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.
Click here to read the Queensland press release
|