By Debbie Strickland

In a Phase II trial, Coulter Pharmaceutical Inc.'s Bexxar — a "hot," or radiolabeled, monoclonal antibody therapy for low-grade non-Hodgkin's lymphoma — is outperforming the "cold," unlabeled version of the same anti-CD20 monoclonal antibody.

The company presented interim comparison data on Bexxar at the American Society for Therapeutic Radiology and Oncology meeting in Orlando.

Preliminary data were generated from 15 patients of a planned 78-patient, randomized, controlled Phase II trial.

Seventy-five percent of patients in the Bexxar arm responded to Bexxar, while 43 percent responded to the unlabeled antibody. Two patients in the Bexxar arm experienced complete remission vs. one in the control group.

The longest time to progression for Bexxar-treated patients was nine months compared with five months in the unlabeled antibody patients.

Both treatments were well-tolerated, according to Coulter, with the only significant toxicity being temporary and reversible myelosuppression.

"Though the trial is still ongoing, the results do indicate a trend toward more durable complete remissions and a higher overall response rate using radiolabeled Bexxar in treating non-Hodgkin's lymphoma," said Susan Knox, an associate professor of radiation oncology at Stanford University Medical Center, in Palo Alto, and a principal investigator for the trial.

Because of the drug's success thus far, patients randomized to the unlabeled antibody arm are allowed to cross over to the Bexxar arm following disease progression.

Also in separate, pivotal Phase II/III trials, Bexxar is Coulter's most advanced product candidate.

About $15 million of the proceeds generated in a $42 million offering completed earlier this month will support development of the drug, including manufacturing scale-up, clinical trial costs and pre-launch marketing. (See BioWorld Today, Oct. 13, 1997, p. 1.)

Coulter's shares (NASDAQ:CLTR) closed Monday at $16.25, up $0.563. *

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