Complementation Dependent Enzyme Prodrug Therapy Enables Targeted Activation of Prodrug on HER2-Positive Cancer Cells

Area of Science:

• Oncology
• Biotechnology
• Molecular Biology

Background:

• Antibodies are utilized for targeted delivery of cytotoxins to diseased cells.
• Antibody-directed enzyme prodrug therapy (ADEPT) aims to activate prodrugs at tumor sites but faces clinical challenges due to systemic toxicity.

Purpose of the Study:

• To design and evaluate a novel antibody-fragment split enzyme platform for site-specific activation of small molecule prodrugs.
• To overcome the limitations of traditional ADEPT by ensuring enzyme activity is regained only upon target binding.

Main Methods:

• A library of fusion constructs for a split enzyme platform targeting HER2 was created and evaluated.
• The optimal split enzyme pair was identified based on targeting efficiency and complementation.
• Substrate specificity was screened using chromogenic, fluorogenic, and prodrug substrates.
• The system's efficacy was tested on HER2-positive cells.

Main Results:

• An antibody-fragment split enzyme platform was successfully designed, regaining activity upon binding to HER2.
• The optimal split enzyme pair demonstrated high substrate specificity.
• Treatment of HER2-positive cells showed a 7-fold increase in toxicity with the activated prodrug compared to the prodrug alone.

Conclusions:

• The developed split enzyme platform enables site-specific activation of prodrugs, enhancing targeted cancer therapy.
• This approach offers a promising therapeutic strategy for HER2-positive cancers, addressing previous ADEPT limitations.