乙肝新藥：TAF(替諾福韋艾拉酚胺)相比TDF(替諾福韋)更強
終于批準了， Gilead 一年前就放出了風聲，這個藥物的臨床效果不錯， 雖然不及治療丙肝的Harvoni 那么革命行的效果， 但對于乙肝患者而言這也是的突破了。 11月10號，Gilead Sciences公司宣布，美國FDA已經批準其新藥產品Vemlidy(tenofovir alafenamide，TAF)25mg，每日一次治療伴有代償性肝病的慢性乙型肝炎病毒(HBV)感染。
Vemlidy是一種創(chuàng)新型、靶向性、tenofovir前藥，與Gilead的先前產品 300mg的Viread (tenofovir disoproxil fumarate, TDF)相比， 只需要少于十分之一的劑量就可達到類同的抗病毒功效。
臨床數(shù)據顯示，與Viread相比，Vemlidy具有更大的血漿穩(wěn)定性而且可更有效地將tenofovir遞送到肝細胞，所以可以使用更低的給藥劑量，導致血液中富含更少的tenofovir。因為上述原因，與Viread相比，Vemlidy有效改善了針對腎臟和骨骼的安全性參數(shù)。
TDF與TAF分子式對比，左為TDF，右為TAF，來自網絡
Vemlidy在兩個國際型3期臨床試驗(研究108和研究110)試驗中，獲得了長達48周的數(shù)據支持。共有1298名初治和有過治療的慢性HBV感染成人患者參與臨床試驗。研究108使用Vemlidy或Viread隨機化治療了425例HBeAg陰性患者，研究110使用Vemlidy或Viread隨機化治療了873名HBeAg陽性患者。
兩個研究都達到了它們的主要臨床研究終點：在治療第48周時，基于血漿HBV DNA水平低于29 IU/mL的慢性乙型肝炎患者的百分比這一指標中，Vemlidy顯示出了相對Viread的非劣效性。
另外，Vemlidy和Viread在兩項研究中患者的耐受性均表現(xiàn)良好，由于不良反應而中止治療的分別為1.0%和1.2%。兩個研究中常見的不良反應主要包括頭痛，腹痛，疲勞，咳嗽，惡心和背痛，并且不良反應的發(fā)生率在接受Vemlidy或Viread治療的患者基本相同。
Gilead Sciences公司總裁兼席執(zhí)行官 John Milligan 博士說：“自20世紀90年代中期以來，吉利德一直致力于改善和簡化慢性乙型肝炎患者的治療。Vemlidy是在近十年內被批準用于治療這種疾病(慢乙肝)的第一個藥物，我們很高興能提供一個新的有效的治療選擇，以幫助促進患者的長期健康護理?！?
不過值得注意的是Vemlidy在其產品標簽中有一個黑框警告，提醒注意治療后嚴重急性加重性乙肝，伴有脂肪變性的嚴重肝腫大，以及乳酸性酸中毒風險。
參考英文原文
《U.S. Food and Drug Administration Approves Gilead’s Vemlidy? (Tenofovir Alafenamide) for the Treatment of Chronic Hepatitis B Virus Infection》
Gilead Sciences, whose hepatitis C dynasty has been slipping, has won approval for its next-gen hepatitis B treatment.
The Foster City, CA-based drugmaker said Thursday that the FDA had approved Vemlidy, a once-daily treatment for adults with chronic hepatitis B virus (HBV) with compensated liver disease. The drug, however, comes with a black-box warning for risks.
Gilead ($GILD) already has a hep B treatment, Viread, but said today that the new drug can be given at one-tenth the dose of Viread and so has better renal and bone laboratory safety parameters than its predecessor.
Dr. Calvin Pan, a clinical professor of medicine at NYU Langone Medical Center and an investigator in the Vemlidy clinical trials, said the improved renal and bone safety parameters were an important development for the 2.2 million people in the U.S. suffering from the life-threatening disease.
approval comes at a time when Gilead’s one-time powerhouse hep C treatments Sovaldi and Harvoni have fallen victim to competition and payer discounting, with sales plummeting 31% for the last quarter. The results missed consensus estimates by 3%, even with help from the recent rollout of Epclusa, a regimen that spans all hep C genotypes.
Investors are still looking for Gilead to buy something significant that can pull it out of the dive, as it did when it acquired the asset that turned into Sovaldi and Harvoni. It was rumored to be looking at cancer biotech Medivation, but blocked folks from the deal with a $14 billion bid.
CEO John Milligan told investors that the company is “currently very, very active” in looking for M&A deals but will only “do things when they make sense for us and not before then.”
Editor's Note: The story was updated with information about the EU's CHMP recommending Vemlidy.
