Dual Targeting of Cancer Cells with DARPin-Based Toxins for Overcoming Tumor Escape.

Elena Shramova,Sergey Deyev,Anastasia Ryabova,Elena Konovalova,Georgij Telegin,Galina Proshkina,Aleksey Schulga,Victoria Shipunova,Roman Kamyshinsky,Andrey Konevega

doi:10.3390/cancers12103014

Abstract

Simple SummaryTargeted therapy of solid tumors represents a great challenge because of heterogeneity of tumor-associated antigen expression. To overcome this obstacle we propose a dual targeting therapy based on protein preparations capable of recognizing different of tumor-associated antigens on a tumor cell producing a directed cytotoxic effect. The dual specific therapy of breast carcinoma-bearing mice using the designed preparations eliminates both the primary tumor and distant metastases. The mono-targeting therapy aimed at single tumor-associated antigen did not suppress metastases at all. The proposed approach can serve as a potential therapeutic strategy that surpasses mono-specific targeting strategies in the anti-cancer efficacy.We report here a combined anti-cancer therapy directed toward HER2 and EpCAM, common tumor-associated antigens of breast cancer cells. The combined therapeutic effect is achieved owing to two highly toxic proteins—a low immunogenic variant of Pseudomonas aeruginosa exotoxin A and ribonuclease Barnase from Bacillus amyloliquefaciens. The delivery of toxins to cancer cells was carried out by targeting designed ankyrin repeat proteins (DARPins). We have shown that both target agents efficiently accumulate in the tumor. Simultaneous treatment of breast carcinoma-bearing mice with anti-EpCAM fusion toxin based on LoPE and HER2-specific liposomes loaded with Barnase leads to concurrent elimination of primary tumor and metastases. Monotherapy with anti-HER2- or anti-EpCAM-toxins did not produce a comparable effect on metastases. The proposed approach can be considered as a promising strategy for significant improvement of cancer therapy.

Highlights

Cancer is a second leading cause of death globally and one of the biggest challenges facing biomedical scientists
We have shown that liposomes functionalized with human epidermal growth factor receptor 2 (HER2)-specific designed ankyrin repeat proteins (DARPins) can be an effective vehicle for proteins delivery to cancer cells [28]
We used this method for the preparation of ligand-targeted liposomes comprising large quantities of encapsulated toxic protein for the treatment of HER2-positive cancer in vivo

Summary

Introduction

Cancer is a second leading cause of death globally and one of the biggest challenges facing biomedical scientists. Despite the considerable progress made in targeted cancer treatment, the heterogeneity of solid tumor greatly limits precision oncology therapy. Dual targeting strategies applying targeting moieties recognized different receptors in tumor population can be a solution of this problem. Tumor targeting with naked antibodies and antibody-drug conjugates has become an established strategy for cancer-related therapy in clinics, if conventional therapies have failed [1,2]. A solution might come from the use of alternative non-IgG binding scaffolds [5,6]. Due to their small size, high affinity to target and robust production scaffold proteins represent an attractive alternative to immunoglobulin proteins

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