London and San Diego, September 27, 2002 - According to study data presented at the 42nd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), once-daily suppressive therapy with VALTREX® (valaciclovir) tablets, manufactured by GlaxoSmithKline (GSK), reduced transmission of symptomatic genital herpes (a visible outbreak) by 77 percent in healthy heterosexual monogamous couples. In addition, suppressive therapy with VALTREX reduced the overall acquisition of the virus (determined by a positive blood test and/or laboratory confirmation) by 50 percent. Throughout the study, all couples were provided with condoms and counselled on safer sexual behaviour at all study visits.

"This study now shows that once-daily suppressive therapy may help individuals with genital herpes protect their partner." said study investigator, Dr Raj Patel, consultant genito-urinary physician at the Southampton University Hospital in the UK.

Experts estimate that genital herpes, which is a contagious, lifelong infection, affects in the range of four to 40% of adults in European countries.¹ However, nine out of ten of those are unaware they have genital herpes and may only have experienced a mild initial outbreak without recognising recurring symptoms of the disease. Though the disease is most contagious during an outbreak, symptoms do not have to be present to infect someone else. In fact, experts confirm most transmission of genital herpes occurs without symptoms being present, known as asymptomatic viral shedding, and when the infected person is unaware of being infectious.

"GlaxoSmithKline is committed to research into the prevention and treatment of genital herpes. GSK supports the CDC recommendations for safer sex practices, including the use of condoms. We are excited by the results of this important study with VALTREX. While VALTREX is not approved for reduction of transmission of genital herpes, we are currently evaluating our options," said Clarence Young, MD, Vice President, Clinical Development and Medical Affairs, GlaxoSmithKline.

ABOUT THE STUDY
This study compared VALTREX and placebo for the reduction of risk of transmission of genital herpes, herpes simplex virus type 2 (HSV-2), in heterosexual monogamous couples discordant for the presence of HSV-2 antibody - one partner had genital herpes (source partner) and the other did not (susceptible partner). A total of 1,484 couples (743 VALTREX, 741 placebo) were included in the intent-to-treat population. The HSV-2 seropositive source partner with a history of less than 10 episodes per year was randomised in a 1:1 ratio to receive VALTREX 500 mg once daily or placebo for eight months. The HSV-2 seronegative susceptible partner was monitored for clinical and subclinical (serological) acquisition of HSV-2 during the eight-month study period. Each endpoint was confirmed by an external Endpoint Committee before unblinding and required clinical signs/symptoms as well as laboratory confirmation of HSV-2 infection.

The susceptible partner was tested once a month and told to visit the clinic at the first sign of an outbreak. All couples were provided with condoms and counselled on safer sexual behaviour at all study visits.

The study showed that once-daily suppressive therapy with VALTREX reduced transmission of symptomatic genital herpes by 77 percent versus the placebo group in monogamous heterosexual couples. Seventeen subjects (2.3%) in the placebo group versus 4 subjects (0.5%) in the VALTREX group acquired symptomatic genital herpes. In addition, suppressive therapy reduced the overall acquisition of the virus, defined as symptomatic genital herpes and/or seroconversion, by 50 percent versus placebo. Twenty-eight subjects (3.8%) in the placebo group versus 14 subjects (1.9%) in the VALTREX group acquired HSV-2 infection. The most frequently reported adverse events were headache (VALTREX 29%, placebo 26%) and nasopharyngitis (VALTREX 16%, placebo 15%). The effect of VALTREX on transmission of genital herpes has not been studied among individuals with multiple partners, non-heterosexual couples, and couples not counseled on using safer sexual practices.

ABOUT GENITAL HERPES
Recent data from the Centers for Disease Control and Prevention (CDC) estimate more than one million new infections of HSV-2 occur yearly in the United States. While genital herpes is not a life-threatening disease, the virus never leaves the body, making it a lifelong condition that can recur at various times with or without symptoms. Symptoms of genital herpes may include a cluster of blisters, bumps or rashes in the genital area, or on the thighs or buttocks. To help prevent spreading the disease to others, sexual contact should be avoided during outbreaks and following safer sex practices, including the use of condoms, is recommended.

This study was sponsored by GlaxoSmithKline, maker of VALTREX® (valaciclovir) tablets.

GlaxoSmithKline is one of the world's leading research-based pharmaceutical and health care companies. GlaxoSmithKline is committed to improving the quality of human life by enabling people to do more, feel better and live longer.

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