These results were published in the Annals of Oncology.
Studies have suggested that bone marrow cells known as endothelial progenitor cells (EPCs) may play an important role in the spread of cancer. EPCs appear to help cancer cells survive and grow in other organs. A drug that depletes copper—tetrathiomolybdate—may interfere with EPCs and reduce the spread of cancer.
The effects of tetrathiomolybdate were evaluated in a Phase II clinical trial among women with high-risk breast cancer. The study enrolled 40 women, 11 of whom had triple-negative breast cancer (cancer that is estrogen receptor-negative, progesterone receptor-negative, and HER2-negative). The women had already undergone other treatment and had no detectable cancer at the time of study enrollment, but all were considered to be at high risk of recurrence.
Tetrathiomolybdate was used to reduce copper levels to a specified range. Treatment was generally well tolerated. The current report focuses on results after the first year of treatment.
- Copper depletion was most efficient in women with triple-negative breast cancer: 91% achieved target copper levels after one month of treatment, compared with 41% of women with other types of breast cancer.
- Copper depletion produced a significant reduction in EPC levels.
- 85% of women overall (and 82% of women with triple-negative breast cancer) remained free of recurrence for at least 10 months. Of the 11 women with triple-negative breast cancer, only two relapsed within 10 months.
These results suggest that copper depletion may reduce the risk of cancer recurrence in women with high-risk breast cancer, including women with triple-negative breast cancer. A Phase III clinical trial will be necessary in order to confirm efficacy and safety of this approach.
Reference: Jain S, Cohen J, Ward MM et al. Tetrathiomolybdate-associated copper depletion decreases circulating endothelial progenitor cells in women with breast cancer at high risk of relapse. Annals of Oncology. Early online publication February 13, 2013.