Abstract CT133: A phase 1b multicenter study of anti-TIM3 (S095018/Sym023) in combination with anti-PD1 (Sym021) in patients with advanced/metastatic recurrent biliary tract cancer

Abstract Background: TIM3 is an inhibitory immunoreceptor linked to decreased activity of immune cells in the tumor microenvironment. S095018 is a human anti-TIM3 IgG2 antibody which blocks binding of phosphatidyl serine to TIM3 promoting the stimulation of T-cells, dendritic cells (DCs) and macrophages. Sym021 is a humanized IgG1 antibody that inhibits binding of PD-1 with its ligands PD-L1 and PD-L2. Preclinical data demonstrated that Sym021 combined with S095018 results in enhanced immunostimulatory antitumor activity. Methods: S095018 in combination with Sym021 was tested in patients with advanced/metastatic biliary tract cancer whose disease progressed under treatment with at least one line of systemic therapy and who had not received prior treatment with PD-1/-L1 inhibitors (NCT04641871). The dose/schedule of Sym021 and S095018 was 3mg/kg IV Q2W and 10mg/kg IV Q2W, respectively. Primary endpoints included overall response rate (ORR) using RECIST v1.1 and incidence/severity of adverse events. Key secondary endpoints included PK parameters, disease control rate (DCR), progression free survival (PFS) and overall survival (OS). Results As of 31-Oct-2023, 35 patients with stage IV biliary tract cancer (34 cholangiocarcinoma, 1 gallbladder adenocarcinoma) received S095018 in combination with Sym021. All patients were naïve to prior immune checkpoint inhibitor treatment. Twenty-two patients (62.9%) had received 1 prior antineoplastic systemic treatment for advanced/metastatic disease, 34.3% had received ≥2 prior treatments for advanced/metastatic disease. Overall, 34 patients (97.1%) discontinued treatment, 85.7% due to disease progression. Best overall response was 2 PR (5.7%), 11 SD (31.4%), 18 PD (51.4%) and 4 not evaluable. Median PFS and OS were 1.9 months (90% CI 1.8-3.7) and 13.4 months (90% CI 8.2-27.1) respectively. Disease control rate (CR+PR+SD) with SD≥16 weeks, ≥24 weeks and ≥12 months was 28.6%, 22.9% and 8.6% respectively. Treatment emergent adverse events of any grade occurring in >5% of patients included fatigue, pruritus, alkaline phosphatase increase, amylase increase, IRR (each 8.6%) and hypothyroidism, hyperthyroidism, AST increase, lipase increase and myalgia (each 5.7%). Exploratory biomarker analyses in paired tumor biopsies (N=18) showed an intratumoral increase in CD8 T-cell density, as well as upregulation of gene signatures related to IFNg signaling, antigen presentation, T-cell activation and cytotoxicity upon treatment. Baseline tumor biopsies from the two patients who achieved confirmed PR showed high PD-L1 expression. Conclusions: S095018 in combination with Sym021 exhibited antitumor activity in patients with advanced/metastatic recurrent biliary tract cancer who had not received prior treatment with PD-1/-L1 inhibitors. The combination was well tolerated without new safety signals. Further biomarker analysis is ongoing. Citation Format: Francois Ghiringhelli, Richard Kim, Teresa Macarulla, Irene Moreno, Albiruni Razak, Jordi Rodon, Chih-Yi Liao, Thomas Marron, Judith Raimbourg, Helene Kaplon, Julia Geromini, Najah Harouki, Christelle Rodrigues, Pauline Darcel, Niels Jorgen Skartved, Rikke Hald, Daleen Lopez-Ravnborg, Peng He, Xenophon Ianopoulos, Vasileios Askoxylakis, Nehal J. Lakhani, Sarah Davis, Amit Mahipal. A phase 1b multicenter study of anti-TIM3 (S095018/Sym023) in combination with anti-PD1 (Sym021) in patients with advanced/metastatic recurrent biliary tract cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT133.