BLU-945, a potent and selective next-generation EGFR TKI, has antitumor activity in models of osimertinib-resistant non-small-cell lung cancer

Introduction: Despite the availability of several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), most patients with non-small-cell lung cancer (NSCLC) eventually develop resistance to these agents. Notably, EGFR_C797S mutations confer resistance to the third-generation EGFR-TKI osimertinib and no approved post-osimertinib targeted pharmacology options are currently available. BLU-945 is a novel, reversible, and orally available next-generation EGFR-TKI that selectively targets EGFR-activating (EGFRm) and resistance mutations (including EGFR_C797S) with nanomolar potency while sparing wild-type EGFR in vitro.

Methods: In vitro activity of BLU-945 as a single agent and in combination with osimertinib was tested in engineered EGFR-mutant cell lines as well as patient-derived cells and patient-derived organoids. In vivo activity was evaluated in osimertinib-resistant patient-derived xenograft mouse models. Three patient cases from the global, first-in-human, phase I/II SYMPHONY trial (NCT04862780) demonstrating the clinical efficacy of BLU-945 were reported.

Results: In vitro BLU-945 demonstrated inhibited cell viability and growth of EGFR-mutant/osimertinib-resistant cell lines. BLU-945 demonstrated in vivo tumor shrinkage in osimertinib-resistant models of NSCLC (osimertinib second line: EGFR_L858R/C797S and third line: EGFR_ex19del/T790M/C797S and L858R/T790M/C797S) both as monotherapy and in combination with osimertinib. BLU-945 also demonstrated tumor shrinkage in patients from the SYMPHONY trial.

Conclusion: Our findings demonstrate the preclinical and early clinical activity of BLU-945 in EGFRm NSCLC progressing on previous EGFR-TKIs.