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Zytiga Dosage option -25%?

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Posted 8/3/2018 7:30 PM (GMT 0)
Getting ready to start Zytiga because after Lupron Casodex/Taxotere regimen, my doc wants PSA to get to 0.1, whereas now it's "only" down to 0.60. That doc also told me that in the UK, there's a practice of using 25% of the normal dose of Zytiga if you take it a certain way--and that effectiveness is nearly the same as a full dose. He didn't elaborate on how this was done, but I'm following up with him ASAP.
Anyone heard of using 25% dose with nearly the effectiveness of a full dose?? Thanks
Posted 8/3/2018 8:32 PM (GMT 0)
I am sure there are others better equipped to answer this, but it is my understanding that Zytiga taken in the dose normally prescribed can have serious side effects, particularly on the liver. This is increased when taken with food, which is why you are told to take it on an empty stomach.

However some studies have been done which show that a smaller dose taken WITH food (particularly high fat food) can be just as effective without increasing the risk of side effects.

I assume that is what your doc is referring to. And given the high cost of Zytiga, it offers an option to reduce costs.

Chas
Posted 8/4/2018 12:17 AM (GMT 0)
When they originally did the dose-finding study on Zytiga, they used the 1000 mg/day fasting dose. So that's the dose they have the most info on. Above that optimum dose, you're getting more toxicity and not much treatment, so you should not exceed that. More is not better. Because absorption varies with food intake, and the amount absorbed will vary from man to man, they left 1000 mg/day fasting as the standard dose.

But the stuff is expensive, and many men would like to take smaller doses if they can get the same benefit. There have been 3 small studies of low dose Zytiga with food:

With a low fat meal (n=36):

ascopubs.org/doi/10.1200/JCO.2017.76.4381

With a high-fat meal (n=21):

/meetinglibrary.asco.org/record/98068/abstract

Comparing low fat (n=6) and high-fat (n=18):

/accp1.onlinelibrary.wiley.com/doi/abs/10.1002/jcph.564

All of the studies were very small, so you should only reduce the dose under advisement and close observation by your oncologist.
Posted 8/4/2018 2:14 AM (GMT 0)
The drug manufacturer (Janssen) does not want men to reduce their dosage, but the reality is that many men take Zytiga with food with no ill effects. My husband takes four pills a day with food and has been going so for 7 months to get the absorption levels he needs for it to work. One pill with food and monitoring your blood levels for the first few months is worth trying if your doctor agrees. More studies are coming out confirming lower dose Zytiga with food is as beneficial as 4 pills on an empty stomach for many patients.The old studies were what was used to get the drug approved but are no longer necessarily relevant. Good luck
Posted 8/6/2018 1:10 PM (GMT 0)
Following this one. My husband has been wanting to lower his Zytiga. We've also talked about asking the MO if he can half the Predisone as I've heard of that being done as well. He did the same thing with taxotere. A lot of these dosages for treatments seem to be very "loose" and aren't based on weight or condition. It's a one like typical medications. I think this is why it's important to have an oncologist who can listen and think outside the box.
Posted 8/6/2018 3:04 PM (GMT 0)
Be careful about cutting the prednisone - do it slowly if you do it at all. It serves a different function (replacement) with Zytiga. If you go too low, he may get too-high cortisol levels (production is increased to compensate, which will have adverse effects. You should only change the prednisone dosage (usually two 5 mg pills/day) if he is getting SEs from it. With docetaxel, its use is more controversial.
Posted 8/6/2018 6:38 PM (GMT 0)
Thanks all. I'm now waiting to see if insurance will cover Zytiga... Since Lupron / Casodex appears to still be working fine (lower PSA's ever since Taxotere ended two months ago), it may not be covered. We'll see. But as for the prednisone, my recommended dose is 5 mg/day. MO Doc said it used to be 10 mg/day, but has been lowered. Are your recommended doses 5 or 10mg? THANKS
Posted 8/6/2018 6:49 PM (GMT 0)
I'm saying that you must have an adequate replacement dose.
Posted 8/6/2018 7:45 PM (GMT 0)
Steve,
PSA=0.6 ng/mL, I suppose, and dropping.
What is the doctor's rationale for 'forcing' the PSA to go to 0.1?

We all know that there are risks associated with the Zytiga...

Why not keep it 'in reserve' for when the cells stop responding to the current (triple) regimen?
Posted 8/6/2018 9:09 PM (GMT 0)
Doc's belief is that 0.1 is the ultimate goal as 0.6 still has some cancer there. I've also heard others here that have stressed the goal of a 0.1 for Stage IV folks like me. Starting Zytiga now he also believes will extend the usefulness of the HT, maybe as long as 12-18 months more. I have another Onc Doc that is indifferent on getting it to 0.1. He's happy with PSA still dropping to 0.6 and says we could wait until PSA rises, HT starts losing its effectiveness, etc. before starting Zytiga.

One of my DOCs is for playing offense -- the other, defense. I guess I'm leaning toward the offensive approach. Thanks
Posted 8/7/2018 12:32 AM (GMT 0)
OK; thanks for the explanation.
Maybe the insurance will make the decision...

Whatever, best wishes!
Posted 8/8/2018 12:13 AM (GMT 0)
This month I began month 60 on Zytiga. Current PSA is less than 0.01 I have had wonderful results with the medication. Janssen offers a patient assistance program to help with the cost. After copay assistance my co-pay is $10 a month. Cost may not be your reason for wanting to lower the dose but I do believe in following the label.
Posted 8/8/2018 2:28 AM (GMT 0)
I am currently off zytiga & prednisone due to high liver numbers. They finally started reversing. Couple more weeks of blood work and then I may start a lower dose. Hate to quit zytiga after scoring zero twice in a row.
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