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Science Fighting Cancer On Multiple Fronts

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http://www.forbes.com/lifestyle/health/ ... 25925.html


Science Fighting Cancer On Multiple Fronts

By Amanda Gardner

HealthDay Reporter

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. Joseph 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 William 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.

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