Targeting EGFR1 and EGFR2 in Bladder Cancer: Receptor Profiling and Therapeutic Potential of 213Bi Alpha-Particle Therapy

<title>Abstract</title> <p> Background Bladder cancer is a major global health burden, with non-muscle-invasive bladder cancer (NMIBC) accounting for the majority of cases. Current standard-of-care therapy with BCG fails in up to 30–40% of patients, highlighting the need for alternative bladder-sparing treatments. This study characterized EGFR1 and EDFR2 receptors and evaluated targeted alpha-particle therapy using ²¹³ Bi-labeled trastuzumab plus cetuximab in human bladder cancer cell lines in vitro. Results Trastuzumab and cetuximab exhibited specific, high-affinity binding to all human bladder cancer cells; however, EGFR1 receptors/cell were more abundant than EGFR2. Treatment with ²¹³ Bi-trastuzumab+cetuximab resulted in dose-dependent cytotoxicity in SCaBER and RT4 cells and activated DNA damage and cell death markers. ²¹³ Bi treatments induced dose-dependent transcriptional changes by inducing irreparable DNA damage, disrupting DNA repair pathways, and activating multiple regulated cell death mechanisms. Immunoblot analysis showed that Chk1 and Wee1 expression and activation were comparable in ²¹³ Bi-trastuzumab+cetuximab and untreated controls after 48h of treatment with 0.3 MBq of ²¹³ Bi. RNA sequencing data demonstrated dose-dependent downregulation of G2M-checkpoint markers at 0.3 and 0.56 MBq of ²¹³ Bi. Conclusion Targeted alpha therapy using combined ²¹³ Bi-labeled trastuzumab+cetuximab demonstrated strong preclinical efficacy in human bladder cancer cell lines, indicating its potential for further clinical development. </p>