Leap Therapeutics, Inc. announced the Company will be presenting new long-term follow-up data in first-line patients with advanced gastric or gastroesophageal junction adenocarcinoma (GEA) from Part A of the DisTinGuish study, a Phase 2 clinical trial evaluating Leap's anti-Dickkopf-1 (DKK1) antibody, DKN-01, in combination with BeiGene's tislelizumab and chemotherapy, at the upcoming 2023 American Society of Clinical Oncology (ASCO) Annual Meeting taking place in Chicago, IL on June 2-6, 2023. Key Findings Part A DisTinGuish: Median overall survival (OS) of 19.5 months and median progression-free survival (PFS) of 11.3 months exceeds benchmark results in the overall first-line patient population (n=25) - Compelling OS and PFS results in all four important biomarker subgroups - 18.7 months OS and 10.7 months PFS in PD-L1-low (vCPS < 5) patients (n=16) - 22.0 months OS and 11.6 months PFS in PD-L1-high (vCPS > 5) patients (n=6) - 16.9 months OS and 11.3 months PFS in DKK1-high patients (n=12) - 24.4 months OS and 12.0 months PFS in DKK1-low patients (n=9). Additional patient with a partial response after 22 months on therapy improves objective response rate (ORR) to 73% in the overall modified intent-to-treat population (n=22), with one (5%) complete response (CR), 15 (68%) partial responses (PR), 5 (23%) best responses of stable disease (SD), and 1 (5%) non-evaluable (NE) - 86% ORR in PD-L1-low patients (n=14: 12 PR, 2 SD) - 67% ORR in PD-L1-high patients (n-6: 1 CR, 3 PR, 1 SD, 1 NE) - 90% ORR in DKK1-high patients (n=10: 9 PR, 1 NE) - 67% ORR in DKK1-low patients (n=9: 1 CR, 5 PR, 3 SD).

Consistent with previous results, combination was well tolerated with manageable toxicity, with most adverse events related to DKN-01 being low-grade (76%).