A phase II study evaluating KN026 monotherapy in patients (pts) with previously treated, advanced HER2-expressing gastric or gastroesophageal junction cancers (GC/GEJC).

• DOI: 10.1200/jco.2022.40.16_suppl.4040
• Publication Date: 2022-06-06T16:16:56Z
• Authors: Jianming Xu; Rongrui Liu; Jieer Ying; Jun Wu; Feng Ye; Nong Xu; Yanqiao Zhang; Rusen Zhao; Xiaojun Xiang; Jianhong Wang; Xiaoyan Lin; Huiting Xu; Shegan Gao; SuXia Luo; Baohong Guo; Xionghui Li; Yangzhi Su; Qian Wang
• Keywords: Pertuzumab; Clinical endpoint

4040 Background: Outcomes of second or later-line treatment for pts with advanced GC/GEJC remain inferior. KN026 is a novel HER2-targeted bispecific antibody composed VH regions trastuzumab and pertuzumab, targeting the HER2 juxtamembrane domain (IV) dimerization (II) simultaneously. has shown promising antitumor efficacy in preclinical phase I studies. Here we present results monotherapy previously treated, HER2-expressing GC/GEJC. Methods: In this multi-center, single-arm, open-label, 2-cohort II study, adult were assigned into high-level cohort (Cohort 1: IHC3+ IHC 2+ ISH+) low-level 2: 1+/2+ ISH- 0/1+ISH+). was given intravenously 10 mg/kg QW, 20 Q2W, 30 Q3W. Primary endpoints objective response rate (ORR) duration (DoR) assessed by investigators per RECIST 1.1. Secondary included progression-free survival (PFS), overall (OS), safety outcomes. This trial registered at ClinicalTrials.gov (NCT03925974). Results: At data cut-off (Oct. 29, 2021), 45 enrolled treated KN026; 39 eligible evaluation (25 Cohort 1 14 2). 1, ORR 56% (95%CI 35%-76%) PR; median DoR 9.7 months (mo) 4.2-not evaluable (NE)). follow-up 14.7 mo 9.4-16.5), PFS 8.3 4.2-11.4), OS 16.3 (95% CI 11.0- NE). 2, 14% 2%-43%), being 6.2 3.2-NE). 27.5 4.1-NE), 1.4 1.4-4.1), 9.6 3.5-14.9). The table shows who have progressed on prior treatment. KN026-related adverse events (TRAEs) observed 37 (82%) pts; most common TRAEs (any grade) increased aspartate aminotransferase (12, 27%), alanine (9, 20%), rash (7,16%), anemia infusion-related reaction (7,16%). Four reported 5 grade 3 TRAEs, including reaction, renal hydrocele, ureteral stenosis, blood pressure, abnormal hepatic function (1 each). No 4 occurred. Conclusions: yielded mild to moderate toxicities Further investigation warranted. Clinical information: NCT03925974. [Table: see text]