总部位于加利福尼亚州帕萨迪纳市的生物技术公司Arrowhead最近宣布公司开发的用于治疗乙肝的RNAi药物ARC-520取得良好研究数据。该消息一经披露，公司股价应声上扬。ARC-520采用了Arrowhead公司独有的Dynamic Polyconjugates输送系统。其原理是通过RNA干扰封闭乙肝病毒某些蛋白的表达，造成病毒无法增殖，然后再利用机体的免疫系统对剩余病毒进行清除。
根据前期研究显示，这一技术在黑猩猩上的敲除效率达到log0.8，而此次临床二期研究证明，在人体中ARC-520的药效时间比在非人类灵长类动物中更持久，达到了8周左右。另一方面，研究结果显示，适用ARC-520治疗乙肝不会造成明显的副作用。药物使用剂量也是此次临床二期研究的重要部分，研究人员目前已经测试了1mg/kg和2mg/kg两种剂量，而3mg/kg剂量组的研究也正在进行中。
Arrowhead公司现有三种RNAi药物正处于研发过程，其中ARC-520是走的最远的一个项目。此外Arrowhead公司还有治疗癌症的小分子非RNA药物Cyclosert也正处于临床二期研究过程中。
详细英文报道：
Arrowhead Research reported Aug. 12 that patients in its Phase II clinical trial of the ARC-520 RNA interference candidate for hepatitis B had a "similar" knockdown to those reported in primate studies. The stock price bounced around a bit as investors considered the somewhat vague declaration, but fell at the very end of the trading day to close at $12.00 from an opening-day price of $13.00.
The knockdown (a metric measuring reduction of the virus in a patient's body) in chimpanzee studies was log 0.8; investors were expecting a reduction in the log 1.0 range, says TheStreet's Adam Feuerstein.
In addition, Arrowhead said that the duration of the knockdown was longer than in nonhuman primates and continued after 8 weeks, which is the most recent time point available. The company also said that the candidate appears safe and has not resulted in any serious adverse events so far. Dosing is also being considered in the trial. Dosing of 1 mg/kg and 2 mg/kg have been tested so far, and tests of the 3-mg/kg dose are under way, with the blessing of an institutional review board.
ARC-520 is designed to switch off production of hepatitis B genes using Arrowhead's Dynamic Polyconjugates delivery platform, with the hopes that the patient's immune system can fight off the remaining virus. It is the farthest along of the company's three RNAi candidates. The non-RNAi, anticancer small molecule Cyclosert is also in Phase II.
Arrowhead, based in Pasadena, CA, reported a net loss of $11.6 million in Q3 of fiscal year 2014 and cash on hand of $188.5 million, up from $29.8 million in September 2013.
The stock's volatility continues. Reflecting the uncertainty surrounding the still-unproven RNAi delivery technique, Arrowhead stock has risen about 50 cents to $12.50 in the first hour of today's market session on heavy trading.
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