Purpose: Osimertinib is an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) indicated for the treatment of EGFR mutated (EGFRm)-driven lung adenocarcinomas. Osimertinib significantly improves progression-free survival in first-line treated patients with EGFRm advanced NSCLC. Despite the durable disease control, the majority of patients receiving osimertinib eventually develop disease progression.
Experimental design: ctDNA profiling analysis on-progression plasma samples from patients treated with osimertinib in both first (Phase 3, FLAURA trial) and second-line trials (Phase 3, AURA3 trial) revealed a high prevalence of PIK3CA/AKT/PTEN alterations. In vitro and in vivo evidence using CRISPR engineered NSCLC cell lines and PXD models support a functional role for PIK3CA and PTEN mutations in the development of osimertinib resistance.
Results: These alterations are functionally relevant as EGFRm NSCLC cells with engineered PIK3CA/AKT/PTEN alterations develop resistance to osimertinib and can be re-sensitized by treatment with the combination of osimertinib and the AKT inhibitor capivasertib. Moreover, xenograft and PDX in vivo models with PIK3CA/AKT/PTEN alterations display limited sensitivity to osimertinib relative to models without alteration, and in these double mutant models capivasertib and osimertinib combination elicits an improved anti-tumor effect versus osimertinib alone.
Conclusions: Together, this approach offers a potential treatment strategy for patients with EGFRm-driven NSCLC that have a sub-optimal response, or develop resistance, to osimertinib through PIK3CA/AKT/PTEN alterations.