Endogenous NIS expression in triple-negative breast cancers

Area of Science:

• Oncology
• Molecular Biology
• Radiopharmaceuticals

Background:

• The sodium iodide symporter (NIS) facilitates iodide uptake in cells and is present in about 70% of breast cancers.
• Functional NIS expression offers a potential route for therapeutic targeting of tumor cells using radioactive iodine (131I).
• Triple-negative breast cancers (TNBCs) currently have limited treatment options, primarily relying on chemotherapy.

Purpose of the Study:

• To investigate and characterize the expression of NIS in triple-negative breast cancers.
• To assess the potential of NIS as a therapeutic target in this specific breast cancer subtype.

Main Methods:

• Immunohistochemical analysis of NIS expression in archival tissue samples from 23 triple-negative breast cancer patients.
• Evaluation of plasma membrane immunoreactivity for NIS.
• Scintigraphic imaging with 123I and dosimetric analysis in one patient with a NIS-expressing tumor.

Main Results:

• NIS expression was detected in 65.2% of triple-negative breast cancer cases, with 47.8% showing strong expression.
• Plasma membrane NIS immunoreactivity was observed in 4 tumors, with equivocal results in another 4.
• Scintigraphy confirmed tumor-specific radioiodide uptake in a patient with a large, therapy-resistant primary breast cancer, demonstrating higher isotope concentration compared to normal breast tissue.

Conclusions:

• A significant proportion of triple-negative breast cancer cells exhibit strong NIS expression.
• These findings support the potential utility of NIS-directed 131I-radioablative strategies for treating triple-negative breast cancer patients.