This year's American Society of Clinical Oncology meeting will feature presentations on a number of drugs, some proven, others still being studied. But once again, the conference likely will produce volatility in the biotech sector in the days ahead of the annual event.

As in the past, ASCO rules limit the release of trial abstracts only to members before the meeting. Investor speculation, along with the possibility of a few leaks from among the thousands of ASCO members, will factor into stock movements in the days leading up to the meeting, at which the results of dozens of drug trials will be revealed.

Data at this year's meeting, taking place May 13-17 in Orlando, Fla., will focus on lung, kidney and breast cancer treatments.

Companies large and small will be in attendance, and analysts expect one well-known name,

Genentech

(DNA)

, to grab a good deal of the spotlight, as it prepares to present the results on 150 trials at the meeting.

Abgenix

(ABGX)

,

Cell Therapeutics

(CTIC) - Get Report

,

Millennium Pharmaceuticals

(MLNM)

,

Regeneron

(REGN) - Get Report

,

Sanofi-Aventis

and

Viragen

(VRA) - Get Report

are among the host of those whose research will be discussed during the course of the ASCO presentations.

Expanding Indications

For starters, Genentech will share trial data on Avastin as a second-line colorectal cancer treatment, as a renal cell cancer treatment, and in combination with Tarceva in renal cancer and head and neck cancer. Avastin, co-developed with

Roche

, is currently approved for use as a first-choice treatment for metastatic colorectal cancer.

Jim Birchenough of Lehman Brothers lists 32 Avastin trials slotted for presentation at the ASCO meeting. Lehman makes a market in the securities it covers.

Of the trials listed, analysts highlighted those focused on the drug's possible use as an additional therapy for non-small-cell lung cancer, including a study comparing the use of tumor-stopping drugs paclitaxel and carboplatin, with and without Avastin.

Also at the meeting, Genentech and

OSI Pharmaceuticals

(OSIP)

will report the results of trials using Tarceva in second- and third-line treatments and in a range of tumor types, as well as first line trials on non-small-cell lung and pancreatic cancers.

Safety and efficacy data from Tarceva trials in patients age 70 and over also are expected, as well as results of the drug's quality-of-life benefits in poor candidates for chemotherapy. Investors also will finally see data from trials using combination Avastin/Tarceva therapy in renal cell and head and neck cancers.

Meanwhile, Genentech and

Biogen Idec

(BIIB) - Get Report

will offer results on Rituxan combined with

Celgene's

(CELG) - Get Report

Revlimid to treat leukemia, and in therapies with several other drugs in a range of clinical settings. Rituxan is currently used to treat non-Hodgkin's lymphoma.

Genentech also will offer interim results from phase II trials of Omnitarg in prostate and ovarian cancer.

Others to Watch

Among the conference's other attendees, researchers will present data on the drug Sorafenib in renal cell carcinoma from

Onyx Pharmaceuticals

(ONXX)

and German drug giant

Bayer

(BAY)

. An interim analysis of a phase III kidney cancer trial showed improved progression-free survival, said Ronald Ellis of Leerink Swann.

Ellis reiterated his outperform rating on Onyx and said "positive results of the trial provide for greater confidence in the success of other clinical trials (e.g., liver cancer and melanoma) and positions Sorafenib well competitively." Ellis sees Sorafenib possibly reaching the market in the first quarter of 2006.

However, he expects Sutent, a possible Sorafenib competitor from

Pfizer

(PFE) - Get Report

, to come to market with another indication in this year's fourth quarter, then gain label expansion to include kidney cancer in early 2006. Leerink Swann says it receives compensation from the companies it covers.

Onyx and Bayer also will present abstracts on metastatic melanoma, non-small-cell lung cancer, head and neck cancer, and nasopharyngeal carcinoma.

Erbitux Expectations

Several first- and second-line Erbitux trial abstracts are scheduled for ASCO, and Jim Reddoch of Friedman Billings Ramsey expects the response rate to the

ImClone

(IMCL)

drug to be comparable with Avastin's; that could boost the drug's reputation among oncologists. FBR does and seeks to do business with the companies it covers.

Trial results on the effectiveness of the drug combined with a regimen of other treatments in patients with stage two colon cancer will be among those disclosed at the meeting. Clinical data from trials of Erbitux plus paclitaxel and carboplatin as a treatment for ovarian, peritoneal and fallopian tube cancers also will be presented.

ImClone recently announced plans to file for approval of Erbitux as a treatment for head and neck cancer by the end of the year, instead of its previous target of the second quarter of this year. David Molowa of UBS believes investors may have muted expectations for Erbitux, considering the delay.

"While we expect incremental data presentations at ASCO in May, we do not believe this will garner a significant change in investor sentiment," he said. "We do not anticipate any sustainable movement from current trading levels until we see greater visibility surrounding growth prospects for Erbitux." UBS has received investment banking compensation from the companies it covers.

Ultimately, traders and investors should be aware of the sometimes dramatic effect the meetings can have on the sector before, during and after the results are announced to the public.

"Watch out for unexplained volatility in cancer stocks over the next several weeks," cautioned Steve Harr, director of biotechnology research at Morgan Stanley. "In the meantime, we will continue to work to change ASCO's policy."