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Updated: Jun 28, 2026
Optimization of a Quantitative Micro-neutralization Assay
Published on: December 14, 2016
Development and Validation of a Quasi-Quantitative Bioassay for Neutralizing Antibodies Against CP-870,893
Daniel J Baltrukonis1, Deborah Finco-Kent, Thomas T Kawabata
1Worldwide Safety Sciences, Pfizer Global Research and Development, Groton, Connecticut, USA.
Abstract:
The human monoclonal antibody CP-870,893 is a CD40 receptor agonist currently being developed for the treatment of cancer. A bioassay to measure neutralizing antibodies (Nab) to CP-870,893 in 5% human serum matrix was developed and validated utilizing the Daudi cell line and flow cytometric detection. Additionally, samples from CP-870,893 treated cynomolgus monkeys were analyzed in the bioassay and compared to results obtained using a competitive receptor-binding (CRB) Nab immunoassay to determine if the CRB assay may be used in place of the bioassay. Treatment of Daudi cells for 2 d with CP-870,893 leads to a concentration-dependent increase in CD54 cell surface expression. The presence of antidrug Nab attenuates CP-870,893 binding to CD40 and the induction of CD54. An anti-idiotype monoclonal antibody (Mab) and a monkey sera pool were identified as positive controls for neutralization of CP-870,893. During development, it was observed that the assay robustness was altered by culture media and FBS substitutions. For validation the following parameters were established: cutpoint factors in the presence (0.779) and absence (1.282) of 50 ng/ml CP-870,893, linear region of the concentration-response (1-100 ng/ml CP-870,893), intra- and inter-assay precision (CV
Insights
A novel bioassay was developed to detect neutralizing antibodies against the cancer drug CP-870,893. This assay, using flow cytometry, can quantify these antibodies in human serum and may be a suitable alternative to traditional methods.
Area of Science:
- Immunology
- Pharmacology
- Biotechnology
Background:
- CP-870,893 is a human monoclonal antibody and CD40 receptor agonist developed for cancer treatment.
- Measuring neutralizing antibodies (Nab) is crucial for assessing drug efficacy and safety.
- Existing methods for Nab detection may require optimization for specific drug candidates.
Purpose of the Study:
- To develop and validate a sensitive bioassay for quantifying neutralizing antibodies (Nab) against CP-870,893 in human serum.
- To evaluate the suitability of a competitive receptor-binding (CRB) immunoassay as an alternative to the bioassay.
- To assess the impact of various factors on assay robustness and performance.
Main Methods:
- A Daudi cell line-based bioassay utilizing flow cytometry was developed to measure Nab against CP-870,893.
- The bioassay was validated by establishing parameters including cut-point factors, linear range, precision, specificity, sensitivity, ruggedness, and stability.
- Samples from CP-870,893 treated cynomolgus monkeys were analyzed using both the bioassay and a CRB Nab immunoassay.
Main Results:
- The bioassay demonstrated a concentration-dependent increase in CD54 expression upon CP-870,893 treatment, which was attenuated by Nab.
- Validation established robust assay parameters, including cut-point factors, a linear region of 1-100 ng/ml CP-870,893, and acceptable precision (CV ≤ 25%).
- A strong correlation (R² = 0.94) was observed between the bioassay and CRB assay results in monkey samples, suggesting the CRB assay's potential as an alternative.
Conclusions:
- The validated bioassay is suitable for quasi-quantitative analysis of neutralizing antibodies against CP-870,893 in human serum.
- The competitive receptor-binding (CRB) Nab immunoassay shows promise as a suitable alternative to the bioassay for monitoring CP-870,893 neutralization.
- Assay development requires careful consideration of factors like culture media and fetal bovine serum (FBS) for optimal robustness.
