Anti-Human IL-23A (p19) (Tildrakizumab) [Clone MK-3222] — Fc Muted™

Research-grade Tildrakizumab biosimilars are used as calibration standards or reference controls in pharmacokinetic (PK) bridging ELISAs by generating standard curves that allow for the accurate quantification of Tildrakizumab concentration in human serum samples.

Essential context and supporting details:

• The biosimilar (e.g., research-grade Tildrakizumab) is typically supplied in a lyophilized (freeze-dried) form with a defined concentration and is reconstituted, then serially diluted in blank serum or a suitable matrix to prepare calibration standards spanning the expected concentration range in patient samples.
• These standards are included in each ELISA plate run to create a standard curve—usually by plotting absorbance (colorimetric signal) versus drug concentration—enabling the concentration of Tildrakizumab in unknown samples to be interpolated from this curve.
• Reference controls or quality control (QC) samples, often at low, medium, and high concentrations, are run alongside standards to assess assay accuracy and precision across the range of quantification.
• Typically, the same biosimilar standard used for calibration is also used as a reference control for validation and monitoring assay performance, supporting comparability and traceability across studies and labs.
• In PK bridging ELISAs developed for biosimilars, using a research-grade biosimilar as the standard ensures that the assay can reliably measure either the originator or biosimilar version, which is critical for bioequivalence and bridging studies.

Workflow summary:

• Prepare a dilution series of the research-grade Tildrakizumab biosimilar in human serum or assay buffer to cover the desired analytical range (e.g., 0.1–100 μg/mL).
• Apply standards, controls, and samples to ELISA plates, following validated protocols for incubation, washing, and detection (e.g., using HRP-conjugated antibodies and colorimetric readout).
• Generate a standard curve using the known concentrations, and calculate the Tildrakizumab concentration in patient serum samples by interpolation using four-parameter logistic regression or similar.

This use of calibrated biosimilar in assay setup ensures consistency, traceability, and regulatory compliance for pharmacokinetic measurements in clinical and research settings, allowing for accurate comparison between biosimilar and originator products.

The primary in vivo models for studying anti-IL-23A (p19) antibody effects on tumor growth and tumor-infiltrating lymphocytes (TILs) are murine syngeneic tumor models; use in humanized models is rarer, largely due to species-restricted IL-23A interactions and antibody specificity.

Syngeneic Mouse Tumor Models:

• Common models: B16F10 melanoma, CT26 colon carcinoma, and RENCA renal carcinoma.
  • B16F10 melanoma is frequently used to examine mechanisms of immunosuppression and immune cell dynamics, including how the IL-23/IL-23R axis influences Treg identity and TIL composition.
  • RENCA is noted for a highly immune-infiltrated microenvironment, whereas B16F10 is poorly infiltrated, which allows researchers to compare antibody effects across different immune contexts.
  • CT26 features robust CD8+ T cell infiltration, making it suitable for studying cytotoxic responses after blocking IL-23A.

Experimental features:

• Administration: A research-grade anti-IL-23A (p19) antibody is generally administered systemically (e.g., intraperitoneal), and tumor growth is monitored over time.
• TIL profiling: These models permit extensive flow cytometry or single-cell RNA-seq analysis of TILs to assess how anti-IL-23A changes the abundance or activation state of Tregs, CD8+ T cells, myeloid-derived suppressor cells, and other immune subsets.
• Insight: Such studies reinforce that IL-23 supports immunosuppressive Treg programs in tumors, and antagonism may enhance anti-tumor CD8+ T cell activity.

Humanized Mouse Models:

• Use of humanized mice (with a reconstituted human immune system) for anti-IL-23A, p19 studies is possible but far less common, primarily due to the need for cross-reactive antibodies and the cost/complexity involved.
  • Most existing published research on IL-23/p19 blockade in tumors focuses on mouse syngeneic models, while humanized models are more often used for other checkpoint therapies.
  • Antibodies such as BI 655066 (humanized anti-IL-23 mAb) have been generated for clinical purposes, but in vivo tumor experiments with these reagents in humanized mice are not well documented in the preclinical literature.

Key summary table:

Conclusion:
Murine syngeneic models—notably B16F10, CT26, and RENCA—are the principal systems used to study anti-IL-23A administration, tumor growth inhibition, and TIL analysis in vivo. Use of humanized models for this purpose is far less common due to practical constraints and is not yet standard for mechanistic IL-23A/p19 tumor immunology investigations.

Researchers studying synergistic effects in immune-oncology models often use combinations of checkpoint inhibitors, such as anti-CTLA-4, anti-LAG-3, and biosimilars, but there is currently limited specific evidence of direct use of the Tildrakizumab biosimilar (anti-IL-23A) with other checkpoint inhibitors in published preclinical or clinical synergy studies. The underlying combination rationale is to target distinct immune pathways—checkpoint inhibition (CTLA-4/LAG-3/PD-1) unleashes T cell responses, while cytokine-targeted antibodies like Tildrakizumab modulate antigen-presenting cell and T cell differentiation and potentially reduce suppressive signals in the tumor microenvironment.

Context and Supporting Details:

• Checkpoint inhibitor combination logic: Combining inhibitors of multiple immune checkpoints (e.g., CTLA-4, PD-1/PD-L1, LAG-3) is established as a strategy to increase anti-tumor immune activity, overcome resistance to monotherapy, and broaden the impact on T cell activation and exhaustion. Distinct mechanisms, such as CTLA-4 blockade enhancing T cell priming in lymph nodes and PD-1/PD-L1 blockade acting at peripheral tumor sites, can yield additive or synergistic effects.

• Role of IL-23 inhibition (Tildrakizumab): Tildrakizumab targets the IL-23/Th17 axis, which can contribute to tumor progression and immune suppression. By modulating cytokine signals, IL-23 blockade may alter the tumor microenvironment, potentially making it more permissive for T cell-mediated attack induced by checkpoint inhibitors. Preclinical rationale supports combining cytokine-targeted agents with ICIs to amplify anti-tumor immunity, though specific experimental proof for Tildrakizumab with anti-CTLA-4 or anti-LAG-3 biosimilars in cancer models is not described in current literature.

• Practical use in models: In preclinical studies, researchers typically:

  • Administer biosimilars (e.g., Tildrakizumab, anti-CTLA-4, anti-LAG-3) together in mouse tumor models or engineered cell lines.
  • Assess tumor growth inhibition, immune cell activation (especially T cells and dendritic cells), cytokine profiles, and survival outcomes.
  • Use flow cytometry, immunohistochemistry, and gene expression profiling to characterize changes in immune cell subsets and signaling.
  • Monitor safety (adverse events, autoimmunity markers, immunogenicity).

• Challenges and caveats: Major hurdles are increased risk of immune-related toxicities (noted in past combinations like anti-CTLA-4 plus anti-PD-1), and sometimes unpredictable interactions that may not always yield synergy. Data on combination therapy with cytokine inhibitors (e.g., anti-IL-23A) and checkpoint blockade are mostly extrapolated from related agents; robust cancer data on tildrakizumab biosimilar combinations is currently lacking.

Additional Relevant Information:

• Most combination immune-oncology studies currently focus on dual or triple checkpoint blockade (PD-1/LAG-3, CTLA-4/PD-1), with cytokine blockers like Tildrakizumab primarily investigated in autoimmunity and not widely reported in oncology synergy experiments.
• Tildrakizumab biosimilar is available for research use and could be utilized to probe IL-23's role in the tumor microenvironment alongside checkpoint inhibition, but peer-reviewed synergy results are not yet reported.
• Safety/tolerability of Tildrakizumab is established in other indications, but immune-related adverse events should be carefully monitored when used in combination, based on prior evidence in other antibody combinations.

In summary, while the conceptual basis and methodology for combining Tildrakizumab biosimilar with checkpoint inhibitors in immune-oncology models is well described, there is a lack of direct published data showing their synergistic effects. Existing literature primarily explores multi-checkpoint combinations and preclinical rationales; actual experimental details with Tildrakizumab biosimilar plus anti-CTLA-4 or anti-LAG-3 must still be developed and published.

A Tildrakizumab biosimilar is used as both capture and detection reagent in a bridging ADA (anti-drug antibody) ELISA to monitor and compare a patient's immune response against the biosimilar and the original therapeutic drug. In this assay format, the biosimilar molecule is labeled in two ways: one portion is typically biotinylated (for capture on a streptavidin-coated plate), and another is labeled (often with HRP or a similar enzyme) for detection.

Key points on assay setup and rationale:

• Bridging Assay Principle: In the ADA ELISA, patient serum containing anti-drug antibodies (if present) will bind to both the capture (biotinylated) and detection (enzyme-labeled) forms of the biosimilar. This forms a "bridge" between the two labeled drug molecules, generating a measurable signal.
• Use of the Biosimilar: Using the biosimilar as the reagent (rather than the originator) ensures the assay detects antibodies reactive to the biosimilar's specific molecular structure, which is central for assessing biosimilar immunogenicity.
• Assay Validation: Before routine use, the assay must demonstrate that the biosimilar and originator have antigenic equivalence—meaning they both bind similarly to a panel of control antibodies. This testing assures that anti-drug antibodies against either version (biosimilar or originator) can be reliably detected in patient samples.
• Regulatory Recommendation: Current guidance recommends a single, biosimilar-based assay for comparative immunogenicity because it simplifies validation and provides a consistent platform for monitoring patient immune responses across both biosimilar and reference treatments, provided cross-reactivity and equivalence are shown.
• Interpretation of Results: The appearance of a signal indicates the presence of anti-drug antibodies against Tildrakizumab (the biosimilar and, by validated equivalence, the reference product). High circulating drug levels can interfere with this assay ("drug tolerance" limitation), potentially leading to false negatives if the drug concentration in the serum exceeds the assay’s tolerance threshold.

Summary Table—ADA Bridging ELISA Using Tildrakizumab Biosimilar

This approach allows for sensitive and specific detection of anti-Tildrakizumab antibodies in patient samples and is central to demonstrating biosimilar immunogenicity comparability as required by regulatory agencies.