There have been some amazing remissions of MSI-hi with Keytruda. I have an inkling that it may work better with ADT, but I have no data and his approach seems reasonable to me.
If ADT + abiraterone was working you should continue with that treatment and when it starts to fail (radiographic progression) your could start Keytruda which could lead to a good control of the cancer.
You could start ADT and Keytruda now, but you should be aware of negative side effects of keytruda.
You qualify for chemo only if ADT plus abiraterone failed since your tumor load is small The cancer had only 3 mets. Docetaxel offers and advantage to patients with a higher tumor load.
You don't qualify for triple therapy since triple therapy is only used in de novo metastatic hormone sensitive cancer and you had been treated with ADT plus abiraterone for several months.
For cryin' out loud I'd like a treatment break too (my situation is not so dissimilar to yours)! But for the other poor souls reading this, your decision to take a risk was not really a "taking a risk". Risk suggests uncertainty. I'm curious what your doctors thought of this. Stopping therapy (Abiraterone and Lupron are powerful - but have side-effects) would seem to have predictably left the door open for reenergized PCa cells. I really hope you can get back on track! And what about exercise? It's like another free powerful therapy!
Thanks for the reply. I was 59 when diagnosed with de novo metastatic PC. Gut wrenching. I was in perfect health up to that point.
Everyone's different. For me, I made the decision that if I can't be me (my activities too limited, debilitating fatigue etc.) then I would stop treatment. I won't go through my remaining days as some form of shell just to extend my existence a bit.
There are exceptions of course, but most of these treatments only minimally extend life. But at what cost?
I had read that ARASENS triplet was only for de novo, but then I see this which apparently finds it is favorable for recurrent as well:
"In ARASENS, the treatment effect of darolutamide on OS was favourable in patients with de novo (HR 0.71; 95% CI 0.59 to 0.85) and recurrent (HR 0.61; 95% CI 0.35 to 1.05) metastatic hormone-sensitive prostate cancer" .
The problems is that you already had been treated with abiraterone and ADT. You are not recurrent and ready to start triple therapy. Consult with your onco.
Chemo will help you have more than 4-5 metastases. In general does not offer an advantage in oligo metastatic cancer
Two newly discovered mets to ribs makes me recurrent mHSPC. I have not had abiraterone, only ADT, for 10 months, quit 2.5 years ago soon after SBRT to a single met. Do you know if that makes results from ARASENS irrelevant for me? I cannot find data on pre-recurrence medication history of the 168 patients with recurrent mHSPS showing benefit, albeit with less statistical power and partly only suggestive. But surely these would have had ADT previously.....?
I understand that docetaxel is prescribed for low-volume less than 3 mets, low-risk patients in this group.
Table 1 in link below.
Darolutamide Plus Androgen-Deprivation Therapy and Docetaxel in Metastatic Hormone-Sensitive Prostate Cancer by Disease Volume and Risk Subgroups in the Phase III ARASENS Trial | Journal of Clinical Oncology (ascopubs.org)
These are the publications of the ARASENS trial, i think you could qualify if your doctor agrees to do chemo in an oligometastatic cancer. You could do ADT plus abiraterone, enzalutamide, darolutamide etc..
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Treatment Summary
What marker is useful if PSA is not? 
High grade prostate cancer: Large Tumor, High Gleason (9), Low PSA. What next?
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