Phase I study of TQB3728 tablets, an oral inhibitor of apoptosis proteins in patients with advanced solid tumor.

e13104 Background: Apoptosis proteins are frequently upregulated in human cancers and are associated with resistance to therapeutic agents and poor outcomes. TQB3728 antagonizes the function of inhibitor of apoptosis proteins (IAPs), thereby inhibiting NF-кB signaling pathways and promoting cancer cell death. This first-in-human study aims to evaluate the maximum-tolerated dose (MTD), safety, pharmacokinetics, pharmacodynamics, and antitumor activity of TQB3728 in patients with advanced solid tumors after the failure of standard therapy. Methods: This study combined an accelerated dose titration design with a 3+3 dose escalation design. Three dosage schedules were explored. First of all, TQB3728 was given orally once a week, on a 28-day cycle (DS1). The starting dose of 25mg was escalated by 100% in a single patient until the third dose, then diverted to a 3+3 dose escalation design. The other two dosage schedules were TQB3728 given once daily on days 1-14 every 3 weeks (DS2) and daily every 4 weeks (DS3). The primary endpoint was safety, maximum tolerated or maximum administered dose (MTD), and the secondary endpoints were pharmacokinetics, pharmacodynamics, and tumor response per RECIST v1.1. Results: As of Dec 15, 2023, 23 patients (pts) received at least one dose of TQB3728 (dose range, 25 to 600mg). Based on the pharmacokinetics and safety of DS1, then DS2 (dose range, 100 to 200mg) and DS3 (dose range, 100 to 200mg) were investigated. The median follow-up period was 8.5m (range, 0.5 to 25m). No dose-limited toxicity and cytokine release syndrome were observed. The main treatment-related adverse events (TRAEs) were nausea (56.5%), lymphopenia (56.5%), dizziness (39.1%), hypersomnia (34.8%), increased aspartate aminotransferase (30.4%), increased alanine aminotransferase (26.1%), vomiting (26.1%), anemia (21.7%), decreased appetite (21.7%), and grade≥3 TRAE were lymphopenia (8.7%), anemia (4.4%). As for DS1, the average T max and t 1/2 were 2 h and 9.6 h, respectively. The exposure did not increase with the dose above 150mg. Moreover, the average T max was about 2.3 h and 0.8 h, and t 1/2 was 6.6 h and 7 h in DS2 and DS3, respectively. There was no significant accumulation with continuous medication. Additionally, Plasma MCP-1 increased at 3-6h postdose at high dose; cIAP-1 levels in PBMCs were undetected. Two pts (8.7%) had stable disease >6 weeks as the best treatment response. Conclusions: TQB3728 was well tolerated at doses up to 600mg but had limited anti-tumor activity in advanced solid tumor. According to the preliminary results, TQB3728 administered orally in combination with conventional chemo-radiotherapy is under exploration. Clinical trial information: NCT04523285 .