New Class of Hsp90 C-Terminal Domain Inhibitors with Anti-tumor Properties 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 limited treatment options.
• Heat shock protein 90 (Hsp90) is a key regulator of oncogenic protein stability and a promising target for cancer therapy.
• Targeting the Hsp90 C-terminal domain (CTD) offers a novel therapeutic strategy.

Purpose of the Study:

• To optimize the Hsp90 CTD inhibitor TVS21 for enhanced efficacy against triple-negative breast cancer.
• To evaluate the antiproliferative activity and molecular mechanisms of novel Hsp90 CTD inhibitors.
• To assess the in vivo efficacy and safety profile of lead compounds in a TNBC model.

Main Methods:

• Biochemical assays and NMR binding studies to characterize inhibitor-Hsp90 interactions.
• Molecular modeling to guide inhibitor design and optimization.
• In vitro antiproliferative assays using breast cancer cell lines, including MDA-MB-231 TNBC cells.
• In vivo efficacy and safety studies using a TNBC xenograft mouse model.

Main Results:

• Newly synthesized Hsp90 CTD inhibitors demonstrated increased antiproliferative activity against breast cancer cell lines.
• Compounds 89 and 104 were identified as highly effective, inducing apoptosis, inhibiting proliferation, and degrading oncogenic proteins without causing a heat shock response.
• In vivo studies showed compound 89 exhibited comparable efficacy to the clinical candidate AUY922 with an improved safety profile in a TNBC xenograft model.

Conclusions:

• Optimization of Hsp90 CTD inhibitors yields potent and safe therapeutic candidates for triple-negative breast cancer.
• Compounds 89 and 104 represent promising leads for further development in TNBC treatment.
• Hsp90 CTD inhibition offers a viable strategy to address the unmet medical need in TNBC therapy.