First-in-human phase 1 trial of the safety, tolerability, pharmacokinetics of BY101298: Initial report from dose escalation cohort.
Authors: Jinming Yu, Yuping Sun, Qi Dang, Yan Zhang, Jintong Du, Yonggang Wei, Fei Ye, Rui Liu, Qi Zhao, Zhiyong Li
Journal: Journal of Clinical Oncology (2024)

e15132 Background: Radiotherapy (RT) is a cornerstone of cancer treatment, leveraging the effect of ionizing radiation to induce DNA damage, primarily through DNA double-strand breaks (DSBs). Non-homologous end joining (NHEJ) stands as the predominant pathway for repairing DSBs, with DNA-dependent protein kinases (DNA-PK) playing a pivotal role in NHEJ pathway. DNA damage repair can compromise tumor cells sensitivity to RT, potentially leading to the development of radiation resistance. BY101298, an innovative and highly selective DNA-PK inhibitor, works to diminish DSBs repair. In synergy with RT or chemotherapy, BY101298 enhances tumor cells eradication, preventing local recurrence and metastasis, thereby improving clinical benefits for cancer patients. Methods: This phase Ⅰa multicenter, open-label, dose-escalation study assessed the safety, tolerability, and clinical efficacy of BY101298. Oral doses ranged from (50 mg to 400 mg once/day [QD]) in continuous 28-day cycles. Primary outcome was safety and tolerability; secondary outcome was PK; exploratory outcome was DNA-PK phosphorylation (PD). Adverse events (AEs) were monitored per the Common Terminology Criteria for Adverse Events (CTCAE version5.0). Responses were assessed every other cycle using Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Results: Data from 9 pts with advanced solid tumors (cutoff: 26 December 2023; 2 men, 7 women; median age 58.0) revealed a linear increase in BY101298 AUC exposure and C max with dose escalation. Daily dosing for 15 consecutive days showed no AUC increase. Serum drug concentration correlated significantly with DNA-PK phosphorylation. All pts, previously systemic treated, received doses of 50 mg QD (n = 2), 100 mg QD (n = 3), and 200 mg QD (n = 4). Median treatment duration was 30 days (range: 1-57), with one patient (11.1%) continuing. Median relative dose intensity was 100%. Common treatment-related AEs (≥25%), primarily grade 1, included hypoalbuminemia (n = 5, 55.56%); anemia (n = 4, 44.44%); nausea (n = 3, 33.33%); weight decreased (n = 3, 33.33%). No pts experienced ≥Gr3 AEs. Two pts experienced serious AEs (none of which were considered treatment-related). No treatment discontinuations, dose reductions, or deaths attributed to treatment-related. The final dose group, representing the fourth cohort, is scheduled to commence shortly and is expected to conclude in April as per our estimation. Conclusions: In pts with advanced solid tumors, BY101298 exhibits a favorable safety profile and manageable toxicity. Vomiting was noted as a potential risk associated with BY101298. Further studies are imperative to elucidate the efficacy of BY101298 in combination with radiotherapy among pts with advanced solid tumors. Research Sponsor: This study received support from Chengdu Baiyu Pharmaceutical Co., Ltd. Clinical trial information: CTR20230997.