Biomira Inc.'s Theratope vaccine in combination withlow-dose cyclophosphamide produced statisticallysignificant extended survival in breast cancer patientswhen compared to other vaccine regimens in a Phase IItrial.

The projected median survival in the standard group,which included intravenous cyclophosphamide beforeTheratope, is 19.7 months vs. 12.6 months in patientswho were given oral cyclophosphamide or nocyclophosphamide before treatment.

"When we started the clinical trials we assumed low-dosecyclophosphamide was necessary to alter immuneresponse," Grant MacLean, the principal investigator forthe study and a medical oncologist at the Cross CancerInstitute in Edmonton, Alberta, told BioWorld Today."This is the first study showing intravenouscyclophosphamide was essential. The immune responsewas much stronger when IV cyclophosphamide wasused."

MacLean presented data from the 48-patient studyThursday afternoon at a conference in San Diego onvaccines. The study on which he reported was conductedover two and one half years at the Cross Center Instituteand at Guy's Hospital in London, and included womenwith metastatic disease.

Theratope contains a synthetic mimic of the antigen,Sialyl-Tn, loaded on a protein carrier so it's presented inan immunogenic form. An adjuvant mixed in helps stirimmune response. Cyclophosphamide is a cytotoxic agentoften used in chemotherapy and other regimens.

"The vaccine produces an immune response, thecyclophosphamide enhances that response, and patientswho have strong immune responses induced by thevaccine live longer," MacLean said. The correlationbetween strength of immune response and survival also isseen in patients with other cancers, he said.

The study involved one group from a large Phase IIprogram of Theratope as a single agent for cancer.Another study is using the vaccine in combination withalpha interferon.

Jane Jack, investor relations coordinator for Edmonton-based Biomira, said the results presented by MacLean are"telling us we're on the right track. We have what webelieve is a product candidate that could be consideredfor further testing." n

-- Jim Shrine

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