Simultaneous quantification of total antibody and antibody-conjugated drug for XMT-1522 in human plasma using immunocapture-liquid chromatography/mass spectrometry

A validated LC-MS/MS method for the quantitation of daratumumab in rat serum using rapid tryptic digestion without IgG purification and reduction

Daratumumab, a humanized monoclonal antibody utilized in treating immunoglobulin light-chain amyloidosis and relapsed/refractory multiple myeloma, was quantified in rat serum through a simple, economical and effective liquid chromatography tandem-mass spectrometry (LC-MS/MS) method. A surrogate peptide, LLIYDASNR, derived from trypsin hydrolysis, was quantitatively analyzed with LLIYDASN [13C6, 15N4] RAT as an internal standard. This corrected variations from sample pretreatment and mass spectrometry response, involving denaturation and trypsin hydrolysis in a two-step process lasting approximately 1 hour. Methodological validation demonstrated a linear range of 1 µg/mL to 1000 µg/mL in rat serum. Precision, accuracy, matrix effect, sensitivity, stability, selectivity, carryover, and interference met acceptance criteria. The validated LC-MS/MS approach was successfully applied to a pharmacokinetic study of daratumumab in rats at an intravenous dose of 15 mg/kg.

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.

Development and validation of pharmacokinetics assays for a novel HER2-targeting antibody-drug conjugate (SHR-A1201): Application to its dose-escalation pharmacokinetic study

Approximately 25% of breast cancer patients with HER2 overexpression tend to have a high risk of disease progression and death. Various HER2-targeting therapies have been approved for treatment. Recently, a novel antibody-drug conjugate, SHR-A1201, is being researched and developed. For the pharmacokinetic study of SHR-A1201, suitable bioanalytical methods are needed for quantifying unconjugated cytotoxin, cytotoxin-conjugated antibodies and total antibodies. In this research, bioanalytical methods involving a highly sensitive LC-MS/MS assay for unconjugated cytotoxic payload DM1 in human plasma, ELISA strategies for DM1-conjugated trastuzumab and total trastuzumab in human serum were developed, validated and successfully applied to a phase I dose-escalation pharmacokinetic study of SHR-A1201. The pharmacokinetic properties and exposure-to-dose proportionality was evaluated for SHR-A1201. According to the bioanalytical method validation guidance, the bioanalytical methods were fully validated and the validation results met the acceptance criteria. The nonspecific binding of DM1 and dimer was avoided for the LC-MS/MS assay. In the dose-escalation pharmacokinetic study of SHR-A1201, a potential dose-proportional pharmacokinetics was observed over the dose from 1.2 mg/kg to 4.8 mg/kg. The validated bioanalytical strategies are robust and reproducible and these bioanalytical methods will contribute to better understanding of the pharmacokinetic properties of SHR-A1201.

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.

Immunoconjugates for Cancer Targeting: A Review of Antibody-Drug Conjugates and Antibody-Functionalized Nanoparticles

Targeted therapy has been recently highlighted due to the reduction of side effects and improvement in overall efficacy and survival from different types of cancers. Considering the approval of many monoclonal antibodies in the last twenty years, cancer treatment can be accomplished by the combination of monoclonal antibodies and small molecule chemotherapeutics. Thus, strategies to combine both drugs in a single administration system are relevant in the clinic. In this context, two strategies are possible and will be further discussed in this review: antibody-drug conjugates (ADCs) and antibody-functionalized nanoparticles. First, it is important to better understand the possible molecular targets for cancer therapy, addressing different antigens that can selectively bind to antibodies. After selecting the best target, ADCs can be prepared by attaching a cytotoxic drug to an antibody able to target a cancer cell antigen. Briefly, an ADC will be formed by a monoclonal antibody (MAb), a cytotoxic molecule (cytotoxin) and a chemical linker. Usually, surface-exposed lysine or the thiol group of cysteine residues are used as anchor sites for linker-drug molecules. Another strategy that should be considered is antibody-functionalized nanoparticles. Basically, liposomes, polymeric and inorganic nanoparticles can be attached to specific antibodies for targeted therapy. Different conjugation strategies can be used, but nanoparticles coupling between maleimide and thiolated antibodies or activation with the addition of ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC)/ N-hydroxysuccinimide (NHS) (1:5) and further addition of the antibody are some of the most used strategies. Herein, molecular targets and conjugation strategies will be presented and discussed to better understand the in vitro and in vivo applications presented. Also, the clinical development of ADCs and antibody-conjugated nanoparticles are addressed in the clinical development section. Finally, due to the innovation related to the targeted therapy, it is convenient to analyze the impact on patenting and technology. Information related to the temporal evolution of the number of patents, distribution of patent holders and also the number of patents related to cancer types are presented and discussed. Thus, our aim is to provide an overview of the recent developments in immunoconjugates for cancer targeting and highlight the most important aspects for clinical relevance and innovation.

Determining the Stoichiometry of a Protein-Polymer Conjugate Using Multisignal Sedimentation Velocity Analytical Ultracentrifugation

Advances in polymer science have broadened the applications of protein-polymer conjugates as biopharmaceuticals and biotechnology reagents. The complex nature of these conjugates makes characterization challenging. Here, we describe the use of multisignal sedimentation velocity analytical ultracentrifugation to measure the polymer-to-protein ratio. To demonstrate the principle, we applied this approach to a series of antibody-drug conjugates with different polymer-to-protein ratios and various degrees of heterogeneity, and validated results with orthogonal analytical techniques. We found that multisignal sedimentation velocity can provide accurate information on key attributes including polymer-to-protein ratio, which is important for maximizing the therapeutic potential of future protein-polymer conjugates.

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.