乙肝新药：TAF(替诺福韦艾拉酚胺)相比TDF(替诺福韦)更强

终于批准了， Gilead 一年前就放出了风声，这个药物的临床效果不错， 虽然不及治疗丙肝的Harvoni 那么革命行的效果， 但对于乙肝患者而言这也是的突破了。 11月10号，Gilead Sciences公司宣布，美国FDA已经批准其新药产品Vemlidy(tenofovir alafenamide，TAF)25mg，每日一次治疗伴有代偿性肝病的慢性乙型肝炎病毒(HBV)感染。

Vemlidy是一种创新型、靶向性、tenofovir前药，与Gilead的先前产品 300mg的Viread (tenofovir disoproxil fumarate, TDF)相比， 只需要少于十分之一的剂量就可达到类同的抗病毒功效。

临床数据显示，与Viread相比，Vemlidy具有更大的血浆稳定性而且可更有效地将tenofovir递送到肝细胞，所以可以使用更低的给药剂量，导致血液中富含更少的tenofovir。因为上述原因，与Viread相比，Vemlidy有效改善了针对肾脏和骨骼的安全性参数。

TDF与TAF分子式对比，左为TDF，右为TAF，来自网络

Vemlidy在两个国际型3期临床试验(研究108和研究110)试验中，获得了长达48周的数据支持。共有1298名初治和有过治疗的慢性HBV感染成人患者参与临床试验。研究108使用Vemlidy或Viread随机化治疗了425例HBeAg阴性患者，研究110使用Vemlidy或Viread随机化治疗了873名HBeAg阳性患者。

两个研究都达到了它们的主要临床研究终点：在治疗第48周时，基于血浆HBV DNA水平低于29 IU/mL的慢性乙型肝炎患者的百分比这一指标中，Vemlidy显示出了相对Viread的非劣效性。

另外，Vemlidy和Viread在两项研究中患者的耐受性均表现良好，由于不良反应而中止治疗的分别为1.0%和1.2%。两个研究中常见的不良反应主要包括头痛，腹痛，疲劳，咳嗽，恶心和背痛，并且不良反应的发生率在接受Vemlidy或Viread治疗的患者基本相同。

Gilead Sciences公司总裁兼席执行官 John Milligan 博士说：“自20世纪90年代中期以来，吉利德一直致力于改善和简化慢性乙型肝炎患者的治疗。Vemlidy是在近十年内被批准用于治疗这种疾病(慢乙肝)的第一个药物，我们很高兴能提供一个新的有效的治疗选择，以帮助促进患者的长期健康护理。”

不过值得注意的是Vemlidy在其产品标签中有一个黑框警告，提醒注意治疗后严重急性加重性乙肝，伴有脂肪变性的严重肝肿大，以及乳酸性酸中毒风险。

参考英文原文

《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.