One of the problems with genetic tests is in evaluating the data which exists
to validate the predictive accuracy of them. Generally, a large number of
archival specimens are batch processed together, within a very narrow time
frame, by the same research team, so all the technical variables are minimized,
which makes it much easier to get good results than in a "real world" setting,
where specimens are tested over a period of weeks, months, years, by different
people, with different laboratory reagents, as occurs in the "real
world."
<p>
Evaluating "real world" data, requires specimens that are tested
as they are logged into the lab in question, in "real time." No one is
publishing "real world" studies, except private laboratories performing
cell-based tests, which can only do "real world" studies, because their studies
require fresh, viable specimen, which must be accessioned and tested in "real
time," under "real world" conditions.
<p>
Tests to identify molecular predisposing mechanisms still does not
guarentee that a drug will be effective for an individual patient. Nor can they,
for any patient or even large groups of patients, discriminate the potential for
clinical activity among different agents of the same class. All the gene
mutation or amplification studies can tell us is whether or not the cells are
potentially susceptible to a mechanism of attack. They don't tell you if one
drug is better or worse than some other drug which may target a particular
pathway.
<p>
It would be more advantageous to sort out what's the best "profile" in
terms of which patients benefit from this drug or that drug. Can they be
combined? What's the proper way to work with all the new drugs? If a drug works
extremely well for a certain percentage of cancer patients, identify which ones
and "personalize" their treatment. If one drug or another is working for some
patients then obviously there are others who would also benefit. But, what's
good for the group (population studies) may not be good for the
individual.
<p>
It may be very important to zero in on different genes and proteins.
However, when actually taking the "targeted" drugs, do the drugs even enter the
cancer cell? Once entered, does it immediately get metabolized or pumped out, or
does it accumulate? In other words, will it work for every patient?
<p>
All the validations of this gene or that protein provides us with a variety
of sophisticated techniques to provide new insights into the tumorigenic
process, but if the "targeted" drug either won't "get in" in the first place or
if it gets pumped out/extruded or if it gets immediately metabolized inside the
cell, it just isn't going to work.