Abstract CT150: Result of an open-label phase 2 trial of dual TORC1/TORC2 inhibitor onatasertib (ATG-008) in HBV+ advanced hepatocellular carcinoma (HCC) subjects who have received at least one prior line of systemic therapy (TORCH)

Background: The mammalian target of rapamycin (mTOR) is a serine/threonine kinase related to the lipid kinases of the phosphoinositide 3-kinase (PI3K) family, which has been confirmed to be closely related to the development of a variety of human cancers. Onatasertib (ATG-008) is a 2nd generation mTOR inhibitor which inactivates both mTORC1 and mTORC2. Our previous clinical investigation (NCT01177397) has demonstrated preliminary evidence of antitumor activity of onatasertib across multiple solid and hematologic malignancies, with encouraging signals of activity in subjects with hepatitis B virus (HBV)+ unresectable, refractory HCC. Methods: Asian patients with advanced HBV+ HCC who had experienced progressive disease after at least 1 line of systemic therapy were enrolled in this study. Onatasertib was administered orally once a day (QD) at 3 dose levels (15 mg, 30 mg and 45 mg) or 20 mg twice daily (BID). The primary endpoints were pharmacokinetics (PK), safety and efficacy (NCT03591965). Results: As of July 11, 2022, 73 patients were enrolled and evaluated. The median age was 52.0 years and the median follow up duration was 26.5 months. The mean number of prior lines was 1.8. 63 patients (86.3%) had at least one Grade 3-4 treatment emergent adverse event (TEAE), and 25 (34.2%) had at least one serious adverse event (SAE). Among the 73 subjects, 3 achieved confirmed partial response (PR), all in the 45 mg QD cohort. 18 pts were enrolled in the 45 mg QD cohort, in which 11 (61.1%) pts had received at least 2 prior lines of systemic therapy and 15 (83.3%) pts had been exposed to an anti-PD-1/PD-L1 antibody. The overall response rate (ORR) in the 45 mg QD cohort was 16.7%. The median progression-free survival (mPFS) was 3.0 months (95% CI 1.9, 4.6) in the intention to treat (ITT) population and was 5.3 months (95% CI 1.9, 7.6) in the 45mg QD cohort. Median overall survival time (mOS) was not evaluable in the 45 mg QD cohort and the mOS was 13.4 months (95% CI 7.4, 19.8) in the ITT population. Onatasertib demonstrated linear pharmacokinetics between 15 mg QD and 45 mg QD in this Asian population and there was no significant exposure accumulation after multiple dosing, as previously seen in the US population. Conclusion: Onatasertib (ATG-008) showed encouraging single agent antitumor activity in patients with HBV+ advanced HCC after at least 1 prior systemic therapy, notably in the 45 mg QD dose level, in which most patients had been previously exposed to anti-PD-L1/PD-1 therapy. The results indicates that onatasertib has potential efficacy in HBV+ HCC patients who failed prior CPI treatment. Further study may be warranted, particularly in HBV+ HCC patients who have failed prior anti-VEGFR and anti-PDL1/PD-1 therapy. Citation Format: Shukui Qin, Xiaoyan Lin, Zhiqaing Meng, Zhenggang Ren, Yuxian Bai, Shanzhi Gu, Li Zheng, Qiu Li, Sun-Yong Oh, Yabing Guo, Yoong-Koo Kang, Wei-Yu Kao, Wei Li, Jung-Hwan Yoon, Helong Zhang, Pei-Jer Chen, Tsai-Sheng Yang, Jeong Heo, Zhendong Zheng, Hui Xie, Zhinuan Yu. Result of an open-label phase 2 trial of dual TORC1/TORC2 inhibitor onatasertib (ATG-008) in HBV+ advanced hepatocellular carcinoma (HCC) subjects who have received at least one prior line of systemic therapy (TORCH) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT150.