FDA Approval of Abiraterone Acetate (ZYTIGA)
Abiraterone (ZYTIGA) was approved for use in men who have progressed from hormonal therapy to chemotherapy and then failed chemotherapy.
In essence, they are going back to hormone therapy.
This seemingly odd sequence, in my opinion, was the easiest way to get the drug approved by the FDA.
However, I think it would make sense to use it before chemotherapy (that is to say, that I believe there will be substantial “off label” use – not that I am officially recommending off-label use).
I believe that, for the present, it will be the last step in hormonal therapy.
The fact that the patients have to take prednisone that lowers their immune system will make it a little difficult to integrate with Provenge, which requires enough white blood cells for the effect. Chemotherapy with docetaxel or cabazitaxel also lowers the white blood count, which makes Provenge therapy more difficult.
Provenge was also approved for men who have failed chemotherapy. Also, with Provenge, there is currently no way to tell whether the immunotherapy is working, because it does not produce any evidence of tumor progression. One just gives the Provenge every other week for 3 courses and “declares victory.”
My guess is that many patients will be treated with standard hormonal therapy, then abiraterone, then chemo, and then Provenge. This routine may change with further experience.