2014年12月10日讯 /生物谷BIOON/ --Bluebird公司最近透露，公司开发的用于治疗一种罕见遗传性血液疾病--重型β-地中海贫血症--的药物LentiGlobin BB305临床研究进展顺利。
重型β-地中海贫血症是一种由于β-球蛋白基因缺陷，导致患者机体无法产生足够的血红蛋白而出现的疾病。这种疾病的临床症状包括严重贫血和脾增大等。
LentiGlobin BB305利用经过修饰的慢病毒向患者体内输送正常基因片段，通过重组，能够使患者正常表达该基因产物。在今年的美国血液学会年会上，公司报告了使用其疗法的四名患者的状况，数据显示，在接受治疗后长达三个月的时间内，这些患者的病情都得到了明显的改善。而随后，Bluebird公司又公布了关于LentiGlobin BB305的另一项临床前期研究，在这一研究中，使用了这种药物的两名患者体内产生的β-球蛋白水平明显提升，且药物的时效分别达到了5个月和3个月。同时这些患者中并未观察到有明显副作用。这一消息无疑激励了投资者的热情，促使公司股价大涨。
不同于其他的基因疗法，LentiGlobin BB305并未直接将基因插入到患者细胞内，而是通过先分离患者的一部分造血干细胞，将正常β-球蛋白替换到这些细胞中，从而达到治疗效果。这样一方面便于研究人员控制基因的输送，另一方面也能明显降低这一药物潜在的副作用。根据BlueBird公司估计，全世界每年会有4万名新生儿患有这种罕见病。
罕见病是指那些发病率极低的疾病。罕见疾病又称"孤儿病"，在中国没有明确的定义。不过根据世界卫生组织（WHO）的定义，罕见病为患病人数占总人口的0.65‰～1‰的疾病。世界各国根据自己国家的具体情况，对罕见病的认定标准存在一定的差异。例如，美国将罕见病定义为每年患病人数少于20万人（或发病人口比例小于1/1500）的疾病。正是因为罕见病的患病人数过少，因此在早先许多生物医药厂家并未对这一领域进行过多关注.不过,随着FDA颁布了一系列罕见病研发的优惠政策后，也吸引了许多生物医药公司投入其中。如今，几乎所有的国际生物医药巨头，都在这一市场中有着自己的产品.
详细英文报道：
Bluebird bio's experimental therapy for the genetic blood disorder beta-thalassemia major is working just as the biotech ($BLUE) planned, using a single dose to wean two more patients off of the chronic transfusions required to treat the disease.
The disorder results from a defective beta-globin gene that stops patients from producing the hemoglobin they need, often resulting in symptoms like severe anemia and an enlarged spleen. Bluebird's treatment, LentiGlobin BB305, uses a modified lentivirus to deliver a corrective copy of the gene through a one-time infusion, ideally getting beta-thalassemia major patients back to manufacturing beta-globin on their own.
And, so far, LentiGlobin BB305 is doing exactly that. In preliminary results presented at the annual the American Society of Hematology meeting, the first four patients treated with bluebird's therapy remain transfusion-free after at least three months follow up, affirming the treatment's promise as a functional cure for the disease. That adds two more transfusion-free patients to the two bluebird disclosed over the summer, news that sent its shares up more than 50% in June. Bluebird's latest update boosted its stock price as much as 40% after hours on Monday.
The new data come from two ongoing studies of LentiGlobin BB305. In the latest, bluebird has dosed 5 patients with beta-thalassemia major, finding that the first two are producing increasing amounts of beta-globin and have been transfusion-free for 5 and 3 months, respectively. The remaining three subjects need more time before bluebird can draw any conclusions on efficacy, the company said.
In the second study, involving two beta-thalassemia major patients and one with severe sickle cell disease, the two previously discussed subjects are still churning out beta-globin and remain free of the need for transfusions for 12 and 9 months, respectively. As for the sickle cell patient, bluebird said it's still too early to make efficacy inferences.
LentiGlobin BB305 has so far been well tolerated across both studies, the company said, with no gene therapy-related serious adverse events observed.
Now bluebird, a 2012 Fierce 15 honoree, is working to complete enrollment in both studies next year, targeting 22 patients in total. As the data on LentiGlobin BB305 mature, the biotech plans to start working with experts, patient groups and authorities to map out a regulatory plan for the treatment, Chief Medical Officer Dr. David Davidson said.
LentiGlobin BB305 differs from many of the other gene therapies in development around the world, which involve inserting corrective genes directly into a patient. Instead, bluebird's method works by removing a patient's hematopoietic stem cells, equipping them with a functional beta-globin gene and then reinserting them through infusion.
About 40,000 children are born with beta-thalassemia around the world each year, according to bluebird.