Synthesis and evaluation of raloxifene derivatives as a selective estrogen receptor down-regulator

Area of Science:

• Endocrinology
• Oncology
• Medicinal Chemistry

Background:

• Estrogen receptors (ERs) are critical drivers of ER-positive breast cancer growth.
• Selective estrogen receptor down-regulators (SERDs) that inhibit ligand binding and induce ER degradation are needed for effective treatment.
• Previous studies indicated tamoxifen derivatives with long alkyl chains could down-regulate ERα.

Purpose of the Study:

• To expand the repertoire of available SERDs by designing and synthesizing novel raloxifene derivatives.
• To evaluate the SERD activities of these new compounds with varying alkyl chain lengths.
• To identify potent SERD candidates for ER-positive breast cancer therapy.

Main Methods:

• Synthesis of raloxifene derivatives with diverse alkyl chain lengths.
• Evaluation of ERα binding affinity for all synthesized compounds.
• Assessment of SERD activity, including ER down-regulation and antagonistic effects.
• Comparison of the most potent derivative's activity against a known ER antagonist.

Main Results:

• All synthesized raloxifene derivatives demonstrated ERα binding.
• Compound RC10, featuring a decyl group, exhibited the most potent SERD activity.
• RC10 displayed superior antagonistic activity compared to a non-SERD competitive ER antagonist.
• Ligand core replaceability and alkyl chain length were identified as key factors influencing SERD activity.

Conclusions:

• The ligand core of SERDs is amenable to modification, with alkyl chain length being crucial for activity.
• RC10 represents a highly potent SERD candidate with significant potential for ER-positive breast cancer treatment.
• These findings provide valuable insights for the development of next-generation SERDs.