Hi --
We were on vacation, now back....
Just to add a bit to the discussion -- the vaccine currently in trial at Hopkins is a therapeutic vaccine, that is, designed to be given to people who have an
HPV-caused cancer. The theory is that it will stimulate the person's T-cells to destroy the virus. Right now it is being tested only on people who have had successful treatment for an
HPV+ cancer (both oral and cervical) and are considered cancer-free, since it is not yet a substitute for proven effective treatments for those with active cancer. It has been successful in animal trials, which is an good thing but no guarantee it will do the same for humans. So still many years off...
The focus on immune boost is because people who have had an
HPV+ cancer have demonstrated that for some reason their immune system was not effective in eliminating the virus initially (Dr. Gillison and others estimate that 80% of us get infected with high-risk
HPV within 4 years of becoming sexually active, however most of us shed the virus and in those who do not, only a smaller percent actually develop cancer.) The time-line for this is uncertain but Dr. Gillison again has said that 10-15 years (or even more) after initial infection is not out of the question. Thus the futility of trying to figure out where it came from. Plus the fact that (as was posted above) the doctors cannot rule out infection by oral contact (read "kissing") etc.
HPV, including the high-risk strains, are ubiquitous.
The way the first phase of this vaccine trial works is that there are four cohorts (dose levels) of the vaccine -- no placebo arm -- and the trial started with the lowest dose. Each cohort must receive their 4 vaccinations and be followed up for several months to be sure there are no side effects before the next higher dose is given. At this time I believe the final cohort is about to start. (And not all are men, I think there is one or maybe two women in the oral cancer arm). After all cohorts are finished, then the blood and sera samples taken throughout will be analyzed. Was there an immune boost against
HPV-16 and if so, was it dose-dependent? The blood and sera are also being tested for "markers" -- i.e., genetic fragments -- of
HPV. If there is a positive response then a Phase II trial will be designed, and I am not sure what this will look like.
Why is this important? -- in
HPV+ cancers the p53 gene, which regulates cell repair and cell death, is only disabled by the
HPV oncogene. (In contrast, cancers caused by smoking usually have mutated or abnormal p53 genes). What happens if the virus is eliminated? A recent study took
HPV+ cancer cells in vitro (cell culture) and used an RNA probe to disable the
HPV oncogenes. 90% of the cancer cells died within 48 hours. Thus there is reason to think that if the virus can be eliminated, the cancer will also be controlled. Or, at the minimum, it would be another powerful "bullet" against the disease.
I think that in Australia and at least one other country boys as well as girls can receive Gardisil. I know many doctors who deal with oral cancer feel that boys should also be vaccinated. It is too bad when ignorance stands in the way of improved health.
One other thing, there was a Swedish study which showed a slightly increased rate of oral cancer in men whose wives had cervical cancer. Have the reference somewhere...
Unfortunately despite the publicity over the
HPV study last May, a lot of of doctors are still unaware of this link. Our RO told us he had two new tonsil cancer patients, both young men, non-smokers -- both
HPV+ -- and the oncologists who diagnosed them had never heard of this.
Gail
