Clinical response to tepotinib according to circulating tumor (ct) DNA biomarkers in patients with advanced NSCLC with high-level MET amplification (METamp) detected by liquid biopsy (LBx)

9121 Background: Tepotinib, a potent, highly selective, oral, MET inhibitor, showed meaningful activity in patients (pts) with NSCLC with high-level METamp by LBx in VISION. Exploratory biomarker analyses are presented herein. Methods: Pts had 0–2 prior therapy lines, high-level METamp by LBx (Guardant360; MET copy number ≥2.5), and no MET exon 14 skipping or EGFR/ ALK alterations. Pts received tepotinib 500 mg once daily (450 mg active moiety). Primary endpoint was objective response by independent review; data cut-off: Aug 20, 2021. Exploratory biomarker analysis included LBx at baseline (BL), on treatment, and end of treatment (EOT). Early molecular response (eMR) was defined as undetectable METamp 6–8 weeks on treatment. Results: 24 pts were enrolled (median age: 63.4 years [yrs]; smokers: 88%; ECOG PS 1: 88%; adenocarcinoma: 67%). Treatment duration was ≥1 yr in five pts and ≥2 yrs in two pts (both ongoing). Overall, objective response rate (ORR) was 41.7% (95% CI: 22.1, 63.4). Treatment-naïve pts (n=7) had an ORR of 71.4% (29.0, 96.3), median (m) DOR was 14.3 months (2.8, not estimable [ne]), and mPFS was 15.6 months (1.4, ne). BL biomarker analyses according to clinical benefit (CR/PR/SD [n=11] vs PD/NE [n=13]) showed association with better outcomes in pts with focal METamp, or without MYCamp or RB1 mutation (Table). MYCamp/ RB1 mutation was detected in 4/7 pts with neuroendocrine/not otherwise specified histology; MYCamp in 2/3 pts with neuroendocrine histology. Low BL ctDNA mutant allele frequency (MAF) was associated with better outcomes. 14 pts had eMRs (ORR 71.4%); persistent METamp (n=4) was associated with lack of clinical response. 2/9 pts with EOT biomarker profiles had emerging resistance mechanisms (MET kinase domain mutations Y1230 and D1228); both had METamp re-emergence. Treatment-related adverse events included edema (composite term; any grade: 46%; Grade 3: 13%) and constipation (any grade: 17%; Grade ≥3: 0%). Conclusions: Tepotinib showed meaningful activity, especially in first line, in the first trial of a MET inhibitor in EGFR WT NSCLC with high-level METamp to enroll based on a convenient LBx assay. BL biomarker analyses indicated focal METamp, MYC/RB1 WT, and low ctDNA MAF were associated with improved outcomes. Serial LBx could monitor molecular response and evaluate resistance. Clinical trial information: NCT02864992. [Table: see text]