Immunomedics develops E1-L-thP1 protein complex for targeted delivery of siRNAs to diverse solid cancers

Immunomedics, Inc. (Nasdaq:IMMU), a biopharmaceutical company focused on developing monoclonal antibodies to treat cancer and other serious diseases, today reported the development of a novel protein complex, designated as E1-L-thP1, for targeted delivery of small interfering ribonucleic acids (siRNAs) to diverse solid cancers.

RNA interference (RNAi) is a natural process in cells in which short RNA molecules control which genes are active.  In preclinical settings, RNAi has been shown to shut down the production of a number of cancer-related proteins.  Despite the potential of RNAi to silence specific genes, the full therapeutic potential of RNAi remains to be realized due to a lack of effective delivery system to target cells in vivo.

To address this critical need, the Company created E1-L-thP1 using its patented Dock-and-Lock protein engineering platform technology. E1-L-thP1 is made up of hRS7, the Company's proprietary humanized anti-TROP-2 antibody, linked with 4 copies of human protamine.  Protamines are small proteins that bind to nucleic acids and, as such, are good candidates for delivering siRNAs to target cells.

E1-L-thP1 was found to internalize in cells that express the TROP-2 antigen, suggesting the binding ability of hRS7 remains intact in the fusion protein. More importantly, it effectively delivered siRNAs into TROP-2-expressing cancer cells, causing cell death. Further evaluation of the in vitro and in vivo efficacy of E1-L-thP1 for delivery of CD74- and CEACAM6-specific siRNAs to treat TROP-2-expressing pancreatic cancer is ongoing.

"RNAi is an important new field of cancer research and we are pleased to be making advances here," commented Cynthia L. Sullivan, President and CEO. "Given that TROP-2 is expressed in the vast majority of human cancers that include breast, colon, stomach, lung, prostate, ovary, endometrium, uterine, cervix and pancreas, E1-L-thP1 represents a potential novel tool in the arsenal of an oncologist to fight cancer if its efficacy can be confirmed in a clinical setting."