Epidermal Growth Factor Based Targeted Toxin for the Treatment of Bladder Cancer

Abstract

Background/Aim: Reports on over-expression of the epidermal growth factor receptor (EGFR) in bladder cancer and its function in tumorigenesis have suggested to target this antigen. Materials and Methods: We generated the targeted toxin EGF-PE40 consisting of the human epidermal growth factor (EGF) as the binding domain and PE40, a truncated version of Pseudomonas Exotoxin A, as the toxin domain. EGF-PE40 was tested on EGFR-expressing bladder cancer cells in view of binding via flow cytometry, and cytotoxicity via WST viability assay. Induction of apoptosis was examined by western blot. Results: The targeted toxin specifically triggered cytotoxicity in the bladder cancer cells with 50% inhibitory concentration (IC 50 ) values in the low nanomolar or picomolar range, and was about 1,250-to 1,500-fold more cytotoxic than the EGFR inhibitor erlotinib. Cytotoxicity of EGF-PE40 was based on the induction of apoptosis. Conclusion: EGF-PE40 represents a promising candidate for the future treatment of bladder cancer.Bladder cancer (BC) is the 10th most common cancer worldwide. Approximately 573,000 new cases and 213,000 deaths from this tumor are expected every year, with highest incidence rates in Europe and North America (1). About 70% of BC cases are non-muscle invasive at the time of diagnosis.They are treated by transurethral resection of the tumor (TURBT) followed by adjuvant intravesical treatment with Bacillus Calmette-Guerin (BCG) or mitomycin (2). However, in about 70% of patients the tumor recurs and in 10-20% of these cases it progresses to muscle-invasive BC (3). Only 50% of patients with muscle-invasive BC survive 5 years despite undergoing radical cystectomy (4). For patients with metastatic disease, cisplatin-based chemotherapy is the standard of care, conferring a median overall survival of 13-16 months (5, 6). Despite therapeutic progress in recent years, e.g. with immune checkpoint inhibitors (7, 8), BC is still characterized by a high recurrence rate and a complex and expensive treatment with numerous local and systemic side effects (9). Therefore, new targeted treatment options are urgently needed.In recent years, EGFR has aroused great interest as new target for the treatment of BC. EGFR was mainly detected in the membrane of BC cells and is only sparsely distributed in the cytoplasm (10). EFGR expression was detected in 55-58% of bladder transitional cell carcinoma samples (10, 11) and in 75% of invasive BC tissues (12). In contrast, only 10% of non-cancer bladder mucous membrane tissues samples were found to be EGFR positive (10).EGFR signaling has been shown to regulate cell proliferation, apoptosis, angiogenesis, invasion, and tumor metastasis in preclinical models of transitional cell carcinoma (TCC) of the bladder (13). EGFR expression was positively correlated with clinical stage, pathologic grade, and recurrence of BC, and negatively correlated with prognosis and survival (10,14).Targeting EGFR with the monoclonal antibody Cetuximab, however, yielded disappointing results in patients with BC,...

Targeted elastin-like polypeptide fusion protein for near-infrared imaging of human and canine urothelial carcinoma

“…The difference in the EGFR expression by the two canine cell lines is reflected by the magnitude of Cy5.5-N24-EGF binding, showing about a 10-fold higher binding of Cy5.5-N24-EGF to K9TCC-SH compared to K9TCC-Original. Competition was also performed at 4°C to limit rapid (~5 min) internalization of the EGF-EGFR complex [ 24 , 25 ]. Figure 2C , 2D show the results from competition studies of Cy5.5-N24-EGF at 4°C vs. 37°C for both cell lines.…”

“…This was a significant improvement compared to the 10-fold enhancement reported for an EGFR-antibody conjugated NIR agent in canine UC cell lines [ 10 ]. Some of the other approaches leveraging the EGF-EGFR axis, like EGF-toxin conjugates, have displayed a 10–50-fold enhancement [ 24 , 25 ]. Competition studies were performed both in vitro and ex vivo at different temperatures in the presence of unlabeled serum and/or EGF.…”

The Prognostic Value of the Circulating Tumor Cell-Based Four mRNA Scoring System: A New Non-Invasive Setting for the Management of Bladder Cancer

“…In fact, EGFR signaling regulates numerous cellular pathways associated with tumor invasion and metastasis in preclinical models of BC. Moreover, recently, the targeted toxin EGF-PE40, obtained by combining the ligand EGF with PE40, a truncated version of Pseudomonas Exotoxin A, was generated and the expression of EGFR in BC cells was used to internalize the toxin and promote cell death [58].…”