What about vaccines?

[Guest guest]

Science Fighting Cancer On Multiple Fronts

By Gardner

WEDNESDAY, June 1 (HealthDay News) -- One of the most exciting

developments to come out of the recent meeting of the American Society

of Clinical Oncologists was the news that Avastin, a colorectal cancer

drug, also prolonged progression-free survival in breast cancer and

advanced non-small cell lung cancer patients.

Many experts hailed the accomplishment as a proof-of-concept for

anti-angiogenesis drugs specifically and targeted therapies more

generally, which have been in the works for years but only recently

have started to pay off in terms of effective medications.

In contrast, research into cancer vaccines -- the focus of researchers

for more than a century -- has yet failed to deliver any meaningful

results. Several vaccine studies were presented at the ASCO

conference, but none of the compounds studied are anywhere near the

marketplace, experts say.

Right now in the world of cancer research, vaccines seem to have ceded

their top spot to angiogenesis.

" The winds move back and forth, " confirmed Dr. ph P. Eder,

clinical director of translational pharmacology and early clinical

drugs at the Dana Farber/Harvard Cancer Center in Boston.

The parallel paths of these two avenues of research have one thing in

common, however: They each highlight the challenges and promise of the

ongoing quest for new, more effective cancer treatments.

Anti-angiogenesis drugs such as Avastin (bevacizumab) work by

inhibiting the formation of new blood vessels that feed tumors.

The idea was promising when it was first put forth, but solid results

proved elusive and skeptics soon stepped forward. Some experts worried

the approach might stimulate excessive patient bleeding or interfere

with wound healing. This has not turned out to be the case, however,

largely because existing drugs target very specific cell receptors.

On the other hand, anti-cancer vaccine initiatives continue to bear

little fruit in terms of promising treatments, mainly because the

biology behind them is so complex.

" The immune system itself, and all the controls and counter-controls

and back-up controls are much more complicated than we still fully

understand, " said C. Phelps, scientific program director of

the research department at the

American Cancer Society in Atlanta.

" By comparison, angiogenesis is much better understood, " he said. " Not

to say that it's not complicated, but by comparison it's dramatically

less complicated. "

Vaccines do have several potential advantages over more traditional

drugs, which keeps scientific interest in them alive. " One of the most

attractive parts of the vaccine approach is trying to stimulate the

body's natural responses, something we would believe is always

operative and is successful at eliminating tumor cells as they arise, "

Phelps explained. Immunization also has the advantage of being

non-toxic, because doctors are not introducing a foreign substance to

the body.

The most promising vaccine trials have been in the areas of melanoma

and renal cell cancers, Phelps said, and in these areas there have

been enough " limited glimpses at success " to keep vaccines on the

research radar.

Eder agreed that vaccine research isn't likely to subside any time

soon.

" I certainly wouldn't count vaccines out. It's still a valid theory, "

added Dr. Len Lichtenfeld, deputy chief medical officer of the

American Cancer Society in Atlanta.

And, Lichtenfeld pointed out, " When we have success, we tend to forget

the problems. "

" Although we're now seeing the fruits of our labor in angiogenesis and

other targeted therapies, five and 10 years ago there were significant

questions about whether this science would translate from test tubes

into clinical practice, " he said.

Perhaps the key to successful cancer therapy lies not in a " one/or "

approach, but rather in " both/and " combination strategies, Phelps

said.

" We imagine that treatment is always going to be multi-modal, " Phelps

said. " The best combinations are probably going to be approaches that

are quite different, so if we can apply a vaccination protocol to

stimulate the immune system and a [second] protocol to inhibit growth

of new blood cells, that can have a tumor de-bulking kind of

approach. "

" The more different the approaches are in combination, probably the

better, " he added. " Immune approaches, as well as anti-angiogenesis,

are both going to be useful. "

More information

The Angiogenesis Foundation has more on angiogenesis therapies.