Antibody Coupled Drug Discovery Service

Tek Biotech has been engaged in preclinical (CRO) services for many years. We provide one-stop service from preclinical study protocol design to antibody coupled drug (ADC) discovery and animal validation, which greatly simplifies the development of ADCs and other biocouplings.

Unlike traditional chemotherapy treatments, which can damage healthy cells, antibody-drug couplers (ADCs) are targeted drugs that deliver chemotherapy drugs to cancer cells. ADCs deliver chemotherapy through a junction attached to a monoclonal antibody that binds to a specific target expressed on the cancer cell. Upon binding to the target (oncoprotein or receptor), the ADC releases the cytotoxic drug into the cancer cell.

“Fully human” monoclonal antibodies, which have been engineered to carry human antibody genes, are ideal delivery platforms for ADCs. They are highly targeted and cell specific, with long circulating half-lives and low immunogenicity. The chemical “connector” that links the antibody to the cytotoxic drug is highly stable and prevents cleavage (splitting) of the ADC before it enters the tumor. The anticancer drug (or “payload”) penetrates the tumor and causes cell death by destroying the DNA of the cancer cells or by preventing new cancer cells from forming and spreading.

█ Coupling Technology

Cysteine Coupling

Tek Biotech can selectively reduce an antibody's interchain disulfide bonds to produce sulfhydryl groups that can be used for conjugation, while leaving the intrachain disulfide bonds intact. Using this cysteine-based coupling strategy, the antibody is first treated with a reducing agent, such as dithiothreitol (DTT) or tris (2-carboxyethyl) phosphine (TCEP), which converts the interchain disulfides to free cysteine residues. The free sulfhydryl group (SH) of the antibody can then be concatenated with a thiol-reactive junction (e.g., a junction containing maleimide) to form an ADC, which is a heterogeneous mixture of ADC species containing 0-8 drugs per antibody (DAR ≤ 8). This is an efficient strategy that does not require expensive and time-consuming redesign of the antibody structure.

Tek Biotech can engineer unpaired cysteine residues on each heavy chain, which can then be used to concatenate with thiol-reactive junctions to create a more homogeneous ADC with a drug-to-antibody ratio of 2. Tektronix has extensive experience in producing ADCs by this method.

Lysine Coupling

Lysine-based conjugation is one of the widely used non-specific conjugation strategies. The side-chain ε-amino groups of lysine residues are good affinity reagents, which means that lysine residues exposed on the surface of an antibody have greater solvent accessibility in structurally flexible regions that can be used as sites for drug binding.

Typically, lysine coupling involves reacting a junction-payload construct with an activated ester (e.g., N-hydroxysuccinimide ester) with the lysine residues of an antibody to form an ADC. alternatively, the lysine residues of an antibody can be chemically modified to incorporate other chemical functional groups into the antibody. Tek Biotech has extensive experience with a range of lysine coupling technologies for ADC development.

Effective Carrier

Tek Biotech can develop payloads in many forms, including protein, DNA, RNA and various other fragmentation technologies. Our nano-antibodies prepared based on phage display technology have about 60% similarity to human antibodies, with a molecular weight size of 15 kDa (150 kDa for traditional antibodies), which makes it easier to be humanized. Meanwhile, the specificity is strong, the affinity is high, and the spatial site resistance is smaller.

█ Analysis and Characterization of Antibody-drug Couplers

Tek Biotech offers a wide range of analytical methods to support selection from the early antibody discovery stage to the clinical testing stage. Antibodies are screened for better formulations and their propensity for aggregation and chemical degradation is studied under stress conditions. In-depth physiochemical characterization allows identification of the presence of post-translational modifications, including specific carbohydrate epitopes such as α-galactose or N-ethanoylneuraminic acid.

Structural Characterization:

Biophysical Methods:

Protein and Peptide Identification

Provides services to identify single proteins, single protein targets, and whole cell lysate proteomics studies. Includes:

-- Protein identification and characterization

-- Protein sequence confirmation

-- PAGE, protein blotting

-- Whole cell lysate proteomics studies

-- Identification of HLA-DR presenting peptides

ADC Characterization

Tek Biotech has extensive expertise in the characterization of antibody-drug couplers to support the selection of better candidates for clinical studies. Early ADC candidates can be generated from different antibodies, different types of conjugates and payloads to screen for effective target solutions. A range of in-house methods can be used to support candidate selection and manufacturability assessment by determining formulation stability, in vitro serum assays, in vivo analysis and testing binding and potency under different conditions.

█ Analytical Method Development

Tek Biotech's laboratories are equipped with a range of advanced analytical and preparative UPLC and LC instruments. Combined with our wide range of LC-MS capabilities (TOF, Q-TOF, Orbitrap-MS, and MALDI-MS), and 500-MHz and 300-MHz NMR spectrometers, this allows us to provide our clients with a very comprehensive analytical service that can be used for method development for early stage research purposes.

Currently, we can perform method development for the following projects:

1. Analytical and preparative UPLC and LC

2. LC-MS and LC-MS/MS for small and large molecules

3. GC-MS (headspace analysis)

4. All types of chromatography (size exclusion/gel filtration chromatography SEC, reversed-phase RP, hydrophobic interaction chromatography HIC, hydrophobic interaction liquid chromatography HILIC, ion exchange chromatography IEX, chiral separations)

5. NMR molecular structure analysis, including protein NMR

6. 1D-NMR analysis (300 MHz, 500 MHz, 1H, 13C, 31P, 19F, multi-dimensional)

7. 2D-NMR analysis (gCOSY, ROESY, TOCSY, gHMQC, HSQC with multiple editing, HSQC with CH only, gHSQCAD-TOCSY, gHMBCAD)

8. Stability studies at different temperatures and humidities

█ Other available analyses:

-- Karl Fischer titration

-- Spinning

-- ATR FT-IR analysis