Development and validation of bioanalytical assays for the quantification of 9MW2821, a nectin-4-targeting antibody-drug conjugate

We designed and developed 9MW2821, an anti-Nectin-4 antibody-drug conjugate (ADC) with an enzymatically cleavable valine-citrulline linker and monomethyl auristatin E (MMAE) as the payload. Four bioanalytical assays for total antibodies, conjugated antibodies, conjugated payload, and free payload were then developed and validated for the comprehensive evaluation of the multiple drug forms of 9MW2821. Specific sandwich enzyme-linked immunosorbent assays were used to quantify total antibodies and conjugated antibody, showing good drug-to-antibody ratio (DAR) tolerance. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine free MMAE, and conjugated MMAE was quantified using a combination of ligand-binding assay (LBA) and LC-MS/MS. Based on these four assays, we studied the serum stability and monkey pharmacokinetic profiles of 9MW2821, and the in vivo DAR of 9MW2821 was calculated and dynamically monitored. In conclusion, we developed and validated series of bioanalytical assays to quantify multiple forms of 9MW2821, a new ADC, and used the assays to evaluate the serum stability and monkey pharmacokinetic characteristics. The results indicate good linker stability and suggest that the developed assays can be further used in clinical settings.

Bioanalytical Approaches to Support the Development of Antibody-Oligonucleotide Conjugate (AOC) Therapeutic Proteins

RNA interference (RNAi) is a biological process that evolved to protect eukaryotic organisms from foreign genes delivered by viruses. This process has been adapted as a powerful tool to treat numerous diseases through the delivery of small-interfering RNAs (siRNAs) to target cells to alter aberrant gene expression.Antibody-oligonucleotide conjugates (AOCs) are monoclonal antibodies with complexed siRNA or antisense oligonucleotides (ASOs) that have emerged to address some of the challenges faced by naked or chemically conjugated siRNA, which include rapid clearance from systemic circulation and lack of selective delivery of siRNA to target cells.It is essential to characterize the ADME properties of an AOC during development to optimize distribution to target tissues, to minimize the impact of biotransformation on exposure, and to characterize the PK/PD relationship to guide translation. However, owing to the complexity of AOC structure, this presents significant bioanalytical challenges, and multiple bioanalytical measurements are required to investigate the pharmacokinetics and biotransformation of the antibody, linker, and siRNA payload.In this paper, we describe an analytical workflow that details in vivo characterization of AOCs through measurement of their distinct molecular components to provide the basis for greater understanding of their ADME properties. Although the approaches herein can be applied to in vitro characterization of AOCs, this paper will focus on in vivo applications. This workflow relies on high-resolution mass spectrometry as the principal means of detection and leverages chromatographic, affinity-based, and enzymatic sample preparation steps.

Immunocapture LC-MS methods for pharmacokinetics of large molecule drugs

Implementation of immunocapture LC-MS methods to characterize the pharmacokinetic profile of large molecule drugs has become a widely used technique over the past decade. As the pharmaceutical industry strives for speediness into clinical development without jeopardizing quality, robust assays with generic application across the pipeline are becoming instrumental in bioanalysis, especially in early-stage development. This review highlights the capabilities and challenges involved in hybrid immunocapture LC-MS techniques and its continued applications in nonclinical and clinical pharmacokinetic assay design. This includes a comparison of LC-MS-based approaches to conventional ligand-binding assays and the driving demands in large molecule drug portfolios including growing sensitivity requirements and the unique challenges of new modalities requiring innovation in the bioanalytical laboratory.

Clinical pharmacology strategies to accelerate the development of polatuzumab vedotin and summary of key findings

The favorable benefit-risk profile of polatuzumab vedotin, as demonstrated in a pivotal Phase Ib/II randomized study (GO29365; NCT02257567), coupled with the need for effective therapies in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL), prompted the need to accelerate polatuzumab vedotin development. An integrated, fit-for-purpose clinical pharmacology package was designed to support regulatory approval. To address key clinical pharmacology questions without dedicated clinical pharmacology studies, we leveraged non-clinical and clinical data for polatuzumab vedotin, published clinical data for brentuximab vedotin, a similar antibody-drug conjugate, and physiologically based pharmacokinetic and population pharmacokinetic modeling approaches. We review strategies and model-informed outcomes that contributed to regulatory approval of polatuzumab vedotin plus bendamustine and rituximab in R/R DLBCL. These strategies made polatuzumab vedotin available to patients earlier than previously possible; depending on the strength of available data and the regulatory/competitive environment, they may also prove useful in accelerating the development of other agents.

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

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

Development and Validation of an ADA-Tolerant Assay for Quantification of an Exatecan-Based ADC in Monkey Plasma

BACKGROUND

The development of an anti-drug antibody (ADA)-tolerant pharmacokinetic (PK) assay is important when the drug exposure is irrelevant to toxicity in the presence of ADA. We aimed to develop and validate an ADA-tolerant assay for an exatecan-based antibody-drug conjugate (ADC) in monkey plasma.

RESULTS

The assay tolerated 5.00 µg/mL of ADA at 12 µg/mL of ADC. Its accuracy and precision results satisfied the acceptance criteria. Furthermore, the assay was free from hook and matrix effects and exhibited good dilutional linearity. Additionally, the ADC in plasma samples was stable under different storage conditions.

METHOD

An ADA-tolerant ADC assay was configured with an anti-payload antibody for capture, and a drug-target protein combined with a horseradish peroxidase (HRP)-labeled antibody against a drug-target-protein tag for detection. Samples were firstly acidified to dissociate drug and ADA complexes, and to convert the carboxylate form to the lactone form of exatecan molecules; then, the ADAs in the samples were removed with a naked antibody-coated microplate. The treated samples were further incubated with coated anti-payload antibody and captured ADC molecules were quantified by the detection reagent. The developed assay was optimized and validated against regulatory guidelines.

CONCLUSIONS

The assay met both methodological and sample-related ADA tolerance requirements, and was applicable to a nonclinical study in cynomolgus monkeys.

Ethnic sensitivity assessment: Polatuzumab vedotin pharmacokinetics in Asian and non-Asian patients with previously untreated diffuse large B-cell lymphoma in POLARIX

This ethnic sensitivity analysis used data from the phase III POLARIX study (NCT03274492) to assess polatuzumab vedotin pharmacokinetics (PKs) in Asian versus non-Asian patients with previously untreated diffuse large B-cell lymphoma and examined the appropriateness of extrapolating global study findings to Asian patients. PK and population PK (PopPK) analyses assessed polatuzumab vedotin analyte exposures by ethnicity (Asian [n = 84] vs. non-Asian [n = 345] patients) and region (patients enrolled from Asia [n = 80] vs. outside Asia [n = 349]). In patients from Asia versus outside Asia, observed mean antibody-conjugated monomethyl auristatin E (acMMAE) concentrations were comparable (1.2% lower at cycle [C]1 postdose, 4.4% higher at C4 predose; and 6.8% lower at C4 postdose in patients from Asia). Observed mean unconjugated MMAE was lower in patients from Asia by 6.5% (C1 postdose), 20.0% (C4 predose), and 15.3% (C4 postdose). In the PopPK analysis, C6 area under the curve and peak plasma concentrations were also comparable for acMMAE (6.3% and 3.0% lower in Asian vs. non-Asian patients, respectively) and lower for unconjugated MMAE by 19.1% and 16.7%, respectively. By region, C6 mean acMMAE concentrations were similar, and C6 mean unconjugated MMAE concentrations were lower, in patients enrolled from Asia versus outside Asia, by 3.9%-7.0% and 17.3%-19.7%, respectively. In conclusion, polatuzumab vedotin PKs were similar between Asian and non-Asian patients by ethnicity and region, suggesting PKs are not sensitive to Asian ethnicity and dose adjustments are not required in Asian patients to maintain efficacy and safety.

Development of a semi-automated MHC-associated peptide proteomics (MAPPs) method using streptavidin bead-based immunoaffinity capture and nano LC-MS/MS to support immunogenicity risk assessment in drug development

Major histocompatibility complex (MHC)-Associated Peptide Proteomics (MAPPs) is an ex vivo method used to assess the immunogenicity risk of biotherapeutics. MAPPs can identify potential T-cell epitopes within the biotherapeutic molecule. Using adalimumab treated human monocyte derived dendritic cells (DCs) and a pan anti-HLA-DR antibody (Ab), we systematically automated and optimized biotin/streptavidin (SA)-capture antibody coupling, lysate incubation with capture antibody, as well as the washing and elution steps of a MAPPs method using functionalized magnetic beads and a KingFisher Magnetic Particle processor. Automation of these steps, combined with capturing using biotinylated-Ab/SA magnetic beads rather than covalently bound antibody, improved reproducibility as measured by minimal inter-and intra-day variability, as well as minimal analyst-to-analyst variability. The semi-automated MAPPs workflow improved sensitivity, allowing for a lower number of cells per analysis. The method was assessed using five different biotherapeutics with varying immunogenicity rates ranging from 0.1 to 48% ADA incidence in the clinic. Biotherapeutics with ≥10%immunogenicity incidence consistently presented more peptides (1.8-28 fold) and clusters (10-21 fold) compared to those with <10% immunogenicity incidence. Our semi-automated MAPPs method provided two main advantages over a manual workflow- the robustness and reproducibility affords confidence in the epitopes identified from as few as 5 to 10 donors and the method workflow can be readily adapted to incorporate different capture Abs in addition to anti-HLA-DR. The incorporation of semi-automated MAPPs with biotinylated-Ab/SA bead-based capture in immunogenicity screening strategies allows the generation of more consistent and reliable data, helping to improve immunogenicity prediction capabilities in drug development. MHC associated peptide proteomics (MAPPs), Immunogenicity risk assessment, in vitro/ex vivo, biotherapeutics, Major Histocompatibility Complex Class II (MHC II), LC-MS, Immunoaffinity Capture, streptavidin magnetic beads.

Pharmacokinetics and toxicity considerations for antibody-drug conjugates: an overview

Antibody-drug conjugates (ADCs) is one of the fastest-growing drug-delivery systems. It involves a monoclonal antibody conjugated with payload via a ligand that directly targets the expressive protein of diseased cell. Hence, it reduces systemic exposure and provides site-specific delivery along with reduced toxicity. Because of this advantage, researchers have gained interest in this novel system. ADCs have displayed great promise in drug delivery and biomedical applications. However, a lack of understanding exists on their mechanisms of biodistribution, metabolism and side effects. To gain a better understanding of the therapeutics, careful consideration of the pharmacokinetics and toxicity needs to be undertaken. In this review, different pharmacokinetics parameters including distribution, bioanalysis and heterogeneity are discussed for developing novel therapeutics.

Hybrid liquid chromatography high resolution and accuracy mass spectrometry approach for quantification of antibody-drug conjugates at the intact protein level in biological samples

Preclinical in vivo and in vitro characterization of Antibody-Drug Conjugates (ADCs) involves the development of several bioanalytical methods to address many drug exposure questions. The current pharma industry approach requires at least three different assays that must be run, i.e., total antibody (mAb), conjugated payload or conjugated mAb, and free payload assays. Herein we present analytical performances of a quantitative hybrid Ligand Binding/Liquid Chromatography High Resolution and Accuracy Mass Spectrometry (LB/LCHRAM) method that can condense much of the necessary bioanalytical information in one method. The method includes an immuno-capture step, and it detects whole ADC molecules. It was applied to plasma mouse samples and showed reliable bioanalytical performance according to full method validation standards. Quantitation using extracted ion chromatograms and deconvoluted mass peaks was evaluated. The limit of quantitation resulted in 0.5ng of protein on column with a linear dynamic range spanning from 0.5 to 10μg/mL. Moreover, lower drug-to-antibody ratio (DAR) ADC species can be simultaneously detected, also enabling qualitative characterization of in vivo ADC conjugation.

Enhanced Pharmacokinetic Bioanalysis of Antibody-drug Conjugates using Hybrid Immunoaffinity Capture and Microflow LC-MS/MS

The increasing complexity and diversity of antibody-drug conjugates (ADCs) have led to a need for comprehensive and informative bioanalytical methods to enhance pharmacokinetic (PK) understanding. This study aimed to evaluate the feasibility of a hybrid immunoaffinity (IA) capture microflow LC-MS/MS (μLC-MS/MS) method for ADC analysis, utilizing a minimal sample volume for PK assessments in a preclinical study. A robust workflow was established for the quantitative analysis of ADCs by the implementation of solid-phase extraction (SPE) and semi-automation in µLC-MS/MS. Utilizing the µLC-MS/MS approach in conjunction with 1 µL of ADC-dosed mouse plasma sample volume, standard curves of two representative surrogate peptides for total antibody (heavy chain, HC) and intact antibody (light chain, LC) ranged from 1.00 ng/mL (LLOQ) to 5000 ng/mL with correlation coefficients (r2) values of > 0.99. The linear range of the standard curve for payload as a surrogate for the concentration of total ADC was from 0.5 ng/mL (LLOQ) to 2000 ng/mL with high accuracy and precision (< 10% CV at all concentrations). Moreover, a high correlation of concentrations of total antibody between two assay approaches (µLC-MS and ELISA) was achieved with less than 20% difference at all time points, indicating that the two methods are comparable in quantitation of total antibody in plasma samples. The µLC-MS platform demonstrated a greater dynamic range, sensitivity, robustness, and good reproducibility. These findings demonstrated that the cost-effective µLC-MS method can reduce reagent consumption and minimize the use of mice plasma samples while providing more comprehensive information about ADCs being analyzed, including the total antibody, intact antibody, and total ADC.

Detection of antibody-conjugate payload in cynomolgus monkey serum by a high throughput capture LC-MS/MS bioanalysis method

Antibody-drug conjugate (ADC) plays a vital role in oncology indications. The efficacy and toxicity of ADC generally depend on the concentration of the drugs in the body system, and physiologically-based pharmacokinetic (P.K.) is a quantitative tool to understand the drug concentration in the body. To characterize the whole drug carefully, sophisticated bioanalysis was required. ADC bioanalysis generally needs multiple analysis strategies, which can accurately quantify total antibody (TAb), antibody-drug conjugate (ADC), antibody-conjugate payload (ac-payload), and free-payload. In this work, we mainly described and validated a high throughput capture Liquid Chromatography tandem-Mass Spectrometry (LC-MS/MS) bioanalysis method to detect the concentrations of ac-payload (such as MMAE) in cynomolgus monkey serum. This method was allowed to determinate the Drug to Antibody Ratio (DAR), obtained by n of ac-payload/ n of TAb. In addition, the technique could significantly improve the throughput of the pre-coated antibody on a 96-well plate. Besides, this method had no interference or carryover in endogenous substances and showed linearity (R² ≥0.99) in the concentration range within 15.6-2000.0 ng/mL. The inter-run accuracy ranged from 75.8 % to 120.0 %, and precision was within ≤ 20.0 %. Meanwhile, selectivity and the benchtop stability of the method were also validated. This optimization method was successfully applied to the change of average DAR in P.K. study.

Integrated summary of immunogenicity of polatuzumab vedotin in patients with relapsed or refractory B-cell non-Hodgkin’s lymphoma

Polatuzumab vedotin, marketed under the trade name POLIVY®, is a CD79b-targeted antibody-drug conjugate that preferentially delivers a potent anti-mitotic agent (monomethyl auristatin E) to B cells, resulting in anti-cancer activity against B-cell malignancies. In 2019, polatuzumab vedotin in combination with rituximab and bendamustine was approved by the United States Food and Drug Administration for the treatment of adult patients with diffuse large B-cell lymphoma who have received at least two prior therapies. Recent Health Authority guidance recommendations for submitting an Integrated Summary of Immunogenicity were followed including a comprehensive immunogenicity risk assessment, bioanalytical strategy, and immunogenicity data to support the registration of polatuzumab vedotin. Key components of the polatuzumab vedotin Integrated Summary of Immunogenicity and data are presented. Validated semi-homogeneous bridging enzyme-linked immunosorbent assays were used to detect anti-drug antibodies (ADA) to polatuzumab vedotin and characterize the immune response in patients with non-Hodgkin’s lymphoma. The overall incidence of ADA observed for polatuzumab vedotin was low across seven clinical trials. The low incidence of ADA is likely due to the mechanism of action of polatuzumab vedotin that involves targeting and killing of B cells, thereby limiting the development to plasma cells and ADA secretion. Furthermore, patients are co-medicated with rituximab, which also targets B cells and results in B-cell depletion. Therefore, the immunogenicity risk is considered low and not expected to impact the polatuzumab vedotin benefit/risk profile.

Implementation of Systematic Bioanalysis of Antibody–Drug Conjugates for Preclinical Pharmacokinetic Study of Ado-Trastuzumab Emtansine (T-DM1) in Rats

Antibody–drug conjugates (ADCs) are composed of monoclonal antibodies covalently bound to cytotoxic drugs by a linker. They are designed to selectively bind target antigens and present a promising cancer treatment without the debilitating side effects of conventional chemotherapies. Ado-trastuzumab emtansine (T-DM1) is an ADC that received US FDA approval for the treatment of HER2-positive breast cancer. The purpose of this study was to optimize methods for the quantification of T-DM1 in rats. We optimized four analytical methods: (1) an enzyme-linked immunosorbent assay (ELISA) to quantify the total trastuzumab levels in all drug-to-antibody ratios (DARs), including DAR 0; (2) an ELISA to quantify the conjugated trastuzumab levels in all DARs except DAR 0; (3) an LC–MS/MS analysis to quantify the levels of released DM1; and (4) a bridging ELISA to quantify the level of anti-drug antibodies (ADAs) of T-DM1. We analyzed serum and plasma samples from rats injected intravenously with T-DM1 (20 mg/kg, single dose) using these optimized methods. Based on these applied analytical methods, we evaluated the quantification, pharmacokinetics, and immunogenicity of T-DM1. This study establishes the systematic bioanalysis of ADCs with validated assays, including drug stability in matrix and ADA assay, for future investigation on the efficacy and safety of ADC development.

Current Analytical Strategies for Antibody–Drug Conjugates in Biomatrices

Antibody–drug conjugates (ADCs) are a new class of biotherapeutics, consisting of a cytotoxic payload covalently bound to an antibody by a linker. Ligand-binding assay (LBA) and liquid chromatography-mass spectrometry (LC-MS) are the favored techniques for the analysis of ADCs in biomatrices. The goal of our review is to provide current strategies related to a series of bioanalytical assays for pharmacokinetics (PK) and anti-drug antibody (ADA) assessments. Furthermore, the strengths and limitations of LBA and LC-MS platforms are compared. Finally, potential factors that affect the performance of the developed assays are also provided. It is hoped that the review can provide valuable insights to bioanalytical scientists on the use of an integrated analytical strategy involving LBA and LC–MS for the bioanalysis of ADCs and related immunogenicity evaluation.

ADME and DMPK considerations for the discovery and development of antibody drug conjugates (ADCs)

 The therapeutic concept of antibody drug conjugates (ADCs) is to selectively target tumour cells with small molecule cytotoxic drugs to maximise cell kill benefit and minimise healthy tissue toxicity.An ADC generally consists of an antibody that targets a protein on the surface of tumour cells chemically linked to a warhead small molecule cytotoxic drug.To deliver the warhead to the tumour cell, the antibody must bind to the target protein and in general be internalised into the cell. Following internalisation, the cytotoxic agent can be released in the endosomal or lysosomal compartment (via different mechanisms). Diffusion or transport out of the endosome or lysosome allows the cytotoxic drug to express its cell-killing pharmacology. Alternatively, some ADCs (e.g. EDB-ADCs) rely on extracellular cleavage releasing membrane permeable warheads.One potentially important aspect of the ADC mechanism is the 'bystander effect' whereby the cytotoxic drug released in the targeted cell can diffuse out of that cell and into other (non-target expressing) tumour cells to exert its cytotoxic effect. This is important as solid tumours tend to be heterogeneous and not all cells in a tumour will express the targeted protein.The combination of large and small molecule aspects in an ADC poses significant challenges to the disposition scientist in describing the ADME properties of the entire molecule.This article will review the ADC landscape and the ADME properties of successful ADCs, with the aim of outlining best practice and providing a perspective of how the field can further facilitate the discovery and development of these important therapeutic modalities.

Recent Advances in Translational Pharmacokinetics and Pharmacodynamics Prediction of Therapeutic Antibodies Using Modeling and Simulation

Therapeutic monoclonal antibodies (mAbs) have been a promising therapeutic approach for several diseases and a wide variety of mAbs are being evaluated in clinical trials. To accelerate clinical development and improve the probability of success, pharmacokinetics and pharmacodynamics (PKPD) in humans must be predicted before clinical trials can begin. Traditionally, empirical-approach-based PKPD prediction has been applied for a long time. Recently, modeling and simulation (M&S) methods have also become valuable for quantitatively predicting PKPD in humans. Although several models (e.g., the compartment model, Michaelis–Menten model, target-mediated drug disposition model, and physiologically based pharmacokinetic model) have been established and used to predict the PKPD of mAbs in humans, more complex mechanistic models, such as the quantitative systemics pharmacology model, have been recently developed. This review summarizes the recent advances and future direction of M&S-based approaches to the quantitative prediction of human PKPD for mAbs.

Development of a Physiologically-Based Pharmacokinetic Model for Whole-Body Disposition of MMAE Containing Antibody-Drug Conjugate in Mice

PURPOSE

To quantitate and mathematically characterize the whole-body pharmacokinetics (PK) of different ADC analytes following administration of an MMAE-conjugated ADC in tumor-bearing mice.

METHODS

The PK of different ADC analytes (total antibody, total drug, unconjugated drug) was measured following administration of an MMAE-conjugated ADC in tumor-bearing mice. The PK of ADC analytes was compared with the whole-body PK of the antibody and drug obtained following administration of these molecules alone. An ADC PBPK model was developed by linking antibody PBPK model with small-molecule PBPK model, where the drug was assumed to deconjugate in DAR-dependent manner.

RESULTS

Comparison of antibody biodistribution coefficient (ABC) values for total antibody suggests that conjugation of drug did not significantly affect the PK of antibody. Comparison of tissue:plasma AUC ratio (T/P) for the conjugated drug and total antibody suggests that in certain tissues (e.g., spleen) ADC may demonstrate higher deconjugation. It was observed that the tissue distribution profile of the drug can be altered following its conjugation to antibody. For example, MMAE distribution to the liver was found to increase while its distribution to the heart was found to decrease upon conjugation to antibody. MMAE exposure in the tumor was found to increase by ~20-fold following administration as conjugate (i.e., ADC). The PBPK model was able to a priori predict the PK of all three ADC analytes in plasma, tissues, and tumor reasonably well.

CONCLUSIONS

The ADC PBPK model developed here serves as a platform for translational and clinical investigations of MMAE containing ADCs.

Multiplexed Quantitative Analysis of Antibody-Drug Conjugates with Labile CBI-Dimer Payloads In Vivo Using Immunoaffinity LC-MS/MS

Quantitative analysis of antibody-drug conjugates (ADCs) involves cleavage of ADCs into smaller analytes representing different components and subsequent measurements from multiple assays for a more comprehensive pharmacokinetic (PK) assessment. Multiple PK analytes including the drug remaining conjugated to the antibody (or antibody-conjugated drug, acDrug) and total antibody can be accessed simultaneously using a multiplex assay by proteolytic digestion of an ADC, if the sites of conjugation are homogeneous for an ADC and the linker drug is stable to proteases. Herein, a multiplexed immunoaffinity liquid chromatography-mass spectrometry (LC-MS)/MS PK assay is described involving immunoaffinity enrichment, enzymatic conversion of prodrug, trypsin digestion, and LC-MS/MS as applied to next-generation ADCs constructed from linker drugs bearing dimeric cyclopropabenzindole (CBI) payloads (duocarmycin analogues). The cytotoxic payload is chemically labile, requiring extensive optimization in sample preparation steps to stabilize the drug without ex vivo modification and to convert the prodrug into a single active form of the drug. The qualification data for this assay format showed that this approach provides robust acDrug and total antibody data and can be extended to ADCs with different monoclonal antibody frameworks and linker chemistries. Applications of this multiplexed assay to support preclinical studies are presented.

Enzyme-linked immunosorbent assays for quantification of MMAE-Conjugated ADCs and total antibodies in cynomolgus monkey sera

Antibody-drug conjugates (ADCs) are commonly heterogeneous and require extensive assessment of exposure-efficacy and exposure-safety relationships in preclinical and clinical studies. In this study, we report the generation of a monoclonal antibody against monomethyl auristatin E (MMAE) and the development, validation, and application of sensitive and high-throughput enzyme-linked immunosorbent assays (ELISA) to measure the concentrations of MMAE-conjugated ADCs and total antibodies (tAb, antibodies in ADC plus unconjugated antibodies) in cynomolgus monkey sera. These assays were successfully applied to in vitro plasma stability and pharmacokinetic (PK) studies of SMADC001, an MMAE-conjugated ADC against trophoblast cell surface antigen 2 (TROP-2). The plasma stability of SMADC001 was better than that of similar ADCs coupled with PEG4-Val-Cit, Lys (m-dPEG24)-Cit, and Val-Cit linkers. The developed ELISA methods for the calibration standards of ADC and tAb revealed a correlation between serum concentrations and the OD₄₅₀ values, with R² at 1.000, and the dynamic range was 0.3–35.0 ng/mL and 0.2–22.0 ng/mL, respectively; the intra- and inter-assay accuracy bias% ranged from −12.2% to −5.2%, precision ranged from −12.4% to −1.4%, and the relative standard deviation (RSD) was less than 6.6% and 8.7%, respectively. The total error was less than 20.4%. The development and validation steps of these two assays met the acceptance criteria for all addressed validation parameters, which suggested that these can be applied to quantify MMAE-conjugated ADCs, as well as in PK studies. Furthermore, these assays can be easily adopted for development of other similar immunoassays.

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A specific monoclonal antibody against MMAE was generated via hybridoma technology.

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ELISA was used to quantify MMAE-ADCs with a calibration range of 0.5–35 ng/mL.

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ELISA was used to quantify total antibodies with a calibration range of 0.6–22 ng/mL.

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Pharmacokinetic profiles of SMADC001 in cynomolgus monkeys were investigated.

Introduction to Antibody-Drug Conjugates

Antibody-drug conjugates (ADCs) are innovative biopharmaceutical products in which a monoclonal antibody is linked to a small molecule drug with a stable linker. Most of the ADCs developed so far are for treating cancer, but there is enormous potential for using ADCs to treat other diseases. Currently, ten ADCs have been approved by the United States Food and Drug Administration (FDA), and more than 90 ADCs are under worldwide clinical development. Monoclonal antibodies have evolved from research tools to powerful therapeutics in the past 30 years. Tremendous strides have been made in antibody discovery, protein bioengineering, formulation, and delivery devices. This manuscript provides an overview of the biology, chemistry, and biophysical properties of each component of ADC design. This review summarizes the advances and challenges in the field to date, with an emphasis on antibody conjugation, linker-payload chemistry, novel payload classes, drug-antibody ratio (DAR), and product development. The review emphasizes the lessons learned in the development of oncology antibody conjugates and look towards future innovations enabling other therapeutic indications. The review discusses resistance mechanisms to ADCs, and give an opinion on future perspectives.

Risk-Based Pharmacokinetic and Drug-Drug Interaction Characterization of Antibody-Drug Conjugates in Oncology Clinical Development: An International Consortium for Innovation and Quality in Pharmaceutical Development Perspective

Antibody-drug conjugates (ADCs) represent a rapidly evolving area of drug development and hold significant promise. To date, nine ADCs have been approved by the US Food and Drug Administration (FDA). These conjugates combine the target specificity of monoclonal antibodies with the anticancer activity of small-molecule therapeutics (also referred to as payload). Due to the complex structure, three analytes, namely ADC conjugate, total antibody, and unconjugated payload, are typically quantified during drug development; however, the benefits of measuring all three analytes at later stages of clinical development are not clear. The cytotoxic payloads, upon release from the ADC, are considered to behave like small molecules. Given the relatively high potency and low systemic exposure of cytotoxic payloads, drug-drug interaction (DDI) considerations for ADCs might be different from traditional small molecule therapeutics. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ Consortium) convened an ADC working group to create an IQ ADC database that includes 26 ADCs with six unique payloads. The analysis of the ADC data in the IQ database, as well as nine approved ADCs, supports the strategy of pharmacokinetic characterization of all three analytes in early-phase development and progressively minimizing the number of analytes to be measured in the late-phase studies. The systemic concentrations of unconjugated payload are usually too low to serve as a DDI perpetrator; however, the potential for unconjugated payloads as a victim still exists. A data-driven and risk-based decision tree was developed to guide the assessment of a circulating payload as a victim of DDI.

Overcoming challenges associated with the bioanalysis of cysteine-conjugated metabolites in the presence of antibody-drug conjugates

Aim: Investigations have shown that for the antibody-drug conjugate (ADC) belantamab mafodotin, concentrations of the cysteine-conjugated metabolite, Cys-mcMMAF, were overestimated in the presence of the ADC during sample processing when utilizing a historical SPE method. Results: A new assay was developed utilizing an acidic protein precipitation to remove the ADC early in the extraction process, thus eliminating the risk of overestimating Cys-mcMMAF in the presence of belantamab mafodotin. In vitro experiments demonstrated a linear relationship between the concentration of belantamab mafodotin and the release of Cys-mcMMAF. Extensive stability assessments were performed to cover storage of study samples. Conclusion: This work emphasized the critical importance of understanding the performance of a bioanalytical method for free toxic payload in the presence of the ADC.

Impact of Physiologically Based Pharmacokinetics, Population Pharmacokinetics and Pharmacokinetics/Pharmacodynamics in the Development of Antibody-Drug Conjugates

Antibody‐drug conjugates are important molecular entities in the treatment of cancer, with 8 antibody‐drug conjugates approved by the US Food and Drug Administration since 2000 and many more in early‐ and late‐stage clinical development. These conjugates combine the target specificity of monoclonal antibodies with the potent anticancer activity of small‐molecule therapeutics. The complex structure of antibody‐drug conjugates poses unique challenges to pharmacokinetic (PK) and pharmacodynamic (PD) characterization because it requires a quantitative understanding of the PK and PD properties of multiple different molecular species (eg, conjugate, total antibody, and unconjugated payload) in different tissues. Quantitative clinical pharmacology using mathematical modeling and simulation provides an excellent approach to overcome these challenges, as it can simultaneously integrate the disposition, PK, and PD of antibody‐drug conjugates and their components in a quantitative manner. In this review, we highlight diverse quantitative clinical pharmacology approaches, ranging from system models (eg, physiologically based pharmacokinetic [PBPK] modeling) to mechanistic and empirical models (eg, population PK/PD modeling for single or multiple analytes, exposure‐response modeling, platform modeling by pooling data across multiple antibody‐drug conjugates). The impact of these PBPK and PK/PD models to provide insights into clinical dosing justification and inform drug development decisions is also highlighted.

First-in-Human Study of PF-06647020 (Cofetuzumab Pelidotin), an Antibody-Drug Conjugate Targeting Protein Tyrosine Kinase 7, in Advanced Solid Tumors

PURPOSE

We investigated safety, tolerability, pharmacokinetics, and antitumor activity of the protein tyrosine kinase 7 (PTK7)-targeted, auristatin-based antibody-drug conjugate (ADC) PF-06647020/cofetuzumab pelidotin (NCT02222922).

PATIENTS AND METHODS

Patients received PF-06647020 intravenously every 3 weeks at 0.2-3.7 mg/kg or every 2 weeks at 2.1-3.2 mg/kg, in sequential dose escalation, following a modified toxicity probability interval method. In dose expansion, pretreated patients with advanced, platinum-resistant ovarian cancer, non-small cell lung cancer (NSCLC), or triple-negative breast cancer (TNBC) received PF-06647020 2.8 mg/kg every 3 weeks.

RESULTS

The most common, treatment-related adverse events for PF-06647020 administered every 3 weeks were nausea, alopecia, fatigue, headache, neutropenia, and vomiting (45%-25%); 25% of patients had grade ≥ 3 neutropenia. Two patients experienced dose-limiting toxicities (grade 3 headache and fatigue) at the highest every 3 weeks dose evaluated. The recommended phase II dose was 2.8 mg/kg every 3 weeks. The overall safety profile observed with PF-06647020 administered every 2 weeks was similar to that of the every 3 weeks regimen. Systemic exposure for the ADC and total antibody generally increased in a dose-proportional manner. Antitumor activity was observed in treated patients with overall objective response rates of 27% in ovarian cancer (n = 63), 19% in NSCLC (n = 31), and 21% in TNBC (n = 29). Responders tended to have moderate or high PTK7 tumor expression by IHC.

CONCLUSIONS

This PTK7-targeted ADC demonstrated therapeutic activity in previously treated patients with ovarian cancer, NSCLC, and TNBC at a dose range of 2.1-3.2 mg/kg, supporting further clinical evaluation to refine dose, schedule, and predictive tissue biomarker testing in patients with advanced malignancies.

A phase 2 study of polatuzumab vedotin + bendamustine + rituximab in relapsed/refractory diffuse large B-cell lymphoma

Polatuzumab vedotin (pola) is a CD79b‐targeted antibody‐drug conjugate delivering a potent antimitotic agent (monomethyl auristatin E) to B cells. This was an open‐label, single‐arm study of pola 1.8 mg/kg, bendamustine 90 mg/m², rituximab 375 mg/m² (pola + BR) Q3W for up to six cycles in patients with relapsed/refractory (R/R) diffuse large B‐cell lymphoma (DLBCL) who received ≥1 prior line of therapy and were ineligible for autologous stem cell transplantation (ASCT) or experienced treatment failure with prior ASCT. Primary endpoint was complete response rate (CRR) at the end of the treatment (EOT) by positron emission tomography–computed tomography (PET‐CT) using modified Lugano Response Criteria. Secondary endpoints included efficacy, safety, and pharmacokinetics. Thirty‐five patients (median age 71 [range 46‐86] years) were enrolled. Twenty‐three (66%) patients had refractory disease, and 23 (66%) had ≥2 prior lines of therapy. At a median follow‐up of 5.4 (0.7‐11.9) months, patients received a median of five treatment cycles. CRR was 34.3% (95% confidence interval [CI] 19.1‐52.2) at EOT. Overall response rate was 42.9% at EOT, and median progression‐free survival was 5.2 months (95% CI 3.6‐not evaluable). Median overall survival was not reached. No fatal adverse events (AEs) were observed. Grade 3‐4 AEs were mainly hematological: anemia (37%), neutropenia (31%), white blood cell count decreased (23%), thrombocytopenia/platelet count decreased/neutrophil count decreased (20% each), and febrile neutropenia (11%). Grade 1‐2 peripheral neuropathy (PN; sensory and/or motor) was reported in 14% of patients; there were no ≥grade 3 PN events. This study (JapicCTI‐184048) demonstrated the efficacy and safety of pola + BR in Japanese patients with R/R DLBCL who were ineligible for ASCT.

The role of ligand-binding assay and LC-MS in the bioanalysis of complex protein and oligonucleotide therapeutics

Ligand-binding assay (LBA) and LC-MS have been the preferred bioanalytical techniques for the quantitation and biotransformation assessment of various therapeutic modalities. This review provides an overview of the applications of LBA, LC-MS/MS and LC-HRMS for the bioanalysis of complex protein therapeutics including antibody-drug conjugates, fusion proteins and PEGylated proteins as well as oligonucleotide therapeutics. The strengths and limitations of LBA and LC-MS, along with some guidelines on the choice of appropriate bioanalytical technique(s) for the bioanalysis of these therapeutic modalities are presented. With the discovery of novel and more complex therapeutic modalities, there is an increased need for the biopharmaceutical industry to develop a comprehensive bioanalytical strategy integrating both LBA and LC-MS.

Characterization of Antibody-Drug Conjugate Pharmacokinetics and in Vivo Biotransformation Using Quantitative Intact LC-HRMS and Surrogate Analyte LC-MRM

Antibody-drug conjugates (ADCs) pose challenges to bioanalysis because of their inherently intricate structures and potential for very complex catabolism. Common bioanalysis strategy is to measure the concentration of ADCs and Total Antibody (Ab) as well as deconjugated warhead in circulation. The ADCs and the Total Ab can be quantified with ligand binding assays (LBA) or with hybrid immunocapture-liquid chromatography coupled with multiple reaction monitoring mass spectrometry (LBA-LC-MRM). With the LBA-LC-MRM approach, a surrogate analyte, often the signature peptide, and released warhead can be used for the quantification of the Total Ab and ADCs, respectively. Recent advances in analytical instrumentation, especially the development of high resolution mass spectrometers (HRMS), have enabled characterization and quantification of intact macromolecules such as ADCs. The LBA-LC-HRMS approach employs immunocapture, followed by chromatographic separation at the macromolecule level and detection of the intact analyte. We developed an intact quantification method with 1-10 μg/mL linear dynamic range using 25 μL of plasma sample volume. This method was qualified for the measurement of naked monoclonal antibody (mAb), a site-specific cysteine-conjugated ADC with drug to antibody ratio ∼2 (DAR2) and a site-nonspecific cysteine-conjugated ADC (DAR8) in rat plasma. Samples from a rat pharmacokinetic (PK) study were analyzed with both methods. For the naked mAb, the results from both assays matched well. For ADCs, new species were observed from the LBA-HRMS method. The results demonstrated that potential biotransformation of the ADC was unveiled using the intact quantification approach while not being observed with traditional LBA-LC-MRM approach. Our work demonstrated an application of novel intact quantification by supporting animal PK studies. Moreover, our results suggest that the intact quantification method can provide novel perspectives on ADC in vivo characterization and quantification, which can benefit future drug candidate optimization as well as the immunogenicity impact evaluation and safety assessment.

Clinical pharmacology strategies in supporting drug development and approval of antibody-drug conjugates in oncology

Antibody–drug conjugates (ADCs) are important molecular entities in the treatment of cancer. These conjugates combine the target specificity of monoclonal antibodies with the potent anti-cancer activity of small-molecule therapeutics. The complex structure of ADCs poses unique challenges to characterize the drug’s pharmacokinetics (PKs) and pharmacodynamics (PDs) since it requires a quantitative understanding of the PK and PD properties of multiple different molecular species (e.g., ADC conjugate, total antibody and unconjugated cytotoxic drug). As a result, clinical pharmacology strategy of an ADC is rather unique and dependent on the linker/cytotoxic drug technology, heterogeneity of the ADC, PK and safety/efficacy profile of the specific ADC in clinical development. In this review, we summarize the clinical pharmacology strategies in supporting development and approval of ADCs using the approved ADCs as specific examples to illustrate the customized approach to clinical pharmacology assessments in their clinical development.

What makes a good antibody-drug conjugate?

Introduction: Antibody-Drug Conjugates (ADCs) are becoming increasingly important weapons in the fight against cancer, as evidenced by the growing number of approved products. The complex nature of an ADC means that there is a vast array of choices to consider in the design of such drugs.Areas covered: We provide an overview of developments in each facet of ADC structure: the antibody, linker, and payload. Looking at the current clinical landscape, we discuss trends that have led to the evolution of ADC design.Expert opinion:Following a history of setbacks and high discontinuation rates, the understanding of the ADC field has grown. If developers can obtain a firm grasp of the structure-function relationship of their molecule, we expect the advances in ADC design to translate to improved clinical success. Moreover, the breadth of ADC applications will continue to expand to target new indications with novel targets and payloads.

Impact of Drug Conjugation and Loading on Target Antigen Binding and Cytotoxicity in Cysteine Antibody-Drug Conjugates

Antibody-drug conjugates (ADCs) consist of a target-specific antibody that is covalently conjugated to a drug via a linker. ADCs are designed to deliver cytotoxic drugs (payloads), specifically to cancer cells, while minimizing systemic toxicity. Conventional cysteine conjugation typically results in the formation of ADC molecules containing a heterogeneous mixture of 2, 4, 6, and 8 drug-loaded species. The drug-to-antibody ratio (DAR) of the mixture represents the weighted average of these species. In this report, we have investigated the impact of the hydrophobicity of payloads and the overall drug loading on the in vitro binding and cytotoxicity of ADC species. Several ADCs were prepared by conventional cysteine conjugation using different payloads. ADC species with different DAR values were purified from the ADC mixture and characterized by standard analytical techniques. These ADC species were evaluated for target antigen binding using an immunoassay, enzyme-linked immunosorbent assay (ELISA). The potency was assessed using a cell-based cytotoxicity assay. These structure-function studies lead to a better understanding of factors that impact the in vitro target binding and cytotoxicity of ADC species. ADC species containing hydrophobic payloads with high DAR were found to have lower target binding by ELISA compared to that of the unconjugated antibody or the heterogeneous reference ADC with DAR ∼4. Under similar assay conditions, the ADCs conjugated to hydrophilic payloads did not show a significant impact on the target binding. The cytotoxic potency of ADC species increased with increasing level of drug loading in the cell-based cytotoxicity assay.

Assessments of the In Vitro and In Vivo Linker Stability and Catabolic Fate for the Ortho Hydroxy-Protected Aryl Sulfate Linker by Immuno-Affinity Capture Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometric Assay

Antibody-drug conjugate (ADC) linkers play an important role in determining the safety and efficacy of ADC. The Ortho Hydroxy-Protected Aryl Sulfate (OHPAS) linker is a newly developed linker in the form of a di-aryl sulfate structure consisting of phenolic payload and self-immolative group (SIG). In this study, using two bioanalytical approaches (namely "bottom-up" and "middle-up" approaches) via the liquid chromatography-quadrupole time-of-flight mass spectrometric (LC-qTOF-MS) method, in vitro and in vivo linker stability experiments were conducted for the OHPAS linker. For comparison, the valine-citrulline-p-aminobenzyloxycarbonyl (VC-PABC) linker was also evaluated under the same experimental conditions. In addition, the catabolite identification experiments at the subunit intact protein level were simultaneously performed to evaluate the catabolic fate of ADCs. As a result, the OHPAS linker was stable in the in vitro mouse/human plasma as well as in vivo pharmacokinetic studies in mice, whereas the VC-PABC linker was relatively unstable in mice in vitro and in vivo. This is because the VC-PABC linker was sensitive to a hydrolytic enzyme called carboxylesterase 1c (Ces1c) in mouse plasma. In conclusion, the OHPAS linker appears to be a good linker for ADC, and further experiments would be warranted to demonstrate the efficacy and toxicity related to the OHPAS linker.

Clinical pharmacology of vc-MMAE antibody-drug conjugates in cancer patients: learning from eight first-in-human Phase 1 studies

vc-MMAE antibody–drug conjugates (ADCs) consist of a monoclonal antibody (mAb) covalently bound with a potent anti-mitotic toxin (MMAE) through a protease-labile valine-citrulline (vc) linker. The objective of this study was to characterize the pharmacokinetics (PK) and explore exposure–response relationships of eight vc-MMAE ADCs, against different targets and for diverse tumor indications, using data from eight first-in-human Phase 1 studies. PK parameters of the three analytes, namely antibody-conjugated MMAE (acMMAE), total antibody, and unconjugated MMAE, were estimated using non-compartmental approaches and compared across the eight vc-MMAE ADCs. Relationships between analytes were assessed by linear regression. Exposure–response relationships were explored with key efficacy (objective response rate) and safety (Grade 2+ peripheral neuropathy) endpoints. PK profiles of acMMAE, total antibody and unconjugated MMAE following the first dose of 2.4 mg/kg were comparable across the eight ADCs; the exposure differences between molecules were small relative to the inter-subject variability. acMMAE exposure was strongly correlated with total antibody exposure for all the eight ADCs, but such correlation was less evident between acMMAE and unconjugated MMAE exposure. For multiple ADCs evaluated, efficacy and safety endpoints appeared to correlate well with acMMAE exposure, but not with unconjugated MMAE over the doses tested. PK of vc-MMAE ADCs was well characterized and demonstrated remarkable similarity at 2.4 mg/kg across the eight ADCs. Results from analyte correlation and exposure–response relationship analyses suggest that measurement of acMMAE analyte alone might be adequate for vc-MMAE ADCs to support the clinical pharmacology strategy used during late-stage clinical development.

Application of a Two-Analyte Integrated Population Pharmacokinetic Model to Evaluate the Impact of Intrinsic and Extrinsic Factors on the Pharmacokinetics of Polatuzumab Vedotin in Patients with Non-Hodgkin Lymphoma

PURPOSE

The established two-analyte integrated population pharmacokinetic model was applied to assess the impact of intrinsic/extrinsic factors on the pharmacokinetics (PK) of polatuzumab vedotin (pola) in patients with non-Hodgkin lymphoma (NHL) following bodyweight-based dosing.

METHODS

Model simulations based on individual empirical Bayes estimates were used to evaluate the impact of intrinsic/extrinsic factors as patient subgroups on Cycle 6 exposures. Intrinsic factors included bodyweight, age, sex, hepatic and renal functions. Extrinsic factors included rituximab/obinutuzumab or bendamustine combination with pola and manufacturing process. The predicted impact on exposures along with the established exposure-response relationships were used to assess clinical relevance.

RESULTS

No clinically meaningful differences in Cycle 6 pola exposures were found for the following subgroups: bodyweight 100-146 kg versus 38-<100 kg, age ≥ 65 years versus <65 years, female versus male, mild hepatic impairment versus normal, mild-to-moderate renal impairment versus normal. Co-administration of rituximab/obinutuzumab or bendamustine, and change in the pola manufacturing process, also had no meaningful impact on PK.

CONCLUSIONS

In patients with NHL, bodyweight-based dosing is adequate, and no further dose adjustment is recommended for the heavier subgroup (100-146 kg). In addition, no dose adjustments are recommended for other subgroups based on intrinsic/extrinsic factors evaluated.

Conjugation Site Influences Antibody-Conjugated Drug PK Assays: Case Studies for Disulfide-Linked, Self-Immolating Next-Generation Antibody Drug Conjugates

Immunoaffinity (IA) LC-MS/MS pharmacokinetic (PK) assays are widely used in the field for antibody drug conjugates (ADCs) containing peptide linkers that are enzymatically cleavable, such as MC-ValCit-PAB. Conjugate PK assay strategies for these ADCs involve cleavage with cathepsin B or papain to release and measure the antibody-conjugated drug (acDrug) concentration. However, robust acDrug PK methods for disulfide-linked self-immolating ADCs are lacking as they are a different conjugation modality. We developed acDrug PK assays for next-generation disulfide-linked ADCs involving immunoaffinity capture, chemical cleavage, and LC-MS/MS. Disulfide-linked ADCs captured from plasma were chemically reduced at basic pH to release the linker-drug, followed by self-immolation to liberate the active drug, and quantified by MRM LC-MS/MS. Herein, we detail the development and optimization of this chemical cleavage acDrug PK assay, resulting in robust accuracy and precision (±20%). The conjugation site of the linker-drug on the antibody was found to affect the kinetics of drug release. Multiple biophysical and chemical characteristics, such as tertiary structure, fractional solvent accessibility, pK_a of the conjugation site, surrounding residue's pI, and electrostatic charge, may directly impact the drug release kinetics. Similar site-specific stability has been previously reported for ADCs in vivo. The assay development and qualification data for this original assay format are presented along with its application to multiple in vitro and in vivo studies across species.

Phase 1b study of anti-NaPi2b antibody-drug conjugate lifastuzumab vedotin (DNIB0600A) in patients with platinum-sensitive recurrent ovarian cancer

OBJECTIVE

This study investigated the safety and tolerability of lifastuzumab vedotin (DNIB0600A) (LIFA), an antibody-drug conjugate, in patients with recurrent platinum-sensitive ovarian cancer (PSOC).

METHODS

In this open-label, multicenter phase 1b study, LIFA was administered intravenously once every 3 weeks (Q3W) with starting dose 1.2 mg/kg in a 3 + 3 dose-escalation scheme. All patients received carboplatin at dose AUC 6 mg/mL·min (AUC6) Q3W for up to 6 cycles. Dose expansion cohorts were enrolled ± bevacizumab 15 mg/kg Q3W.

RESULTS

Patients received LIFA at 1.2, 1.8, and 2.4 mg (n = 4, 5, and 20, respectively) with carboplatin. The maximum tolerated dose was not reached. The recommended phase 2 dose (RP2D) was LIFA 2.4 mg/kg + carboplatin AUC6 (cycles 1-6), with or without bevacizumab 15 mg/kg. Twelve patients received RP2D with bevacizumab. All patients experienced ≥1 adverse event (AE). The most common treatment-related AEs were neutropenia, peripheral neuropathy, thrombocytopenia, nausea, fatigue, anemia, diarrhea, vomiting, hypomagnesaemia, aspartate aminotransferase increased, alanine aminotransferase increased, and alopecia. Thirty-four (83%) patients experienced grade ≥ 3 AEs, the most frequent of which were neutropenia and thrombocytopenia. Nine (22%) patients experienced serious AEs. Pulmonary toxicities (34%), considered a potential risk of LIFA, included one patient who discontinued study treatment due to grade 2 pneumonitis. The median duration of progression-free survival was 10.71 months (95% CI: 8.54, 13.86) with confirmed complete/partial responses in 24 (59%) patients. Pharmacokinetics of mono-therapy LIFA was similar in combination therapy.

CONCLUSION

LIFA in combination with carboplatin ± bevacizumab demonstrated acceptable safety and encouraging activity in PSOC patients.

Current LC-MS-based strategies for characterization and quantification of antibody-drug conjugates

The past few years have witnessed enormous progresses in the development of antibody-drug conjugates (ADCs). Consequently, comprehensive analysis of ADCs in biological systems is critical in supporting discovery, development and evaluation of these agents. Liquid chromatography-mass spectrometry (LC-MS) has emerged as a promising and versatile tool for ADC analysis across a wide range of scenarios, owing to its multiplexing ability, rapid method development, as well as the capability of analyzing a variety of targets ranging from small-molecule payloads to the intact protein with a high, molecular resolution. However, despite this tremendous potential, challenges persist due to the high complexity in both the ADC molecules and the related biological systems. This review summarizes the up-to-date LC-MS-based strategies in ADC analysis and discusses the challenges and opportunities in this rapidly-evolving field.

Pharmacokinetics of polatuzumab vedotin in combination with R/G-CHP in patients with B-cell non-Hodgkin lymphoma

Purpose

The phase Ib/II open-label study (NCT01992653) evaluated the antibody-drug conjugate polatuzumab vedotin (pola) plus rituximab/obinutuzumab, cyclophosphamide, doxorubicin, and prednisone (R/G-CHP) as first-line therapy for B-cell non-Hodgkin lymphoma (B-NHL). We report the pharmacokinetics (PK) and drug–drug interaction (DDI) for pola.

Methods

Six or eight cycles of pola 1.0–1.8 mg/kg were administered intravenously every 3 weeks (q3w) with R/G-CHP. Exposures of pola [including antibody-conjugated monomethyl auristatin E (acMMAE) and unconjugated MMAE] and R/G-CHP were assessed by non-compartmental analysis and/or descriptive statistics with cross-cycle comparisons to cycle 1 and/or after multiple cycles. Pola was evaluated as a potential victim and perpetrator of a PK drug–drug interaction with R/G-CHP. Population PK (popPK) analysis assessed the impact of prior treatment status (naïve vs. relapsed/refractory) on pola PK.

Results

Pola PK was similar between treatment arms and independent of line of therapy. Pola PK was dose proportional from 1.0 to 1.8 mg/kg with R/G-CHP. Geometric mean volume of distribution and clearance of acMMAE ranged from 57.3 to 95.6 mL/kg and 12.7 to 18.2 mL/kg/day, respectively. acMMAE exhibited multi-exponential decay (elimination half-life ~ 1 week). Unconjugated MMAE exhibited formation rate-limited kinetics. Exposures of pola with R/G-CHP were similar to those in the absence of CHP; exposures of R/G-CHP in the presence of pola were comparable to those in the absence of pola.

Conclusions

Pola PK was well characterized with no clinically meaningful DDIs with R/G-CHP. Findings are consistent with previous studies of pola + R/G, and support pola + R/G-CHP use in previously untreated diffuse large B-cell lymphoma.

Electronic supplementary material

The online version of this article (10.1007/s00280-020-04054-8) contains supplementary material, which is available to authorized users.

Quantification of an Antibody-Conjugated Drug in Fat Plasma by an Affinity Capture LC-MS/MS Method for a Novel Prenyl Transferase-Mediated Site-Specific Antibody-Drug Conjugate

The novel prenyl transferase-mediated, site-specific, antibody–drug conjugate LCB14-0110 is comprised of a proprietary beta-glucuronide linker and a payload (Monomethyl auristatin F, MMAF, an inhibitor for tubulin polymerization) attached to human epidermal growth factor receptor 2 (HER2)-targeting trastuzumab. A LC-MS/MS method was developed to quantify the antibody-conjugated drug (acDrug) for in vitro linker stability and preclinical pharmacokinetic studies. The method consisted of affinity capture, enzymatic cleavage of acDrug, and LC-MS/MS analysis in the positive ion mode. A quadratic regression (weighted 1/concentration²), with the equation y = ax² + bx + c, was used to fit calibration curves over the concentration range of 19.17~958.67 ng/mL for acDrug. The qualification run met the acceptance criteria of ±25% accuracy and precision values for quality control (QC) samples. The overall recovery was 42.61%. The dilution integrity was for a series of 5-fold dilutions with accuracy and precision values ranging within ±25%. The stability results indicated that acDrug was stable at all stability test conditions (short-term: 1 day, long-term: 10 months, Freeze/Thaw (F/T): 3 cycles). This qualified method was successfully applied to in vitro linker stability and pharmacokinetic case studies of acDrug in rats.

IQ consortium perspective: complementary LBA and LC–MS in protein therapeutics bioanalysis and biotransformation assessment

Increasingly diverse large molecule modalities have driven the need for complex bioanalysis and biotransformation assessment involving both traditional ligand-binding assays (LBA) and more recent hybrid immunoaffinity LC–MS platforms. Given the scientific expertise in LBA and LC–MS typically resides in different functions within the industry, this has presented operational challenges for an integrated approach for bioanalysis and biotransformation assessment. Encouragingly, over time, the industry has recognized the complementary value of the two platforms. This has not been an easy transition as organizational structures vary widely within the industry. However, there are tremendous benefits in adopting fully integrated strategies for biopharma. This IQ consortium paper presents current perspectives across the biopharma industry. It highlights the technical and operational challenges in current large molecule bioanalysis, the value of collaborations across LBA and LC–MS, and scientific expertise for fully integrated strategies for bioanalysis and biotransformation.

Determination of ADC Concentration by Ligand-Binding Assays

Total antibody, conjugated antibody or antibody-conjugated drug, and free drug are key analytes required to establish exposure-response relationships for ADCs. Therefore, bioanalytical strategies for ADCs include ligand-binding assays (LBA) and LC-MS/MS methods. Here we describe detailed methodology to develop a solid-phase-based enzyme-linked immunosorbent assay (ELISA), which is the most widely used LBA to quantify large-molecule components of ADC in biological matrices such as plasma, serum, tumor, or tissue homogenates. The approach presented here is designed to quantify total antibody concentrations in ADC containing samples, and can be easily adapted to quantify conjugated antibody concentrations.

Integrated Two-Analyte Population Pharmacokinetic Model of Polatuzumab Vedotin in Patients With Non-Hodgkin Lymphoma

A two‐analyte integrated population pharmacokinetic (PK) model that simultaneously describes concentrations of antibody‐conjugated monomethyl auristatin E (acMMAE) and unconjugated MMAE following repeated administrations of polatuzumab vedotin (pola) was developed based on data from four clinical studies of pola in patients with non‐Hodgkin lymphoma. A two‐compartment model with a nonspecific, time‐dependent linear clearance, a linear time‐dependent exponentially declining clearance, and a Michaelis–Menten clearance provided a good fit of the acMMAE plasma PK profiles. All three acMMAE elimination pathways contributed to the input to the central compartment of unconjugated MMAE, which was also described by a two‐compartment model. Population PK parameters, covariate effects, and interindividual variability of model parameters were estimated. The impact of clinically relevant covariates on PK exposures of each analyte were quantified and reported to support key label claims.

Immunoaffinity LC–MS/MS to quantify a PEGylated anti-Factor D Fab biotherapeutic in cynomolgus monkey serum

Aim: To develop a sensitive hybrid immunoaffinity LC–MS/MS monkey serum assay to quantify multiple components of anti-Factor D; a complex PEGylated Fab biotherapeutic explored as a therapy for age-related macular degeneration. Materials & methods: Immunoaffinity enrichment of PEGylated anti-Factor D Fab, including fully conjugated, partially conjugated and unconjugated (i.e., free) Fab species, using a capture reagent coupled to magnetic beads was performed. The surrogate peptides derived from the therapeutic Fab via trypsin digestion were measured to obtain the total Fab concentrations. Results & conclusion: The method demonstrated the ability to accurately quantify both PEGylated and unconjugated Fab species. It was successfully validated with a LLOQ at 25.0 ng/ml.

High-Resolution Characterization of ADCs by Orbitrap LCMS

Antibody-drug conjugates (ADCs) have complex molecular structures as they are composed of both small and large molecules, and they often undergo biotransformation over time in circulation. Here we describe a high-resolution Orbitrap MS approach for the characterization of ADC biotransformation and stability. Compared with conventional approach by Q-TOF MS, the method described here significantly improved the mass resolution and enabled more comprehensive characterization of ADC catabolites. It is particularly beneficial for characterizing ADC biotransformations with small mass changes.

Time-to-Event Modeling of Peripheral Neuropathy: Platform Analysis of Eight Valine-Citrulline-Monomethylauristatin E Antibody-Drug Conjugates

Peripheral neuropathy (PN) is a common long-term debilitating toxicity of antimicrotubule agents. PN was the most frequent adverse event resulting in dose modifications and/or discontinuation of treatment for valine-citrulline-monomethylauristatin E antibody-drug conjugates (ADCs) developed at Genentech. A pooled time-to-event analysis across eight ADCs (~700 patients) was performed to evaluate the relationship between the ADC exposure and the risk for developing a clinically significant (grade ≥ 2) PN. In addition, the impact of demographic and pathophysiological risk factors on the risk for PN was explored. The time-to-event analysis suggested that the development of PN risk increased with ADC exposure, treatment duration, body weight, and previously reported PN. This model can be used to inform clinical strategies such as adaptations to dosing regimen and/or treatment duration as well as inform clinical eligibility to reduce the incidence of grade ≥ 2 PN.