GSK REPORTS NEW FINDINGS ON PREPANDEMIC VACCINE

New preclinical and clinical trial data show, for the first time, that GlaxoSmithKline's (GSK) candidate prepandemic split-antigen H5N1 vaccine provides a substantial level of cross-immunity against a "drifted" strain of H5N1, the company announced. GSK said the immune response elicited with this vaccine could help prime the immune system to rapidly respond to variants of H5N1 and therefore protect the vaccinated population in a influenza pandemic.

One study demonstrated that GSK's proprietary adjuvanted candidate prepandemic vaccine, containing very low levels of the Vietnam H5N1 antigen, elicits a strong cross-immune neutralizing antibody response in humans against the Indonesian strain of the virus. The neutralizing antibody seroconversion factor at day 42 was shown to be 25 times greater when the vaccine contained the adjuvant system compared with that observed in the control group immunized with a non-adjuvanted vaccine.

The second study showed that the vaccine could protect against two diverse H5N1 flu strains, again at very low levels of antigen. The in vivo data from the preclinical studies demonstrated that GSK's adjuvanted vaccine, containing the Vietnam H5N1 strain, was not only able to protect against a challenge with the vaccine virus strain, but it also provides 96 percent cross-protection against a lethal challenge with the drifted Indonesia strain.

"The data confirm that our pre-pandemic influenza vaccine has the ability to recognize and kill an H5N1 strain that is different to the one contained in the vaccine," Jean Stéphenne, president of GSK Biologicals, said. "This means that proactive administration of our prepandemic vaccine before or just after the start of the pandemic could help to substantially slow down the spread of disease."

Earlier this year GSK announced the application for its H5N1 split-antigen prepandemic vaccine had been accepted for review by the European Medicines Agency.