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Prostvac Trial Later vs. HDT Now

Timlong
Posts: 35
Joined: Nov 2011

My friend Tim is two years post RP and IMRT.  Age is 53, Gleason 9, PSA 22, 12/12 positive, EPE, SVI and PNI. RP was non-nerve sparing which included 12 lymph nodes which showed no cancer however he is most likely metastatic.

He now has a PSA of .5 which has been rising from the .1 range for about one year now. His PSADT is 4.5 months and Fox Chase Cancer Center wants him to wait until he is 2.0 to get him into a Phase III study involving Prostvac. I have suggested to him to begin HDT now..... My thoughts are why wait and let a cancer progress so you can enter a trial which you only have a 50 percent chance of getting a drug and.... according to my research can give you 4.5 months extended "time to progression" of  his desease. This seems to me that allowing a tumor to form is pretty risky to meet the minimums for acceptance into a trial. If he can buy a year or two of remission with HDT perhaps then other treatments will be available should his desease becomes refractory and it most likely will.

Is my logic correct?  I look at this trial as their final steps to bringing this drug to market. It is not curative.

 

Jeff (friend)

 

 

 

 

VascodaGama's picture
VascodaGama
Posts: 1528
Joined: Nov 2010

Jeff

Your logic is correct but if you take the vaccine as a sequential treatment then starting the vaccine before the hormonal will not diminish or alter any benefit from the hormonal that could be expected to occur at the 0.5 or 2.0 PSA marks.
There is a risk when we allow the tumour to increase freely in size as we see it through a PSA doubling. Aggressive cases need prompt action but the timing to act has no definite level indicating that at 0.5 is better than at 2.0. This is correct in regards to hormonal manipulations; however, according to the rational of the vaccination this therapeutic has shown better results when done at an earlier stage of the cancer, because the action of the vaccine in the immune system takes time before this “immune-response” is ready to tackle the bandit. This is the conclusion proven in the Phase II trial of Prostvac.

If we take your info as correct, Tim will reach to a PSA=2.0 in approximately 7.5 months from the date of his last test (based on progressive exponential calculations). This means that the effects he would gain from an earlier hormonal against a vaccination would be minimal. However, if we add the time he is on trial (without hormonal treatment), then the loss could be significant.

I do not know the requirements indicated by Tim’s doctor or in which trial he has been proposed to enter, but in the Clinical Trials net page (of the National Institute of Health) they indicate about a current PROSTVAC trial done between November 2011 to August 2016, and with the following inclusion Criteria, which does not fit Tim’s present status:

Men, ≥18years of age with documented asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer.

Documented progressive disease post surgical castration or during androgen suppression therapy, or during complete androgen blockade therapy and withdrawal. Documented by either criterion a (Radiological progression), OR criterion b (PSA progression).

1. Radiological progression defined as any new/enlarging bone metastases or new/enlarging lymph node disease, consistent with prostate cancer.
OR
2. PSA progression defined by sequence of rising values separated by > 1 week (2 separate increasing values) over a threshold minimum of 2.0 ng/ml. (PCWG2 PSA eligibility criteria).

Chemotherapy naïve and Vaccinia-experienced (previous smallpox vaccination). Currently using a GnRH agonist or antagonist (unless surgically castrated).

Accordingly, Tim is not a HRPC patient yet and he cannot be under hormonal treatment while on trial. The conclusion is that Tim would need to wait till August of 2016 which may not be practical for his case.

My lay opinion is that vaccination is a good therapy and the opportunity in having it is great if one takes the real thing. Participating in a trial as placebo is more for cases of indolence and lower Gleason scores that can hold a long period without treatment. I think that guys like Tim could benefit from the vaccine done in sequential or together with other therapy (HT plus Vaccine) but unfortunately these trials are expensive, paid by the pharmaceuticals and done for “…their final steps to bringing this drug to market…” as you commented.

Would his doctor accept the combo? At least you can inquire.

Here is the trial;
http://clinicaltrials.gov/show/NCT01322490

Here is the study;
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3449276/

 

Best wishes in Tim’s continuing care.

VGama  Wink

 

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