The question of how long does Zytiga work comes up frequently on traffic sources for this website so I thought I would do my best to answer this.
First it is important to realise that trials showed that 80 % of patients responded to treatment with Abiraterone Acetate (Zytiga). This means that for 20 % of prostate cancer patients Zytiga simply does not work. So in reality for 20 % of patients (i.e. 1 in 5) Zytiga will not work at all.
For the majority that do respond (i.e. 4 out of 5) the reponses can vary enormously. Some men respond dramatically and feel better within a few days with PSA levels declining fast. Other men see a sharp PSA increase for a few months before the levels eventually decline. Others see a slow but steady decline in PSA levels.
20 % of patients show a very good response to Zytiga
20% show a medium response
20% show an initial rise in PSA before it declines
20% show a slow response
The duration of the response also varies from around 6 months up to 6 years. The average response duration from the Phase III clinical trials was 1 year.
i.e. the answer to the question is
On average Zytiga works for 1 year.
When used earlier in the treatment of prostate cancer before chemotherapy the trials showed that Zytiga worked for an average of 2 years.
If used before chemotherapy Zytiga works for 2 years.
The longest Zytiga survivor is 8 years from the Phase I clinical trials in 2004.
There are several 6 year survivors still taking Zytiga from the Phase II clinical trials.
There are hundreds of 4 year survivors on Zytiga from the 1000 cohort of the Phase III trials.
I hope this helps you to understand the soughts of responses that you get with Zytiga, Jez