2012年12月14日美国食品药品监督管理局(FDA)批准raxibacumab注射液治疗吸入性炭疽，一种通过呼吸细菌炭疽芽孢杆菌[bacterium Bacillus anthracis]的孢子所致的一种传染病形式。Raxibacumab还被批准预防吸入性炭疽当另外治疗不能得到或不适当时。
Raxibacumab是一种单克隆抗体中和炭疽芽孢杆菌产生的毒素，该毒素可致大量和不可逆的组织损伤和死亡。
一个单克隆抗体是一种蛋白类似于人抗体，鉴定和中和外来物质像细菌和病毒。炭疽是一种潜在的生物恐怖主义威胁因为孢子对破坏有抗力而且通过释放在空气中容易播散。
FDA批准raxibacumab快车道指定，优先审评，和孤儿产品指定。药物被证实潜在满足紧急医学需求，在没有另外满意治疗存在的领域，分别有提供安全和有效治疗的潜能，和意向治疗一种罕见病。
Raxibacumab是第一个在FDA的动物疗效规则[Animal Efficacy Rule]下被批准的单克隆抗体，这个规则当在人中进行试验不可行或伦理上时允许从适当和对照良好的动物研究的疗效发现支持FDA批准。在这个情中，因为吸入性炭疽是一种罕见和致命性疾病，不可能在人中进行适当疗效试验。
美国FDA药物评价和研究中心抗微生物产品室主任Edward Cox，M.D.，M.P.H说：“炭疽生物恐怖事件发生除了抗菌素 ，将得到 raxibacumab有用治疗，”“尽管抗菌素被批准预防和治疗炭疽感染，raxibacumab是第一个通过中和被细菌炭疽芽孢杆菌产生毒素的被批准药物。
在一项猴研究和三项兔中研究证实Raxibacumab对吸入性炭疽的有效性。所有动物被给予雾化炭疽芽孢杆菌孢子，而在研究结束时通过存活确定疗效。动物结束不同剂量raxibacumab，安慰剂或通常使用治疗炭疽抗菌素。
与用安慰剂治疗动物比较用raxibacumab治疗动物活存更多。在猴研究中64%动物和在一项兔研究44 %动物接受40 mg/kg的暴露于炭疽生存，与之比较安慰剂组无生存。所有生存动物发生毒素中和抗体。在兔中另外研究显示82 %用抗菌素和raxibacumab治疗暴露于炭疽动物生存与之比较单独接受抗菌素治疗为65 %生存。
在326例健康人志愿者中评价raxibacumab的安全性。常见副作用包括皮疹，肢体痛，瘙痒和睡意。
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批准日期：2012年12月14日；公司：Human Genome Sciences，Inc

RAXIBACUMAB注射剂，为静脉使用

Initial U.S. Approval：2012

一般描述
Raxibacumab是一种人IgG1λ单克隆抗体结合炭疽芽孢杆菌毒素的保护性抗原(PA)组分。Raxibacumab的分子量约146道尔顿。Raxibacumab是通过重组DNA技术在一种鼠类细胞表达系统中生产。

作用机制
Raxibacumab是一种单克隆抗体结合炭疽芽孢杆菌的保护性抗原(PA)。[见临床药理学 (12.4)]
适应证和用途
Raxibacumab适用于与适宜抗菌药物联用为治疗由于炭疽芽孢杆菌[Bacillus anthracis]有吸入性炭疽热的成年和儿童患者。和为预防吸入性炭疽热当不能得到另外治疗或不适宜时。(1)
使用限制：
（1）Raxibacumab的有效性是仅仅基于吸入性炭疽热的动物模型疗效研究。(1.2，14.1)
（2）在儿童人群中没有raxibacumab研究。儿童患者给药是来自群体药代动力学方法。 (1.2，8.4)
（3）Raxibacumab不能跨越血脑屏障和不能预防或治疗脑膜炎。Raxibacumab应与适宜抗菌药物联用。(1.2)
剂量和给药方法
（1）用苯海拉明[diphenhydramine]预防给药。 (5.1)
（2）稀释和历时2小时和15分钟静脉输注给药。(2.2)
− 成年：40 mg/kg raxibacumab. (2.1)
−大于50 kg儿童：40 mg/kg raxibacumab. (2.2)
−大于15 kg至50 kg儿童：60 mg/kg raxibacumab. (2.2)
− 15 kg或较小儿童：80 mg/kg raxibacumab. (2.2)
剂型和规格
单次使用小瓶含1700 mg/34 mL (50 mg/mL) raxibacumab溶液. (3)
禁忌证
无。 (4)
警告和注意事项
可能发生输注反应。用苯海拉明预先给药。根据反应的严重程度缓慢或中断输注和给药治疗。(5.1)
不良反应
在健康成年志愿者中常见不良反应(≥1.5%)是：皮疹，四肢疼痛，瘙痒，和睡意。 (6.1)
为报告怀疑不良反应，联系GlaxoSmithKline电话1-888-825-5249或FDA电话1-800-FDA-1088或www.fda.gov/medwatch.

特殊人群中使用
（1）哺乳母亲：当给予哺乳母亲时应谨慎对待。(8.3)
（2）儿童使用：尚未研究在<16岁儿童中的安全性和有效性。(8.4)

HUMAN GENOME SCIENCES BEGINS DELIVERY OF FIRST-IN-CLASS ANTHRAX TREATMENT TO U.S. STRATEGIC NATIONAL STOCKPILE

ABthrax™ (raxibacumab) to the U.S. Strategic National Stockpile for use in the treatment of inhalation anthrax. 
ABthrax is a first-in-class treatment for anthrax, and the first procurement under Project BioShield of a product discovered and developed after the September 11, 2001 terrorist attacks.  It specifically targets the deadly toxins released within the human body by Bacillus anthracis that are the real culprits in anthrax-related deaths.  ABthrax is being developed under a contract entered into in 2006 with the Biomedical Advanced Research and Development Authority (BARDA) of the Office of the Assistant Secretary for Preparedness and Response (ASPR), U.S. Department of Health and Human Services (HHS). 
“We believe ABthrax offers a significant step forward in the treatment of inhalation anthrax and could play an important role in strengthening America’s arsenal against bioterrorism,” said H. Thomas Watkins, President and Chief Executive Officer, HGS.  “From a business perspective, this announcement is strategically important for HGS, because it marks our Company’s first product sales.  We expect to receive $150 million in revenue soon after completion of our delivery to the Strategic National Stockpile.  We are pleased with the progress of our partnership with the U.S. Government, which has resulted in this important milestone, and we are hopeful that fulfillment of this initial order will result in a long-term relationship involving additional deliveries of ABthrax to the Stockpile.”
ABthrax represents a new way to address the anthrax threat. While antibiotics can kill the anthrax bacteria, they are not effective against the deadly toxins that the bacteria produce.  ABthrax targets anthrax toxins after they are released by the bacteria into the blood and tissues. In an inhalation anthrax attack, people may not know they are infected with anthrax until the toxins already are circulating in their blood, and it may be too late for antibiotics alone to be effective.
“We are delighted to have fulfilled this important milestone under our contract with the U.S. Government and we hope we are making a significant contribution to our nation’s security,” said James H. Davis, Ph.D., J.D., Executive Vice President and General Counsel, HGS, and leader of the Company’s ABthrax program with the U.S. Government. “We are particularly pleased with the relationship we have had with BARDA in the development of ABthrax, and we look forward to continuing to work together.”
About Research Findings to Date
In December 2007, HGS announced that the results of two animal studies demonstrated the life-saving potential of ABthrax (raxibacumab).  The results showed that a single dose of raxibacumab, administered without concomitant antibiotics, improved survival rates by up to 64 percent when administered after animals were symptomatic for anthrax disease as a result of inhalation exposure to massively lethal doses of anthrax spores.  These dramatic and statistically significant findings demonstrated a survival benefit in two animal species, which is the requirement for establishing the efficacy of new drugs used to counter bioterrorism.  These data are consistent with the results of previous studies in multiple animal models, which demonstrated that a single dose of raxibacumab given prophylactically provided up to 100% protection against death.
HGS has also completed safety studies of raxibacumab in more than 400 human volunteers.  The clinical results to date suggest that raxibacumab was generally safe and well tolerated.  In addition, clinical data have demonstrated that co-administration of raxibacumab with the antibiotic Cipro (ciprofloxacin) did not affect the pharmacokinetics of either Cipro or raxibacumab, and suggested that raxibacumab can be administered in combination with antibiotics.  This is a key finding given the important role that antibiotics are expected to continue to play in the treatment of anthrax disease.
The Need for New Means to Fight Anthrax Infections
Two options have been available for the prevention or treatment of anthrax infections – a vaccine and antibiotics.  Both are essential to dealing with anthrax, but both have limitations.  The anthrax vaccine takes several weeks following the initial doses before immunity is detectable, and requires multiple injections over a period of eighteen months, in addition to annual booster vaccination, to maintain protective immunity.  Antibiotics are effective in killing anthrax bacteria, but are not effective against the anthrax toxins once those toxins have been released into the blood.  Antibiotics also may not be effective against antibiotic-resistant strains of anthrax.
ABthrax is a human monoclonal antibody to Bacillus anthracis protective antigen that was discovered and developed by HGS, using technology that HGS has integrated into the Company as part of its collaboration with Cambridge Antibody Technology.  Research has shown that protective antigen is the key facilitator in the progression of anthrax infection at the cellular level.  After protective antigen and the anthrax toxins are produced by the bacteria, protective antigen binds to the anthrax toxin receptor on cell surfaces and forms a protein-receptor complex that makes it possible for the anthrax toxins to enter the cells.  ABthrax blocks the binding of protective antigen to cell surfaces and prevents the anthrax toxins from entering and killing the cells. 
In contrast to the anthrax vaccine, the protection afforded by a single dose of ABthrax would be immediate following the rapid achievement of appropriate blood levels of ABthrax.  In contrast to antibiotics, ABthrax acts against the deadly toxins produced by anthrax bacteria.  It may also prevent and treat infections by antibiotic-resistant strains of anthrax.  ABthrax was the first investigational agent against anthrax infection to be evaluated in a clinical study following the 2001 anthrax attacks in the United States.  In 2003, ABthrax received a Fast Track Product designation from the FDA, as well as an Orphan Drug Designation for its use in the treatment of inhalation anthrax disease.
About the ABthrax Contract with the U.S. Government
In June 2006, the U.S. Government exercised its option to purchase ABthrax for the Strategic National Stockpile (Contract Number HHS010020050006C). HGS expects to receive $165 million in revenues from this award, with $150 million to come in the first half of 2009, following delivery of 20,000 doses of ABthrax, and the remainder to come upon FDA licensure of ABthrax.  The purchase award was made by the HHS under the Project BioShield Act of 2004, which is designed to accelerate the development, purchase and availability of medical countermeasures for the Strategic National Stockpile.  Under the contract, HGS has manufactured and is now delivering 20,000 treatment courses of ABthrax to the Stockpile.  Also under the contract, the Company plans to file a Biologics License Application (BLA) with the FDA in the second quarter of 2009.  HGS will receive an additional $15 million from the U.S. Government upon FDA licensure of ABthrax.  
About Human Genome Sciences
The mission of HGS is to apply great science and great medicine to bring innovative drugs to patients with unmet medical needs. The HGS clinical development pipeline includes novel drugs to treat hepatitis C, lupus, inhalation anthrax and cancer. The Company’s primary focus is rapid progress toward the commercialization of its two key lead drugs, Albuferon® (albinterferon alfa-2b) for hepatitis C and LymphoStat-B® (belimumab) for lupus. Phase 3 clinical trials of both drugs are ongoing.  ABthrax™ (raxibacumab) is in late-stage development for inhalation anthrax, and HGS also has three drugs in clinical development for the treatment of cancer, including two TRAIL receptor antibodies and a small-molecule antagonist of IAP (inhibitor of apoptosis) proteins. In addition, HGS has substantial financial rights to certain products in the GSK clinical pipeline including darapladib, which GSK has advanced to Phase 3 development as a potential treatment for coronary heart disease.
For more information about HGS, please visit the Company’s web site at www.hgsi.com. Health professionals and patients interested in clinical trials of HGS products may inquire via e-mail to clinical_trials@hgsi.com or by calling HGS at (301) 610-5790, extension 3550.
HGS, Human Genome Sciences, ABthrax, Albuferon and LymphoStat-B are trademarks of Human Genome Sciences, Inc.