Intermittent Xtandi

[Cancersucks]

Does anyone know the effects of skipping a week here and there of Xtandi?  Know someone doing this and not informing their oncologist.  I wonder how dangerous this is...

[CERICWIN]

I've been on Xtandi for about nineteen months now, my first dose being on July 31, 2014.       The side effects were rather severe at first, and my medical oncologist suggested decreasing the dosage, but I insisted on remaining at the full 160 mg dose, since it was lowering my PSA, and I wanted to give my body a chance to adjust to the effects.

I remained on the full dosage until last summer, when the side effects of the Xtandi, Lupron, Xgeva and Avodart became too intolerable, and we reduced the dosage, but the side effects persisted, and finally my medonc took me off of it for a week.

I still had trouble, and last fall I went down to the minimal 80mg dose of Xtandi, and had some relief.        But my PSA was climbing and the Lupron, etc., wasn't lowering my testosterone to the therapeutic level to 20 or less, so I underwent a bilateral orchiectomy.      

PSA continued to climb, so I went back on 120 mg  (three capsules) of Xtandi daily.

My PSA has continued to go up in small increments, and then I had excruciating pains in the prostate.        

While the bone and lymph gland mets remained pretty well-controlled, the prostate tumor grew, until it's now about the "size of an apple," according to my radiation oncologist.        I attribute the reduction in Xtandi to allowing the prostate tumor to grow again, although it took a couple of months after lowering the dosage to show the symptoms.      Now i'm going through radiation to shrink the infernal prostate for once and for all.  (hopefully).  

I can understand why you would like to take a vacation from Xtandi---it's a powerful drug and has powerful side effects for some guys.     But in my case, reducing the dosage to the minimal didn't work well for me, nor did my one brief vacation.

I've managed for the most part to tolerate severe side effects, as it slowed the progression of the cancer, and I'm completely convinced that Xtandi has increased my survival time and helped to maintain a reasonable quality of life.

CERICWIN

[WendyL]

I don't know whether or how risky it is to skip meds doses, but it is definitely problematic not to be honest about it with the treating clinician, for several reasons including making assumptions about your treatment response, and more importantly your relationship with that person. You are in a treatment team relationship with the provider; if you can't trust that part of your team find someone else!

[JoelT]

I want to reinforce WendyL's comments.  Always be honest with your doctor. It is better to discuss any issues you are having with your doctor so they can help you resolve any issues you are having (you have not shared why you are skipping doses).

Nobody can possibly know the answer to your question from a medical stand point since there have not been any trials looking at this question.  Without good information which we do not have, I can only make a guess.  Xtandi blocks the androgens from accessing the receptors so skipping for a week or so will probably allow the androgens to "feed" the cancer making it stronger and allowing it to progress. 

Best bet, discuss it with your doctor as was suggested by WendyL.

Joel 

[lescoh]

Hi,

First, I would strongly second what the others have been telling you - don't hide what you are doing from your oncologist.  The both of you need to be on the same page with your treatment.

I did want to tell you about a British study reported nearly 2 years ago which may have some relevance for you.  This was to see if the anti-androgen withdrawal response (AAWR), found with Casodex and flutamide, where when these meds are stopped there is a drop in the PSA that usually lasts about a few months, also happens with Xtandi.  They retrospectively studied 30 patients, who were treated with Xtandi for mCRPC for periods ranging from 1+ to 21+ months, and had prior treatment with docetaxel and other heavy duty stuff.  After stopping Xtandi, one patient had a greater than 50% decline in the PSA, and two had a 30-50% decline.  However, there was no mention in the summary I have as to how long these declines lasted, nor if there was any relationship to overall survival.  So this is a limited study with some deficiencies, but it does seem to demonstrate that there is a withdrawal response to stopping Xtandi in a minority of patients.  My oncologist did contact the manufacturer of Xtandi, who stated that they did not have any reports of an Xtandi withdrawal response. 

I hope this is of interest.

Les

[rptrma]

Been on Xtandi for 8 months now. At first it seemed like no serious side effects with PSA going down to around 5 after rising to 35 with only Lupron. Now my appetite is almost completely gone (down 40 pounds) and my sense of taste (not smell) is also almost gone. I am completely miserable and wondering if Zytiga might be an alternative to try. If that doesn't work it's on to Taxotere Chem which will likely really make me sick; but maybe I can at least eat and taste food again while I slowly die?