Discovery of potent and selective STAT3 inhibitors against triple-negative breast cancer

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Triple-negative breast cancer (TNBC) presents significant therapeutic challenges due to its aggressive nature and molecular heterogeneity.
• Constitutive Signal Transducer and Activator of Transcription 3 (STAT3) activation is a key driver in TNBC, contributing to pathogenesis and resistance to treatment, making it a crucial target for precision oncology.
• Developing targeted therapies for TNBC is essential for improving patient outcomes.

Purpose of the Study:

• To optimize a lead compound (LZJ66) for developing novel STAT3 inhibitors.
• To evaluate the efficacy of newly designed compounds against STAT3-driven TNBC.
• To identify a potential candidate for clinical translation in TNBC treatment.

Main Methods:

• Design and synthesis of 42 novel compounds based on LZJ66.
• Biochemical assays to determine STAT3 binding affinity (K_D) of the lead inhibitor.
• In vitro studies using TNBC cell lines (MDA-MB-231, MDA-MB-468) to assess compound efficacy, including STAT3 phosphorylation and cell proliferation inhibition (IC₅₀ values).
• In vivo evaluation of antitumor activity in a TNBC xenograft mouse model.

Main Results:

• Compound W36 demonstrated high binding affinity to STAT3 (K_D = 323.3 nM).
• W36 effectively suppressed STAT3 phosphorylation and proliferation in TNBC cell lines MDA-MB-231 and MDA-MB-468 with low micromolar IC₅₀ values (0.61 ± 0.31 μM and 0.65 ± 0.12 μM, respectively).
• W36 exhibited dose-dependent suppression of TNBC tumor growth in a xenograft model and showed efficacy across various TNBC cell lines.

Conclusions:

• W36 is a potent dual inhibitor of STAT3 phosphorylation and proliferation in TNBC.
• The compound's efficacy in preclinical models supports its potential as a targeted therapy for TNBC.
• Further clinical investigation of W36 is warranted for its therapeutic application in triple-negative breast cancer.