Enhanced cytotoxicity of a Pseudomonas Exotoxin A based immunotoxin against prostate cancer by addition of the endosomal escape enhancer SO1861.

Autor:	Masilamani AP; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany., Huber N; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany., Nagl C; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany., Dettmer-Monaco V; Faculty of Medicine, University of Freiburg, Freiburg, Germany.; Institute for Transfusion Medicine and Gene Therapy, Medical Center-University of Freiburg, Freiburg, Germany.; Center for Chronic Immunodeficiency, Medical Center-University of Freiburg, Freiburg, Germany., Monaco G; Faculty of Medicine, University of Freiburg, Freiburg, Germany.; Institute for Transfusion Medicine and Gene Therapy, Medical Center-University of Freiburg, Freiburg, Germany.; Center for Chronic Immunodeficiency, Medical Center-University of Freiburg, Freiburg, Germany.; Institute of Neuropathology, Medical Center-University of Freiburg, Freiburg, Germany., Wolf I; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany.; Faculty for Biology, University of Freiburg, Freiburg, Germany., Schultze-Seemann S; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany., Taromi S; Faculty of Medicine, University of Freiburg, Freiburg, Germany.; Department of Medicine I, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medical and Life Sciences, University Furtwangen, VS-Schwenningen, Germany., Gratzke C; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany., Fuchs H; Institute of Diagnostic Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany., Wolf P; Department of Urology, Medical Center-University of Freiburg, Freiburg, Germany.; Faculty of Medicine, University of Freiburg, Freiburg, Germany.
Jazyk:	angličtina
Zdroj:	Frontiers in pharmacology [Front Pharmacol] 2023 Jul 06; Vol. 14, pp. 1211824. Date of Electronic Publication: 2023 Jul 06 (Print Publication: 2023).
DOI:	10.3389/fphar.2023.1211824
Abstrakt:	Immunotoxins consist of an antibody or antibody fragment that binds to a specific cell surface structure and a cytotoxic domain that kills the cell after cytosolic uptake. Pseudomonas Exotoxin A (PE) based immunotoxins directed against a variety of tumor entities have successfully entered the clinic. PE possesses a KDEL-like motif (REDLK) that enables the toxin to travel from sorting endosomes via the KDEL-receptor pathway to the endoplasmic reticulum (ER), from where it is transported into the cytosol. There, it ADP-ribosylates the eukaryotic elongation factor 2, resulting in ribosome inhibition and finally apoptosis. One major problem of immunotoxins is their lysosomal degradation causing the need for much more immunotoxin molecules than finally required for induction of cell death. The resulting dose limitations and substantially increased side effects require new strategies to achieve improved cytosolic uptake. Here we generated an immunotoxin consisting of a humanized single chain variable fragment (scFv) targeting the prostate specific membrane antigen (PSMA) and the de-immunized PE variant PE24mut. This immunotoxin, hD7-1(VL-VH)-PE24mut, showed high and specific cytotoxicity in PSMA-expressing prostate cancer cells. We deleted the REDLK sequence to prevent transport to the ER and achieve endosomal entrapment. The cytotoxicity of this immunotoxin, hD7-1(VL-VH)-PE24mutΔREDLK, was greatly reduced. To restore activity, we added the endosomal escape enhancer SO1861 and observed an up to 190,000-fold enhanced cytotoxicity corresponding to a 57-fold enhancement compared to the initial immunotoxin with the REDLK sequence. A biodistribution study with different routes of administration clearly showed that the subcutaneous injection of hD7-1(VL-VH)-PE24mutΔREDLK in mice resulted in the highest tumor uptake. Treatment of mice bearing prostate tumors with a combination of hD7-1(VL-VH)-PE24mutΔREDLK plus SO1861 resulted in inhibition of tumor growth and enhanced overall survival compared to the monotherapies. The endosomal entrapment of non-toxic anti-PSMA immunotoxins followed by enhanced endosomal escape by SO1861 provides new therapeutic options in the future management of prostate cancer. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2023 Masilamani, Huber, Nagl, Dettmer-Monaco, Monaco, Wolf, Schultze-Seemann, Taromi, Gratzke, Fuchs and Wolf.)
Databáze:	MEDLINE
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