Is ADT Necessary Along with Zytiga?

At the ASCO 2019 meeting Ohlmann, etal. presented data from the SPARE trial (NCT02077634) that indicated that it might not be necessary to continue on ADT if you are also taking Zytiga (abiraterone) plus prednisone.  

The trial evaluated if it is necessary for men with castrate resistant metastatic, chemotherapy-naive prostate cancer who are taking Zytiga to continue LHRH-therapy (ADT). 

The trial was an exploratory phase II study of 67 men.  In most of the subject men, their median testosterone levels remained below castrate levels throughout treatment. However, in 18% of the men receiving just Zytiga and prednisone, testosterone levels increased above castrate levels within 28 days after ADT cessation. The median treatment duration was shorter for men receiving ADT plus Zytiga and prednisone.

We can conclude that it isn’t necessary for all men taking Zytiga plus prednisone to continue ADT, but some men will see an increase in their testosterone levels, warranting close monitoring and adding back ADT to their treatment.