Is there any role for re-challenge with enzalutamide or abiraterone after prior failure in metastatic castrate-resistant prostate cancer?

Returning to a therapy on which a patient with mCRPC had previously progressed can be done with docetaxel (Bracarda et al, Future Oncol. 2015;11(22):3083-90; Di Lorenzo et al, Medicine (Baltimore). 2016;95(14):e2754), where a patient may derive clinical benefit to a re-challenge. Typically, the patients who benefit had responded previously to docetaxel and/or had undergone multiple other therapies in between. This approach has been less well studied with AR antagonists. In patients where enzalutamide or abiraterone was discontinued because of drug intolerance, it may be worthwhile to re-challenge at a later time (possibly titrating the dose up depending on what the original toxicity was). I have on occasion re-challenged a patient who had responded well (and then progressed) on abiraterone. I am more apt to try this in a patient where molecular profiling of the metastatic tumor showed amplification of the androgen receptor, and where other therapies are not an option. In my experience, occasionally the PSA will decline but the clinical benefit is minimal and the duration of PSA decline lasts only for a few months.