Abstract CT142: Phase 1 study of BPI-23314, a novel BET inhibitor and degrader, in advanced myeloid leukemia (AML)
Authors: Sun Mingyuan , Jin Xiangyu , Guo Jing , Liu Xiaoyun , Xu Yan , Lan Hong , Wang Jiabing , Zhen Jiangnan , Yang Jing , Ding Lieming , Qi Junyuan 
Published: April 2024

Background: The novel small-molecule inhibitor and degrader, BPI-23314, targeting of the bromodomain and extra-terminal domain (BET) family proteins, BPI-23314, has been showndemonstrated promising preclinical efficacy in hematologic malignancies. This Phase 1 study aims to evaluate the safety, pharmacokinetics, and preliminary efficacy of BPI-23314 monotherapy in patients with relapsed or refractory acute myeloid leukemia (R/R AML).

Methods: This ongoing phase 1 study of BPI-23314 enrolled adult patients with R/R AML. Dose escalation was conducted using a standard 3+3 design, followed by additional expansion cohorts to further assess safety and preliminary efficacy. BPI-23314 tablets were administered orally once daily (QD) or twice daily (BID) in consecutive 21-day cycles. The key endpoints included determining the recommended Phase 2 dose (RP2D), safety, pharmacokinetics, and preliminary efficacy.

Results: As of July 31, 2022, a total of 22 patients diagnosed with R/R AML were treated with BPI-23314 at seven different dose levels, ranging from 5 to 60 mg QD or 40 to 50 mg BID. The median age of the patients was 48 years (range: 19-68 years), and the median treatment duration was 6 weeks (range: 2-9 weeks). The median number of prior therapy lines was 3 (range: 1-4), with 15 (68.2%) being refractory to last line of therapy. Due to the high incidence of grade≥3 anemia, thrombocytopenia, and neutropenia among the patients at baseline, most treatment-emergent adverse events (TEAE) of hematologic toxicities were mainly

correlated with disease progression. Only one patient experienced grade 3 treatment-related adverse events (TRAE) comprising anemia (4.5%) and neutropenia (4.5%). Non-hematologic TRAEs were predominantly of grade 1-2. The most common TRAEs (≥10%) were gastrointestinal reactions (10/22, 45.5%), hypertriglyceridemia (6/22, 27.3%), hyperbilirubinemia (4/22, 18.2%), elevated alanine aminotransferase levels (3/22, 13.6%), and increased gamma-glutamyl transferase levels (3/22, 13.6%). Gastrointestinal reactions characterized by nausea and/or diarrhea were the most commonly reported toxicities. The most common TEAEs associated with disease progression were infection and bleeding. No dose-limiting toxicity or treatment-related deaths were reported during the study period, and the maximum tolerated dose was not reached. Among the evaluable responses in all dose levels for R/R AML patients (n=21), one patient achieved complete response (CR) at a dosage of 40 mg BID while three patients maintained stable disease (SD) across various dosages, including QD at 60 mg and BID at both 40 mg and 50 mg. Furthermore, BPI-23314 demonstrated moderate elimination kinetics, with a plasma half-life ranging from 8.6 to 23.3 hours, while exhibiting dose-proportional exposure.

Conclusion: BPI-23314 monotherapy exhibited preliminary clinical efficacy with manageable adverse events in patients with R/R AML. The study is ongoing. The satisfactory pharmacokinetic attribute and outstanding safety profile of BPI-23314 provide compelling rationales for further exploration of its therapeutic potential.

Citation Format: Mingyuan Sun, Xiangyu Jin, Jing Guo, Xiaoyun Liu, Yan Xu, Hong Lan, Jiabing Wang, Jiangnan Zhen, Jing Yang, Lieming Ding, Junyuan Qi. Phase 1 study of BPI-23314, a novel BET inhibitor and degrader, in advanced myeloid leukemia (AML) [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 CT142.