HPV VACCINE UPDATES
New efficacy data and FDA submissions highlighted; Therapeutic vaccine trials Down Under
Interim data from a Phase III clinical trial with more than 18,000 women from around the world showed GlaxoSmithKline's (GSK) candidate HPV vaccine, Cervarix(r), was 100% effective in preventing significant cervical precancers (CIN 2 or higher) related to HPV types 16 and 18, and also offered partial protection against three other "high risk" HPV type infections individually, and all high risk type infections collectively.
HPV types 16/18, respectively, are found with about 70% of cervical cancers. Primary analysis of the interim data from this study found that Cervarix was 90% effective in blocking precancerous cervical lesions co-infected with HPV 16/18. However, most of the lesions also unexpectedly contained other "high risk" HPV types, leading the investigators to conduct another analysis to determine which HPV types actually caused the lesions.
With this additional analysis, which involved confirming presence of the virus both in the lesions and in previous Pap test samples (i.e. determining persistent infection history), the vaccine proved 100% effective in preventing HPV16/18 related cervical precancers.
The study, which was published in the June 30th issue of The Lancet (Paavonen et al. 369:2161-2170), also contained data that indicate the vaccine offers cross-protection at 38% efficacy against persistent infections lasting twelve months caused by all high-risk HPV types collectively.
GSK submitted Cervarix for review to the U.S. Food and Drug Administration in the spring, with a decision (approval is expected) likely to come in early 2008. In May, regulators in Australia approved the vaccine for the prevention of cervical pre-cancers and cancers in women ages 10-45 years; In July, the regulators in the EU have also have provided a positive recommendation for approval in women ages 10-45 years. Studies suggest the vaccine may be effective in older women: Data presented at the 2007 American Society of Clinical Oncologists Annual Meeting in June indicate Cervarix induces a strong immune response in women up to age 55 (Schwarz et al., Journal of Clinical Oncology, 2007 ASCO Annual Meeting Proceedings Part 1. 25:18S).
Another HPV/cervical cancer vaccine, Merck's Gardsil(r), was approved in the U.S. in 2006. Merck recently submitted a supplemental application to the FDA to expand the labeling for Gardasil(r) to include the prevention of vaginal and vulvar cancers. The vaccine is currently approved for the prevention of cervical cancers and precancers, in addition to vulvar and vaginal pre-cancers, related to two "high risk" HPV types (HPV 16 and 18). Gardasil is also licensed for the prevention of genital warts associated with "low risk" HPV types 6 and 11. In clinical trials, Gardasil prevented virtually all persistent infections and diseases related to the four HPV types covered by the vaccine.
Early Trials Show Therapeutic HPV Vaccine is Safe
An experimental HPV vaccine designed to treat genital warts has shown to be safe midway through clinical trials in Australia, according to the trial manager.
The vaccine, currently being studied by researchers at Queensland University in Brisbane, utilizes technology similar to that found in prophylactic HPV vaccines that seek to protect against HPV infection by stimulating an immune response against to virus much higher that what occurs as the result of natural infection. The Australian vaccine is therapeutic, however, in that it's designed to treat existing cases of external genital warts rather than protect against new HPV infections. Pilot studies done by QU's research partner, Wenzhou Medical College in China, showed the vaccine has potential in treating genital warts in humans.
A press release on QU's site says more than 200 subjects have participated in trials for the vaccine. Trial manager Dr. David Jardine told HPV News "The primary aim of this phase 1B trial are safety and tolerability, which has been shown to date in the trial with no serious adverse events reported in Australia or China at the halfway mark." Dr. Jardine says the trial is slated to continue through April 2008, with investigators now focusing on the effectiveness of the vaccine.
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