The ASCO abstracts are here! The ASCO abstracts are here!

Ever since The American Society of Clinical Oncology (ASCO) began posting the abstracts on-line -- and before that when they were sent to attendees -- investors have clamored to get a glimpse at the data that will be presented at the organization's annual meeting, which is slated for June 4-8 this year.

The changes in stock prices on Friday tell the story of what investors thought of the Thursday-evening release of data abstracts.

Company

Friday's Price Change

Keryx Biopharmaceuticals (Nasdaq: KERX)

11.2%

ZIOPHARM Oncology (Nasdaq: ZIOP)

9.7%

Celldex Therapeutics (Nasdaq: CLDX)

(9.2%)

Source: Capital IQ, a division of Standard & Poor's.

Keryx has already started a phase 3 trial for its colorectal cancer drug perifosine, but the data from the phase 2 trial is still helpful in giving investors confidence that the phase 3 trial will actually work. So far, so good; overall survival increased from 11 months to 18 months when perifosine was added to Roche's Xeloda compared to Xeloda alone.

ZIOPHARM is testing its cancer drug palifosfamide in combination with doxorubicin, a standard chemotherapy drug, compared to doxorubicin alone in patients with soft tissue sarcoma. Adding palifosfamide increased the median time until the tumor began to grow again by 3.4 months. It's on to a phase 3 trial for palifosfamide.

Investors weren't as impressed with Celldex's immunotherapy CDX-110, which Pfizer (NYSE: PFE) named PF-04948568 when it licensed the drug. Interim results from a phase 2b/3 trial showed that 70% of the 40 brain cancer patients hadn't seen their tumors get larger five-and-a-half months after the first treatment. It's somewhat hard to interpret the data because there was no control group, and Pfizer and Celldex will certainly have to run another trial before submitting a marketing application.

Of course, Celldex's decline could also just be investors taking profits. Even after the drop, the stock is still up about 50% year to date.

A couple of other notables
Large companies aren't going to see their stock move that much based on data in an ASCO abstract, but they're still worth following.

Celgene's (Nasdaq: CELG) Revlimid and Rituxan from Roche and Biogen Idec are already approved, but they both have data coming out at ASCO that will greatly affect sales. Most cancer drugs are used until they stop working or the cancer is cured, but Revlimid and Rituxan have been tested as maintenance therapies, used for extended periods of time to keep the cancer in remission. So far, the data looks good, but the companies' presentations and doctors' reactions to them will be a good indication of how much additional sales Revlimid and Rituxan can rack up.

Melanoma is one of the more difficult to treat cancers, but Bristol-Myers Squibb's (NYSE: BMY) ipilimumab and Eli Lilly's (NYSE: LLY) tasisulam both seem to show some activity against the skin cancer. The drugs demonstrated a response in four out of 51 patients and eight out of 68 patients, respectively. That may not seem like much, but because these patients have few options, it's possible to get a drug approved with that little activity.

A couple of un-notables
ASCO has a policy of not releasing the abstracts for the premier presentations until the meeting starts. Unfortunately, investors won't be able to get a preview of the data for high-profile treatments such as Pfizer's lung cancer drug PF-02341066, Delcath Systems' melanoma treatment, and ArQule's lung cancer drug ARQ 197.

It's the presentations that matter anyway
Because the abstracts have to be turned in months before the conference, the data contained in them is out of date for trials that are ongoing. Updated data presented at the conference is what really matters, and you can expect a few more crazy trading days next month after full data is released.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Pfizer is an Inside Value recommendation. The Fool has a disclosure policy.