Abstract CT520: The safety summary of the phase 1a/b trial of QL1706, a novel dual immune checkpoint blockade containing a mixture of anti-PD1 IgG4 and anti-CTLA4 IgG1 antibodies, for advanced malignant tumors

Abstract Background: Anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibody may enhance the efficacy of programmed cell death 1 (PD-1) inhibitor. QL1706 is a novel dual immune checkpoint blockade containing a mixture of anti-PD-1 IgG4 and anti-CTLA4 IgG1 antibodies produced by a single cell line. Here we reported the pooled data of the phase 1a/b trial. Methods: In the phase 1a dose escalation and expansion study (NCT04296994), dose escalation involved six levels (0.3, 1.0, 3.0, 5.0, 7.5, and 10.0 mg/kg, intravenously q3w) using an accelerated 3+3 design. The dose expansion cohorts received selected doses. In phase 1b (NCT05171790), patients with advanced solid tumors were given intravenous QL1706 5.0 mg/kg q3w according to the data in phase 1a. The primary objectives were to define the safety, tolerability, and recommended phase 2 dose (RP2D) of QL1706 in phase 1a, and to evaluate the preliminary efficacy in phase 1b. Results: As of Sept 30, 2021, totally 518 patients with multiple types of advanced cancer (99 in phase 1a and 419 in phase 1b) were enrolled, including lung cancer (175 [33.8%]), nasopharyngeal cancer (134 [25.9%]), cervical cancer (58 [11.2%]), liver cancer (34 [6.6%]), colorectal cancer (27 [5.2%]), and kidney cancer (18 [3.5%]), etc. 494 [95.4%] were previously treated, and 182 (35.1%) received previous immunotherapy. Two patients at 10 mg/kg suffered dose-limiting toxicity. The RP2D of QL1706 was defined as 5.0 mg/kg. After a median follow-up of 6.7 months, treatment-related adverse events (TRAEs) were observed in 374 patients (72.2%). 70 (13.5%) experienced grade ≥3 TRAEs. The most common TRAEs were rash (91 [17.6%]), pruritus (65 [12.5%]), hypothyroidism (60 [11.6%]), AST increased (48 [9.3%]), and hyperthyroidism (46 [8.9%]). The TRAEs that led to drug interruption and drug discontinuation were observed in 67 (12.9%) and 31 patients (6.0%), respectively. The immune-related TRAEs and treatment-related serious adverse events were observed in 223 (43.1%) and 59 patients (11.4%), respectively. 79 (16.9%) patients had a confirmed objective response, 237 (50.6%) patients had a confirmed disease control. Conclusion: QL1706 had a manageable safety profile. QL1706 still showed promising anti-tumor activity although over one-third of the patients received prior immunotherapy. These results supported further investigation of QL1706 for advanced solid tumors. Citation Format: Li Zhang, Hongyun Zhao, Yan Huang, Wenfeng Fang, Yuxiang Ma, Yang Zhang, Xiaoli Wei, Yanhua Yang, Wei Yang, Furong Liu, Zuan Lin, Jianing Li, Qianwen Liu, Benyan Zou, Kunlun Liao, qun Liu. The safety summary of the phase 1a/b trial of QL1706, a novel dual immune checkpoint blockade containing a mixture of anti-PD1 IgG4 and anti-CTLA4 IgG1 antibodies, for advanced malignant tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT520.