Increased Therapeutic Effectiveness of PE-Based Immunotoxins

Patients receiving immunotoxin cancer therapy are less likely to experience the deleterious side-effects associated with non-discriminate therapies such as chemotherapy or radiation therapy. Unfortunately, the continued administration of immunotoxins often leads to a reduced patient response due to the formation of neutralizing antibodies against immunogenic epitopes contained within Pseudomonas exotoxin A (PE). 

To improve the therapeutic effectiveness of PE-based immunotoxins through multiple rounds of drug administration, NIH inventors have sought to identify and remove the human B cell epitopes within PE. Previous work demonstrated that the removal of the murine B cell and T cell epitopes from PE reduced the immunogenicity of PE and resulted in immunotoxins with improved therapeutic activity.

This technology involves the identification and removal of major human B cell epitopes on PE by mutation or deletion. Considering these immunotoxins will be administered to humans, the removal of human immunogenic epitopes is important.  The resulting PE-based immunotoxins have increased resistance to the formation of neutralizing antibodies, and are expected to have improved therapeutic efficacy.