Improved Radium-223 Therapy with Combination Epithelial Sodium Channel Blockade

Area of Science:

• Oncology
• Radiopharmaceuticals
• Gastroenterology

Background:

• Radium-223 dichloride ([223Ra]RaCl2) is an alpha-emitting therapy for bone metastatic castrate-resistant prostate cancer.
• Significant gastrointestinal (GI) uptake of [223Ra]RaCl2 limits therapeutic efficacy and increases toxicity.
• Investigating enteric ion channel modulation to improve [223Ra]RaCl2 distribution and outcomes.

Purpose of the Study:

• To evaluate the impact of modulating enteric ion channels on [223Ra]RaCl2 uptake and efficacy.
• To assess the combined effect of Amiloride and NS-1619 on [223Ra]RaCl2 distribution and tumor growth inhibition.

Main Methods:

• Primary human duodenal organoids (enteroids) used as in vitro GI epithelium models.
• Amiloride (ENaC blocker) and NS-1619 (K+ channel activator) tested for effects on [223Ra]RaCl2 transport.
• In vivo radioactive drug distribution and tumor growth inhibition evaluated in osteosarcoma and prostate cancer models.

Main Results:

• Amiloride significantly shifted [223Ra]RaCl2 uptake from the GI tract to bone remodeling sites, nearly doubling uptake.
• Combination therapy demonstrated significantly greater bone tumor growth inhibition compared to single agents.
• The combination treatment did not result in significant weight loss, indicating improved tolerability.

Conclusions:

• Modulating enteric ion channels with Amiloride and NS-1619 enhances [223Ra]RaCl2 efficacy for bone metastatic cancer.
• This combination strategy offers a potential clinical approach to improve patient outcomes and reduce treatment-related toxicity.
• Approved agents may be readily implemented for improved tolerability and therapeutic benefit in bone metastatic cancer patients.