Anti-Human IL-23A (p19) (Risankizumab) [Clone ABBV-066] — Fc Muted™

Research-grade Risankizumab biosimilars are used as calibration standards or reference controls in PK bridging ELISAs by serving as the quantitative benchmark for drug measurement, ensuring assay comparability across biosimilar and reference products.

A PK bridging ELISA for measuring drug concentrations (such as Risankizumab, a monoclonal antibody) in serum typically uses a standard curve generated from known concentrations of the research-grade biosimilar. Here's how this process is applied:

• Calibration Standard Role: The research-grade biosimilar is prepared at several known concentrations in a serum matrix to establish the standard curve. These standards define the range of quantification and allow sample concentrations to be interpolated from their optical density readings.

• Analytical Standard in Bridging Assays: Best practice in bioanalysis recommends establishing a single PK assay using a single analytical standard—usually the biosimilar—so that both biosimilar and reference (originator) drug samples are quantified against the same calibration curve. This approach reduces variability and avoids the need for multiple assay methods or cross-over studies, supporting robust PK bioequivalence assessment.

• Reference Controls: Alongside the calibration standards, quality control (QC) samples are prepared using both the biosimilar and reference drug at several concentrations. These QC samples are measured in every assay run against the established standard curve to ensure ongoing assay precision and accuracy.

• Assay Qualification and Validation:

  • Before the biosimilar is accepted as the calibration standard, method qualification studies are performed, comparing quantitative equivalence between the biosimilar and the reference product.
  • Statistical methods are used to confirm that the biosimilar and originator have equivalent analytical performance within the pre-specified margin (commonly, a 90% confidence interval for the QC/control ratio within 0.8–1.25).
  • If bioanalytical comparability is confirmed, the biosimilar serves as the assay calibrator for all subsequent PK determinations and validation using both reference and test products.

• ELISA Workflow:

  • Plates are coated with a capture reagent specific for Risankizumab.
  • Serum samples and biosimilar-based standards are added.
  • Detection is achieved via an enzyme-conjugated secondary antibody, followed by a colorimetric readout.
  • The resulting absorbance is proportional to the amount of Risankizumab present in each well, which is interpreted by referencing the standard curve generated from the biosimilar.

Summary Table: Use of Risankizumab Biosimilar as Calibration/Control in PK Bridging ELISA

Key Practice:
Use a single, scientifically verified, research-grade biosimilar as the quantitative standard for all PK determinations in bridging ELISA, with cross-comparability confirmed through rigorous validation and proper reference controls.

The primary in vivo models used to evaluate research-grade anti-IL-23A (p19) antibodies for tumor growth inhibition and characterization of tumor-infiltrating lymphocytes (TILs) are murine syngeneic tumor models. There is little evidence that humanized mouse models are commonly used for this specific anti-IL-23A application, given the species specificity of most research-grade antibodies and the established use of syngeneic systems.

Key Syngeneic Models:

• B16F10 (melanoma) model: Frequently used to study IL-23 in the tumor microenvironment. Administration of anti-IL-23 (often a p19-neutralizing monoclonal antibody) has been shown to suppress tumor metastasis and modulate immune cell subsets, including TILs. In this context, natural killer (NK) cells are often implicated as major effectors in tumor growth inhibition following anti-IL-23 treatment, with less dependence on CD4+ and CD8+ T cells in some studies.
• EG7 (EL4-OVA) model: Used to assess adaptive immunity. Here, anti-IL-23A treatment can promote CD8+ T cell responses and regulate the composition of TILs, contributing to tumor growth control.
• RENCA (renal cell carcinoma), CT26 (colorectal carcinoma), and other syngeneic models: These models are well-profiled for TIL composition and response to immunotherapies, though direct evidence of anti-IL-23A (p19) antibody administration is most detailed for B16F10 and EG7.

Tumor Growth Inhibition and TIL Characterization:

• Studies using anti-IL-23A antibodies in syngeneic models consistently indicate inhibition of tumor growth via immune-mediated mechanisms.
• Detailed TIL analysis often includes flow cytometry to profile changes in CD4+ T cells, CD8+ T cells, NK cells, myeloid populations, and Tregs, sometimes accompanied by transcriptomic or single-cell RNA sequencing approaches for finer immune subset resolution.

Use of Humanized Models:

• Humanized anti-IL-23 or anti-p19 antibodies (e.g., BI 655066) are developed and characterized for affinity and function, but in vivo tumor studies with humanized mice (bearing human immune and tumor components) using anti-IL-23A are far less common or remain preclinical and unpublished for the specific purpose of TIL characterization and tumor inhibition.
• When translation to human cellular contexts is desired, studies often instead leverage primary human tumor or blood samples ex vivo, or advanced scRNA-seq analyses of human tumors for IL-23/IL-23R pathway activity and Treg characterization without in vivo antibody administration.

Summary Table: Syngeneic vs. Humanized Models

Conclusion:
Mouse syngeneic tumor models, particularly B16F10 and EG7, are the primary in vivo systems for studying anti-IL-23A (p19) antibody effects on tumor growth and TIL composition. Humanized models are not yet routinely used for this application in published literature.

Researchers have not yet extensively studied the use of risankizumab biosimilars in direct combination with other checkpoint inhibitors—such as anti-CTLA-4 or anti-LAG-3 biosimilars—in preclinical or clinical immune-oncology models, so published evidence for synergy or protocols is lacking. Most available research focuses on combining traditional immune checkpoint inhibitors (ICIs) like anti-PD-1/PD-L1 with agents targeting distinct immune pathways (such as CTLA-4 and LAG-3) to harness complementary mechanisms for improved antitumor efficacy.

Key context and details:

• Risankizumab is an IL-23 inhibitor primarily used to treat autoimmune conditions (e.g., psoriasis), not directly as a cancer immunotherapy.
• ICIs like anti-CTLA-4 and anti-LAG-3 work by releasing T-cell inhibition, thereby promoting anti-tumor immune responses. Combination strategies (e.g., PD-1 plus CTLA-4 blockade) are well-researched and show synergistic effects in models and clinical trials due to their action in distinct immune compartments.
• There is theoretical interest in testing combinations of IL-23 inhibitors and ICIs because of their complementary immune-modulatory roles, but this has not been systematically studied or reported in published model systems.

What researchers could investigate using risankizumab biosimilars with ICIs:

• The role of IL-23 in tumor immunology is complex and context-dependent. Murine models with loss of IL-23 function produce conflicting evidence: some show decreased tumor development and metastasis, others show increased or unchanged rates, and the overall effect differs by cancer type.
• Risankizumab (targeting IL-23) is more immunomodulatory than broadly immunosuppressive, potentially making it a candidate for combination in certain complex models, such as in patients who need control of immune-related adverse events, or mechanistic studies of T-helper 17 (Th17) cell involvement in tumor immunity.
• There is no documented use of risankizumab biosimilars in synergy studies with CTLA-4, LAG-3, or PD-1 inhibitors in both preclinical or clinical immune-oncology model systems.

Potential adverse events and pharmacological considerations:

• Risankizumab use can cause immune system disorders, infections, and neoplasms—adverse effects that must be carefully monitored when designing combination immunotherapy protocols.
• Combination therapy with multiple ICIs increases both efficacy and toxicity, often resulting in higher rates of grade 3–4 adverse events, so adding further immune modulation (such as IL-23 inhibition) would require rigorous safety studies.

Summary Table: (Based on currently available published data)

In conclusion: There is no substantial published evidence for risankizumab biosimilar synergy studies with checkpoint inhibitors like anti-CTLA-4 or anti-LAG-3 in complex tumor immune models; existing research focuses on ICI/ICI combinations rather than ICI/IL-23 inhibitor combinations. Researchers interested in such combinations would need to develop new preclinical protocols based on preliminary mechanistic rationale and safety data.

In bridging ADA ELISA immunogenicity testing for risankizumab, a risankizumab biosimilar is used as both the capture and detection reagent to specifically measure anti-drug antibodies (ADAs) in a patient's serum.

• Assay Principle: The bridging format exploits the bivalent nature of IgG antibodies. Patient serum is incubated with immobilized risankizumab (biosimilar) on the plate and with labeled risankizumab (biosimilar) in solution. If anti-risankizumab antibodies are present, they bridge the two drug molecules, forming a sandwich detectable by the label.
• Capture and Detection: The biosimilar ensures assay specificity for ADAs targeting risankizumab by mimicking the therapeutic’s epitopes, making it suitable for both capturing ADAs (coated on plate) and detecting the bridged complex (as a conjugate).
• Clinical Monitoring: By quantifying ADA levels using this format, clinicians can assess a patient's immune response to risankizumab therapy, which may impact drug efficacy and safety.

Key Details:

• Risankizumab biosimilars used are produced to maintain the same antigenic determinants as the original drug, ensuring detection of antibodies generated against the therapeutic.
• This approach is applicable in anti-drug antibody assays, with the biosimilar functioning as both reagent and calibrator for assay standardization.
• The bridging ELISA is typically validated for drug interference and sensitivity; it is recognized for its specificity but may exhibit lower sensitivity when free drug is present in patient samples.

Summary Table:

This method is well-established for monitoring immunogenicity in patients receiving monoclonal antibody therapies like risankizumab.