Potential ADCC/ADCP Effects of a Humanized Anti-human Cripto-1 Antibody

Area of Science:

• Oncology
• Immunology
• Biotechnology

Background:

• Cripto-1 (CR-1) is a theranostic biomarker on tumor cells, including cancer stem cells.
• A previously developed humanized anti-CR-1 antibody (ah²CR1-Ab35) showed growth inhibition in cancer cells.

Purpose of the Study:

• To evaluate the potential of ah²CR1-Ab35 to mediate antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP).
• To assess the antibody's efficacy in CR-1-expressing cancer cells.

Main Methods:

• Engineered Jurkat cells expressing CD16a/CD32a with a luciferase reporter system were used as effector cells.
• CR-1 expression was enhanced in MDA-MB-231, MIA-Paca-2, LS 174T, and HEK293 cells.
• Anti-sense plasmids suppressed endogenous CR-1 for background controls.
• Photon counts measured luciferase reactions stimulated by the anti-CR-1 antibody.

Main Results:

• The anti-CR-1 antibody mediated both ADCC and ADCP effects in a dose-dependent manner.
• EC₅₀ values were approximately 1 μM in MDA-MB-231 cells and 1-4 μM in MIA-Paca-2 cells.
• ADCC EC₅₀ was 1-4 μM in LS 174T cells; ADCP was not clearly determined due to low photon counts.

Conclusions:

• The humanized anti-CR-1 antibody can mediate ADCC and ADCP in CR-1-expressing cells.
• Observed effects did not correlate with CR-1 expression levels.
• CR-1 targeting efficacy via ADCC/ADCP may depend on target cell characteristics.