PSMA PET Results post-Chemo and what to do next?

[Cheerr]

After completing 6 cycles of docetaxel, the PSMA scan results are:

- Residual 68Ga-PSMA expressing lesion in the right acetabulum and right ischium (max SUV 8.7) and D11 vertebrae.

- PSMA not expressing multiple skeletal lesions in vertebrae.

- No other evidence of 68-Ga PSMA disease present in the whole-body scan.

- In comparison to the previous scan dated 18 Nov 2019 (after 3rd chemo), there is a decrease in PSMA expression of multiple sclerotic lesions.

Dad is still Hormone-sensitive and has little to no bone pain and is doing better than ever, thanks to chemo.

After 6 cycles of chemo + ADT :

PSA: 0.04 [From 149]

ALP: 81 [From 887]

Doctors Plan:

- Told that's a good response to chemo and only 3 places still haven't reduced yet.

- He wants to start Casodex 50 mg (Bicalutamide) once a day, and if there is a rise in PSA/descrease of blood levels/pain he will then consider shifting to Zytiga.

Mo's initial plan was to start Zytiga immediately, but now due to good response to chemo and a very low PSA, he wants to wait.

He tells me based on some recent results he studied, adding Zytiga immediately did not give a lot of extra benefit. He told me to consider Casodex as a weaker form of Zytiga and wants to use this before moving to Zytiga.

Questions?

I'm concerned why he changed his mind about Zytiga at the last minute after the scan results?

Is Casodex + ADT good to retain the benefits of chemo for long?

Should we add Zytiga only after Casodex as per MO?

[Tall_Allen]

Great response to chemo! That bodes well. Have you had any metastases biopsied yet?

[Cheerr in reply to Tall_Allen]

Thank you. Yes dad had a Bone Marrow biopsy done in the start during diagnosis time. (Last July). It showed Adenocarcinoma and a IHC was run on it later to test for prostate cancer.

Is there any advantage to have the Mets biopsied?

[Tall_Allen in reply to Cheerr]

If they took enough tissue, they can also run a genomic analysis (Foundation One, Caris, etc.) to see if some existing medicines (i.e., Keytruda or PARP inhibitor) might work for him, and to narrow down any clinical trials that might be useful.

[Cheerr in reply to Tall_Allen]

Thanks, does genetic testing help after a person has cancer?

Or only the tumor tissue via Foundation one etc are helpful?

[Tall_Allen in reply to Cheerr]

If you can get tumor tissue tested, it may tell you more than germline testing, if that’s what you mean.

[GP24]

Zytiga will just work for a certain amount of time. Therefore I think your MO wants to use it later and control the disease with ADT+Casodex now.

I'm concerned why he changed his mind about Zytiga at the last minute after the scan results?

The scan results were very good so he decided Zytiga is not needed right now. You do scans to base your treatment decisions on that.

Is Casodex + ADT good to retain the benefits of chemo for long?

Probably, you have to observe this. If not, you can add Zytiga any time.

[Cheerr in reply to GP24]

Thank you for the answers. Yes I think we will start with Casodex and monitor. Hope we get a long time with Casodex.

[Hidden]

I've had 4 doctors tell me not to start Zytiga right after chemotherapy before castrate resistant. My plan was to go on Bicalutamide when my PSA started rising from its nadir of .19, but my medical provider at the time wouldn't do it. My old provider said they would but I had already switched.

I agree with your doctor and the other 4 who would not start Zytiga until castrate resistance.

[Cheerr in reply to Hidden]

Hi Gregg, Yes I recall and I was waiting for your response

I guess when that many doctors have made a point, it does mean something. It could be a way to fetch more time until Zytiga start point and also cause they know it won’t add a lot of benefit if started earlier.

Either way I’d want to trust and go ahead with the doctors decision too then.

Adding Casodex is good, it takes off the anxiety of not taking anything post chemo.

[Hidden in reply to Cheerr]

Yes there is this post chemo anxiety because with chemo you are actively fighting the cancer. I found there was kind of a let down when I stopped chemo even though I was really glad to be done with it.

Concerning Zytiga, my current doctor said something like "You could be on this for a long time" and he said he didn't think there would be an additional benefit to starting earlier. He wanted to hold off as long as possible. What some said was early (HSPc) chemotherapy was studied and early Zytiga, but not both. So they felt there was no study showing that doing both early was beneficial.

I think adding Casodex is a fairly low risk option. Just a couple things I'd keep in mind. 1. Casodex can raise liver enzymes so keep an eye on those. It's not that common, but it does happen in a small percentage of patients. 2. Casodex can become an agonist for prostate cancer so if his PSA starts going up, you would want him to get off of it.

Wishing you and him the best.

[hansjd]

Hi Cheerr My husband's situation is very similar. ADT + 6 Chemo in 2018. different MO added Casudex 8 mo later. When asked about adding Zytiga now his 3rd(!) MO said continue with Casudex until an obvious and dramatic rise in PSA which would indicate it had become an agonist. Stop it then and hope for a good withdrawal response (about 25% - 50% get that) and PSA drops again. Then add Zytiga if PSA still going up. Hope that helps. Cheers

[Patrick-Turner]

Casodex + ADT will not hold down Psa forever, and next drug added ADT is often Zytiga, which may give a year or more of Pca suppression.

But if your dad has a lot of bone mets that do not express PsMa and have low Ga68 SUV, Lu177 may be ineffective in future for those mets. It seems to be your dad has some variable types pf Pca, so may only get partial response with Lu177, so FDG scans may also need to be done to work out what to do later.

Instead of Zytiga, consider Xtandi now because maybe that makes more of the Pca express PsMa avidity which may make Lu177 work better later. There is much research going on about FDG scans and dealing with cases where men only get a partial benefit with Lu177, and the type of Pca that does not respond to Lu177 will become a terrible threat in future. research I know is going on at Peter Mac Hospital in Melbourne, done by a Dr Hoffman, and Google should lead you to videos produced by this man's team there.

Patrick Turner.