Single-cell DNA-seq depicts clonal evolution of multiple driver alterations in osimertinib-resistant patients

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Targeted therapies like osimertinib have improved outcomes for EGFR-mutated non-small-cell lung cancer (NSCLC).
• Tumor resistance to osimertinib frequently develops, often associated with new molecular driver alterations.
• The cellular distribution of these co-occurring alterations (single cell vs. distinct populations) remains a key question.

Purpose of the Study:

• To investigate the mechanisms of acquired resistance to osimertinib in NSCLC.
• To determine if resistance-driving alterations occur within single cancer cells or separate populations.
• To explore combination treatment strategies for osimertinib-resistant NSCLC.

Main Methods:

• Single-cell next-generation sequencing (NGS) of tumor tissues from the MATCH-R trial (NCT0251782).
• Analysis of acquired resistance mechanisms in patients progressing on osimertinib.
• Utilizing patient-derived models, cell lines, and xenografts for drug sensitivity testing.

Main Results:

• Among 45 patients progressing on osimertinib, 9 acquired new targetable alterations (e.g., FGFR3-TACC3, KIF5B-RET, STRN-ALK fusions; BRAF, KRAS mutations).
• Single-cell analysis revealed co-occurrence of two driver alterations within a single cancer cell in four patients.
• High tumor heterogeneity and sequential acquisition of molecular events were observed, necessitating combination therapy.

Conclusions:

• Osimertinib resistance in NSCLC involves distinct molecular driver alterations coexisting with EGFR mutations within single cancer cells.
• Cancer cell population heterogeneity drives osimertinib relapse.
• Combination targeted treatments demonstrate efficacy in overcoming resistance and achieving clinical benefit.