Editor's note: This is the first in a continuing series based on the American Society of Clinical Oncology's 2005 annual meeting. During the next few days TheStreet.com will also examine some of the big themes at this year's ASCO meeting, along with what the future might hold for shareholders of the companies that make cancer drugs.

As the future of cancer treatment was about to go on display for all to see, a swarm of 28,000 people descended on the Orange County Convention Center in Orlando, Fla., to get an even closer look.

This was the annual meeting of the American Society of Clinical Oncology. This was the place where doctors and researchers lauded upcoming drugs as signaling the start of a new era of targeted therapies, a place where educational sessions focused on drugs targeting the specific proteins and blood vessels that contribute to tumor growth.

And in some ways, the 2005 edition felt as if attendees were camping out to get tickets to

Star Wars Episode III

.

The annual ASCO meeting has grown so big that only a few convention halls can accommodate it. The drug companies on hand had plenty of marketing materials to commemorate the meeting, giving doctors, researchers and scientists coffee, computer paraphernalia, laser pointers and even blankets as free gifts.

But this year, the days leading up to the annual cancer conference may have stirred less anticipation among investors than in the past, when rumor and speculation were sure to precede the gathering. Certainly the excitement was there, but perhaps the volume was turned down and the absence of a great number of surprises continued to mute a phenomenon known as the "ASCO effect."

The Known vs. the New

Much of the news at this year's ASCO meeting in Orlando, Fla., wasn't new at all. In many cases, presentations featured finalized trial data that confirmed previously reported interim results. For example, data on

Genentech's

(DNA)

Avastin trials in breast and lung cancer generated some of the biggest headlines, even if the results weren't entirely surprising.

Avastin was unquestionably one of the stars of the meeting. Positive trial data involving the drug overshadowed news from researchers that Tarceva, from Genentech and

OSI

(OSIP)

, showed lower-than-expected tumor-fighting activity in patients with recurring or refractory metastatic breast cancer.

Sven Borho, founding partner of OrbiMed, one of the biggest health care fund managers in the U.S., says he expected ASCO to spur a "buy on the rumor, sell on the news" scenario.

"Everyone expected it, everyone was waiting, but it never actually happens when everyone's waiting," Bohro says. That doesn't mean audiences at the various sessions were falling asleep in their chairs; Bohro said the presentation of positive data on Herceptin breast cancer trials received several minutes of applause.

Most trials involving targeted therapies like Herceptin compared the drug working along with chemotherapy to the results of chemotherapy alone. The effects of such drugs used as single agents remains to be seen. In the past few years, studies have shown that many cancer patients have exhibited genetic mutations in the epidermal growth factor receptor pathway. EGFR-inhibiting drugs target that protein, which promotes tumor cell growth.

Much Still to Learn

Further studies need to be done to find out why some patients who don't show the mutations still benefit from EGFR-targeted drugs and conversely why some patients who do show the mutation don't see positive effects, according to Dr. William Sellers of MD Dana-Farber Cancer Institute in Boston. While EGFR-targeting drugs are more effective in people with the mutation, the drugs can still work, for some unexplained reason, in people without it.

Among lung cancer patients, specific populations show a mutation of the EGFR pathway and are more receptive to targeted drugs than others. The genetic mutation is more often shown in non-smokers, women and East Asians, according to safety and efficacy trials. Still, researchers need to find out which populations the drugs are more effective in and how, then develop tests that will signal patient receptiveness to the drugs.

EGFR drugs include Tarceva, Erbitux from

Imclone

(IMCL)

and

Bristol-Myers Squibb

(BMY) - Get Report

, and Panitumumab from

Amgen

(AMGN) - Get Report

and

Abgenix

(ABGX)

.

Some doctors say that a patient's ideal drug would be a more effective, single agent with fewer side effects, compared with those that are added to toxic chemotherapy regimens currently in trials. And ideally, doctors would understand exactly how the drugs work (unlike with EGFR inhibitors) and would have tests to see whether drugs would be effective in a patient, ruling out unnecessary costs for those that won't.

However, Imclone Chief Medical Officer Dr. Eric Rowinsky says "it's naive to think that any one manipulation by a single agent will produce robust results, except when targets are highly aberrant."

What's important is finding the most effective combinations of cancer drugs, Rowinsky says, but this goal has been a "bottleneck in cancer research."