Related Experiment Video
Updated: Jan 11, 2026
11:31
High-Efficiency Generation of Antigen-Specific Primary Mouse Cytotoxic T Cells for Functional Testing in an Autoimmune Diabetes Model
Published on: August 16, 2019
8.4K
Cell-based potency assay for anti-CD3-anti-CD19 diabody
Tania L Weiss1, Justine Paniagua1, Tonny Johnson1
1Marin Biologic Laboratories, Inc., 378 Bel Marin Keys Blvd, Novato, CA 94949, USA.
Journal of Immunological Methods
|November 13, 2025
Summary
A novel cell-based potency assay was developed to measure GP101, a bispecific diabody immunotherapy. This assay quantifies T-cell-mediated killing of B-cell malignancies, ensuring consistent and effective therapeutic development.
Area of Science:
- Biotechnology
- Immunotherapy
- Assay Development
Background:
- GP101 is a single-chain diabody immunotherapy targeting CD19-expressing B-cell malignancies.
- It redirects T lymphocytes (expressing CD3) to B lymphocytes (expressing CD19) for targeted cell lysis.
- Existing methods require robust assays to ensure efficacy and safety.
Purpose of the Study:
- To develop a Good Manufacturing Practice (GMP) compliant cell-based potency assay for GP101.
- To quantify the cytotoxic potency of GP101 against B-cell lymphoma targets.
- To meet FDA requirements for therapeutic potency assessment.
Main Methods:
- A cytotoxicity assay utilizing a CD3+ T cell line and a fluorescently labeled CD19+ B cell lymphoma line was developed.
- Target cell lysis was measured by detecting released fluorescent dye using a fluorometer.
- The assay was validated for GMP/Good Laboratory Practice (GLP) compliance.
Main Results:
- The assay demonstrated high sensitivity, detecting killing at 60 pg/mL of GP101.
- Over 90% of target B cells were killed within two hours in vitro.
- The assay is suitable for purified GP101, cell-expressed GP101, and bioactivity in blood.
Conclusions:
- A novel, validated GMP potency assay for GP101 was successfully developed.
- The assay provides a reproducible and quantifiable measure of efficacy for GP101.
- This assay platform may be adaptable for other bispecific T-cell engagers and diabody potency assays.
