An Insight into FDA Approved Antibody-Drug Conjugates for Cancer Therapy

Combination non-targeted and sGRP78-targeted nanoparticle drug delivery outperforms either component to treat metastatic ovarian cancer

Metastatic ovarian cancer (MOC) is highly deadly, due in part to the limited efficacy of standard-of-care chemotherapies to metastatic tumors and non-adherent cancer cells. Here, we demonstrated the effectiveness of a combination therapy of GRP78-targeted (TNPGRP78pep) and non-targeted (NP) nanoparticles to deliver a novel DM1-prodrug to MOC in a syngeneic mouse model. Cell surface-GRP78 is overexpressed in MOC, making GRP78 an optimal target for selective delivery of nanoparticles to MOC. The NP + TNPGRP78pep combination treatment reduced tumor burden by 15-fold, compared to untreated control. Increased T cell and macrophage levels in treated groups also suggested antitumor immune system involvement. The NP and TNPGRP78pep components functioned synergistically through two proposed mechanisms of action. The TNPGRP78pep targeted non-adherent cancer cells in the peritoneal cavity, preventing the formation of new solid tumors, while the NP passively targeted existing solid tumor sites, providing a sustained release of the drug to the tumor microenvironment.

Acid-sensitive prodrugs; a promising approach for site-specific and targeted drug release

Drugs administered through conventional formulations are devoid of targeting and often spread to various undesired sites, leading to sub-lethal concentrations at the site of action and the emergence of undesired effects. Hence, therapeutic agents should be delivered in a controlled manner at target sites. Currently, stimuli-based drug delivery systems have demonstrated a remarkable potential for the site-specific delivery of therapeutic moieties. pH is one of the widely exploited stimuli for drug delivery as several pathogenic conditions such as tumor cells, infectious and inflammatory sites are characterized by a low pH environment. This review article aims to demonstrate various strategies employed in the design of acid-sensitive prodrugs, providing an overview of commercially available acid-sensitive prodrugs. Furthermore, we have compiled the progress made for the development of new acid-sensitive prodrugs currently undergoing clinical trials. These prodrugs include albumin-binding prodrugs (Aldoxorubicin and DK049), polymeric micelle (NC-6300), polymer conjugates (ProLindac™), and an immunoconjugate (IMMU-110). The article encompasses a broad spectrum of studies focused on the development of acid-sensitive prodrugs for anticancer, antibacterial, and anti-inflammatory agents. Finally, the challenges associated with the acid-sensitive prodrug strategy are discussed, along with future directions.

Economics of Antibody Drug Conjugates (ADCs): Innovation, Investment and Market Dynamics

PURPOSE OF REVIEW

This review aims to explore the intricate interplay between scientific advancements and economic considerations in the development, production, and commercialization of Antibody Drug Conjugates (ADCs). The focus is on understanding the challenges and opportunities at this unique intersection, highlighting how scientific innovation and economic dynamics mutually influence the trajectory of ADCs in the pharmaceutical landscape.

RECENT FINDINGS

There has been a significant increase in interest and investment in the development of ADCs. Initially focused on hematological malignancies, ADCs are now being researched for use in treating solid tumors as well. Pharmaceutical companies are heavily investing to broaden the range of indications for which ADCs can be effective. According to a report from the end of 2023, the global ADCs market grew from USD 1.4 billion in 2016 to USD 11.3 billion in 2023, with projections estimating a value of USD 23.9 billion by 2032, growing at a CAGR of 10.7%. ADCs represent a promising class of biopharmaceuticals in oncology, with expanding applications beyond hematological malignancies to solid tumors. The significant growth in the ADC market underscores the impact of scientific and economic factors on their development. This review provides valuable insights into how these factors drive innovation and commercialization, shaping the future of ADCs in cancer treatment.

Facile Rebridging Conjugation Approach to Attain Monoclonal Antibody-Targeted Nanoparticles with Enhanced Antigen Binding and Payload Delivery

Adopting conventional conjugation approaches to construct antibody-targeted nanoparticles (NPs) has demonstrated suboptimal control over the binding orientation and the structural stability of monoclonal antibodies (mAbs). Hitherto, the developed antibody-targeted NPs have shown proof of concept but lack product homogeneity, batch-to-batch reproducibility, and stability, precluding their advancement toward the clinic. To circumvent these limitations and advance toward clinical application, herein, a refined approach based on site-specific construction of mAb-immobilized NPs will be appraised. Initially, the conjugation of atezolizumab (anti-PDL1 antibody, Amab) with polymeric NPs was developed using bis-haloacetamide (BisHalide) rebridging chemistry, followed by click chemistry (NP-Fab BisHalide Ab and NP-Fc BisHalide Ab). For comparison purposes, mAb-immobilized NPs developed utilizing conventional conjugation methods, namely, N-hydroxysuccinimide (NHS) coupling and maleimide chemistry (NP-NHS Ab and NP-Mal Ab), were included. Next, flow cytometry and confocal microscopy experiments evaluated the actively targeted NPs (loaded with fluorescent dye) for cellular binding and uptake. Our results demonstrated the superior and selective binding and uptake of NP-Fab BisHalide Ab and NP-Fc BisHalide Ab into EMT6 cells by 19-fold and 13-fold, respectively. To evaluate the PDL1-dependent cell uptake and the selectivity of the treatments, a blocking step of the PDL1 receptor with Amab was performed prior to incubation with NP-Fab BisHalide Ab and NP-Fc BisHalide Ab. To our delight, the binding and uptake of fluorescent NPs were reduced significantly by 3-fold for NP-Fab BisHalide Ab, demonstrating the PDL1-mediated uptake. Moreover, NP-Fab BisHalide Ab and NP-Fc BisHalide Ab were entrapped with the paclitaxel payload, and their cytotoxicity was evaluated. They showed significant enhancements compared to free paclitaxel and NP-NHS Ab. Overall, this work will provide a facile conjugation method that could be implemented to actively target NPs with a plethora of therapeutic mAbs approved for various malignancies.

Heat shock proteins as hallmarks of cancer: insights from molecular mechanisms to therapeutic strategies

Heat shock proteins are essential molecular chaperones that play crucial roles in stabilizing protein structures, facilitating the repair or degradation of damaged proteins, and maintaining proteostasis and cellular functions. Extensive research has demonstrated that heat shock proteins are highly expressed in cancers and closely associated with tumorigenesis and progression. The "Hallmarks of Cancer" are the core features of cancer biology that collectively define a series of functional characteristics acquired by cells as they transition from a normal state to a state of tumor growth, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabled replicative immortality, the induction of angiogenesis, and the activation of invasion and metastasis. The pivotal roles of heat shock proteins in modulating the hallmarks of cancer through the activation or inhibition of various signaling pathways has been well documented. Therefore, this review provides an overview of the roles of heat shock proteins in vital biological processes from the perspective of the hallmarks of cancer and summarizes the small-molecule inhibitors that target heat shock proteins to regulate various cancer hallmarks. Moreover, we further discuss combination therapy strategies involving heat shock proteins and promising dual-target inhibitors to highlight the potential of targeting heat shock proteins for cancer treatment. In summary, this review highlights how targeting heat shock proteins could regulate the hallmarks of cancer, which will provide valuable information to better elucidate and understand the roles of heat shock proteins in oncology and the mechanisms of cancer occurrence and development and aid in the development of more efficacious and less toxic novel anticancer agents.

Revolutionizing triple-negative metastatic breast cancer treatment: sacituzumab Govitecan's role in advancing chemotherapy

Purpose

This review aims to discuss the role and efficacy of Sacituzumab Govitecan in the management of breast cancer.

Summary

Breast cancer is the most prevalent type of cancer among women worldwide. This comprehensive review delves into the advancements brought about by Sacituzumab Govitecan in the treatment of metastatic triple-negative breast cancer (TNBC). With a focus on its mode of action, efficacious role, clinical trials, and comparative advantages over conventional chemotherapy, the review highlights the therapy's precision in targeting cancer cells through monoclonal antibodies. Sacituzumab Govitecan's ability to deliver a chemotherapeutic payload specifically to cancer cells with the Trop-2 receptor sets it apart from traditional chemotherapy, minimizing collateral damage and reducing severe side effects. The impact of Sacituzumab Govitecan on improving progression-free survival, tumor response rates, and, significantly, the quality of life for patients is discussed. This article also sheds light on ongoing trials, FDA recognition, and the therapy's potential to transform breast cancer treatment.

Conclusion

In conclusion, Sacituzumab Govitecan shows potential as an innovative therapeutic option for breast cancer, particularly in metastatic breast cancer and triple-negative breast cancer, but it warrants additional research.

Use of a Cyclic α-Alkylidene-β-Diketone as a Cleavable Linker Strategy for Antibody-Drug Conjugates

In the fast-evolving landscape of targeted cancer therapies, the revolutionary class of biotherapeutics known as antibody-drug conjugates (ADCs) are taking center stage. Most clinically approved ADCs utilize cleavable linkers to temporarily attach potent cytotoxic payloads to antibodies, allowing selective payload release under tumor-specific conditions. In this study, we explored the utilization of 1-(4,4-dimethyl-2,6-dioxocyclohexylidene)ethyl (Dde), a cyclic β-diketone featuring an active alkylidene group, to develop a novel chemically labile linker. This linker was designed to exploit the difference in reduction potential between the intracellular compartment and plasma. Upon reduction of an azido trigger strategically installed neighboring the cyclic β-diketone, the resulting nucleophilic primary amine reacts with the alkylidene group facilitated by a favorable ring closure reaction in accordance with Baldwin's rules. Consequently, this reaction enables the simultaneous release of the attached cytotoxic payload. The therapeutic utility of this novel linker strategy was demonstrated by separate conjugation of the linker to two epidermal growth factor receptor (EGFR)-targeting ligands to afford a peptide-drug conjugate and an ADC. This work comprises a significant contribution to the bioconjugation field by introducing the alkylidene cyclic β-diketone as a tunable scaffold used for the temporary conjugation of therapeutic agents to peptides and proteins.

Developing Analytical ion Exchange Chromatography Methods for Antibody Drug Conjugates Containing the Hydrolysis-Prone Succinimide-Thioether Conjugation Chemistry

Charge variants are one of the most important quality attributes for protein therapeutics, including antibody drug conjugates (ADCs). ADCs are conjugation products between monoclonal antibodies (mAbs) and highly potent payloads. After attaching a payload, the charge profile of a mAb can be modified due to the change in net charge or surface charge. In this study, we present a unique challenge of charge assay development that arises from a desirable engineering of ADCs that incorporates the hydrolysis-prone succinimide-thioether conjugation chemistry. This engineered hydrolysis at conjugation sites is usually not complete during conjugation process and continuously progressing during mild stress. This hydrolysis also creates a carboxylic functional group, which manifests as acidic peaks in the ADC charge profiles. As a result, ion exchange chromatograms become sensitive measurements of this hydrolysis, which often masks the charge profile change due to other important post-translational modifications. In this study, two approaches were explored to address this unique challenge: to remove the hydrolysis heterogeneity by incubating ADCs under high pH conditions to drive complete hydrolysis; and to analyze charge variants at the subunit level after IdeS digestion. Acceptable charge profiles and quantitative integration results were successfully obtained by both approaches.

Mechanism-guided strategies for combating antibiotic resistance

Bacterial antibiotic resistance has been recognized as a global threat to public health. It challenges the antibiotics currently used in clinical practice and causes severe and often fatal infectious diseases. Fighting against antibiotic-resistant bacteria (ARB) is growing more urgent. While understanding the molecular mechanisms that underlie resistance is a prerequisite, several major mechanisms have been previously proposed including bacterial efflux systems, reduced cell membrane permeability, antibiotic inactivation by enzymes, target modification, and target protection. In this context, this review presents a panel of promising and potential strategies to combat antibiotic resistance/resistant bacteria. Different types of direct-acting and indirect resistance breakers, such as efflux pump inhibitors, antibiotic adjuvants, and oxidative treatments are discussed. In addition, the emerging multi-omics approaches for rapid resistance identification and promising alternatives to existing antibiotics are highlighted. Overall, this review suggests that continued effort and investment in research are required to develop new antibiotics and alternatives to existing antibiotics and translate them into environmental and clinical applications.

An Investigation into the In Vitro Targeted Killing of CD44-Expressing Triple-Negative Breast Cancer Cells Using Recombinant Photoimmunotherapeutics Compared to Auristatin-F-Based Antibody-Drug Conjugates

Triple-negative breast cancer (TNBC) is the deadliest form of breast cancer with limited treatment options. The persistence of highly tumorigenic CD44-expressing subpopulation referred to as cancer stem cells (CSCs), endowed with the self-renewal capacity, has been associated with therapeutic resistance, hence clinical relapses. To mitigate these undesired events, targeted immunotherapies using antibody-photoconjugate (APC) or antibody-drug conjugate (ADC), were developed to specifically release cytotoxic payloads within targeted cells overexpressing cognate antigen receptors. Therefore, an αCD44(scFv)-SNAP-tag antibody fusion protein was engineered through genetic fusion of a single-chain antibody fragment (scFv) to a SNAPf-tag fusion protein, capable of self-conjugating with benzylguanine-modified light-sensitive near-infrared (NIR) phthalocyanine dye IRDye700DX (BG-IR700) or the small molecule toxin auristatin-F (BG-AURIF). Binding of the αCD44(scFv)-SNAPf-IR700 photoimmunoconjugate to antigen-positive cells was demonstrated by confocal microscopy and flow cytometry. By switching to NIR irradiation, CD44-expressing TNBC was selectively killed through induced phototoxic activities. Likewise, the αCD44(scFv)-SNAPf-AURIF immunoconjugate was able to selectively accumulate within targeted cells and significantly reduced cell viability through antimitotic activities at nano- to micromolar drug concentrations. This study provides an in vitro proof-of-concept for a future strategy to selectively destroy light-accessible superficial CD44-expressing TNBC tumors and their metastatic lesions which are inaccessible to therapeutic light.

Understanding the Effects of Site-Specific Light Chain Conjugation on Antibody Structure Using Hydrogen Exchange-Mass Spectrometry (HX-MS)

Antibody drug conjugates (ADCs) represent one of the fastest growing classes of cancer therapeutics. Drug incorporation through site-specific conjugation in ADCs leads to uniform drug load and distribution. These site-specific modifications may have an impact on ADC quality attributes including protein higher order structure (HOS), which might impact safety and efficacy. In this study, we conducted a side-by-side comparison between the conjugated and unconjugated mAb. In the ADC, the linker-pyrrolobenzodiazepine was site specifically conjugated to an engineered unpaired C215 residue within the Fab domain of the light chain. Differential scanning calorimetry (DSC) and differential scanning fluorimetry (DSF) indicated a decrease in thermal stability for the CH2 transition of the ADC. Size exclusion chromatography (SEC) analysis showed that conjugation of the mAb resulted in earlier aggregation onset and increased aggregation propensity after 4 weeks at 40 °C. Differential hydrogen-exchange mass spectrometry (HX-MS) indicated that upon conjugation, light chain residues 150-155 and 197-204, close to the conjugation site, showed significantly faster HX kinetics, suggesting an increase in backbone flexibility within this region, while heavy chain residues 32-44 exhibited significantly slower kinetics, suggesting distal stabilization of the mAb backbone.

Recent Advances in Targeted Cancer Therapy: Are PDCs the Next Generation of ADCs?

Antibody-drug conjugates (ADCs) comprise antibodies, cytotoxic payloads, and linkers, which can integrate the advantages of antibodies and small molecule drugs to achieve targeted cancer treatment. However, ADCs also have some shortcomings, such as non-negligible drug resistance, a low therapeutic index, and payload-related toxicity. Many studies have focused on changing the composition of ADCs, and some have even further extended the concept and types of targeted conjugated drugs by replacing the targeted antibodies in ADCs with peptides, revolutionarily introducing peptide-drug conjugates (PDCs). This Perspective summarizes the current research status of ADCs and PDCs and highlights the structural innovations of ADC components. In particular, PDCs are regarded as the next generation of potential targeted drugs after ADCs, and the current challenges of PDCs are analyzed. Our aim is to offer fresh insights for the efficient design and expedited development of innovative targeted conjugated drugs.

Late-Stage Desulfurization Enables Rapid and Efficient Solid-Phase Synthesis of Cathepsin-Cleavable Linkers for Antibody-Drug Conjugates

The synthesis of linker-payloads is a critical step in developing antibody-drug conjugates (ADCs), a rapidly advancing therapeutic approach in oncology. The conventional method for synthesizing cathepsin B-labile dipeptide linkers, which are commonly used in ADC development, involves the solution-phase assembly of cathepsin B-sensitive dipeptides, followed by the installation of self-immolative para-aminobenzyl carbonate to facilitate the attachment of potent cytotoxic payloads. However, this approach is often low yield and laborious, especially when extending the peptide chain with components like glutamic acid to improve mouse serum stability or charged amino acids or poly(ethylene glycol) moieties to enhance linker hydrophilicity. Here, we introduce a novel approach utilizing late-stage desulfurization chemistry, enabling safe, facile, and cost-effective access to the cathepsin B-cleavable linker, Val-Ala-PABC-MMAE, on resin for the first time.

Exploring treatment options in cancer: Tumor treatment strategies

Traditional therapeutic approaches such as chemotherapy and radiation therapy have burdened cancer patients with onerous physical and psychological challenges. Encouragingly, the landscape of tumor treatment has undergone a comprehensive and remarkable transformation. Emerging as fervently pursued modalities are small molecule targeted agents, antibody-drug conjugates (ADCs), cell-based therapies, and gene therapy. These cutting-edge treatment modalities not only afford personalized and precise tumor targeting, but also provide patients with enhanced therapeutic comfort and the potential to impede disease progression. Nonetheless, it is acknowledged that these therapeutic strategies still harbour untapped potential for further advancement. Gaining a comprehensive understanding of the merits and limitations of these treatment modalities holds the promise of offering novel perspectives for clinical practice and foundational research endeavours. In this review, we discussed the different treatment modalities, including small molecule targeted drugs, peptide drugs, antibody drugs, cell therapy, and gene therapy. It will provide a detailed explanation of each method, addressing their status of development, clinical challenges, and potential solutions. The aim is to assist clinicians and researchers in gaining a deeper understanding of these diverse treatment options, enabling them to carry out effective treatment and advance their research more efficiently.

Antibody drug conjugates: Design implications for clinicians

OBJECTIVE

There are currently 11 antibody-drug conjugates (ADC) that are FDA approved for use in oncologic disease states, with many more in the pipeline. The authors aim to review the pharmacokinetic profiles of the components of ADCs to engage pharmacist practitioners in practical considerations in the care of patients. This article provides an overview on the use of ADCs in the setting of organ dysfunction, drug-drug interactions, and management of on- and off-target adverse effects.

DATA SOURCES

A systematic search of the literature on ADCs through September 2023 was conducted. Clinical trials as well as articles on ADC design and functional components, adverse effects, and pharmacokinetics were reviewed. Reviewed literature included prescribing information as well as tertiary sources and primary literature.

DATA SUMMARY

A total of 11 ADCs were reviewed for the purpose of this article. A description of the mechanism of action and structure of ADCs is outlined, and a table containing description of each currently FDA-approved ADC is included. Various mechanisms of ADC toxicity are reviewed, including how ADC structure may be implicated.

CONCLUSION

It is imperative that pharmacist clinicians understand the design and function of each component of an ADC to continue to assess new approvals for use in oncology patients. Understanding the design of the ADC can help a pharmacy practitioner compare and contrast adverse effect profiles to support their multidisciplinary teams and to engage patients in education and management of their care.

Disitamab vedotin, a HER2-directed antibody-drug conjugate, in patients with HER2-overexpression and HER2-low advanced breast cancer: a phase I/Ib study

BACKGROUND

Disitamab vedotin (DV; RC48-ADC) is an antibody-drug conjugate comprising a human epidermal growth factor receptor 2 (HER2)-directed antibody, linker and monomethyl auristatin E. Preclinical studies have shown that DV demonstrated potent antitumor activity in preclinical models of breast, gastric, and ovarian cancers with different levels of HER2 expression. In this pooled analysis, we report the safety and efficacy of DV in patients with HER2-overexpression and HER2-low advanced breast cancer (ABC).

METHODS

In the phase I dose-escalation study (C001 CANCER), HER2-overexpression ABC patients received DV at doses of 0.5-2.5 mg/kg once every two weeks (Q2W) until unacceptable toxicity or progressive disease. The dose range, safety, and pharmacokinetics (PK) were determined. The phase Ib dose-range and expansion study (C003 CANCER) enrolled two cohorts: HER2-overexpression ABC patients receiving DV at doses of 1.5-2.5 mg/kg Q2W, with the recommended phase 2 dose (RP2D) determined, and HER2-low ABC patients receiving DV at doses of 2.0 mg/kg Q2W to explore the efficacy and safety of DV in HER2-low ABC.

RESULTS

Twenty-four patients with HER2-overexpression ABC in C001 CANCER, 46 patients with HER2-overexpression ABC and 66 patients with HER2-low ABC in C003 CANCER were enrolled. At 2.0 mg/kg RP2D Q2W, the confirmed objective response rates were 42.9% (9/21; 95% confidence interval [CI]: 21.8%-66.0%) and 33.3% (22/66; 95% CI: 22.2%-46.0%), with median progression-free survival (PFS) of 5.7 months (95% CI: 5.3-8.4 months) and 5.1 months (95% CI: 4.1-6.6 months) for HER2-overexpression and HER2-low ABC, respectively. Common (≥5%) grade 3 or higher treatment-emergent adverse events included neutrophil count decreased (17.6%), gamma-glutamyl transferase increased (13.2%), asthenia (11.0%), white blood cell count decreased (9.6%), peripheral neuropathy such as hypoesthesia (5.9%) and neurotoxicity (0.7%), and pain (5.9%).

CONCLUSION

DV demonstrated promising efficacy in HER2-overexpression and HER2-low ABC, with a favorable safety profile at 2.0 mg/kg Q2W.

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.

Drug deconjugation-assisted peptide mapping by LC-MS/MS to identify conjugation sites and quantify site occupancy for antibody-drug conjugates

Antibody-drug conjugates (ADCs) are a heterogeneous mixture of conjugated species with varied drug loadings. Depending on conjugation sites, linkers and drugs can exhibit different stability as influenced by the solvent-accessibility and local charge, resulting in different ADC efficacy, pharmacokinetics, and toxicity. Conjugation site analysis is critical for ADC structural characterization to assure product quality and consistency. It enables early conjugation studies at site-specific levels, confirms the absence of unexpected products to support conjugation process development, and aids in ensuring lot-to-lot consistency for comparability studies. Peptide mapping using liquid chromatography-tandem mass spectrometry is the industry standard method for analyzing conjugation sites. However, some concerns remain for this approach as the large and hydrophobic drug moieties often result in poor MS/MS fragmentation quality and impede the identification of conjugation sites. Additionally, the ionization discrepancy between conjugated and unconjugated peptides can lead to a relatively large bias for site occupancy calculation. In this work, we present a simple drug deconjugation-assisted peptide mapping method to identify and quantify the drug conjugation for ADCs with protease-cleavable linkers. Papain-based drug deconjugation was used to remove the highly hydrophobic drug moiety, which significantly improved the quantitation accuracy of conjugation level and the fragmentation quality. Sample preparation conditions were optimized to avoid introducing artificial modifications, allowing the tracking of initial sample status and subsequent changes of quality attributes during process development and stability assessment. This method was applied to analyze thermally-stressed ADC samples to monitor changes of site-specific conjugation levels, DAR, succinimide hydrolysis of the linker, and various PTMs. We believe this is an effective and straightforward tool for conjugation site analysis while simultaneously monitoring multiple quality attributes for ADCs with protease-cleavable linkers.

Chemo- and regio-selective differential modification of native cysteines on an antibody via the use of dehydroalanine forming reagents

Protein modification has garnered increasing interest over the past few decades and has become an important tool in many aspects of chemical biology. In recent years, much effort has focused on site-selective modification strategies that generate more homogenous bioconjugates, and this is particularly so in the antibody modification space. Modifying native antibodies by targeting solvent-accessible cysteines liberated by interchain disulfide reduction is, perhaps, the predominant strategy for achieving more site-selectivity on an antibody scaffold. This is evidenced by numerous approved antibody therapeutics that have utilised cysteine-directed conjugation reagents and the plethora of methods/strategies focused on antibody cysteine modification. However, all of these methods have a common feature in that after the reduction of native solvent-accessible cystines, the liberated cysteines are all reacted in the same manner. Herein, we report the discovery and application of dehydroalanine forming reagents (including novel reagents) capable of regio- and chemo-selectively modifying these cysteines (differentially) on a clinically relevant antibody fragment and a full antibody. We discovered that these reagents could enable differential reactivity between light chain C-terminal cysteines, heavy chain hinge region cysteines (cysteines with an adjacent proline residue, Cys-Pro), and other heavy chain internal cysteines. This differential reactivity was also showcased on small molecules and on the peptide somatostatin. The application of these dehydroalanine forming reagents was exemplified in the preparation of a dually modified antibody fragment and full antibody. Additionally, we discovered that readily available amide coupling agents can be repurposed as dehydroalanine forming reagents, which could be of interest to the broader field of chemical biology.

Incidence and Mitigation of Corneal Pseudomicrocysts Induced by Antibody-Drug Conjugates (ADCs)

Purpose of Review

This study is to highlight the incidence of corneal pseudomicrocysts in FDA-approved antibody-drug conjugates (ADCs), and success of preventive therapies for pseudomicrocysts and related ocular surface adverse events (AEs).

Recent Findings

ADCs are an emerging class of selective cancer therapies that consist of a potent cytotoxin connected to a monoclonal antibody (mAb) that targets antigens expressed on malignant cells. Currently, there are 11 FDA-approved ADCs with over 164 in clinical trials. Various AEs have been attributed to ADCs, including ocular surface AEs (keratitis/keratopathy, dry eye, conjunctivitis, blurred vision, corneal pseudomicrocysts). While the severity and prevalence of ADC-induced ocular surface AEs are well reported, the reporting of corneal pseudomicrocysts is limited, complicating the development of therapies to prevent or treat ADC-related ocular surface toxicity.

Summary

Three of 11 FDA-approved ADCs have been implicated with corneal pseudomicrocysts, with incidence ranging from 41 to 100% of patients. Of the six ADCs that reported ocular surface AEs, only three had ocular substudies to investigate the benefit of preventive therapies including topical steroids, vasoconstrictors, and preservative-free lubricants. Current preventive therapies demonstrate limited efficacy at mitigating pseudomicrocysts and other ocular surface AEs.

Optimizing Solid Tumor Treatment with Antibody-drug Conjugates Using Agent-Based Modeling: Considering the Role of a Carrier Dose and Payload Class

INTRODUCTION

Antibody-drug conjugates (ADCs) show significant clinical efficacy in the treatment of solid tumors, but a major limitation to their success is poor intratumoral distribution. Adding a carrier dose improves both distribution and overall drug efficacy of ADCs, but the optimal carrier dose has not been outlined for different payload classes.

OBJECTIVE

In this work, we study two carrier dose regimens: 1) matching payload potency to cellular delivery but potentially not reaching cells farther away from blood vessels, or 2) dosing to tumor saturation but risking a reduction in cell killing from a lower amount of payload delivered per cell.

METHODS

We use a validated computational model to test four different payloads conjugated to trastuzumab to determine the optimal carrier dose as a function of target expression, ADC dose, and payload potency.

RESULTS

We find that dosing to tumor saturation is more efficacious than matching payload potency to cellular delivery for all payloads because the increase in the number of cells targeted by the ADC outweighs the loss in cell killing on targeted cells. An important exception exists if the carrier dose reduces the payload uptake per cell to the point where all cell killing is lost. Likewise, receptor downregulation can mitigate the benefits of a carrier dose.

CONCLUSIONS

Because tumor saturation and in vitro potency can be measured early in ADC design, these results provide insight into maximizing ADC efficacy and demonstrate the benefits of using simulation to guide ADC design.

Impact on Quality during In-Use Preparation of an Antibody Drug Conjugate with Eight Different Closed System Transfer Device Brands

The aim of this study was to investigate the in-use compatibility of eight commercially available closed system transfer device brands (CSTDs) with a formulated model antibody drug conjugate (ADC). Overall, in-use simulated dosing preparation applying the CSTD systems investigated raised concerns for several product quality attributes. The incompatibilities observed were mainly associated with increased visible and subvisible particles formation as well as significant changes in holdup volumes. Visible and subvisible particles contained heterogeneous mixtures of particle classes, with the majority of subvisible particles associated with silicone oil leaching from CSTD systems during simulated dose preparation upon contact with the ADC formulation. These observations demonstrate that CSTD use may adversely impact product quality and delivered dose which could potentially lead to safety and efficacy concerns during administration. Other product quality attributes measured including turbidity, color, ADC recovery, and purity by size exclusion HPLC, did not show relevant changes. It is therefore strongly recommended to test and screen the compatibility of CSTDs with the respective ADC, in a representative in-use simulated administration setting, during early CMC development, i.e., well before the start of clinical studies, to include information about compatibility and to ensure that the CSTD listed in the manuals of preparation for clinical handling has been thoroughly assessed before human use.

Identification of a Fully Human Antibody VH Domain Targeting Anaplastic Lymphoma Kinase (ALK) with Applications in ALK-Positive Solid Tumor Immunotherapy

The anaplastic lymphoma kinase (ALK, CD247) is a potential target for antibody-based therapy. However, no antibody-based therapeutics targeting ALK have entered clinical trials, necessitating the development of novel antibodies with unique therapeutic merits. Single-domain antibodies (sdAb) bear therapeutic advantages compared to the full-length antibody including deeper tumor penetration, cost-effective production and fast washout from normal tissues. In this study, we identified a human immunoglobulin heavy chain variable domain (VH domain) (VH20) from an in-house phage library. VH20 exhibits good developability and high specificity with no off-target binding to ~6000 human membrane proteins. VH20 efficiently bound to the glycine-rich region of ALK with an EC50 of 0.4 nM and a KD of 6.54 nM. Both VH20-based bispecific T cell engager (TCE) and chimeric antigen receptor T cells (CAR Ts) exhibited potent cytolytic activity to ALK-expressing tumor cells in an ALK-dependent manner. VH20 CAR Ts specifically secreted proinflammatory cytokines including IL-2, TNFα and IFNγ after incubation with ALK-positive cells. To our knowledge, this is the first reported human single-domain antibody against ALK. Our in vitro characterization data indicate that VH20 could be a promising ALK-targeting sdAb with potential applications in ALK-expressing tumors, including neuroblastoma (NBL) and non-small cell lung cancer.

The conjugates of 5'-deoxy-5-fluorocytidine and hydroxycinnamic acids - synthesis, anti-pancreatic cancer activity and molecular docking studies

New amide conjugates 1-6 of hydroxycinnamic acids (HCA) and 5'-deoxy-5-fluorocytidine (5-dFCR), the prodrug of 5-fluorouracil (5-FU), were synthesized and tested in vitro against pancreatic cancer lines (PDAC). The compounds showed slightly higher efficacy against primary BxPC-3 cells (IC50 values of 14-45 μM) than against metastatic AsPC-1 (IC50 values of 37-133 μM), and similar to that of 5-FU for both PDAC lines. Compound 1, which has a para-(acetyloxy)coumaroyl substituent, was found to be the most potent (IC50 = 14 μM) with a selectivity index of approximately 7 to normal dermal fibroblasts (IC50 = 96 μM). The potential pharmacological profiles were discussed on the basis of the ADME data. Docking to the carboxylesterase CES2 showed that the synthesized compounds have the ability to bind via hydrogen bonding between a specific acetate group of the sugar moiety and Ser228, which belongs to the catalytic triad that causes hydrolysis. Docking to albumin, a major transport protein in the circulatory system, revealed a strong interaction of the conjugates at the binding site which is native to warfarin and responsible for its transport in the body.

Enhanced Characterization of Lysine-Linked Antibody Drug Conjugates Enabled by Middle-Down Mass Spectrometry and Higher-Energy Collisional Dissociation-Triggered Electron-Transfer/Higher-Energy Collisional Dissociation and Ultraviolet Photodissociation

As the development of new biotherapeutics advances, increasingly sophisticated tandem mass spectrometry methods are needed to characterize the most complex molecules, including antibody drug conjugates (ADCs). Lysine-linked ADCs, such as trastuzumab-emtansine (T-DM1), are among the most heterogeneous biotherapeutics. Here, we implement a workflow that combines limited proteolysis with HCD-triggered EThcD and UVPD mass spectrometry for the characterization of the resulting middle-down large-sized peptides of T-DM1. Fifty-three payload-containing peptides were identified, ranging in mass from 1.8 to 16.9 kDa, and leading to the unambiguous identification of 46 out of 92 possible conjugation sites. In addition, seven peptides were identified containing multiple payloads. The characterization of these types of heterogeneous peptides represents an important step in unraveling the combinatorial nature of lysine-conjugated ADCs.

ADCT-602, a Novel PBD Dimer-containing Antibody-Drug Conjugate for Treating CD22-positive Hematologic Malignancies

Relapsed or refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) and lymphomas have poor patient outcomes; novel therapies are needed. CD22 is an attractive target for antibody-drug conjugates (ADCs), being highly expressed in R/R B-ALL with rapid internalization kinetics. ADCT-602 is a novel CD22-targeting ADC, consisting of humanized mAb hLL2-C220, site specifically conjugated to the pyrrolobenzodiazepine dimer-based payload tesirine. In preclinical studies, ADCT-602 demonstrated potent, specific cytotoxicity in CD22-positive lymphomas and leukemias. ADCT-602 was specifically bound, internalized, and trafficked to lysosomes in CD22-positive tumor cells; after cytotoxin release, DNA interstrand crosslink formation persisted for 48 hours. In the presence of CD22-positive tumor cells, ADCT-602 caused bystander killing of CD22-negative tumor cells. A single ADCT-602 dose led to potent, dose-dependent, in vivo antitumor activity in subcutaneous and disseminated human lymphoma/leukemia models. Pharmacokinetic analyses (rat and cynomolgus monkey) showed excellent stability and tolerability of ADCT-602. Cynomolgus monkey B cells were efficiently depleted from circulation after one dose. Gene signature association analysis revealed IRAK1 as a potential marker for ADCT-602 resistance. Combining ADCT-602 + pacritinib was beneficial in ADCT-602-resistant cells. Chidamide increased CD22 expression on B-cell tumor surfaces, increasing ADCT-602 activity. These data support clinical testing of ADCT-602 in R/R B-ALL (NCT03698552) and CD22-positive hematologic cancers.

EGFR-Targeted Antibody-Drug Conjugate to Different Aminobisphosphonates: Direct and Indirect Antitumor Effects on Colorectal Carcinoma Cells

Antibody--drug conjugates (ADCs) are a promising delivery system that involves linking a monoclonal antibody (mAb) to a specific drug, such as a cytotoxic agent, to target tumor cells. This new class of antitumor therapy acts as a "biological missile" that can destroy tumor cells while increasing the therapeutic index and decreasing toxicity. One of the most critical factors in ADC design is selecting a target antigen that is highly expressed on the surface of cancer cells. In this study, we conjugated Cetuximab (Cet), a monoclonal antibody that targets the epidermal growth factor receptor (EGFR), to aminobisphosphonates (N-BPs) such as ibandronate (IBA) or risedronate (RIS) or zoledronate (ZA). Cetuximab is administered to patients with metastatic colorectal carcinoma (mCRC) with a wild-type (WT) EGFR transduction pathway. Also, it is well established that N-BPs can trigger the antitumor activity of Vδ2 T cells in both in vitro and in vivo experimental models. The resulting ADCs were added in co-culture to assess the effect on CRC cell line proliferation and sensitivity to Vδ2 T antitumor lymphocytes in comparison with the native antibody. These assays have been performed both in conventional and 3D spheroid cultures. We found that all three ADCs can increase the inhibitory effect on cell proliferation of the WT-EGFR cell line Caco-2 while only Cet-RIS and Cet-ZA can increase the cytotoxicity mediated by Vδ2 T cells against both WT and EGFR-mutated CRC cell lines (Caco-2, DLD-1, and HCT-116). Also, the ADCs can trigger the cell proliferation of Vδ2 T cells present in peripheral blood and tumor specimens. Our findings indicate that anti-EGFR antibodies bound to N-BPs can improve the antitumor effects of the native antibody possibly increasing the therapeutic effect.

Advancing protein therapeutics through proximity-induced chemistry

Recent years have seen a remarkable growth in the field of protein-based medical treatments. Nevertheless, concerns have arisen regarding the cytotoxicity limitations, low affinity, potential immunogenicity, low stability, and challenges to modify these proteins. To overcome these obstacles, proximity-induced chemistry has emerged as a next-generation strategy for advancing protein therapeutics. This method allows site-specific modification of proteins with therapeutic agents, improving their effectiveness without extensive engineering. In addition, this innovative approach enables spatial control of the reaction based on proximity, facilitating the formation of irreversible covalent bonds between therapeutic proteins and their targets. This capability becomes particularly valuable in addressing challenges such as the low affinity frequently encountered between therapeutic proteins and their targets, as well as the limited availability of small molecules for specific protein targets. As a result, proximity-induced chemistry is reshaping the field of protein drug preparation and propelling the revolution in novel protein therapeutics.

The medicinal chemistry evolution of antibody-drug conjugates

Antibody-drug conjugates (ADCs) comprise 3 components of wildly differing sizes: antibody (150 000 Da), linker (typically <500 Da) and payload (typically <500 Da). While the drug-linker makes up only a small percent of the ADC it has a disproportionately massive impact on all aspects of the ADC. Replacing maleimide with bromoacetamide (BrAc) affords stable attachment of the linker to the antibody cysteine, supports total flexibility for linker design and affords a more homogenous ADC. Optimisation of the protease cleavable dipeptide reduces aggregation, facilitates moderation of the physicochemical properties of the ADC and enables long-term stability to facilitate subcutaneous self-administration. Payloads are designed specifically to afford the optimal ADC. Structural information and SAR guide design to improve both potency and selectivity to the small molecule target improving the therapeutic index of resulting ADCs. Minimising the solvent exposed hydrophobic surface area improves the drug-like properties of the ADC, the realisation that the attachment heteroatom can be more than just the site for linker attachment as it can also drive potency and selectivity of the payload and the adoption of a prodrug strategy at project initiation are key areas that medicinal chemistry drives. For an optimal ADC the symbiotic relationship of the three structurally disparate components requires they all function in unison and medicinal chemistry has a huge role to ensure this happens.

Antibody-drug conjugates targeting HER2 for the treatment of urothelial carcinoma: potential therapies for HER2-positive urothelial carcinoma

Urothelial carcinoma (UC) is a common cancer characterized by high morbidity and mortality rates. Despite advancements in treatment, challenges such as recurrence and low response rates persist. Antibody-drug conjugates (ADCs) have emerged as a promising therapeutic approach for various cancers, although their application in UC is currently limited. This review focuses on recent research regarding ADCs designed to treat UC by targeting human epidermal growth factor receptor 2 (HER2), a surface antigen expressed on tumor cells. ADCs comprise three main components: an antibody, a linker, and a cytotoxic payload. The antibody selectively binds to tumor cell surface antigens, facilitating targeted delivery of the cytotoxic drug, while linkers play a crucial role in ensuring stability and controlled release of the payload. Cleavable linkers release the drug within tumor cells, while non-cleavable linkers ensure stability during circulation. The cytotoxic payload exerts its antitumor effect by disrupting cellular pathways. HER2 is commonly overexpressed in UCs, making it a potential therapeutic target. Several ADCs targeting HER2 have been approved for cancer treatment, but their use in UC is still being tested. Numerous HER2 ADCs have demonstrated significant growth inhibition and induction of apoptosis in translational models of HER2-overexpressing bladder cancer. Ongoing clinical trials are assessing the efficacy and safety of ADCs targeting HER2 in UC, with the aim of determining tumor response and the potential of ADCs as a treatment option for UC patients. The development of effective therapies with improved response rates and long-term effectiveness is crucial for advanced and metastatic UC. ADCs targeting HER2 show promise in this regard and merit further investigation for UC treatment.

Chemical immunology: Recent advances in tool development and applications

Immunology was one of the first biological fields to embrace chemical approaches. The development of new chemical approaches and techniques has provided immunologists with an impressive arsenal of tools to address challenges once considered insurmountable. This review focuses on advances at the interface of chemistry and immunobiology over the past two decades that have not only opened new avenues in basic immunological research, but also revolutionized drug development for the treatment of cancer and autoimmune diseases. These include chemical approaches to understand and manipulate antigen presentation and the T cell priming process, to facilitate immune cell trafficking and regulate immune cell functions, and therapeutic applications of chemical approaches to disease control and treatment.

Antibody-platinum (IV) prodrugs conjugates for targeted treatment of cutaneous squamous cell carcinoma

Antibody-drug conjugates (ADCs) are a new type of targeting antibodies that conjugate with highly toxic anticancer drugs via chemical linkers to exert high specificity and efficient killing of tumor cells, thereby attracting considerable attention in precise oncology therapy. Cetuximab (Cet) is a typical antibody that offers the benefits of good targeting and safety for individuals with advanced and inoperable cutaneous squamous cell carcinoma (cSCC); however, its anti-tumor activity is limited to a single use. Cisplatin (CisPt) shows good curative effects; however, its adverse effects and non-tumor-targeting ability are major drawbacks. In this study, we designed and developed a new ADC based on a new cytotoxic platinum (IV) prodrug (C8Pt(IV)) and Cet. The so-called antibody-platinum (IV) prodrugs conjugates, named Cet-C8Pt(IV), showed excellent tumor targeting in cSCC. Specifically, it accurately delivered C8Pt(IV) into tumor cells to exert the combined anti-tumor effect of Cet and CisPt. Herein, metabolomic analysis showed that Cet-C8Pt(IV) promoted cellular apoptosis and increased DNA damage in cSCC cells by affecting the vitamin B6 metabolic pathway in tumor cells, thereby further enhancing the tumor-killing ability and providing a new strategy for clinical cancer treatment using antibody-platinum (IV) prodrugs conjugates.

Engineering approaches for innate immune-mediated tumor microenvironment remodeling

Cancer immunotherapy offers transformative promise particularly for the treatment of lethal cancers, since a correctly trained immune system can comprehensively orchestrate tumor clearance with no need for continued therapeutic intervention. Historically, the majority of immunotherapies have been T cell-focused and have included immune checkpoint inhibitors, chimeric antigen receptor T cells, and T-cell vaccines. Unfortunately T-cell-focused therapies have failed to achieve optimal efficacy in most solid tumors largely because of a highly immunosuppressed 'cold' or immune-excluded tumor microenvironment (TME). Recently, a rapidly growing treatment paradigm has emerged that focuses on activation of tumor-resident innate antigen-presenting cells, such as dendritic cells and macrophages, which can drive a proinflammatory immune response to remodel the TME from 'cold' or immune-excluded to 'hot'. Early strategies for TME remodeling centered on free cytokines and agonists, but these approaches have faced significant hurdles in both delivery and efficacy. Systemic toxicity from off-target inflammation is a paramount concern in these therapies. To address this critical gap, engineering approaches have provided the opportunity to add 'built-in' capabilities to cytokines, agonists, and other therapeutic agents to mediate improved delivery and efficacy. Such capabilities have included protective encapsulation to shield them from degradation, targeting to direct them with high specificity to tumors, and co-delivery strategies to harness synergistic proinflammatory pathways. Here, we review innate immune-mediated TME remodeling engineering approaches that focus on cytokines, innate immune agonists, immunogenic viruses, and cell-based methods, highlighting emerging preclinical approaches and strategies that are either being tested in clinical trials or already Food and Drug Administration approved.

The Conjugates of Indolo[2,3-b]quinoline as Anti-Pancreatic Cancer Agents: Design, Synthesis, Molecular Docking and Biological Evaluations

New amide conjugates of hydroxycinnamic acids (HCAs) and the known antineoplastic 5,11-dimethyl-5H-indolo[2,3-b]quinoline (DiMIQ), an analog of the natural alkaloid neocryptolepine, were synthesized and tested in vitro for anticancer activity. The compound 9-[((2-hydroxy)cinnamoyl)amino]-5,11-dimethyl-5H-indolo[2,3-b]quinoline (2), which contains the ortho-coumaric acid fragment, demonstrated dose-dependent effectiveness against both normal BxPC-3 and metastatic AsPC-1 pancreatic cancer cells. The IC50 values for AsPC-1 and BxPC-3 were 336.5 nM and 347.5 nM, respectively, with a selectivity index of approximately 5 for both pancreatic cancer cells compared to normal dermal fibroblasts. Conjugate 2 did not exhibit any hemolytic activity against human erythrocytes at the tested concentration. Computational studies were performed to predict the pharmacokinetic profile and potential mechanism of action of the synthesized conjugates. These studies focused on the ADME properties of the conjugates and their interactions with DNA, as well as DNA-topoisomerase alpha and beta complexes. All of the conjugates studied showed approximately one order of magnitude stronger binding to DNA compared to the reference DiMIQ, and approximately two orders of magnitude stronger binding to the topoisomerase II-DNA complex compared to DiMIQ. Conjugate 2 was predicted to have the strongest binding to the enzyme-DNA complex, with a Ki value of 2.8 nM.

Genomic and Immunologic Correlates in Prostate Cancer with High Expression of KLK2

The identification of surfaceome proteins is a main goal in cancer research to design antibody-based therapeutic strategies. T cell engagers based on KLK2, a kallikrein specifically expressed in prostate cancer (PRAD), are currently in early clinical development. Using genomic information from different sources, we evaluated the immune microenvironment and genomic profile of prostate tumors with high expression of KLK2. KLK2 was specifically expressed in PRAD but it was not significant associated with Gleason score. Additionally, KLK2 expression did not associate with the presence of any immune cell population and T cell activating markers. A mild correlation between the high expression of KLK2 and the deletion of TMPRSS2 was identified. KLK2 expression associated with high levels of surface proteins linked with a detrimental response to immune checkpoint inhibitors (ICIs) including CHRNA2, FAM174B, OR51E2, TSPAN1, PTPRN2, and the non-surface protein TRPM4. However, no association of these genes with an outcome in PRAD was observed. Finally, the expression of these genes in PRAD did not associate with an outcome in PRAD and any immune populations. We describe the immunologic microenvironment on PRAD tumors with a high expression of KLK2, including a gene signature linked with an inert immune microenvironment, that predicts the response to ICIs in other tumor types. Strategies targeting KLK2 with T cell engagers or antibody-drug conjugates will define whether T cell mobilization or antigen release and stimulation of immune cell death are sufficient effects to induce clinical activity.

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.

Cervical cancer: Novel treatment strategies offer renewed optimism

Cervical cancer poses a significant global public health issue, primarily affecting women, and stands as one of the four most prevalent cancers affecting woman globally, which includes breast cancer, colorectal cancer, lung cancer and cervical cancer. Almost every instance of cervical cancer is associated with infections caused by the human papillomavirus (HPV). Prevention of this disease hinges on screening and immunization of the patients, yet disparities in cervical cancer occurrence exist between developed and developing nations. Multiple factors contribute to cervical cancer, including sexually transmitted diseases (STDs), reproductive and hormonal influences, genetics, and host-related factors. Preventive programs, lifestyle improvements, smoking cessation, and prompt precancerous lesion treatment can reduce the occurrence of cervical cancer. The persistency and recurrence of the cases are inherited even after the innovative treatments available for cervical cancer. For patient's ineligible for curative surgery or radiotherapy, palliative chemotherapy remains the standard treatment. Novel treatment strategies are emerging to combat the limited effectiveness of chemotherapy. Nanocarriers offer the promise of concurrent chemotherapeutic drug delivery as a beacon of hope in cervical cancer research. The primary aim of this review study is to contribute to a thorough understanding of cervical cancer, fostering awareness and informed decision-making and exploring novel treatment methods such as nanocarriers for the treatment of cervical cancer. This manuscript delves into cutting-edge approaches, exploring the potential of nanocarriers and other innovative treatments. Our study underscores the critical need for global awareness, early intervention, and enhanced treatment options. Novel strategies, such as nanocarriers, offer renewed optimism in the battle against cervical cancer. This research provides compelling evidence for the investigation of these novel therapeutic approaches within the medical field. Cervical cancer remains a formidable adversary, but with ongoing advancements and unwavering commitment, we move closer to a future where it is a preventable and treatable disease, even in the most underserved regions.

Anticancer activities of natural antimicrobial peptides from animals

Cancer is the most common cause of human death worldwide, posing a serious threat to human health and having a negative impact on the economy. In the past few decades, significant progress has been made in anticancer therapies, but traditional anticancer therapies, including radiation therapy, surgery, chemotherapy, molecular targeted therapy, immunotherapy and antibody-drug conjugates (ADCs), have serious side effects, low specificity, and the emergence of drug resistance. Therefore, there is an urgent need to develop new treatment methods to improve efficacy and reduce side effects. Antimicrobial peptides (AMPs) exist in the innate immune system of various organisms. As the most promising alternatives to traditional drugs for treating cancers, some AMPs also have been proven to possess anticancer activities, which are defined as anticancer peptides (ACPs). These peptides have the advantages of being able to specifically target cancer cells and have less toxicity to normal tissues. More and more studies have found that marine and terrestrial animals contain a large amount of ACPs. In this article, we introduced the animal derived AMPs with anti-cancer activity, and summarized the types of tumor cells inhibited by ACPs, the mechanisms by which they exert anti-tumor effects and clinical applications of ACPs.

Site-selective peptide functionalisation mediated via vinyl-triazine linchpins

Herein we introduce 3-vinyl-1,2,4-triazines derivatives as dual-reactive linkers that exhibit selectivity towards cysteine and specific strained alkynes, enabling conjugate addition and inverse electron-demand Diels-Alder (IEDDA) reactions. This approach facilitates site-selective bioconjugation of biologically relevant peptides, followed by rapid and highly selective reactions with bicyclononyne (BCN) reagents.

Quantifying the Expanding Landscape of Clinical Actionability for Patients with Cancer

There is a continuing debate about the proportion of cancer patients that benefit from precision oncology, attributable in part to conflicting views as to which molecular alterations are clinically actionable. To quantify the expansion of clinical actionability since 2017, we annotated 47,271 solid tumors sequenced with the MSK-IMPACT clinical assay using two temporally distinct versions of the OncoKB knowledge base deployed 5 years apart. Between 2017 and 2022, we observed an increase from 8.9% to 31.6% in the fraction of tumors harboring a standard care (level 1 or 2) predictive biomarker of therapy response and an almost halving of tumors carrying nonactionable drivers (44.2% to 22.8%). In tumors with limited or no clinical actionability, TP53 (43.2%), KRAS (19.2%), and CDKN2A (12.2%) were the most frequently altered genes.

SIGNIFICANCE

Although clear progress has been made in expanding the availability of precision oncology-based treatment paradigms, our results suggest a continued unmet need for innovative therapeutic strategies, particularly for cancers with currently undruggable oncogenic drivers. See related commentary by Horak and Fröhling, p. 18. This article is featured in Selected Articles from This Issue, p. 5.

Site-Specific Dolasynthen Antibody-Drug Conjugates Exhibit Consistent Pharmacokinetic Profiles across a Wide Range of Drug-to-Antibody Ratios

Key defining attributes of an antibody-drug conjugate (ADC) include the choice of the targeting antibody, linker, payload, and the drug-to-antibody ratio (DAR). Historically, most ADC platforms have used the same DAR for all targets, regardless of target characteristics. However, recent studies and modeling suggest that the optimal DAR can depend on target expression level and intratumoral heterogeneity, target internalization and trafficking, and characteristics of the linker and payload. An ADC platform that enables DAR optimization could improve the success rate of clinical candidates. Here we report a systematic exploration of DAR across a wide range, by combining THIOMAB protein engineering technology with Dolasynthen, an auristatin-based platform with monomeric and trimeric variants. This approach enabled the generation of homogeneous, site-specific ADCs spanning a discrete range of DARs 2, 4, 6, 12, and 18 by conjugation of trastuzumab IgG1 THIOMAB constructs with 1, 2, or 3 engineered cysteines to monomeric or trimeric Dolasynthen. All ADCs had physicochemical properties that translated to excellent in vivo pharmacology. Following a single dose of ADCs in a HER2 xenograft model with moderate antigen expression, our data demonstrated comparable pharmacokinetics for the conjugates across all DARs and dose-dependent efficacy of all test articles. These results demonstrate that the Dolasynthen platform enables the generation of ADCs with a broad range of DAR values and with comparable physiochemical, pharmacologic, and pharmacokinetics profiles; thus, the Dolasynthen platform enables the empirical determination of the optimal DAR for a clinical candidate for a given target.

Chemical technology principles for selective bioconjugation of proteins and antibodies

Proteins are multifunctional large organic compounds that constitute an essential component of a living system. Hence, control over their bioconjugation impacts science at the chemistry-biology-medicine interface. A chemical toolbox for their precision engineering can boost healthcare and open a gateway for directed or precision therapeutics. Such a chemical toolbox remained elusive for a long time due to the complexity presented by the large pool of functional groups. The precise single-site modification of a protein requires a method to address a combination of selectivity attributes. This review focuses on guiding principles that can segregate them to simplify the task for a chemical method. Such a disintegration systematically employs a multi-step chemical transformation to deconvolute the selectivity challenges. It constitutes a disintegrate (DIN) theory that offers additional control parameters for tuning precision in protein bioconjugation. This review outlines the selectivity hurdles faced by chemical methods. It elaborates on the developments in the perspective of DIN theory to demonstrate simultaneous regulation of reactivity, chemoselectivity, site-selectivity, modularity, residue specificity, and protein specificity. It discusses the progress of such methods to construct protein and antibody conjugates for biologics, including antibody-fluorophore and antibody-drug conjugates (AFCs and ADCs). It also briefs how this knowledge can assist in developing small molecule-based covalent inhibitors. In the process, it highlights an opportunity for hypothesis-driven routes to accelerate discoveries of selective methods and establish new targetome in the precision engineering of proteins and antibodies.

Discovery of a novel highly specific, fully human PSCA antibody and its application as an antibody-drug conjugate in prostate cancer

Prostate stem cell antigen (PSCA) is expressed in all stages of prostate cancer, including in advanced androgen-independent tumors and bone metastasis. PSCA may associate with prostate carcinogenesis and lineage plasticity in prostate cancer. PSCA is also a promising theranostic marker for a variety of other solid tumors, including pancreatic adenocarcinoma and renal cell carcinoma. Here, we identified a novel fully human PSCA antibody using phage display methodology. The structure-based affinity maturation yielded a high-affinity binder, F12, which is highly specific and does not bind to 6,000 human membrane proteins based on a membrane proteome array assay. F12 targets PSCA amino acids 63-69 as tested by the peptide scanning microarray, and it cross-reacts with the murine PSCA. IgG1 F12 efficiently internalizes into PSCA-expressing tumor cells. The antimitotic reagent monomethyl auristatin E (MMAE)-conjugated IgG1 F12 (ADC, F12-MMAE) exhibits dose-dependent efficacy and specificity in a human prostate cancer PC-3-PSCA xenograft NSG mouse model. This is a first reported ADC based on a fully human PSCA antibody and MMAE that is characterized in a xenograft murine model, which warrants further optimizations and investigations in additional preclinical tumor models, including prostate and other solid tumors.

Targeted protein degradation through site-specific antibody conjugation with mannose 6-phosphate glycan

Recent developments in targeted protein degradation have provided great opportunities to eliminating extracellular protein targets using potential therapies with unique mechanisms of action and pharmacology. Among them, Lysosome-Targeting Chimeras (LYTACs) acting through mannose 6-phosphate receptor (M6PR) have been shown to facilitate degradation of several soluble and membrane-associated proteins in lysosomes with high efficiency. Herein we have developed a novel site-specific antibody conjugation approach to generate antibody mannose 6-phosphate (M6P) conjugates. The method uses a high affinity synthetic M6P glycan, bisM6P, that is coupled to an Fc-engineered antibody NNAS. This mutant without any effector function was generated by switching the native glycosylation site from position 297 to 298 converting non-sialylated structures to highly sialylated N-glycans. The sialic acid of the glycans attached to Asn298 in the engineered antibody was selectively conjugated to bisM6P without chemoenzymatic modification, which is often used for site-specific antibody conjugation through glycans. The conjugate is mainly homogeneous by analysis using mass spectrometry, typically with one or two glycans coupled. The M6P-conjugated antibody against a protein of interest (POI) efficiently internalized targeted soluble proteins, such as human tumor necrosis factor (TNF), in both cancer cell lines and human immune cells, through the endo-lysosomal pathway as demonstrated by confocal microscopy and flow cytometry. TNF in cell culture media was significantly depleted after the cells were incubated with the M6P-conjugated antibody. TNF internalization is mediated through M6PR, and it is correlated well with cell surface expression of cation-independent M6PR (CI-MPR) in immune cells. A significant amount of CI-MPR remains on the cell surface, while internalized TNF is degraded in lysosomes. Thus, the antibody-M6P conjugate is highly efficient in inducing internalization and subsequent lysosome-mediated protein degradation. Our platform provides a unique method for producing biologics-based degraders that may be used to treat diseases through event-driven pharmacology, thereby addressing unmet medical needs.

Current status and prospects for improved targeted delivery approaches for cancer

Millions of individuals worldwide suffer from the complicated disease known as cancer. Though they frequently have serious side effects and can harm healthy cells, the current cancer treatments, such as radiation therapy and chemotherapy, are effective in many cases. Targeted drug delivery systems have emerged as a promising new paradigm in cancer treatment because they can deliver drugs directly to cancer cells with minimal harm to healthy cells. This review aims to give a broad overview of the state of targeted drug delivery systems for cancer treatment and investigate the technology's potential in the future. We'll go through the various kinds of targeted drug delivery systems, their drawbacks, the most recent developments, and possible future paths for further study and creation. This review aims to provide an overview of the current status of targeted drug delivery systems for cancer treatment, including the different types of targeted drug delivery systems, their limitations, recent advancements, and potential future directions for research and development. By examining the field's current state and exploring prospects, this review aims to highlight the potential of targeted drug delivery systems for improving cancer treatment and ultimately enhancing patient outcomes.

Diminazene aceturate-induced cytotoxicity is associated with the deregulation of cell cycle signaling and downregulation of oncogenes Furin, c-MYC, and FOXM1 in human cervical carcinoma Hela cells

Diminazene aceturate (DIZE) is an FDA-listed small molecule known for the treatment of African sleeping sickness. In vivo studies showed that DIZE may be beneficial for a range of human ailments. However, there is very limited information on the effects of DIZE on human cancer cells. The current study aimed to investigate the cytotoxic responses of DIZE, using the human carcinoma Hela cell line. WST-1 cell proliferation assay showed that DIZE inhibited the viability of Hela cells in a dose-dependent manner and the observed response was associated with the downregulation of Ki67 and PCNA cell proliferation markers. DIZE-treated cells stained with acridine orange-ethidium and JC-10 dye revealed cell death and loss of mitochondrial membrane potential (Ψm), compared with DMSO (vehicle) control, respectively. Cellular immunofluorescence staining of DIZE-treated cells showed upregulation of caspase 3 activities. DIZE-treated cells showed downregulation of mRNA for G1/S genes CCNA2 and CDC25A, S-phase genes MCM3 and PLK4, and G2/S phase transition/mitosis genes Aurka and PLK1. These effects were associated with decreased mRNA expression of Furin, c-Myc, and FOXM1 oncogenes. These results suggested that DIZE may be considered for its effects on other cancer types. To the best of our knowledge, this is the first study to evaluate the effect of DIZE on human cervical cancer cells.

Engineering CD276/B7-H3-targeted antibody-drug conjugates with enhanced cancer-eradicating capability

CD276/B7-H3 represents a promising target for cancer therapy based on widespread overexpression in both cancer cells and tumor-associated stroma. In previous preclinical studies, CD276 antibody-drug conjugates (ADCs) exploiting a talirine-type pyrrolobenzodiazepine (PBD) payload showed potent activity against various solid tumors but with a narrow therapeutic index and dosing regimen higher than that tolerated in clinical trials using other antibody-talirine conjugates. Here, we describe the development of a modified talirine PBD-based fully human CD276 ADC, called m276-SL-PBD, that is cross-species (human/mouse) reactive and can eradicate large 500-1,000-mm3 triple-negative breast cancer xenografts at doses 10- to 40-fold lower than the maximum tolerated dose. By combining CD276 targeting with judicious genetic and chemical ADC engineering, improved ADC purification, and payload sensitivity screening, these studies demonstrate that the therapeutic index of ADCs can be substantially increased, providing an advanced ADC development platform for potent and selective targeting of multiple solid tumor types.

A CD6-targeted antibody-drug conjugate as a potential therapy for T cell-mediated disorders

The selective targeting of pathogenic T cells is a holy grail in the development of new therapeutics for T cell-mediated disorders, including many autoimmune diseases and graft versus host disease. We describe the development of a CD6-targeted antibody-drug conjugate (CD6-ADC) by conjugating an inactive form of monomethyl auristatin E (MMAE), a potent mitotic toxin, onto a mAb against CD6, an established T cell surface marker. Even though CD6 is present on all T cells, only the activated (pathogenic) T cells vigorously divide and thus are susceptible to the antimitotic MMAE-mediated killing via the CD6-ADC. We found CD6-ADC selectively killed activated proliferating human T cells and antigen-specific mouse T cells in vitro. Furthermore, in vivo, whereas the CD6-ADC had no significant detrimental effect on normal T cells in naive CD6-humanized mice, the same dose of CD6-ADC, but not the controls, efficiently treated 2 preclinical models of autoimmune uveitis and a model of graft versus host disease. These results provide evidence suggesting that CD6-ADC could be further developed as a potential therapeutic agent for the selective elimination of pathogenic T cells and treatment of many T cell-mediated disorders.

SGN-B6A: A New Vedotin Antibody-Drug Conjugate Directed to Integrin Beta-6 for Multiple Carcinoma Indications

Integrin beta-6, a component of the heterodimeric adhesion receptor alpha-v/beta-6, is overexpressed in numerous solid tumors. Its expression has been shown by multiple investigators to be a negative prognostic indicator in diverse cancers including colorectal, non-small cell lung, gastric, and cervical. We developed SGN-B6A as an antibody-drug conjugate (ADC) directed to integrin beta-6 to deliver the clinically validated payload monomethyl auristatin E (MMAE) to cancer cells. The antibody component of SGN-B6A is specific for integrin beta-6 and does not bind other alpha-v family members. In preclinical studies, this ADC has demonstrated activity in vivo in models derived from non-small cell lung, pancreatic, pharyngeal, and bladder carcinomas spanning a range of antigen expression levels. In nonclinical toxicology studies in cynomolgus monkeys, doses of up to 5 mg/kg weekly for four doses or 6 mg/kg every 3 weeks for two doses were tolerated. Hematologic toxicities typical of MMAE ADCs were dose limiting, and no significant target-mediated toxicity was observed. A phase I first-in-human study is in progress to evaluate the safety and antitumor activity of SGN-B6A in a variety of solid tumors known to express integrin beta-6 (NCT04389632).

Synergistic Approach of Antibody-Photosensitizer Conjugate Independent of KRAS-Mutation and Its Downstream Blockade Pathway in Colorectal Cancer

Here, a novel approach is presented to improve the efficacy of antibody-drug conjugates (ADC) by integrating antibody-mediated immunotherapy and photodynamic therapy (PDT) in a combination therapy system utilizing an antibody-photosensitizer conjugate (APC) platform based on a poloxamer polymer linker. To specifically target Kirsten rat sarcoma 2 viral oncogene homolog (KRAS)-mutated cancer cells, an antibody antiepidermal growth factor receptor (EGFR), cetuximab, with a poloxamer linker coupled with the photosensitizer chlorin e6 through click chemistry (cetuximab-maleimide-poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-chlorine e6 conjugate, CMPXC) is synthesized. CMPXC is cytotoxic upon laser treatment, achieving a 90% cell death by suppressing KRAS downstream signaling pathways associated with ERK and AKT proteins, confirmed using RNA sequencing analysis. In KRAS-mutated colorectal cancer mouse models, CMPXC significantly enhances antitumor efficacy compared with cetuximab treatment alone, resulting in an 86% reduction in tumor growth. Furthermore, CMPXC treatment leads to a 2.24- and 1.75-fold increase in dendritic and priming cytotoxic T cells, respectively, highlighting the immune-activating potential of this approach. The findings suggest that the APC platform addresses the challenges associated with ADC development and EGFR-targeted therapy, including the synergistic advantages of antibody-mediated immunotherapy and PDT.