Immunotoxin targeting CD133(+) breast carcinoma cells

Area of Science:

• Oncology
• Immunotherapy
• Cancer Biology

Background:

• CD133 is a marker for tumor-initiating cells and a poor prognostic indicator in many cancers.
• An anti-CD133 immunotoxin, dCD133KDEL, was previously developed and showed efficacy in head and neck cancer xenografts.
• The systemic tolerability and efficacy of dCD133KDEL in other cancer types were not yet established.

Purpose of the Study:

• To evaluate the tolerability and efficacy of dCD133KDEL in a systemic human breast carcinoma model.
• To investigate the role of CD133-positive cells in tumor self-renewal.
• To explore combination therapies for addressing tumor heterogeneity.

Main Methods:

• Developed an immunotoxin (dCD133KDEL) targeting CD133 by fusing an anti-CD133 antibody fragment with deimmunized PE38KDEL.
• Assessed dCD133KDEL selectivity and efficacy in MDA-MB-231 breast cancer cells and a systemic intrasplenic tumor model in mice.
• Evaluated combination therapy with dCD133KDEL and another immunotoxin.

Main Results:

• dCD133KDEL selectively inhibited CD133-expressing MDA-MB-231 breast cancer cells.
• Systemic administration of dCD133KDEL led to tumor regression or growth inhibition in a metastatic breast cancer model.
• Combination therapy with dCD133KDEL and a bulk tumor targeting immunotoxin demonstrated superior efficacy.

Conclusions:

• dCD133KDEL is a promising therapeutic agent for breast cancer, particularly when targeting CD133-expressing cells.
• Systemic administration of dCD133KDEL is tolerable and effective in a metastatic model.
• Combination therapies targeting both CD133+ cells and bulk tumor mass may overcome tumor heterogeneity.