Horinouchi, Hidehito

8524 Background: Teliso-V is a c-Met–directed antibody-drug conjugate comprising telisotuzumab and the microtubule polymerization inhibitor monomethyl auristatin E (MMAE) payload. In the Ph2 LUMINOSITY study (NCT03539536), Teliso-V showed durable responses and manageable safety (Camidge et al, JCO 2024;42:3000-11) resulting in its accelerated approval in locally advanced/metastatic NSQ NSCLC with high c-Met protein OE (3+, ≥50%), as determined by an FDA-approved test. MET amp is a negative prognostic risk factor in advanced NSCLC, frequently associated with recurrent disease. High levels of MET amp and c-Met OE are hallmarks of MET -addicted tumors. Here, we analyzed the effects of MET amp on clinical responses to Teliso-V in LUMINOSITY. Methods: MET amp was evaluated by FISH and ctDNA in baseline samples from 108 NSQ EGFR WT NSCLC pts with c-Met OE (3+, ≥25%). MET amp by FISH was defined as having focal MET amp (MET/CEP7 ≥2.0) with MET gene copy number (GCN) ≥4. MET amp (focal) by ctDNA was defined as having plasma MET GCN ≥4 with no co-amplification in CDK6 and EGFR. c-Met OE by Immunohistochemistry (IHC; SP44) was defined as 3+ tissue staining intensity in ≥25% tumor cells (high c-Met OE: 3+, ≥50%; intermediate [int] c-Met OE: 3+, 25% to 49%). Exploratory analysis of tumor response was assessed in 76 efficacy evaluable pts with c-Met OE and MET amp assay results. Results: MET amp was detected in 34% (37/108) of pts with c-Met OE (3+, ≥25%) and was enriched by c-Met levels: 22% (11/50) in pts with Int c-Met OE (3+, 25% to 49%) and 45% (26/58) in pts with high c-Met OE (3+, ≥50%). The effects of MET amp on tumor response in LUMINOSITY are shown in Table 1. The majority of c-Met OE pts (79%) with PFS ≥10 mo (n=14) had GCN ≥10 and/or c-Met IHC 3+ ≥50%. No new safety signals were reported in pts with c-Met OE and MET amp. Conclusions: MET amp is more common in pts with high c-Met OE in this retrospective subgroup analysis. Tumor activity with Teliso-V was observed regardless of MET amp status. The impact of MET amp in pts with c-Met OE will be further evaluated in ongoing Phase 3 study (NCT04928846). Teliso-V efficacy in NSQ EGFR -WT NSCLC pts with c-Met OE with or without MET amp in LUMINOSITY. Total c-Met OE(3+, ≥25%) Total c-Met OE(3+, ≥25%) Intermediate c-Met OE(3+, ≥25%-49%) Intermediate c-Met OE(3+, ≥25%-49%) High c-Met OE(3+, ≥50%) High c-Met OE(3+, ≥50%) MET amp(N) No (N=53) Yes (N=23) No (N=30) Yes (N=7) No (N=23) Yes (N=16) ORR %(95% CI) 28 (18.0, 41.6) 39 (22.2, 59.2) 23 (11.8, 40.9) 57 (25, 84.2) 35 (18.8, 55.1) 31 (14.2, 55.6) PFS,median, mo(95% CI) 5.26 (3.71, 8.11) 8.02 (4.47, 14.65) 5.32 (2.69, 8.11) 7.52 (4.47, NA) 4.17 (3.25, 8.87) 8.02 (3.06, 25.92) OS,median, mo(95% CI) 14.5 (8.18, 17.38) 13.86 (6.54, 22.24) 14.03 (3.65, 17.02) 9.79 (6.54, NA) 16.26 (5.59, 36.44) 13.86 (3.06, 30.29)

3014 Background: Macrocyclic next-generation tyrosine kinase inhibitors (TKIs) have transformed outcomes in ALK- and ROS1-positive NSCLC; such creatively designed medicines are similarly needed to improve outcomes in EGFR-mutant NSCLC. Using a novel, mutant-selective macrocyclic structure, BH-30643 was designed for super-potency against driver EGFRm, largely sparing wildtype (WT) EGFR, and with unique invulnerability to resistance from C797S with or without T790M. Here we report emerging first-in-human dose-escalation data from the SOLARA trial (NCT06706076). Methods: Phase 1 dose escalation used a BOIN design with backfill at potentially efficacious doses. Expansion cohorts targeted populations of interest. Patients (pts) had advanced NSCLC with EGFR and/or HER2 mutations detected on local testing (tissue or plasma). Measurable disease was required; asymptomatic untreated brain metastases (BM) were permitted. Objectives included safety, PK, and RECIST response rate (ORR). Plasma NGS was performed at baseline and on treatment. Results: As of 01/05/2026, 72 pts enrolled into dose escalation and backfill across 7 dose levels at a total daily dose of 20mg -160mg, median age 62, 44% Asian, 65% with history of BM, median of 3 prior lines of treatment (range 1-12). EGFR mutations included classical (38 pts), exon20ins (14 pts) and other/atypical (18 pts) or HER2 mutations (2 pts). Plasma exposures at doses of 40mg BID and above achieved > 10x coverage over target EC90 and exceeded exposure levels of most contemporary EGFR TKIs. Common TRAE ( > 10%) were WT EGFR-associated, including diarrhea (38%), rash (28%), fatigue (15%), stomatitis (13%), and were predominantly grade 1. Bilirubin elevation was seen in 26 pts (36%) related to off-target UGT1A1 inhibition (Gilbert’s-like). Grade 3 TRAE were seen in 15 pts (18%), most commonly bilirubin (8/15); DLTs included bilirubin increase and mucositis, occurring at doses ≥ 60mg BID. No pneumonitis was observed. Responses were observed across diverse EGFRm subsets, including in CNS. Including expansion pts, 28 pts enrolled with C797S on their most recent informative molecular testing (6 with concurrent MET+ or KRAS+), with 23 still on therapy. Of 17 with on-treatment scans, partial responses (confirmed or ongoing) were seen in 10 (59%); ORR was comparable with (50%) or without (66%) T790M. Of 9 pts with baseline C797S detected in ctDNA (3 with T790M), 7 had > 99% reduction of C797S VAF on treatment. Conclusions: Leveraging a novel macrocyclic scaffold, BH-30643 is the first TKI monotherapy to demonstrate clinical responses against C797S both with or without T790M. High plasma exposures combined with super-potency, CNS activity, and favorable safety offers potential for deep and durable EGFR inhibition. Enrollment into backfill and expansion cohorts is ongoing to better characterize activity in both TKI-naïve and resistant pts. Clinical trial information: NCT06706076 .