Sailybio Launches the Anti-FMC63 Detection Antibody
The global cell immunotherapy industry has grown explosively in recent years, and CAR-T therapy has become the most groundbreaking innovation in hematologic oncology. Among the many targets available, CD19 has established itself as the “golden target” for CAR-T therapy because it is expressed broadly, stably and specifically on the surface of the great majority of B-cell malignancies.
CD19 CAR-T constructs that use the FMC63 scFv as their antigen-binding domain — with high affinity, high specificity and low off-target toxicity — have become the mainstream configuration in global CAR-T development and account for the overwhelming majority of clinical and commercial products. Whether in preclinical research, process development, pilot-scale manufacturing, regulatory filing and lot release, or clinical PK/PD studies, accurate, stable and interference-free measurement of FMC63-CAR expression is a core step in keeping a product safe, effective and on schedule.
Part 1 Product Introduction
FMC63 is a single-chain variable fragment (scFv) derived from the classic mouse monoclonal antibody raised against human CD19. It is the core “guidance head” element of a CD19 CAR-T: it recognizes and binds the CD19 antigen with high precision and directs T cells to kill tumor cells in a targeted manner. It is today the most widely used standard sequence in CD19 CAR-T products worldwide.
Figure 1. Anti-FMC63 mAb, supplied at a working concentration of 1 mg/mL.
Part 2 Four Core Advantages
Exceptional specificity: it recognizes FMC63 only, so the result can be trusted
As a high-quality anti-idiotypic antibody, this product binds only to CAR molecules built on the FMC63 sequence. It does not cross-react with other proteins on the T-cell surface, with serum components or with impurities in the assay system. From the outset, therefore, the readout truly reflects CAR-positive rate and expression intensity, with no false-positive interference.
Flexible labeling options: compatible with flow cytometry on any platform
The line is available as unconjugated antibody and with four commonly used fluorescent labels — FITC, PE, APC and AF647. Each fits directly onto flow cytometers from BD, Thermo, Beckman and every other major brand. One-step staining, with no secondary antibody incubation, greatly simplifies handling, shortens assay time and improves laboratory efficiency.
Stringent quality control: high purity, high stability, high value
• Purity ≥ 95%, which effectively lowers non-specific background.
• Standard working concentration 1 mg/mL — economical in use and flexible to dilute.
• Store at 2–8 °C protected from light; stable for up to 12 months.
• Small lot-to-lot variation and excellent reproducibility for long-term projects.
Core application scenarios
• Accurate measurement of CAR-T positive rate and expression level.
• Process development and in-process monitoring (transfection efficiency, expression stability).
• Quality control (QC) and establishment of lot-release criteria.
• Pharmacokinetic (PK) and pharmacodynamic (PD) studies.
• Method optimization, validation and cost control.
Part 3 Quality Validation Data
In their corresponding fluorescence channels, the FITC- and PE-labeled Anti-FMC63 antibodies give a high signal-to-noise ratio, low non-specific binding and consistent staining. They also combine readily into multicolor panels, adapting to different experimental designs and detection platforms with reliable data and good reproducibility.
Figure 2. Binding activity of Anti-FMC63 mAb. MFI versus antibody concentration (μg/mL).
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Figure 3. PE-anti-FMC63 mAb (red, 1:200) shows strong binding to FMC63-expressing cells.
Figure 4. FMC63-overexpressing 293T cells stained with FITC-anti-FMC63 diluted 1:200 (red) and left unstained (blue).Part 4 Product Catalog
Table 1. Anti-FMC63 mAb product catalog.
Related Product
A further best-selling product, Anti-G4S linker (905-5) mAb, is also available. Its details are given below, and a trial can be requested at the same time.
Table 2. Anti-(G4S)n Linker (905-5) Rabbit mAb product catalog.
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About Sailybio
Shanghai Sailybio Biopharmaceutical Co., Ltd. is a specialized and innovative enterprise dedicated to primary cell isolation and preparation, preclinical druggability research and evaluation, and clinical CRO services. The company was formed through the strategic merger of Shanghai Sailybio Biotechnology Co., Ltd. and Shanghai Xuanfeng Biotechnology Co., Ltd. Both companies have long held leading positions in niche segments such as immune cell collection and preparation services, and continue to lead the industry forward, contributing to the rapid growth of the biopharmaceutical sector.
The company now operates more than 1,000 m² of R&D laboratory space together with an experienced biopharmaceutical R&D and clinical project management team, providing clients with professional services in primary cell isolation and preparation, preclinical druggability evaluation, clinical project services, and reagents and consumables. The company has established a set of professional standards to ensure compliance with international regulations and standards.
Since its founding in 2015, the company has held to its mission of “continuously creating greater value for customers and employees”, concentrating on innovative drug R&D and aiming to become a globally leading service provider to pharmaceutical companies.
