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Provenge and other immunotherapies and PSA

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Posted 5/6/2015 10:37 AM (GMT 0)
I understand that there is a survival benefit with Provenge, it continues to work in your system, and all the good things about it. But I don't understand why, if it's killing PC cells, can"t PSA be used as a marker to gauge treatment effectiveness?

Does this hold true for other immunotherapies for PC? Can they not use PSA as a marker as well?

Do other cancers that use immunotherapies have a similar dilemma where the primary marker(s) for their type of cancer can't be used to monitor effectiveness?

Thanks
Jerry
Posted 5/6/2015 11:45 AM (GMT 0)
I have been thinking a lot about PSA as a sentinel for improvement or progression for some time now. I recently joined a trial at NIH and began taking Xtandi. After roughly 90 days my PSA hs dropped y 92%. Wow! But is it just ho-hum? Scans performed yesterday indicated only a 10% reduction in the tumors in my lungs. This has always been a question with me as to why the PSA drop is so large when the tumor size reduction is small if at all. My hypothesis is that the medicines are very good a suppressing the tumor's ability to express PSA but not very good at actually reducing the tumor burden. The marketing arm of the pharma industry is very very good at touting and presenting the results in the most favorable manner.

As for Provenge I have not seen anthing that indicates a reduction in tumor burden and it is known that PSA is mostly unresponsive to it. When it was first approved I went to the FDA site and read the approval. The most striking line in all of the hype was the admission that Provenge did not halt progression of the disease. To me, at least, arresting progression or regression of the disease is what I would want in a treatment.

As for your central question the answer is yes/no. The trial I am in uses ProstVac but they do not rely on PSA for measurement of success but it is measured. The trial specifically states that progression as measured by scan is the only measure of success or failure. BTW I did not get the vaccine so I am in the medicine (xtandi) arm of the trial.

Best to you,
Don

Don
Posted 5/6/2015 8:17 PM (GMT 0)
In late 2013 I had rising PSA while on Lupron and CT scan showed two lymph nodes slightly enlarged. I started on Casodex and had 3 Provenge treatments in Dec 2013 and Jan 2014.

Now as of 4/24/15 my PSA is down to 0.57 and both lymph nodes are reduced to about 20% of their previous size.

I am not sure how much of the improvements are due to Casodex vs Provenge but I am extremely happy with the results.

Sam
Posted 5/10/2015 2:01 PM (GMT 0)
Thanks Don and Sam.
Posted 5/10/2015 9:16 PM (GMT 0)
I have a friend (just returned from lunch with him) who is on this same Xtandi/Prostvac trial. He was randomized to both treatments. He had Provenge a year ago. I told him I was surprised that the trial admitted Provenge patients and he said there is a subset of previous Provenge patients, of which he is one, on this trial. So perhaps the Prostvac people are betting it is better than Provenge, if it is not better than an existing combo (or something).
Posted 5/10/2015 9:51 PM (GMT 0)
Jerry - I viewed the Provenge as can;t hurt, might help.

I measured the combined result of SBRT, Zytiga and Provenge, not the Provenge by itsef.

I guess time will tell how rapidly my PSA increases from <0.01 when I go off the Zytiga at end of this month. Already had my last one month Lupron shot a couple weeks ago.

So the only thing still on the job after the half lifes will be the Provenge.

Plan is to stay on ADT til PSA >=1 and then do scans and decide whether to go back on HT.

If I can keep the doubling time at 9 months, that would be about 63 months or 5 years.

Who knows what wonder drugs will make it through the pipeline by then.
Posted 5/10/2015 10:19 PM (GMT 0)
Jim,

Sounds like a plan. However, you may never need any further therapies. Your mutil pronged attack sent your PC to the next universe.

I was just curious if other immunotherapies affect PSA.

Talk soon,
Jerry
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