New pan-ALK inhibitor-resistant EML4::ALK mutations detected by liquid biopsy in lung cancer patients

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Tyrosine kinase inhibitors (TKIs) are effective against ALK and ROS1 fusion-positive non-small cell lung cancer (NSCLC).
• Patient relapse after TKI treatment is common, often caused by acquired kinase domain mutations.
• Understanding resistance mechanisms is critical for improving long-term patient outcomes.

Purpose of the Study:

• To identify novel EML4::ALK mutations in TKI-relapsed NSCLC patients.
• To characterize the resistance profiles of newly identified ALK mutations.
• To evaluate the efficacy of existing and investigational TKIs against these resistance mutations.

Main Methods:

• Deep-sequencing of circulating tumor DNA (ctDNA) from TKI-relapsed NSCLC patients.
• Functional characterization of identified EML4::ALK variants in a Ba/F3 cell model.
• Assessment of drug sensitivity to multiple clinical and investigational TKIs.

Main Results:

• Three new EML4::ALK substitutions (L1198R, C1237Y, L1196P) were identified in the plasma of NSCLC patients.
• The C1237Y and L1196P variants conferred resistance to 5 clinical and 2 investigational TKIs.
• These mutations represent significant mechanisms of acquired resistance to ALK-targeted therapies.

Conclusions:

• Novel EML4::ALK mutations are present in circulating DNA of TKI-relapsed NSCLC patients.
• Specific mutations like C1237Y and L1196P confer broad resistance to current and emerging TKIs.
• These findings highlight the need for strategies to overcome TKI resistance in ALK-positive NSCLC.