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发表于 2002-8-8 03:10
也有美国人写文责骂Gilead公司(不要脸的Gilead)主要是Gilead的tenofovir和adefovir相似同样可以治疗HBV, 但是他们想出两个药. 作者也提出了几个关于adefovir的问题;
明天FDA将举行听政会听取其它乙肝药物的临床试药问题和未来乙肝治疗的动向.
adefovir可能不日通过.
Shame on Gilead Date: Wed, 7 Aug 2002 00:12:56 EDT
On August 6, Gilead Sciences got what it desperately wanted: approval by the FDA Advisory Committee to recycle the failed HIV drug, adefovir, for the
treatment of chronic hepatitis B in adults -- and hopefully a boost to its
flagging stock prices (Nasdaq: GILD).
While the FDA Advisory Committee unanimously voted in favorof approving
adefovir, the majority of Committee members did so with clearly articulated
skepticism and a several critical caveats:
-- Data that showed adefovir's capacity to reduce hepatitisB virus (HBV) is
limited, that is, the data only showed effectiveness for 48 weeks, not more.
-- Kidney toxicities directly related to adefovir beyond 48 weeks also could
not be ruled out. (Previously, adefovir has shown in HIV clinical trials to
cause kidney damage in up to one-third of patients. Hence, the adefovir was ruled unsafe by the FDA at higher doses used for HIV because of kidney damage.)
-- Treatment duration is unknown and therefore kidney damage, prompted by
long-term use of the drug for HBV, is also unknown.
-- Risk of potentially fatal liver "flares" upon cessation of the drug is
high.
-- Special caution should be paid to HIV/HBV co-infected patients, especially
with regard to simultaneous use with Gilead's HIV drug, tenofovir.
Gilead researchers presented data (studies 437 and 438) that showed treatment cessation of adefovir caused liver enzymes (ALT) to flare to 10 times the upper limit of normal. When patients in those studies took adefovir for one year, then stopped, one in four experienced ALT elevations to greater than ten times normal.
While this "liver flare" complication can ocur with cessation of other
anti-HBV drugs, given adefovir's potential for kidney damage over time, this
risk seems especially ominous for patients who must choose between potential
liver damage or potential kidney damage.
Gilead researchers also noted that adefovir has not been studied in HIV/HBV co-infected patients using -- or who have used -- the anti-HIV drug tenofovir also known as Viread. Although Gilead asked the FDA for approval in HIV/HBV co-infected patients, the company had not studied adefovir in patients concurrently taking tenofovir (Study 460i).
The reason for this, according to Gilead's Vice President ofClinical Research
Carol Brosgart, MD, was because enofovir has similar activity to adefovir?
When pressed to respond to the issue of tenofovir鈥檚 anti-HBV activity,
Brosgart admitted that independent studies have shown that the anti-HBV
activity of tenofovir and adefovir are nearly identical. However, she stated
that "Gilead has no plans to develop tenofovir for HBV."
Recently published reports have confirmed that tenofovir has at least equal, if not better, activity against HBV.
Ironically, last year the FDA concluded that tenofovir was safe and effective against HIV.
Given tenofovir's clean bill of health for safety by the FDA -- and
accumulating evidence of tenofovir's anti-HBV activity -- it would seem
ethically responsible that Gilead would pursue tenofovir for HBV. This is not
the case.
Gilead held steadfast to its decision not to pursue tenofovir for HBV
treatment. Instead, it has chosen to market adefovir, a drug that has proven toxic to kidneys at higher doses.
While the Advisory Committee decision is not binding, the FDA generally
rules in favor of the Committee. A final decision by the FDA is expected
soon.
On August 7, the FDA will hold public hearings about future clinical trial
designs for the treatment of HBV.
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