NEW YORK (CNN/Money) - Johnson & Johnson said Monday a drug it is developing for treating tumors has been ineffective in treating gastrointestinal cancers in late-stage trials.

J&J said that Phase III clinical trials of the drug known as "R115777," in combination with another treatment, did not improve overall survival in patients suffering from gastrointestinal cancer compared with a placebo.

Shares of J&J (JNJ: down $0.65 to $60.82, Research, Estimates) edged down less than 1 percent in afternoon trading.

"We are disappointed that these studies in gastrointestinal cancers did not achieve their primary endpoints," said Mary Ellen Rybak, vice president in charge of oncology at J&J, in a statement. "However, results from studies in other tumor types also are being presented at (the American Society of Clinical Oncology) and are encouraging."

The ASCO annual meeting is being held this week in Orlando, Fla.

There was also further discouraging news for Bristol-Myers Squibb and ImClone for their cancer drug Erbitux, this time involving its effectiveness in treating head and neck cancer.

In a late-stage trial of 120 head and neck cancer patients treated with cisplatin, a chemotherapy drug, half were also given Erbitux, and half were given a placebo.

Those given Erbitux did not show any statistically significant improvement over those given the placebo over two months, according to data released Sunday at ASCO.

The average amount of time until tumors got worse in patients taking Erbitux was 4.10 months, compared with 3.37 months in the placebo group, a statistically insignificant three-week difference.

ImClone (IMCL: down $1.77 to $11.64, Research, Estimates) shares dropped more than 11 percent, but shares of Bristol-Myers (BMY: up $0.36 to $30.83, Research, Estimates) rose in afternoon trading.

In December, the U.S. Food and Drug Administration refused to consider Erbitux for approval for use against colon cancer, saying trials of the drug were flawed. ImClone's shares have fallen more than 80 percent since then.

Data were presented on several smaller trials of Erbitux.

A separate head and neck cancer trial showed tumors shrank in 11.5 percent of patients. A mid-stage study of lung cancer patients, taking Erbitux plus the chemotherapy drug Taxotere, showed tumors shrank in 26 percent of patients, compared with 7 percent of patients treated only with Taxotere.

Another mid-stage trial for colon cancer showed that six patients, or 10.5 percent, showed a 50 percent tumor reduction, and in 21 patients, or 37 percent, the disease stabilized.

Investigators said that while the drug appears to show some promise, the numbers are too small to draw definitive conclusions.  

-- from staff and wire reports