-Affinity achieves the best performance and can advance the development of antibody design. It is freely available as an easy-to-use web server at https://www.digitalgeneai.tech/solution/affinity .

Targeted Nanofitin-drug Conjugates Achieve Efficient Tumor Delivery and Therapeutic Effect in an EGFRpos Mouse Xenograft Model

Adjusting the molecular size, the valency and the pharmacokinetics of drug conjugates are as many leverages to improve their therapeutic window, notably by affecting tumor penetration, renal clearance, and short systemic exposure. In that regard, small tumor-targeting ligands are gaining attention. In this study, we demonstrate the benefits of the small Nanofitin alternative scaffolds (7 kDa) as selective tumor-targeting modules for the generation of drug conjugates, focusing on Nanofitins B10 and D8 directed against the EGFR. Owing to their small size and monovalent format, the two Nanofitins displayed a fast and deep tumor penetration in EGFR-positive A431 xenografts in BALB/c nude mice after intravenous administration, yielding to a targeting of respectively 67.9% ± 14.1 and 98.9% ± 0.7 of the tumor cells as demonstrated by IHC. Conjugation with the monomethyl auristatin E toxin provided homogeneous Nanofitin-drug conjugates, with an overall yield of ≥97%, for in vivo assessment in a curative xenograft model using bioluminescent, EGFR-positive, A431 cells in BALB/c nude mice. Internalization was found critical for efficient release of the toxin. Hence, the intravenous administration of the D8-based construct showed significant antitumor effect in vivo as determined by monitoring tumor volumes and bioluminescence levels over 2 months.

HPLC-DAD validated method for DM4 and its metabolite S-Me-DM4 quantification in biological matrix for clinical and pharmaceutical applications

The present study focuses on the development and validation of an HPLC-DAD methodology for the detection of a potent chemotherapeutic agent, Maytansinoid Ravtansine (DM4), and its metabolite, S-methyl-DM4 (S-Me-DM4), in plasma samples. Methodologically, after a simple protein precipitation with acetonitrile and after drying 1 mL of supernatant, the sample (suspended with N,N-Dimethylacetamide, DMA) was directly analyzed by HPLC under isocratic elution using a mobile phase comprising milliQ water and methanol (25:75, v:v), both acidified with 0.1 % v:v formic acid. Employing a flow rate of 1.0 mL/min and a reversed-phase GraceSmart RP18 column thermostated at 40 °C, we achieved complete resolution and separation of DM4 and S-Me-DM4 within 13 min. The optimized injection volume of 20 μL and the wavelength set at 254 nm were utilized for quantitative analyses. Rigorous validation has not only ensured its reliability and reproducibility but has also addressed potential limitations associated with methodological inconsistency. The limit of detection and quantification of the method were 0.025 and 0.06 μg/mL for both the analytes, respectively. The calibration curve showed a good linearity in the range 0.06-20 μg/mL. For both analytes, the intraday precision and trueness were 2.3-8.2 % and -1.1 to 3.1 %, respectively, while the interday values were 0.7-10.1 % and -10.4 to 7.5 %, respectively. The developed methodology enables the concurrent determination and quantification of free DM4 and its metabolite, free S-Me-DM4, making it a valuable tool for assessing the pharmacokinetics and pharmacodynamics of DM4-based therapies. In addition, the procedure was successfully applied to analyse the presence of free DM4 or its metabolite, free S-Me-DM4, in human plasma samples spiked with the 1959-sss/DM4 antibody-drug conjugate (ADC). The utilization of the herein validated methodology allowed to confirm the presence of these analytes, thereby providing insights into their potential release from the ADC structure.

Antibody-drug conjugates: Recent advances in payloads

Antibody‒drug conjugates (ADCs), which combine the advantages of monoclonal antibodies with precise targeting and payloads with efficient killing, show great clinical therapeutic value. The ADCs' payloads play a key role in determining the efficacy of ADC drugs and thus have attracted great attention in the field. An ideal ADC payload should possess sufficient toxicity, low immunogenicity, high stability, and modifiable functional groups. Common ADC payloads include tubulin inhibitors and DNA damaging agents, with tubulin inhibitors accounting for more than half of the ADC drugs in clinical development. However, due to clinical limitations of traditional ADC payloads, such as inadequate efficacy and the development of acquired drug resistance, novel highly efficient payloads with diverse targets and reduced side effects are being developed. This perspective summarizes the recent research advances of traditional and novel ADC payloads with main focuses on the structure-activity relationship studies, co-crystal structures, and designing strategies, and further discusses the future research directions of ADC payloads. This review also aims to provide valuable references and future directions for the development of novel ADC payloads that will have high efficacy, low toxicity, adequate stability, and abilities to overcome drug resistance.

Molecular Biology Mechanisms and Emerging Therapeutics of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that is conventionally characterized by the absence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2), accounting for approximately 15-20% of all breast cancers. Compared to other molecular phenotypes, TNBC is typically associated with high malignancy and poor prognosis. Cytotoxic agents have been the mainstay of treatment for the past few decades due to the lack of definitive targets and limited therapeutic interventions. However, recent developments have demonstrated that TNBC has peculiar molecular classifications and biomarkers, which provide the possibility of evolving treatment from basic cytotoxic chemotherapy to an expanding domain of targeted therapies. This review presents a framework for understanding the current clinical experience surrounding molecular biology mechanisms in TNBC (Figure 1). Including immunotherapy, polymerase (PARP) and PI3K/AKT pathway inhibitors, antibody-drug conjugates, and androgen receptor (AR) blockade. Additionally, the role of miRNA therapeutics targeting TNBC and potential strategies targeting cancer stem cells (CSCs) are discussed and highlighted. As more and more treatments arise on the horizon, we believe that patients with TNBC will have a new sense of hope.

A comprehensive overview on antibody-drug conjugates: from the conceptualization to cancer therapy

Antibody-Drug Conjugates (ADCs) represent an innovative class of potent anti-cancer compounds that are widely used in the treatment of hematologic malignancies and solid tumors. Unlike conventional chemotherapeutic drug-based therapies, that are mainly associated with modest specificity and therapeutic benefit, the three key components that form an ADC (a monoclonal antibody bound to a cytotoxic drug via a chemical linker moiety) achieve remarkable improvement in terms of targeted killing of cancer cells and, while sparing healthy tissues, a reduction in systemic side effects caused by off-tumor toxicity. Based on their beneficial mechanism of action, 15 ADCs have been approved to date by the market approval by the Food and Drug Administration (FDA), the European Medicines Agency (EMA) and/or other international governmental agencies for use in clinical oncology, and hundreds are undergoing evaluation in the preclinical and clinical phases. Here, our aim is to provide a comprehensive overview of the key features revolving around ADC therapeutic strategy including their structural and targeting properties, mechanism of action, the role of the tumor microenvironment and review the approved ADCs in clinical oncology, providing discussion regarding their toxicity profile, clinical manifestations and use in novel combination therapies. Finally, we briefly review ADCs in other pathological contexts and provide key information regarding ADC manufacturing and analytical characterization.

Targeted drug conjugate systems for ovarian cancer chemotherapy

Ovarian cancer is a highly lethal disease that affects women. Early diagnosis and treatment of women with early-stage disease improve the probability of survival. Unfortunately, the majority of women with ovarian cancer are diagnosed at advanced stages 3 and 4 which makes treatment challenging. While the majority of the patients respond to first-line treatment, i.e. cytoreductive surgery integrated with platinum-based chemotherapy, the rate of disease recurrence is very high and the available treatment options for recurrent disease are not curative. Thus, there is a need for more effective treatment options for ovarian cancer. Targeted drug conjugate systems have emerged as a promising therapeutic strategy for the treatment of ovarian cancer. These systems provide the opportunity to selectively deliver highly potent chemotherapeutic drugs to ovarian cancer, sparing healthy normal cells. Thus, the effectiveness of the drugs is improved and systemic toxicity is greatly reduced. In this review, different targeted drug conjugate systems that have been or are being developed for the treatment of ovarian cancer will be discussed.

Recognizing CRISPR as the new age disease-modifying drug: Strategies to bioengineer CRISPR/Cas for direct in vivo delivery

Clustered regularly interspaced short palindromic repeats (CRISPR) have established itself as a frontier technology in genetic engineering. Researchers have successfully used the CRISPR/Cas system as precise gene editing tools and have further expanded their scope beyond both imaging and diagnostic applications. The most prominent utility of CRISPR is its capacity for gene therapy, serving as the contemporary, disease-modifying drug at the genetic level of human medical disorders. Correcting these diseases using CRISPR-based gene editing has developed to the extent of preclinical trials and possible patient treatments. A major impediment in actualizing this is the complications associated with in vivo delivery of the CRISPR/Cas complex. Currently, only the viral vectors (e.g., lentivirus) and non-viral encapsulation (e.g., lipid particles, polymer-based, and gold nanoparticles) techniques have been extensively reviewed, neglecting the efficiency of direct delivery. However, the direct delivery of CRISPR/Cas for in vivo gene editing therapies is an intricate process with numerous drawbacks. Hence, this paper discusses in detail both the need and the strategies that can potentially improve the direct delivery aspects of CRISPR/Cas biomolecules for gene therapy of human diseases. Here, we focus on enhancing the molecular and functional features of the CRISPR/Cas system for targeted in vivo delivery such as on-site localization, internalization, reduced immunogenicity, and better in vivo stability. We additionally emphasize the CRISPR/Cas complex as a multifaceted, biomolecular vehicle for co-delivery with therapeutic agents in targeted disease treatments. The delivery formats of efficient CRISPR/Cas systems for human gene editing are also briefly elaborated.