Lee, Keun-Wook

380 Background: KRAS amplifications (amp) occur in ~2% of solid tumors, representing a high unmet need for effective targeted therapies. BI3706674 binds to GDP-bound KRAS and locks KRAS protein in an inactive form. In preclinical models, BI3706674 has shown potent inhibition of KRAS-amp tumors. Methods: This is a Phase Ia/b trial (NCT06056024) to explore the safety, pharmacokinetics (PK), pharmacodynamics (PD) and efficacy of BI 3706674 in patients (pts) with unresectable or metastatic KRAS wild type amp or KRAS G12V mutated (mut) solid tumors. The trial aimed to define the maximum tolerated dose (MTD). Pts (ECOG 0 -1) received BI 3706674 daily per os at 50 - 1200 mg doses. Dose escalation (DE) was guided by a Bayesian logistic regression model. This report focuses on KRAS wt amp pts from Phase Ia (DE). Results: As of 31 July 2025, 46 pts had received BI 3706674. Pts (n=15/46) with KRAS wt amp tumors had upper gastrointestinal tract (uGI) cancer [n=9: gastric (GAC;n=5), oesophageal (EAC; n=2), gastroesophageal junction (GEJC; n=2) cancers], Cholangiocarcinoma (n=1), colorectal (CRC; n=4), and ovarian (OC; n=1) cancers. Pts were treated at 200 mg (n=2), 400 mg (n=1), 800 mg (n=5), 1200 mg (n=7) doses; males: n=11; ECOG 1: n=10; median age - 62 years (range 38–83); median number of prior treatment lines was 3 (range 1-6). AEs were reported in 15 pts (100%), including 12 pts (80%) with treatment-related AEs (TRAE). High-grade AEs (Grade 3-5) were reported in 10 pts (66.7%), including 4 pts (26.7%) with TRAEs. SAEs were reported in 7 pts (46.7%), including 2 pts (13.3%) with TRAEs. The most-frequent AEs were mostly low-grade (Grade 1-2) diarrhoea (10 pts, 66.7%), nausea (10 pts, 66.7%), and vomiting (9 pts, 60.0%), often reported as TRAE. Two dose limiting toxicities were observed in 1200 mg group: nausea (Grade 3) and vomiting (Grade 3). MTD was not reached. BI 3706674 PK parameters followed the predicted non-linear PK model; dose dependent systemic exposure reached plateau at 800 mg. 12/15 pts with KRAS wt amp tumors, including 10/12 pts in 800 – 1200 mg groups, were efficacy evaluable; Disease control rate (DCR) was 58.3% (7/12 pts): 3/ 12 pts with partial response (PR), 4/12 had stable disease (SD), 5/12 pts - disease progression (PD). In 800 – 1200 mg groups 1 - OC, 2 – CRC pts achieved SD. PK/PD/efficacy correlation data is pending. Conclusions: BI 3706674 showed a tolerable safety profile and clinical efficacy in pts with KRAS amp tumors. Study results provide clinical proof of concept. KRAS wt amp is a druggable target and KRAS-targeting treatment is active in KRAS wt amp uGI cancer pts. Clinical trial information: NCT06056024 . Anticancer activity of BI 3706674 in efficacy evaluable pts with KRAS wt amp tumors. All pts, 200 – 1200 mg, N=12 Pts with uGI cancers,800 – 1200mg, N=7 ORR, n (%) 3* (25%) 3* (43%) SD, n (%) 4 (33.3%) 1 (14%) DCR, n (%) 7 (58.3%) 4 (57%) PD, n (%) 5 (41.7%) 3 (43%) *Tumor shrinkage: -60.3%, -34% and 34.3%.

158 Background: PIK3CA mutations are common in CRC and may be a negative prognostic factor. INAVO is a potent and selective PI3Kα inhibitor that also promotes mut p110α degradation. BEV and CETUX are standard treatment (tx) components for RAS mut and RAS -wildtype (wt) mCRC, respectively. The Phase I/Ib INTRINSIC open-label umbrella study (NCT04929223) evaluates targeted therapies in biomarker-selected mCRC subpopulations. We report INAVO + BEV and INAVO + CETUX results. Methods: Patients (pts) with PIK3CA mut, RAS mut mCRC received INAVO (9 mg oral once daily) + BEV (intravenous [IV] 15 mg/kg every 3 weeks). Pts with PIK3CA mut, RAS wt mCRC received INAVO + CETUX (IV 400 mg/m 2 then 250 mg/m 2 weekly thereafter). Primary endpoint: confirmed objective response rate (cORR). Secondary endpoints included disease control rate (DCR), duration of response (DoR), and safety. Progression-free survival (PFS) and overall survival (OS) were exploratory. Results: At the clinical cut-off dates, 16 pts were enrolled in the BEV arm; 35, in the CETUX arm. Most had ≥2 metastatic sites at enrollment (n = 16 [100%] and 30 [85.8%], respectively) and ≥2 prior lines of metastatic therapy (16 [100%] and 28 [80.0%]). In the BEV arm, 3 pts (18.8%) had no prior BEV. In the CETUX arm, 25 pts (71.4%) had no prior CETUX; 17 (48.6%) had prior anti-EGFR therapy. All pts in the BEV arm and 34 in the CETUX arm were evaluated for efficacy and safety. Median follow-up was 9.4 months (mo; interquartile range: 5.5–14.4) and 12.6 mo (8.9–16.6), respectively. Efficacy is shown in the Table. All pts had adverse events (AEs); 15 (93.8%) and 34 (100%), respectively, had tx-related AEs (TRAEs); 5 (31.2%) and 12 (35.3%), grade 3–4 TRAEs; 2 (12.5%) and 11 (32.4%), serious AEs. One grade 5 AE (infusion-related reaction) occurred (CETUX arm). Dose reduction/interruption due to AEs occurred in 12 (75.0%) and 27 (79.4%) pts; tx withdrawal due to AEs, in 0 and 4 (11.8%) pts, respectively. Hyperglycemia was the most common AE, TRAE, and AE leading to dose reduction/interruption in both cohorts. Hypertension was observed more frequently with BEV; dermatitis acneiform and dry skin, with CETUX. Conclusions: INAVO + BEV and INAVO + CETUX showed encouraging efficacy in pts with PIK3CA mut mCRC, with no new or unexpected safety signals. Clinical trial information: NCT04929223 . INAVO + BEV(n = 16) INAVO + CETUX(n = 34) cORR, all PR, n (%) 1 (6.3) 7 (20.6)* SD, n (%) 10 (62.5) 17 (50.0) Progressive disease, n (%) 3 (18.8) 9 (26.5) Missing/NE, n (%) 2 (12.5) 1 (2.9) mDoR, mo (90% CI) 7.7 (NE) 4.4 (4.2–5.3) DCR, n (%) 11 (68.8) 15 (44.1) mPFS, mo (90% CI) 4.2 (2.8–6.8) 3.5 (2.8–4.4) mOS, mo (90% CI) 11.0 (8.5–14.5) 12.8 (10.7–13.8) CI, confidence interval; m, median; NE, not evaluable; PR, partial response; SD, stable disease. *3 pts with PRs received prior anti-EGFR therapy; 1 had a best prior response of SD (last dose 233 days before study tx) and 2 had best prior responses of PRs (last doses 134 and 171 days before study tx).