Antibody-Drug Conjugates (ADCs): Navigating Four Pillars of Safety, Development, Supply Chain and Manufacturing Excellence

Antibody-drug conjugates (ADCs) are pioneering biologics that merge antibodies’ specificity with small molecules’ potency. With a handful of FDA-approved ADCs in the market and many under development, ADCs are poised to revolutionize therapeutics. This paper examines the complexities of ADC production, emphasizing the importance of process characterization and the pivotal role of supply chain characteristics, safety requirements, and Contract Manufacturing Organizations (CMOs) with proficiency. The swift transition of antibody-drug conjugate (ADC) programs from early to advanced clinical stages underscores the urgency for quick and efficient commercial launch preparation. This article delves into strategies to hasten commercial readiness, supply chain strategy, the significance of partnering with adept contract development and manufacturing organizations (CDMOs), and the challenges of ADC production.

Excellent effects and possible mechanisms of action of a new antibody–drug conjugate against EGFR-positive triple-negative breast cancer

Background:Triple-negative breast cancer(TNBC)is the most aggressive subtype and occurs in approximately 15%–20%of diagnosed breast cancers.TNBC is characterized by its highly metastatic and recurrent features,as well as a lack of specific targets and targeted therapeutics.Epidermal growth factor receptor(EGFR)is highly expressed in a variety of tumors,especially in TNBC.LR004-VC-MMAE is a new EGFR-targeting antibody–drug conjugate produced by our laboratory.This study aimed to evaluate its antitumor activities against EGFR-positive TNBC and further studied its possible mechanism of antitumor action.Methods:LR004-VC-MMAE was prepared by coupling a cytotoxic payload(MMAE)to an anti-EGFR antibody(LR004)via a linker,and the drug-to-antibody ratio(DAR)was analyzed by HIC-HPLC.The gene expression of EGFR in a series of breast cancer cell lines was assessed using a publicly available microarray dataset(GSE41313)and Western blotting.MDA-MB-468 and MDA-MB-231 cells were treated with LR004-VC-MMAE(0,0.0066,0.066,0.66,6.6 nmol/L),and the inhibitory effects of LR004-VC-MMAE on cell proliferation were examined by CCK-8 and colony formation.The migration and invasion capacity of MDA-MB-468 and MDA-MB-231 cells were tested at different LR004-VCMMAE concentrations(2.5 and 5 nmol/L)with wound healing and Transwell invasion assays.Flow cytometric analysis and tumorsphere-forming assays were used to detect the killing effects of LR004-VC-MMAE on cancer stem cells(MDA-MB-468 and MDA-MB-231 cells).The mouse xenograft models were also used to evaluate the antitumor efficacy of LR004-VC-MMAE in vivo.Briefly,BALB/c nude mice were subcutaneously inoculated with MDA-MB-468 or MDAMB-231 cells.Then they were randomly divided into 4 groups(n=6 per group)and treated with PBS,naked LR004(10 mg/kg),LR004-VC-MMAE(10 mg/kg),or doxorubicin,respectively.Tumor sizes and the body weights of mice were measured every 4 d.The effects of LR004-VC-MMAE on apoptosis and cell cycle distribution were analyzed by flow cytometry.Western blotting was used to detect the effects of LR004-VC-MMAE on EGFR,ERK,MEK phosphorylation and tumor stemness marker gene expression.Results:LR004-VC-MMAE with a DAR of 4.02 were obtained.The expression of EGFR was found to be significantly higher in TNBC cells compared with non-TNBC cells(P<0.01).LR004-VC-MMAE inhibited the proliferation of EGFRpositive TNBC cells,and the ICvalues of MDA-MB-468 and MDA-MB-231 cells treated with LR004-VC-MMAE for 72 h were(0.13±0.02)nmol/L and(0.66±0.06)nmol/L,respectively,which were significantly lower than that of cells treated with MMAE[(3.20±0.60)nmol/L,P<0.01,and(6.60±0.50)nmol/L,P<0.001].LR004-VC-MMAE effectively inhibited migration and invasion of MDA-MB-468 and MDA-MB-231 cells.Moreover,LR004-VC-MMAE also killed tumor stem cells in EGFR-positive TNBC cells and impaired their tumorsphere-forming ability.In TNBC xenograft models,LR004-VC-MMAE at 10 mg/kg significantly suppressed tumor growth and achieved complete tumor regression on day 36.Surprisingly,tumor recurrence was not observed until the end of the experiment on day 52.In a mechanistic study,we found that LR004-VC-MMAE significantly induced cell apoptosis and cell cycle arrest at G/M phase in MDAMB-468[(34±5)%vs.(12±2)%,P<0.001]and MDA-MB-231[(27±4)%vs.(18±3)%,P<0.01]cells.LR004-VC-MMAE also inhibited the activation of EGFR signaling and the expression of cancer stemness marker genes such as Oct4,Sox2,KLF4 and EpCAM.Conclusions:LR004-VC-MMAE showed effective antitumor activity by inhibiting the activation of EGFR signaling and the expression of cancer stemness marker genes.It might be a promising therapeutic candidate and provides a potential therapeutic avenue for the treatment of EGFR-positive TNBC.

Bispecific antibody drug conjugates:Making 1+1>2

Bispecific antibody‒drug conjugates(BsADCs)represent an innovative therapeutic category amalgamating the merits of antibody‒drug conjugates(ADCs)and bispecific antibodies(BsAbs).Positioned as the next-generation ADC approach,BsADCs hold promise for ameliorating extant clinical challenges associated with ADCs,particularly pertaining to issues such as poor internalization,off-target toxicity,and drug resistance.Presently,ten BsADCs are undergoing clinical trials,and initial findings underscore the imperative for ongoing refinement.This review initially delves into specific design considerations for BsADCs,encompassing target selection,antibody formats,and the linker–payload complex.Subsequent sections delineate the extant progress and challenges encountered by BsADCs,illustrated through pertinent case studies.The amalgamation of BsAbs with ADCs offers a prospective solution to prevailing clinical limitations of ADCs.Nevertheless,the symbiotic interplay among BsAb,linker,and payload necessitates further optimizations and coordination beyond a simplistic“1+1”to effectively surmount the extant challenges facing the BsADC domain.

Click chemistry and drug delivery:A bird's-eye view

Click chemistry has been proven to be very useful in drug delivery.Due to the availability of a large number of click reactions with a various characteristics,selection of appropriate chemistry for a given application is often not a trivial task.This review is written for pharmaceutical researchers who are interested in click chemistry applications and yet may not be click chemistry experts.For this,the review gives an overview of available click reactions organized by application types.Further,the general understanding of click reactions being fast and high yielding sometimes overshadows the need to analyze reaction kinetics in assessing suitability of a given reaction for certain applications.For this,we highlight the need to analyze the relationship among reaction kinetics,concentration effects,and reaction time scales,knowing that lack of such analysis could easily lead to failures.Further,possible issues such as chemical stability with various click reagents are also discussed to aid experimental designs.Recent examples and extensive references are also provided to aid in-depth understanding of technical details.We hope this review will help those interested in using click chemistry in drug delivery to select the appropriate reactions/reagents and minimize the number of pitfalls.

Treatment‐related adverse events of antibody‐drug conjugates in clinical trials:A systematic review and meta‐analysis

Background:The wide use of antibody‐drug conjugates(ADCs)is transforming the cancer‐treatment landscape.Understanding the treatment‐related adverse events(AEs)of ADCs is crucial for their clinical application.We conducted a meta‐analysis to analyze the profile and incidence of AEs related to ADC use in the treatment of solid tumors and hematological malignancies.Methods:We searched the PubMed,Embase,and Cochrane Library databases for articles published from January 2001 to October 2022.The overall profile and incidence of all‐grade and grade≥3 treatment‐related AEs were the primary outcomes of the analysis.Results:A total of 138 trials involving 15,473 patients were included in this study.The overall incidence of any‐grade treatment‐related AEs was 100.0%(95%confidence interval[CI]:99.9%–100.0%;I2=89%)and the incidence of grade≥3 treatment‐related AEs was 6.2%(95%CI:3.0%–12.4%;I2=99%).Conclusions:This study provides a comprehensive overview of AEs related to ADCs used for cancer treatment.ADC use resulted in a high incidence of any‐grade AEs but a low incidence of grade≥3 AEs.The AE profiles and incidence differed according to cancer type,ADC type,and ADC components.

Research Progress of Nectin-4 as a Targeted Therapy for Ovarian Cancer

Ovarian cancer is one of the most common gynecological malignancies. The 5-year survival rate of ovarian cancer is only 50%, which is considered to be the most lethal gynecologic malignant tumor.The high mortality of ovarian cancer patients can be attributed to chemotherapy resistance, extensive intraperitoneal metastasis and other factors.Tumor antigens are expressed on the surface of tumor cells and represent potential drug targets.One of the antigens is tumor associated nectin-4, which is a member of the immune globulin superfamily.This review highlights the role of nectin-4 as a therapeutic target for ovarian cancer, and discusses the relevant research data, which is an effective new direction in the treatment of ovarian cancer.Although there are still some challenges, targeted therapy is still a promising treatment for ovarian cancer.

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.

Recent advances of antibody drug conjugates for clinical applications

Antibody drug conjugates(ADCs)normally compose of a humanized antibody and small molecular drug via a chemical linker.After decades of preclinical and clinical studies,a series of ADCs have been widely used for treating specific tumor types in the clinic such as brentuximab vedotin(Adcetris?)for relapsed Hodgkin’s lymphoma and systemic anaplastic large cell lymphoma,gemtuzumab ozogamicin(Mylotarg?)for acute myeloid leukemia,ado-trastuzumab emtansine(Kadcyla?)for HER2-positive metastatic breast cancer,inotuzumab ozogamicin(Besponsa?)and most recently polatuzumab vedotin-piiq(Polivy?)for B cell malignancies.More than eighty ADCs have been investigated in different clinical stages from approximately six hundred clinical trials to date.This review summarizes the key elements of ADCs and highlights recent advances of ADCs,as well as important lessons learned from clinical data,and future directions.

Expert consensus on the clinical application of antibody‐drug conjugates in the treatment of malignant tumors(2021 edition)

Antibody‐drug conjugates(ADCs)are targeted biological agents composed of a cytotoxic drug linked to a monoclonal antibody through a linker.The monoclonal antibody targets tumor cells and transports small‐molecule cytotoxic drugs for specific delivery and minimal off‐target side effects.It is necessary for clinicians to understand the molecular characteristics and mechanisms of ADCs.Patients'survival mainly depends on the appropriate dose and course of treatment and also on proper management of adverse reactions.This consensus provides a systematic review of commercially available ADCs and further discusses the clinical application and management of ADCs.

Antibody drug conjugate development in gastrointestinal cancers:hopes and hurdles from clinical trials

Gastrointestinal(GI)cancers represent the leading cause of cancer-related mortality worldwide.Antibody drug conjugates(ADCs)are a rapidly growing new class of anti-cancer agents which may improve GI cancer patient survival.ADCs combine tumour-antigen specific antibodies with cytotoxic drugs to deliver tumour cell specific chemotherapy.Currently,only two ADCs[brentuximab vedotin and trastuzumab emtansine(T-DM1)]have been Food and Drug Administration approved for the treatment of lymphoma and metastatic breast cancer,respectively.Clinical research evaluating ADCs in GI cancers has shown limited success.In this review,we will retrace the relevant clinical trials investigating ADCs in GI cancers,especially ADCs targeting human epidermal growth receptor 2,mesothelin,guanylyl cyclase C,carcinogenic antigen-related cell adhesion molecule 5(also known as CEACAM5)and other GI malignancy specific targets.We will review potential hurdles for their success and provide new perspective for future treatment.

Monoclonal antibody pharmacogenomics in cancer treatment

Conventionally, in the pharmacokinetic/pharmacodynamic analysis of small molecule compounds such as cytotoxic anticancer drugs, polymorphism analysis of genes related to absorption, distribution, metabolism, and excretion has been performed in addition to the analyses of blood concentrations of drugs. Such pharmacogenetic factors play an important role in predicting therapeutic effects and adverse events and in the proper use of drugs. With the recent launch of immune checkpoint inhibitors (ICIs) and the rapid development of antibody-drug conjugates (ADCs) currently underway, there is no doubt that antibody drugs, which are large molecule compounds, will become key drugs in anticancer drug treatment. However, the pharmacokinetic and pharmacodynamic analysis of antibody drugs is still not sufficient, and further elucidation of factors and mechanisms affecting their dynamics in the human body is necessary. Moreover, the pharmacogenomic factors of antibody drugs have not yet been fully studied. There are many factors that should be clarified, such as factors that regulate the host immune response in ICI therapy and the effects of ATP-binding cassette transporter and cytochrome P450 on the payload of ADCs. This review provides an outline of antibody drugs in cancer treatment and summarizes the pharmacogenomic factors of antibody drugs known to date.