Discovery of a benzimidazole-based dual FLT3/TrKA inhibitor targeting acute myeloid leukemia

• Published in: Bioorganic & medicinal chemistry 2022-02, Vol.56, p.116596-116596, Article 116596
• Main Authors: Dokla, Eman M.E., Abdel-Aziz, Amal Kamal, Milik, Sandra N., McPhillie, Martin J., Minucci, Saverio, Abouzid, Khaled A.M.
• Format: Article
• Language: English
• Subjects: Acute myeloid leukemia; Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Benzimidazole; Benzimidazoles - chemical synthesis; Benzimidazoles - chemistry; Benzimidazoles - pharmacology; Cell Line; Cell Proliferation - drug effects; Cell Survival - drug effects; Dose-Response Relationship, Drug; Drug Discovery; Drug Screening Assays, Antitumor; Dual kinase inhibitor; FLT3; fms-Like Tyrosine Kinase 3 - antagonists & inhibitors; fms-Like Tyrosine Kinase 3 - metabolism; Humans; Models, Molecular; Molecular Structure; Protein Kinase Inhibitors - chemical synthesis; Protein Kinase Inhibitors - chemistry; Protein Kinase Inhibitors - pharmacology; Receptor, trkA - antagonists & inhibitors; Receptor, trkA - metabolism; Scaffold hopping; Structure-Activity Relationship; TrKA
• ISSN: 0968-0896; 1464-3391
• DOI: 10.1016/j.bmc.2021.116596

[Display omitted] •A benzimidazole derivative with nanomolar activity against FLT3 and TrKA kinase.•4ACP was identified via scaffold hopping & structural simplification of quizartinib.•4ACP prompted apoptotic and necrotic cell death and G0/G1 cell cycle arrest.•4ACP exhibited selective antiproliferative profile and low toxicity in normal cells.•4ACP represents a novel FLT3/TrKA dual kinase inhibitor for targeted therapy of AML. FMS-like tyrosine kinase 3 (FLT3) enzyme overexpression and mutations are the most common molecular abnormalities associated with acute myeloid leukemia (AML). In addition, recent studies investigated the role of tropomyosin receptor kinase A (TrKA) enzyme fusions in promoting AML growth and survival. Based on these premises, targeting both kinases using dual inhibitors would constitute a promising therapeutic approach to target resistant AML. Guided by ligand-based design and structure simplification of the FLT3 inhibitor, quizartinib, we developed a benzimidazole-based small molecule, 4ACP, that exhibited nanomolar activity against wild-type FLT3, FLT3-Internal tandem duplications (FLT3-ITD), and FLT3-D835Y (FLT3-TKD) mutation (IC50 = 43.8, 97.2, and 92.5 nM respectively). Additionally, 4ACP demonstrated potent activity against colon cancer KM12 cell line (IC50 = 358 nM) and subsequent mechanistic deconvolution identified TrKA enzyme as a second plausible target (IC50 = 23.6 nM) for our compound. 4ACP manifested preferential antiproliferative activity against FLT3-ITD positive AML cell lines (MV4-11 IC50 = 38.8 ± 10.7 nM and MOLM-13 IC50 = 54.9 ± 4.1 nM), while lacking activity against FLT3-ITD negative AML cell lines. Western blot analysis confirmed 4ACP ability to downregulate ERK1/2 and mTOR signaling downstream of FLT3-ITD in AML cells. Furthermore, 4ACP prompted apoptotic and necrotic cell death and G0/G1 cell cycle arrest as indicated by cell cycle analysis. 4ACP did not show cytotoxic effects on normal BNL and H9c2 cells and demonstrated decreased activity against c-Kit enzyme, hence, indicating lower probability of synthetic lethal toxicity and a relatively safer profile. In light of these data, 4ACP represents a novel FLT3/TrKA dual kinase inhibitor for targeted therapy of AML.