Adjuvant debuts in new hep B vaccine

Adjuvants are formulated compounds or additives that, when combined with vaccine antigens, help to either direct or boost the body's immune system. The new adjuvant, developed by US company Corixa, is called MPL and is a constituent of GlaxoSmithKline Biologicals' Fendrix, approved yesterday for the treatment of patients at particularly high risk of developing HBV, such as those receiving dialysis for kidney failure.

Dialysis patients' immune response is typically lower than in healthy individuals, so there is a need for a vaccine with an improved immunogenicity profile to ensure that patients are protected against HBV infections. Clinical studies have shown that Fendrix provides a higher, more rapid and longer-lasting antibody response to HBV compared to older vaccines.

The new product is a follow-up to GSK Bio's Engerix-B hepatitis B vaccine that, along with other hepatitis vaccines in GSK's portfolio - Havrix for hepatitis A and TwinRix to protect against both hepatitis A and B - achieved sales of £102 million (€149m) in the first nine months of 2004.

Engerix-B has been on the market for 15 years and has already been administered to over a billion people. To cater for high-risk groups which do not get a good response from this vaccine, GSK elected to develop a new version, using the same HBV antigen but also AS04, a proprietary adjuvant based on Corixa's MPL. The resulting vaccine - Fendrix - has an increased immune potency, allowing two dose administration rather than three.

MPL is a derivative of the lipid A molecule found in Gram-negative bacteria, and is one of the most potent regulators of the immune response, used by the body to alert itself to bacterial infections. It has been shown clinically to be more effective than alum, the most widely used adjuvant in vaccines, in generating antibody responses. Corixa has developed a proprietary technology for extracting it from bacterial cell walls.

The adjuvant is also being used in a number of GSK's developmental vaccines, including one that could be the first effective vaccine for malaria, according to clinical studies reported last year.

It is also a component of GSK Bio's genital herpes vaccine, which showed 100 per cent efficacy against genital herpes in women in a Phase III trial published in 2002. Other adjuvanted vaccines in GSK Bio's pipeline include a vaccine for the prevention of cervical cancer and a vaccine in Phase I clinical trials against tuberculosis.

GSK is Corixa's primary partner for the MPL adjuvant, and the two firms have a manufacturing and supply agreement, running to the end of 2012, that grants GSK access to the current maximum output of Corixa's MPL manufacturing facility (approximately 2 kilograms a year).

CFCs replaced in US​

Meanwhile, GSK has become the first company to completely switch over its entire metered dose inhaler portfolio away from ozone-depleting chlorofluorocarbon (CFC) propellants to the newer, more environmentally friendly hydrofluoroalkanes (HFAs). Flovent (fluticasone propionate) is the last of GSK's asthma and chronic obstructive pulmonary disease (COPD) products to make the transfer.

In Europe 75 per cent of CFCs used in metered dose inhalers have been phased out, but the US is lagging behind. At present, the federal government has only signalled an intention to phase out around half of its CFC usage by 2006/7.