Anti-Human IGF1R (CD221) (Teprotumumab) [Clone RG1507]

Research-grade Teprotumumab biosimilars serve as calibration standards or reference controls in pharmacokinetic (PK) bridging ELISA assays by providing a well-characterized analyte of known concentration, enabling accurate quantification of Teprotumumab concentrations in serum samples from clinical and preclinical studies.

The utilization process typically involves:

• Assay Calibration: The biosimilar is used to build a standard curve, which defines the relationship between signal intensity (e.g., absorbance in ELISA) and drug concentration. Lyophilized research-grade Teprotumumab biosimilars are reconstituted to specified concentrations and serially diluted to cover the assay’s quantitation range (e.g., 0.31–5 μg/mL, as specified in commercial kits).

• Reference Control: The standard (calibrator) must mimic the pharmacological and biophysical properties of the clinical drug as closely as possible to ensure assay accuracy. Both biosimilars and the reference drug are typically evaluated for bioanalytical equivalency before one is selected as the primary calibrator.

• Bridging ELISA Protocol: In a bridging ELISA, serum samples, calibration standards (biosimilar), and quality controls are processed together. Anti-drug antibodies (such as anti-idiotype antibodies specific to Teprotumumab) or the drug’s therapeutic target (e.g., recombinant IGF-1R coated plates) capture and detect Teprotumumab (or biosimilar) from samples. The calibrator curve is used to interpolate the concentration of unknown samples.

Key points for biosimilar use in PK bridging ELISA:

• Single Analytical Standard Approach: Regulatory and industry best practice is to use a single PK assay with a single analytical standard—often the biosimilar—for quantifying both biosimilar and reference drug in test samples. This reduces assay variability and avoids complications from running parallel standard curves for each product. However, rigorous analytical comparability testing must be performed first to confirm both materials (biosimilar and reference) are interchangeable in the assay.

• Quality Control (QC): QCs, prepared from both the biosimilar and the reference, are assayed to ensure the method accurately measures both products across the analytical range, supporting method validation and regulatory requirements.

• Format and Handling: Standards are usually supplied lyophilized and reconstituted for each run. Stability and storage conditions are tightly controlled to maintain assay consistency.

In summary, research-grade Teprotumumab biosimilars are used as calibrators or controls by first demonstrating equivalence to the clinical reference product, then preparing serial dilutions to generate a calibration curve in the PK bridging ELISA to quantify drug concentrations in serum. The use of a single, validated standard (often the biosimilar) for both test and reference measurements ensures accuracy and regulatory compliance.

The primary in vivo models for administering research-grade anti-IGF1R (CD221) antibodies to study tumor growth inhibition and analyze tumor-infiltrating lymphocytes (TILs) are human tumor xenograft models (in immunodeficient mice) and syngeneic mouse tumor models. The choice of model depends on study objectives, particularly whether immune responses (TIL profiling) or direct tumor growth inhibition are being prioritized.

Model Overview

Key Findings from Literature:

• Human Xenograft (Immunodeficient mice):
  Most published studies of anti-IGF1R antibodies (e.g., hR1, AVE1642, IMC-A12) use human tumor xenograft models in immunodeficient mice to assess tumor growth inhibition. While these models are robust for evaluating anti-tumor efficacy, their lack of an adaptive immune system limits their use for detailed TIL analysis and immune profiling.

  • Example: hR1 antibody and its multivalent variant Hex-hR1 were tested against RH-30 rhabdomyosarcoma xenografts in nude mice (immunodeficient), assessing tumor growth inhibition, but not TILs.

  • Example: AVE1642 was combined with chemotherapy in LCC6 (breast cancer) xenografts to study sequencing effects on tumor growth and apoptosis, but immune infiltrates were not assessed.

• Syngeneic Mouse Models (Immunocompetent mice):
  These models are widely used in immunotherapy research to robustly study TILs and the immune microenvironment. Tumor lines such as RENCA, EMT6, CT26, B16F10 are routinely characterized for their unique immune infiltrates and response to antibody-based therapies. However, published studies specifically using anti-IGF1R (CD221) antibodies in these models are sparse, likely due to species cross-reactivity limitations.

  • Example: Immune changes and TILs are well characterized in models such as RENCA (kidney), CT26 (colon), EMT6 (mammary), and B16F10 (melanoma), but primarily in the context of immunotherapy targets like PD-1/PD-L1 or OX40, rather than anti-IGF1R.

• Humanized Mouse Models:
  These permit engraftment of both human immune system and human tumors in immunodeficient mice, offering the potential to study both anti-tumor efficacy and human TILs. While this is theoretically the ideal model for your stated goals, published use of anti-IGF1R antibodies in true humanized tumor-immune in vivo models is very limited.

Summary Table: Model Use for Anti-IGF1R (CD221) Antibodies

Essential context:

• Nearly all published work on in vivo anti-IGF1R therapy focuses on human tumor xenografts in immunodeficient mice, which do not allow characterization of mouse or human TILs, due to lack of an immune system.
• Syngeneic models are standard for immunotherapy and immune profiling (TILs), but published reports of anti-IGF1R use in these models are rare, probably because anti-IGF1R antibodies often do not cross-react with murine IGF1R, or efficacy questions are focused on human receptors.
• Humanized mouse models represent the gold standard for simultaneous tumor growth and human TIL analysis but are not yet widely used with anti-IGF1R antibodies in published research.

If you are seeking published models that both use anti-IGF1R antibodies, demonstrate tumor growth inhibition, and enable TIL profiling in vivo, options in the literature are extremely limited. Most research separates these purposes due to model constraints.

References from current literature:

• hR1/Hex-hR1 antibodies: Human tumor xenograft (RH-30 in nude mice).
• AVE1642 antibody: Human breast cancer xenograft models (LCC6, MCF-7).
• IMC-A12 antibody: Pediatric xenograft testing, no immune profiling.
• TIL profiling: Syngeneic mouse models, with a focus on CT26, RENCA, EMT6, B16F10, but not with anti-IGF1R antibodies.

In summary:

• Human xenograft models (immunodeficient mice): Standard for tumor growth inhibition with anti-IGF1R antibodies.
• Syngeneic models: Standard for TIL/immune analysis, not for anti-IGF1R unless antibody is murinized or cross-reactive.
• Humanized mice: Theoretical best fit for both goals but rarely used for anti-IGF1R in published studies.

For your specific experimental needs, custom development (e.g., a murine-reactive anti-IGF1R in a syngeneic model or humanized system) may be required.

Researchers investigating synergistic effects of Teprotumumab biosimilars in combination with immune checkpoint inhibitors (such as anti-CTLA-4 or anti-LAG-3 biosimilars) in immune-oncology models are generally guided by principles established for combining targeted therapies with immune-modulating agents. However, there is currently no direct, published evidence or clinical trial data specifically documenting the use of Teprotumumab in combination with checkpoint inhibitors in immune-oncology models as of the most recent literature.

Context and Current Approaches:

• Teprotumumab is a fully human monoclonal antibody targeting the insulin-like growth factor-1 receptor (IGF-1R), approved for thyroid eye disease (TED) and studied in autoimmune pathways, with its mechanism centered on inhibiting IGF-1R-mediated signaling in immune and stromal cells.
• Immune checkpoint inhibitors (ICIs) such as anti-CTLA-4 and anti-LAG-3 monoclonal antibodies block negative regulators of T-cell activation, aiming to enhance anti-tumor immunity.
• The combination of ICIs with targeted therapies (such as ALK, PI3K, or CDK inhibitors) is an active area of research in oncology, with the rationale that targeted inhibition can modulate the tumor microenvironment to make tumors more susceptible to immune-mediated attack.

Experimental Strategies for Synergy:

• In general, researchers use syngeneic or humanized mouse models and ex vivo immune cell culture systems to compare the effects of:
  • Targeted therapy alone (e.g., Teprotumumab biosimilar)
  • Checkpoint inhibitor alone (e.g., anti-CTLA-4, anti-LAG-3)
  • Combination of both agents, assessing for additive or synergistic effects on tumor regression, immune cell activation, and changes in the tumor microenvironment.
• Key experimental readouts include tumor growth delay, survival advantage, T-cell infiltration, exhaustion marker expression, and cytokine profiling.
• Synergy is usually defined quantitatively by demonstrating effects (such as increased tumor regression or immune activation) greater than the sum of effects from each monotherapy.

Scientific Rationale (Based on Analogous Combinations):

• While Teprotumumab specifically targets IGF-1R, the IGF-1 axis is implicated in tumor immune evasion and stromal remodeling, suggesting that blockade could enhance the efficacy of immunotherapies by altering the tumor microenvironment to support immune infiltration and effector function (by analogy to PI3K/AKT/mTOR and ALK target combinations with ICIs).
• Combination approaches often require careful toxicity assessment, as seen in other targeted agent + ICI combinations.

Key Caveat:

• There is no reported or published data directly applying this approach to Teprotumumab biosimilars with checkpoint inhibitors yet. The approach, however, aligns with current trends in immune-oncology research, and may be under preclinical investigation.

Summary Table:

Conclusion:
Researchers have established the general framework and rationale for combining targeted therapies like IGF-1R inhibitors (exemplified by Teprotumumab) with checkpoint inhibitors in immune-oncology, but specific data involving Teprotumumab biosimilars with anti-CTLA-4 or anti-LAG-3 has not been published in the peer-reviewed literature. The combination remains a logical direction for future experimental and clinical studies, based on analogous strategies involving other targeted agents.

A Teprotumumab biosimilar is used in a bridging anti-drug antibody (ADA) ELISA as both the capture and detection reagent to identify patient antibodies that bind to teprotumumab, thus monitoring the patient’s immune response against the therapeutic drug.

In a bridging ADA ELISA, the assay setup typically involves the following steps:

• Capture Step: The plate is coated with Teprotumumab biosimilar, either directly or via biotin/avidin coupling, to capture any ADAs present in the patient’s serum that recognize teprotumumab.

• Detection Step: After washing, the same Teprotumumab biosimilar—but labeled (commonly with HRP, biotin, or digoxigenin)—is added. If ADAs are present, they bridge between the immobilized capture teprotumumab and the labeled detection teprotumumab.

This format is called a “bridging assay” because ADAs with at least two antigen-binding sites (i.e., bivalent antibodies) can bridge the capture and detection molecules. This approach is widely used for monoclonal antibody drugs, including teprotumumab.

Key details:

• Why use a biosimilar? The biosimilar molecule is highly similar in structure and immunogenic epitopes to the therapeutic teprotumumab. It can therefore serve as a stand-in for the actual therapeutic for both capture and detection, ensuring specificity for antibodies generated in response to the drug.
• Detection sensitivity and selectivity: Only antibodies that specifically bind teprotumumab will form a “bridge” and give a signal, allowing for assessment of the immune response (ADA formation) directly against the therapeutic.
• Example ELISA steps:
  • Coat plate with teprotumumab (capture).
  • Add patient serum (potential ADA).
  • Add labeled teprotumumab (detection).
  • Add substrate for signal development (e.g., TMB for HRP).
  • Measure signal proportional to ADA amount.

Applications:

• This ADA assay helps in monitoring immunogenicity, as the presence of anti-teprotumumab antibodies can affect drug efficacy or safety.
• The same approach has been used for many other monoclonal antibody therapies, using recombinant or biosimilar versions as capture/detection reagents in the bridging ELISA format.

There is no specific information in the results about a teprotumumab biosimilar in ADA assays for teprotumumab, but the cited methodology is standard for monoclonal therapeutic antibody monitoring and is applicable by analogy.

If you need more specificity (such as the chemical labeling method or validation steps), please clarify.