Why is this effective HSP90 inhibitor not being developed in HER2+ breast cancer?

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Heat shock protein 90 (HSP90) is a molecular chaperone crucial for the stability of client proteins, including receptor tyrosine kinases.
• The human epidermal growth factor receptor 2 (HER2) is frequently overexpressed in certain breast cancers, driving tumor growth and progression.
• Targeting HSP90 offers a potential strategy to destabilize and degrade HER2, thereby inhibiting cancer cell proliferation.

Purpose of the Study:

• To evaluate the therapeutic potential of combining an HSP90 inhibitor with a HER2-targeted therapy.
• To assess the activity of tanespimycin in combination with trastuzumab in patients with HER2-overexpressing metastatic breast cancer.

Main Methods:

• Administration of tanespimycin (an HSP90 inhibitor) concurrently with trastuzumab (a HER2-targeted antibody).
• Clinical evaluation of treatment response in patients with metastatic breast cancer characterized by HER2 overexpression.

Main Results:

• The combination of tanespimycin and trastuzumab demonstrated clinical activity in the studied patient population.
• This combination therapy represents a viable approach for managing HER2-overexpressing metastatic breast cancer.

Conclusions:

• Inhibition of HSP90 effectively leads to the degradation of the HER2 receptor.
• The combination of tanespimycin and trastuzumab is an active therapeutic strategy for HER2-overexpressing metastatic breast cancer.
• This combination therapy is among novel HER2-targeted treatments poised to improve outcomes for this breast cancer subtype.