Being able to make better decisions about drug sequencing and combinations has become one of the current hot topics in prostate cancer research. Given that we have a number of newer drugs to use this is an important clinical issue as we make important treatment decisions.
Making these clinical decisions is tough. The fact is that prostate cancer is a very heterogeneous disease and so drug responses are not consistent. Compounded by the fact that none of our treatments are effective for an extended time period knowing how to accurately predict drug response is vital.
One example of research dealing with this issue examines the efficacy of abiraterone acetate (Zytiga). It sought to specify the clinical factors associated with the duration of abiraterone response in men with castrate resistant prostate cancer.
In a small (n=161 men) retrospectively study, the researchers examined patient characteristics, types and duration of prostate cancer therapies to see what parameters might effect the duration of Zytiga response.
The researchers found that the lower the PSA at the time Zytiga was started, the longer primary ADT duration, no prior exposure to ketoconazole, no prior chemotherapy and longer chemotherapy duration were associated with a longer response to Zytiga.
Simply stated, there was a correlation of a longer response in men who had a with smaller disease burden or less exposure to other prostate cancer therapies.
The study was not heavily powered (only 161 men) and was retrospective so its conclusions, despite being very interesting, need to be considered with a grain of salt. However, you can still comsider these findings when making treatment decisions.
Prostate Cancer Prostatic Dis. 2016 Aug 9. doi: 10.1038/pcan.2016.31. McKay RR, Werner, etal.