Abiraterone vs Enzalutamide + Radiation

[PhilipSZacarias]

I would like to solicit the valued opinion of members of the HU community regarding the potential benefits of abiraterone or enzalutamide when undergoing radiotherapy. It is well known that radiation therapy can elicit a beneficial immunogenic response (i.e., abscopal effect) and that concurrent ADT improves the outcomes further (I am presently on (Lupron). I will be undergoing SBRT for a T12 metastasis and commencing abiraterone before the radiation - as a general rule, multimodal therapy is better than mono modal. There are many reports on the beneficial effect of concurrent abiraterone when undergoing radiotherapy, but not many discussing enzalutamide. One of my oncologists suggested that either abiraterone or enzalutamide could be used but noted that prednisone must be taken with abiraterone, and it is well known that prednisone is immunosppressive. I was considering taking a short course of enzalutamide during radiotheray and then switching to abiraterone after a couple of months. The literature also indicates that the sequence abiraterone-->enzalutamide is more favourable then enzalutamide-->abiraterone, but these are in settings where failure has occurred in the first hormone therapy.

Your comments, are appreciated. Cheers, Phil

[Tall_Allen]

There is no known benefit to including either drug with met-directed therapy. However, you should probably be using one of them if you are metastatic anyway:

prostatecancer.news/2019/12...

Prednisone, in the amounts used with abiraterone, are not immunosuppressive - it only replaces the cortisol that abiraterone eliminates.

[PhilipSZacarias in reply to Tall_Allen]

Thank you Tall_Allen. The 5 mg dose is within the immunosuppressive range but it makes sense that it replaces the missing cortisol and therefore not likely to affect the immune system. Cheers, Phil

[Tall_Allen in reply to PhilipSZacarias]

Yes, it is only immunosuppressive if there is cortisol produced by the adrenals already.

[fmenninger]

I’m currently on a similar treatment program. Combo abi/Lupron with prednisone and 26 igimrt rad to lower disease burden. I have 10 more rads left and doing pre-aerobic exercise just before getting zapped as this may help in the rad treatment, based on clinical trials. My RO says go for it as it will it hurt the rad treatments and any exercise will help with rad fatigue.

[Magnus1964]

The better way is to choose one, start it a month or so before radiation and stay with it though radiation and after.

[curious-mind1]

Hi PhilipSZacarias my dad took enzalutamide before abiraterone when his cancer metastasized to his bones. Enzalutamide brough his PSA down over the course of 3 months, but he had the most severe, neurological side-effects from it, to the point where he stopped eating and was bed-ridden. Once that happened, he was switched to Zytiga, the side-effects were minimal in comparison (just rather extreme muscle loss over time), and Zytiga brought his PSA down to undetectable within 1 year. He ended taking Zytiga for 5 years, until his sudden death from a burst aneurysm.

So in summary, his experience was positive with both drugs, in the sense that they both worked, with Zytiga being the better by far.

Best,

Art

[PhilipSZacarias in reply to curious-mind1]

Thank you Curious-Mind1/Art

[monte1111]

Good post. Well thought out. By a flip of the coin I went to Xtandi after chemo. It has worked well for 3 years. Some questions have no answers. Best of wishes. Flip that coin.

[Scootman]

I was on Xtandi for 4 months and had no success and was just prescribed xtiga yesterday with 5 mg of prednisone . Met with Radiology Oncologistist today he wanted to do radium but my other oncologists over road him stating that they want me to try the xtiga even though they did not think it would work. ( does not make sense to me}. So they are going to try and do the SBRT and he told me this is just for the pain not to try and treat the cancer.Frustrated I want something to try and stop cancer from spreading. I wish I had more info to give you . Scootman good luck

[PhilipSZacarias in reply to Scootman]

Hello Scootman, if you had a poor response to Xtandi then it is likely that the response to Zytiga (which has a different mechanism of action) may also be poor...but you never know with certainty, so still worthwhile to try. There are blood tests that test for the presence of the AR-V7, an androgen receptor variant, that can predict the efficacy of the drugs. If Zytiga fails then you can request docetaxel, if you never had it before, or cabazitaxel if have have. Request that the SBRT be performed with the intention to ablate. The radiation may stimulate the immune system due to the generation of cancer antigens and slow progression. Good luck as well. We all need it. Cheers, Phil