A Fluorescent Probe Targeting EGFR for the Stratification of Prostate Cancer Cells.

Effective stratification of cancer patients is critical yet challenging for evaluating therapeutic strategies. In this study, we designed a competitive, modular fluorescent probe targeting the oncogenic epidermal growth factor receptor (EGFR) kinase. This probe specifically inhibits EGFR kinase activity in a dose-dependent manner, selectively labels EGFR-overexpressing cells in flow cytometry, and sensitively binds to EGFR oncogenic mutants. Utilizing probe-based cytometry to subtype urine samples from prostate cancer patients, we discovered that samples with overexpressed wild-type EGFR did not respond sensitively to the probe, aligning with findings from an early multi-center clinical study. Notably, one sample with low EGFR expression exhibited the highest sensitivity to the probe, leading to the identification of three non-characterized mutations, including the activating mutation V745M, on the EGFR kinase. This case involved a tumor that had progressed to the castration-resistant metastatic stage.