Monday, May 30, 2011

Endoxifen: The New Breast Cancer Treatment?

Thanna and Katelyn's presentation on the effects of Tamoxifen prompted my curiosity concerning a metabolite of Tamoxifen, Endoxifen. As we learned in their presentation, Tamoxifen is metabolized into Endoxifen within the body through the activity of cytochrome P450 enzymes, namely CYP3A4 and CYP2D6. Unfortunately, women who are deficient in this enzyme are unable to reap the full benefits of Tamoxifen.

During the presentation, I wondered if it was possible to orally administer Endoxifen. My research led me to an article from the Mayo Clinic, expressing their hope in the possibility of Endoxifen becoming an orally administered drug, yet there was little information concerning actual studies or experiments to test the effectiveness of Endoxifen.
From further research, I found that Endoxifen, when orally administered to female rats, was absorbed with ease and showed 787% higher exposure and 1500% higher concentration when compared to rats who were administered Tamoxifen. Another study involved the administration of Endoxifen to female mice, once daily for 28 days, in doses of 2, 4, and 8 mk/kg. Various doses were found successful in the prevention of human tumor grafts.
I also found a clinical study (currently recruiting members) meant to"test the safety and effectiveness of daily endoxifen in individuals with hormone receptor-positive solid tumors that have not responded to standard treatment." This trial started in December 2010, and is to be completed by September 2012.
While no substantial results have yet been reached, I was interested to see that the medical community is definitely researching the possibility of treating patients with Endoxifen, and so far, the implications are favorable.