Anti-Human IL-23A (p19) (Tildrakizumab) [Clone MK-3222]

Research-grade Tildrakizumab biosimilars can be used as calibration standards or reference controls in pharmacokinetic (PK) bridging ELISA assays to quantify drug concentration in serum by creating a standard curve against which patient or experimental sample concentrations are measured.

Essential context and supporting details:

• Purpose in ELISA: In PK studies, a validated ELISA is used to determine the serum concentration of a monoclonal antibody drug like tildrakizumab at various time points following administration. Calibration standards made with known concentrations of the biosimilar are essential to generate a standard curve for quantification.

• Preparation of Standards and Controls:

  • Calibration standards are prepared by spiking pooled human serum (or appropriate blank matrix) with known concentrations of the research-grade tildrakizumab biosimilar.
  • These standards typically span the assay’s quantifiable range (for example, 0.1–100 µg/mL or per manufacturer’s specifications).
  • Reference controls (quality controls, QCs) are prepared at low, medium, and high concentrations within the validated range and included in each assay run to monitor accuracy and precision.

• Assay Procedure:

  • The ELISA (often sandwich-type) uses anti-idiotype or drug-specific capture and detection antibodies.
  • Calibration standards and QC samples are run alongside unknown serum samples in the same assay plate.
  • The absorbance (or signal) from each standard is measured and plotted to generate a standard curve, typically using four-parameter logistic regression.
  • Concentrations in unknown samples are then interpolated from this curve.

• Biosimilar as a Standard: Research-grade tildrakizumab biosimilars can be used interchangeably with reference product for calibration if comparability is established (matching structure, activity, and binding characteristics), supporting accurate and reproducible quantitation.

• PK Bridging: In bridging ELISA, the biosimilar standard allows the assay to detect both the originator and biosimilar drug, ensuring consistency across studies, especially when bridging PK comparability between products is required.

• Validation: Assays are validated for sensitivity, specificity, recovery, and reproducibility using these standards and controls under defined conditions before use in regulated studies.

Key Points:

• Calibration standards: Serial dilutions of biosimilar in matrix (serum) covering assay’s dynamic range.
• Reference controls: Fixed concentrations spanning the range, used to ensure assay consistency.
• Purpose: Enable accurate measurement of tildrakizumab concentration in PK studies.
• Requirement: Standards and controls must mimic the circulating form of the drug in serum to reflect true patient levels.

No source mentioned direct examples using Tildrakizumab; the described principles are standard for monoclonal antibody PK bridging assays, and examples from other biosimilars (trastuzumab, CMAB007) are fully analogous. For research use, only research-grade (not clinical-grade) biosimilar should be used unless stated otherwise.

The primary in vivo models used to assess anti-IL-23A (p19) antibody activity for tumor growth inhibition and characterization of tumor-infiltrating lymphocytes (TILs) are murine syngeneic tumor models, particularly those where genetic deletion or antibody-mediated blockade of IL-23p19 has been shown to result in altered tumor growth and immune infiltration.

Key syngeneic models:

• Chemical carcinogenesis models:
  • DMBA/TPA-induced skin papilloma: Mice with IL-23p19 deficiency or treated in vivo with anti-IL-23p19 antibodies exhibit reduced tumor formation and increased infiltration of CD8⁺ T cells, with reduced granulocytes and macrophages.
  • MCA-induced fibrosarcoma: IL-23p19-deficient or anti-IL-23–treated mice show resistance to tumor development and altered TIL profiles, particularly increased CD8⁺ T cells and changes in NK cell function.
• Colon cancer models:
  • APC^Min/+^ and CPC-APC models: Loss or blockade of IL-23p19 reduces tumor burden and alters both myeloid and lymphoid TIL composition.
• Additional syngeneic solid tumor models:
  • RENCA (renal carcinoma), CT26 (colon carcinoma), and B16F10 (melanoma) models are also widely used for immunotherapy studies, allowing for assessment of immune infiltration patterns following cytokine or antibody treatment. Studies specifically profiling the TME in these models often include TIL analyses by flow cytometry.

Summary Table: Major Mouse Models for Anti-IL-23A (p19) Antibody Studies

• Humanized mouse models: While not as commonly referenced in studies specifically targeting anti-IL-23A (p19), analysis of the human tumor microenvironment has shown that IL-23A is expressed by tumor-associated macrophages and various T cell subsets in human cancers. This makes humanized mouse models a logical translational next step, but current in vivo TIL characterization data are far more robust in murine syngeneic settings.

Supporting context:

• Studies often use antibody blockade or genetic deletion of IL-23p19 to evaluate both tumor growth and immune composition, especially the density and phenotype of CD8⁺ T cells, regulatory T cells (Tregs), NK cells, and myeloid cells within tumors.
• Characterization of TILs is usually performed by flow cytometry or immunohistochemistry after tumor harvest.
• Syngeneic models remain the standard for these mechanistic studies, while translational application relies on matching human tumors with similar immune microenvironment features.

In conclusion: Mouse syngeneic models—notably, DMBA/TPA skin, MCA fibrosarcoma, APC^Min/+^ colon cancer, RENCA, CT26, and B16F10—are the primary systems where anti-IL-23A (p19) antibody effects on tumor growth and TILs are systematically studied in vivo.

Researchers studying synergistic effects between checkpoint inhibitors typically combine agents targeting distinct immune regulatory pathways to enhance antitumor immunity in complex immune-oncology models. While there is no direct evidence in the results that Tildrakizumab biosimilar (an anti-IL-23A monoclonal antibody) has yet been combined specifically with anti-CTLA-4 or anti-LAG-3 biosimilars in published immune-oncology synergy studies, the established logic and approaches for such combinations provide clear guidance.

Essential context and supporting details:

• Mechanistic Basis of Combination: Combining checkpoint inhibitors that act via different immune pathways—for example, anti-CTLA-4 (restoring T cell activation in lymph nodes), anti-LAG-3 (relieving T cell exhaustion), and anti-PD-1/PD-L1 (preventing suppression at the tumor site)—is shown to increase the activity and overcome limitations of monotherapies. Tildrakizumab, by inhibiting IL-23A, could shift the tumor microenvironment towards enhanced effector T cell functions and reduced immunosuppression.

• Experimental Design in Preclinical Models:

  • Researchers typically use murine tumor models or humanized mouse models, applying each agent either alone or in combination, measuring outcomes such as tumor regression, immune cell infiltration, and cytokine profiles.
  • Synergy is assessed by comparing the efficacy (tumor reduction, survival), immune activation markers, and adverse event profiles across each treatment group.
  • The biosimilars employed are generally research-grade with high purity and consistent molecular characteristics to reduce variability.

• Combination Rationale:

  • Anti-CTLA-4 inhibits regulatory signals in T cells, promoting priming and expansion.
  • Anti-LAG-3 can reverse T cell exhaustion alongside PD-1 blockade.
  • Tildrakizumab blocks IL-23A, which is implicated in promoting chronic inflammation and Treg/Th17 responses; combining it with checkpoint inhibitors may further potentiate cytotoxic T cell responses by minimizing immunosuppressive cytokine production.

• Immune Profiling and Safety:

  • Researchers monitor immune-related biomarkers and adverse events (from mild nasopharyngitis to severe immune toxicity), looking for additive effects or unexpected toxicity profiles.
  • Immunogenicity (antidrug antibodies) is routinely assessed; ADA formation may impact drug levels and must be accounted for when combining biologics.

Additional information:

• The combination of multiple checkpoint inhibitors (such as anti-CTLA-4, anti-LAG-3, anti-PD-1) is clinically and preclinically validated to improve outcomes versus monotherapy, but also increases risk of immune-related adverse events.
• Although direct studies using Tildrakizumab biosimilar in combination with checkpoint inhibitors are not detailed in current results, the strategy would be informed by foundational combination immunotherapy trials and mechanistic rationale outlined above.

In summary, researchers would use Tildrakizumab biosimilar with other checkpoint inhibitors (e.g., anti-CTLA-4, anti-LAG-3 biosimilars) in complex models to dissect synergistic immune activation, tumor control, and toxicity, drawing from validated practices in checkpoint inhibitor research. Experimental approaches and rationale for synergy are well-established, although direct published protocols for Tildrakizumab biosimilar combinations are presently lacking in available literature.

A Tildrakizumab biosimilar can be used as the capture and/or detection reagent in a bridging anti-drug antibody (ADA) ELISA to monitor a patient’s immune response against the therapeutic drug by serving as the antigen that binds to anti-tildrakizumab antibodies present in patient serum.

In a bridging ADA ELISA, the assay format typically operates as follows:

• Capture reagent: Tildrakizumab biosimilar is immobilized onto the ELISA plate, allowing patient-derived ADAs (if present) to bind to the drug.
• Detection reagent: Labeled Tildrakizumab biosimilar (e.g., biotinylated or enzyme-conjugated) is then added; it binds to the other arm of the ADA, “bridging” and forming a sandwich complex that is detectable.

Using the biosimilar as both capture and detection reagent (known as the one-assay approach) is recommended for biosimilar immunogenicity studies to ensure the assay detects antibodies against both the biosimilar and the originator drug and to avoid missing novel immunogenic epitopes that may be unique to the biosimilar. This approach facilitates head-to-head immunogenicity comparisons between the biosimilar and the originator by making antibody detection unbiased and consistent for both forms.

Key aspects of assay validation include:

• Demonstrating antigenic equivalence (similar antibody binding properties) between the biosimilar and originator drug during assay development and validation phases.
• Validating drug tolerance, ensuring that the assay can detect ADAs even in the presence of therapeutic circulating drug concentrations. For tildrakizumab, high drug concentrations (>6 µg/mL) can interfere with ADA detection and cause false-negatives.
• Including positive controls generated using the biosimilar, while showing equivalence in binding and detection with the originator.

Regulatory guidance (FDA/EMA) requires these comparative immunogenicity assessments and rigorous assay validation when biosimilars are used, ensuring clinically meaningful immunogenicity similarity between products.

In summary:

• The biosimilar is used to capture or detect ADA in patient samples.
• The bridging ELISA format is sensitive to immune responses against both biosimilar and originator.
• Rigorous validation ensures equivalence, drug tolerance, and performance so immune responses can be reliably monitored in patients receiving tildrakizumab or its biosimilar.