Screening antibodies for cancer therapeutics

Conservation of Oncofetal Antigens on Human Embryonic Stem Cells Enables Discovery of Monoclonal Antibodies against Cancer. Tan HL, Yong C, Tan BZ, Fong WJ, Padmanabhan J, Chin A, Ding V, Lau A, Zheng L, Bi X, Yang Y, & Choo A. (2018). Scientific Reports, 8 (1):11608.

This study used both Hum-ZAP (Cat. #IT-22) and Streptavidin-ZAP (Cat. #IT-27) to identify and characterize an antibody raised using human embryonic stem cells with potential as a cancer therapeutic.

Summary:  Antibody A19 not only binds to undifferentiated hESCs by flow cytometry, it also reacts with ovarian and breast cancer cell lines with low or no binding to normal cells.
Dose:  In Vitro – Number of viable cells treated showed a decrease in cell number (Hum-ZAP mixed with A19; Streptavidin-ZAP mixed with biotinylated A19).  To determine if there were off-target effects, Hum-ZAP and chA19 were incubated with a non-binding cell line OVCAR10; no apparent cytotoxicity was observed.
In Vivo – 5 x 106 SKOV3 cells were implanted s.c. in NUDE mice and Biotinylated A19-Streptavidin-ZAP (ADC), administered ip.  The controls were free Saporin and naked A19.  By the end of 10 weeks, mice administered with the ADC saw a 60% reduction in tumor size compared to control groups.

Streptavidin-ZAP (Cat. #IT-27) converts biotinylated materials into targeted toxins. Streptavidin is a tetrameric protein (molecular weight 53 kDa in its recombinant form), with each subunit able to bind a single biotin molecule. The bond between streptavidin and biotin is rapid and essentially non-reversible, unaffected by most extremes of pH, organic solvents, and denaturing reagents. It is the strongest known noncovalent biological interaction (Ka = 1015 M-1) between protein and ligand. The streptavidin used to make Streptavidin-ZAP contains no carbohydrate group and has a neutral isoelectric point, which therefore reduces the nonspecific binding as compared to avidin. A variety of molecules, including lectins, proteins, and antibodies, can be biotinylated and reacted with streptavidin-labeled probes or other detection reagents for use in biological assays.

Streptavidin-ZAP is also available in three kit variations: Z-kits (KIT-27-Z) include everything you need to perform in vitro internalization assays with your biotinylated targeting agent. For in vivo assays, use KIT-27-A for antibodies and KIT-27-B for peptides.