SKB BIO (06990) announced that the company will present multiple company-led clinical research results at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, to be held from May 29 to June 2, 2026, in Chicago, Illinois, USA. Among them, the registration studies for the TROP2-targeting antibody-drug conjugate (ADC) sac-TMT (Jiatailai®) and the next-generation selective RET inhibitor fumarate lenbretinib (A400/EP0031, Ningtailai®) have been selected for the metastatic non-small cell lung cancer oral presentation session. The core content is summarized as follows:

**Study #1: Sac-TMT Combined with Pembrolizumab vs. Pembrolizumab as First-Line Treatment for PD-L1-Positive Advanced NSCLC: Results from the Randomized, Controlled Phase 3 OptiTROP Lung05 Study.** The study enrolled 413 patients with locally advanced or metastatic NSCLC who had not received prior systemic therapy, were EGFR/ALK mutation-negative, and had PD-L1-positive expression (defined as Tumor Proportion Score (TPS) ≥1%), covering both squamous and non-squamous histologies. Patients were randomized 1:1 to receive sac-TMT (4 mg/kg every 2 weeks (Q2W)) combined with pembrolizumab (400 mg every 6 weeks (Q6W)) or pembrolizumab monotherapy (400 mg, Q6W). The primary endpoint was progression-free survival (PFS) assessed by blinded independent central review (BICR), with overall survival (OS) as a key secondary endpoint. As of September 29, 2025, the median follow-up was 10.5 months. Results showed: • Significant PFS improvement: BICR-assessed median PFS was not reached (NR) in the combination group vs. 5.7 months with pembrolizumab monotherapy (Hazard Ratio (HR)=0.35; 95% Confidence Interval (CI): 0.26–0.47; p<0.0001). • Markedly higher response rate: BICR-assessed objective response rate (ORR) was 70.2% in the combination group vs. 42.0% in the monotherapy group. • OS data were immature but showed a positive trend favoring the combination (HR=0.55; 95% CI: 0.36–0.85). • Consistent benefit across pre-specified subgroups: PFS HR was 0.28 (95% CI: 0.19–0.41) in patients with PD-L1 TPS 1–49% and 0.47 (95% CI: 0.29–0.77) in those with TPS ≥50%. In non-squamous and squamous NSCLC patients, PFS HR was 0.28 (95% CI: 0.18–0.43) and 0.44 (95% CI: 0.29–0.66), respectively. Regarding safety, the incidence of Grade ≥3 treatment-emergent adverse events (TEAEs) was 55.3% in the combination group and 31.4% in the monotherapy group. The proportion of patients permanently discontinuing sac-TMT and pembrolizumab due to adverse events was 3.8% and 5.3%, respectively; the proportion permanently discontinuing pembrolizumab in the monotherapy group was 4.9%. OptiTROP-Lung05 is the first Phase 3 clinical study to demonstrate that an ADC combined with pembrolizumab significantly improves PFS compared to pembrolizumab monotherapy in the first-line treatment of PD-L1-positive advanced NSCLC, with OS also showing a positive trend. Based on these results, a supplemental New Drug Application (sNDA) for this combination therapy has been accepted by China's National Medical Products Administration (NMPA) and granted priority review.

**Study #2: Efficacy and Safety of the Next-Generation Selective RET Inhibitor (SRI) Fumarate Lenbretinib (A400/EP0031) in a Key Phase 2 Study for Treating Advanced RET Fusion-Positive NSCLC.** As of October 29, 2025, the study enrolled 71 patients who had received prior platinum-based chemotherapy and immunotherapy (pre-treated) and 92 treatment-naïve patients. The median follow-up was 22.6 months and 20.7 months, respectively. Results showed: • Investigator-Review Committee (IRC)-confirmed ORR was 87.1% (95% CI: 77.0–93.9) in pre-treated patients and 81.3% (95% CI: 71.8–88.7) in treatment-naïve patients. • Median PFS (mPFS) was 27.5 months (immature) in pre-treated patients and not reached (NR) in treatment-naïve patients. The 24-month PFS rates were 52.1% and 59.9%, respectively. • Median OS (mOS) was not reached in either group. The 24-month OS rates were 65.7% in pre-treated patients and 74.1% in treatment-naïve patients. • In patients with baseline brain metastases (23 pre-treated, 16 treatment-naïve), ORR was 82.6% and 75.0%, respectively, with 6 patients in each cohort achieving intracranial complete response. Safety was manageable with no new safety signals identified. The incidence of Grade ≥3 treatment-related adverse events (TRAEs) was 40.5%. Only 1.2% of patients (2 cases) permanently discontinued treatment due to TRAEs, and no fatal TRAEs occurred. Based on these results, the New Drug Application (NDA) for fumarate lenbretinib for the treatment of adult patients with RET fusion-positive locally advanced or metastatic NSCLC has been accepted by the NMPA.

Additionally, results from an open-label, first-in-human study of SKB500 in patients with locally advanced or metastatic solid tumors will be presented in a rapid oral session on June 2 at 9:57–10:03 local time (Abstract #3011, Molecular Targeted Agents and Tumor Biology). The full abstracts for the aforementioned studies were published on the official ASCO website on May 21, 2026, local time.