Safety and efficacy of IBI389, an anti-CLDN18.2/CD3 bispecific antibody, in patients with advanced pancreatic ductal adenocarcinoma: Preliminary results from a phase 1 study.
Jihui Hao, Zheng Li, Dai Ruihong, Ying Jieer, Qi Xu, Liwei Wang, Yongdong Jin, Ying Zhao, Yueyin Pan, Lulu Liu, Jun Zhang, Yuping Sun, Zuoxing Niu, Jun Yao, Dong Hua, Mingjun Zhang, Dai Guang-hai, Yulong Zhang, Hui Zhou, Feng Bi
Abstract
4011 Background: CLDN18.2 expression has been observed in various solid tumors. In pancreatic ductal adenocarcinoma (PDAC), positive CLDN18.2 expression was reported in nearly 60% patients (pts), indicating its potential as a novel target for anti-tumor therapy. IBI389 is an anti-CLDN18.2/CD3 bispecific antibody that induces immune synapse formations by linking CD3 molecules in T-cell receptor complexes and CLDN18.2 antigens on the membrane of tumor cells. Herein, we report preliminary result from a phase I study to evaluate safety and efficacy of IBI389 in pts with PDAC. Methods: EligibleCLDN18.2-positivepts with locally advanced, refractory or metastaticPDAC who failed or were intolerant to standard treatments were enrolled. IBI389 monotherapy was intravenously administered at 6 dose levels (5-600 µg/kg, Q3W or Q2W) during the 2-stage dose escalation and the dose expansion. In dose levels ≥ 30 µg/kg, the step-up dosing strategy with priming dose of 3 to 10 µg/kg was applied. The primary objective was safety. Secondary objective was efficacy assessed by investigator per RECIST v1.1 including objective response rate (ORR) and disease control rate (DCR). Results: As of January 9, 2024, a total of 64 CLDN18.2-positive PDAC pts were enrolled (males: 64.1%, females:35.9%, median age: 60.0 years, stage IV: 84.4%). All patients received prior therapy with a median of 2 lines (range: 1 to 5). Treatment-related adverse events (TRAEs) occurred in 62 (96.9%) pts including 35 (54.7%) pts had grade ≥3 TRAEs. The most common grade ≥3 TRAEs (≥5%) were gamma-glutamyl transferase increased (20.3%), lymphocyte count decreased (9.4%) and nausea (7.8%). Cytokine release syndrome (CRS) related adverse events occurred in 33 (51.6%) pts with no grade ≥3 CRS occurred. TEAEs leading to dose interruption and treatment discontinuation occurred in 24 (37.5%) and 3 (4.7%) pts. Preliminary efficacy of IBI389 was observed in pts with CLDN18.2 expression ≥10% (immunohistochemistry 2+/3+) at 600 µg/kg. As of January 31, 2024, there were 23 evaluable pts including 7 pts with PR and 9 pts with SD. The ORR was 30.4% (95%CI: 13.2-52.9) and DCR was 69.6% (95%CI: 47.1-86.8). The median duration of response (DoR) and progression-free survival (PFS) was not reached. More updated data on safety and efficacy will be presented at the meeting. Conclusions: IBI389 showed manageable safety profiles in pts with advanced PDAC. Preliminary efficacy was observed, including in pts with relatively low expression of CLDN18.2. Clinical trial information: NCT05164458 .