The results of a German study showed that researchers appear to have found a way to improve the effectiveness of the drug tamoxifen, which is used to treat breast cancer in younger women who do not respond well to this traditional treatment.
Tamoxifen works by preventing estrogen from binding to proteins on the surfaces of cancer cells, which prevents the cancer from growing.
For the drug to be effective, tamoxifen must be converted by the enzyme CYP2D6 into a form called z-endoxifen, but about a third of patients have low levels of this enzyme. As a result, the transformation process is weakened.
Postmenopausal women can use alternative medications known as aromatase inhibitors, but they are not an option for younger patients. Researchers in the journal Clinical Cancer Research said that giving supplemental Z-endoxifen compensates for the weak conversion process of the drug tamoxifen and makes it more effective.
During this study, 235 patients in the early stages of breast cancer received either tamoxifen alone or with Z-endoxifen, based on how efficiently tamoxifen is converted in their bodies.
The results showed that drug concentrations in the blood of patients who received the combination treatment were similar to those in women who received tamoxifen alone.
According to the report, side effects were mild and similar in both groups.
“With this approach, we provide the first effective solution to a long-standing problem: the insufficient effect of tamoxifen in a large proportion of female patients,” study team leader Matthias Schwab, from the Margarete Fischer-Bosch Institute for Clinical Pharmacology in Stuttgart, Germany, said in a statement.