Internal antigens accessible in breast cancer: implications for tumor targeting

Area of Science:

• Oncology
• Immunology
• Biochemistry

Background:

• Monoclonal antibody (MAb)-mediated cancer therapy often requires absolute specificity for malignant cells and surface target antigens.
• These requirements may be overly stringent for effective clinical application of MAbs.

Purpose of the Study:

• To investigate the potential of targeting intracellular keratin polypeptides in malignant breast epithelium using MAbs.
• To explore if MAb localization can occur in the absence of surface antigens and absolute specificity.

Main Methods:

• Passive infusion of anti-keratin MAbs into fresh surgical specimens of breast carcinoma.
• Assessment of MAb localization within tumor cells.

Main Results:

• Selective localization of anti-keratin MAbs was observed within malignant breast epithelial cells.
• Localization occurred even though keratin is a normal intracellular constituent and MAbs were passively infused.
• Tumor cell permeability to macromolecules is likely responsible for the selective localization.

Conclusions:

• MAb-mediated targeting of intracellular antigens like keratin is feasible in cancer therapy.
• The presence of a permeable tumor cell fraction allows for MAb uptake, suggesting a novel therapeutic strategy.
• This approach could enable targeting of neighboring impermeable tumor cells with conjugated agents.