Abstract 1764: A highly potent novel STAT5 and STAT3 direct dual inhibitor in acute myeloid leukemia

Abstract Background: Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy caused by abnormal differentiation and uncontrolled proliferation of myeloid cells, along with various mutations. FLT3-ITD mutation, found in approximately 25-30% of AML cases, is known to be associated with poor prognosis, including a high risk of relapse and shorter overall survival. Furthermore, acquired point mutations in tyrosine kinase domain (TKD), such as the ‘gatekeeper’ mutation (F691L), is considered as a main culprit of acquired resistance to FLT3 inhibitors in clinic. Different mechanisms of resistance have been reported in FLT3 inhibitor treated patients in clinic and novel strategies have been tried to overcome the resistance issue. Here we report novel direct STAT5 and STAT3 dual inhibitor, CNC-01 would be promising option for FLT3mt AML patients having acquired resistance to FLT3 inhibitors. Methods: We developed CNC-01, a selective dual inhibitor targeting STAT5 and STAT3, which is an orally available small molecule capable of overcoming drug-resistant FLT3-TKD mutations. We established FLT3 inhibitor-resistant models using OCI-AML5 cell lines, incorporating the gatekeeper point mutation (F691) and continuously interleukin 3 (IL3)-expressing cells to mimic the bone marrow microenvironment. The direct binding to STAT5 and STAT3 was confirmed using SPR assay and cryo-EM analysis. We evaluated anti-tumor effects and target gene expression inhibition compared to Gilteritinib, and also assessed its efficacy in Venetoclax non-responsive models. Results: CNC-01 directly binds to STAT5 and STAT3 proteins, which are implicated in resistance to FLT3 inhibitors. By inhibiting pY694-STAT5 and pY705-STAT3, CNC-01 abrogates pro-tumorigenic transcriptional activities mediated by these proteins. Furthermore, CNC-01 demonstrated potent anti-tumor effects and inhibited target gene expression more effectively than Gilteritinib. Synergistic effects were observed when CNC-01 was combined with Venetoclax, a major treatment option for AML. Additionally, CNC-01 showed high anti-tumor effects in Venetoclax non-responsive models. Conclusion: CNC-01, a novel selective direct STAT5 and STAT3 inhibitor, shows promising results in overcoming FLT3 inhibitor resistance and demonstrates efficacy in Venetoclax-resistant models, too. CNC-01 is under preclinical stage and is expected to be highly promising treatment option for AML patients. This program is to submit Phase 1 IND next year. Citation Format: Eunhye Hong, Minjung Kong, Hyeryung Kang, Minhee Kim, So Jung Son, Sungjae Choi, Kyeong Eun Kim, Woon-Ki Cho, Chae Won Kang, gijeong Seong, A Young Ji, Seon Ho Koh, Sehee Cha, Sangyeop Hyun, Ji Min Shin, Eori Nam, Yeon Ju Hong, Chan-Hee Park. A highly potent novel STAT5 and STAT3 direct dual inhibitor in acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1764.