"Xtandi (but not Zytiga or other advanced antiandrogens) prevents acquired resistance to T because it upregulates the AR while it inhibits its activity." Tall_Allen
healthunlocked.com/advanced...
Does this mean you should just automatically favor Xtandi over Zytiga? It would certainly seem so, wouldn't it?
It seems straightforward to me. Or is this more complicated and nuanced than that?
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Update #4
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My synthesis of the discussion so far:
1. There is no downside to choosing Xtandi instead of Zytiga. Each may have side effects that are unique to the individual patient, but you don't know until you try. There is some anecdotal evidence that Xtandi side effects may be more common than Zytiga.
2. If you foresee Bipolar Androgen Therapy (BAT) in your future, it appears there may be good reason to start with Xtandi and stay on it if you find that you tolerate it well.
If you do not see BAT in your future, maybe Zytiga makes more sense. Xtandi is doing some fancy stuff with the Androgen receptors. Simplicity is always good.
And there are always considerations of cost and idiosyncratic side effects.
3. If you are finding that Androgen Deprivation Therapy is no longer working for you, it is worthwhile to get a second opinion on trying BAT for a few months. That second opinion should be from a Medical Oncologist who uses BAT therapy regularly as part of their practice.
4. Nice Explanation of BAT Therapy by Smurtaw:
" o Initially, nearly all prostate tumors are gas guzzlers: very fuel-dependent and powered by the androgen receptor as the engine. When treated with hormonal treatments gas prices increase and most tumors remain fuel-dependent but become more fuel efficient, able to go farther with less gasoline. But then as we make gas plentiful and cheap (high androgens or testosterone) the tumors become less fuel efficient since gas is cheap.
o In each cycle of pBAT, we go from cheap gas to expensive gas. The prostate tumors never settle down into gas guzzlers or gas-efficient vehicles (hormone resistance).
o For this to work we need to be able to make gas very expensive. This is one of the advantages of pBAT. By using testosterone propionate, we can go to very low levels of testosterone during the ADT phase and this makes the gas prices very expensive.
o We can see that, while pBAT will work with men who are hormone resistant, the optimum time to do pBAT is while the cancer is still hormone sensitive. The goal is to prevent it from completing its adaption to a low testosterone environment and pBAT is a means to that end." Smurtaw
5. More from Smurtaw:
"Also, Xtandi is that only ARSI that has been proven to upregulate ARs while also inhibiting them. Upregulation should improve the high T phase of BAT and inhibition improves the low T phase.
Other ARSIs might do this to some degree but it hasn't been tested. Hopefully we will find out more in the next few years." Smurtaw
Smurtaw's Book: "Adaptive Bipolar Androgen Therapy (BAT) for Prostate Cancer: Prostate Cancer Hormonal Treatments" Available on Amazon:
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Update #3
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In response to smurtaw's comments below, I was thinking about how you would investigate whether or not Xtandi's upregulation of the prostate cancer cell Androgen Receptor would inform future treatment decisions.
One way to research this would be a retrospective study of the two groups of patients (Xtandi & Zytiga) and subsequent course of treatment data, but filtering out all the confounding variables.
BUT statistically filtering out all the different prior and subsequent treatment decisions. Even though both groups appear to have similar survival rates, maybe Xtandi suffers from easier future treatment regimes.
Those Docs never ever it seems measure anything other than survival/death rates. That's how the insurance companies justified withholding PSA testing until way too late for many of us.
If you can continue to use Androgen Deprivation Therapy for a longer time. That's a big win. But it is something you have to do looking for. If you limit yourself to cheaper retrospective data, you have lots and lots of confounding variables you need to filter out.
See Also:
"If I was going into it fresh I'd probably pick Xtandi instead of Zytiga. The fact that pBAT has worked so well for me stops me from second-guessing anything." Smurtaw
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Update #2
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From my favorite peer-reviewed journal:
1. Conjecture: "a conjecture is a conclusion or a proposition that is proffered on a tentative basis without proof"
en.wikipedia.org/wiki/Conje...
2. Theory: "A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking..."
3. Theorem: "a statement that has been proved, or can be proved"
For those who now remember the difference in the hierarchy of a conjecture, a theory, and a theorem. Please replace your non-responsive posts with ones that contain substantive content. At the time of this writing, I have not seen one such post. If anyone here can do that, it would be TA, and so far he has failed to do so. Presumably, because he can't? (note the "?" please)
To the extent that no one here can do that, it is a step towards upgrading my proposed Conjecture to a potential Theory. I welcome being proven in error. I really do. But the vacuous spam is not helpful to anyone.
Thank you in advance
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Update #1
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See generally:
Sequential Testosterone and Enzalutamide Prevents Unfavorable Progression
clinicaltrials.gov/ct2/show...
Prostate cancer androgen receptor activity dictates efficacy of bipolar androgen therapy through MYC
"Gasoline" Source
ADT Paradox
Zytiga & BAT
