Covalent inhibition of epidermal growth factor receptor using a long-lived iridium(III)-afatinib probe

Area of Science:

• Medicinal Chemistry
• Cancer Biology
• Bioinorganic Chemistry

Background:

• Epidermal growth factor receptor (EGFR) overexpression drives various human cancers, including squamous cell carcinoma and adenocarcinoma.
• Targeting EGFR is a validated strategy in cancer treatment, but resistance and off-target effects remain challenges.

Purpose of the Study:

• To develop a novel covalent inhibitor of EGFR by conjugating afatinib to an iridium(III) scaffold.
• To evaluate the efficacy, mechanism of action, and theranostic potential of the developed iridium-based EGFR probe.

Main Methods:

• Synthesis and characterization of an iridium(III)-afatinib conjugate (Complex 1).
• Assessment of Complex 1's luminescence in cancer cell lines (A431).
• Confirmation of EGFR engagement using Cellular Thermal Shift Assay (CETSA) and knockdown experiments.
• Evaluation of downstream EGFR signaling inhibition and antiproliferative activity in vitro.

Main Results:

• Complex 1 exhibited enhanced luminescence in EGFR-expressing A431 cells, confirming specific engagement.
• CETSA and knockdown experiments validated EGFR as the target of Complex 1.
• Complex 1 demonstrated irreversible inhibition of EGFR downstream signaling in cancer cells.
• The iridium-based probe displayed potent antiproliferative activity against A431 cells, comparable to afatinib.

Conclusions:

• Complex 1 represents the first reported iridium-based covalent EGFR inhibitor.
• The probe shows potential for further development as a theranostic agent for EGFR-driven cancers.
• Irreversible inhibition and specific targeting offer a promising therapeutic strategy.