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Alefacept,Amevive

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阿法赛特(人源L FA-3/IgG1融合蛋白)


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详细解释:

是和种治疗牛皮癣的新药。
“ 治牛皮癣新药『Amevive』获准美国食品及药物管理局FDA日前批准了又一种牛皮癣新药Amevive,属名为alefacept,用于治疗中度及严重噬斑型牛皮癣成人患者。

  Amevive的作用机制是减少与牛皮癣有关的免疫性反应,后者会增加皮肤感染甚至发生恶性病变的危险。FDA是根据最近完成的两项双盲随机临床治疗结果做出上述批准的。这两项研究总共涉及到1,060例慢性噬斑型牛皮癣成人患者,结果表明Amevive组患者的病变皮肤面积、病变程度以及与此有关的炎症反应都要比对照组得到更为显著的改善。可能发生的副作用包括咽喉痛、眩晕、咳嗽、恶心以及肌肉酸痛等。鉴于目前还不大清楚该药对妊娠的影响,有关专家建议孕妇应当与AME-VIVE药厂(Biogen公司)取得联系,以便后者监测可能对胎儿发生的任何副作用。此外专家们还提醒说,患者在接受 Amevive治疗期间还需要定期检查白细胞数。

Biogen公司的人源L FA-3/IgG1融合蛋白alefacept(AmeviveTM)能够与T-细胞结合,抑制T-细胞激活和产生,导致T-细胞选择性的凋亡,该药已经在美国和欧洲完成了治疗牛皮癣的III 期临床试验。1000名中重度牛皮癣患者参加的试验数据表明,在每周静脉注射该药后,71%的患者牛皮癣面积和严重程度得分(PASI)改善了50%以上,40%的患者PASI改善了75%以上。现在该药在美国和欧洲申请治疗中重度慢性噬斑性牛皮癣。

Drug Name: Amevive (alefacept)

The following information is obtained from various newswires, published medical journal articles, and medical conference presentations.

Company: Biogen
Approval Status: Approved January 2003
Treatment for: Psoriasis

General Information

Amevive (alefacept) is an immunosuppressive dimeric fusion protein that reduces lymphocyte counts (T-cells) thus treating the cause of psoriasis. It is indicated in patients with moderate to severe chronic plaque psoriasis who are candidates for systemic therapy or phototherapy

Amevive is available in either intramuscular injection (15-mg alefacept) or intravenous injection (7.5-mg alefacept) formulations.

Amevive reduces immune cell counts which could increase the chance of developing infection or malignancy.

Clinical Results

Amevive was evaluated in two randomized, double blind, placebo-controlled studies in 726 adult subjects with chronic plaque psoriasis. In both trials, Amevive or placebo was administered once a week for 12 weeks. In total 77% of subjects had previously received systemic therapy and/or phototherapy for psoriasis.

Response to treatment in both studies was defined as the proportion of subjects with a reduction in score on the Psoriasis Area and Severity Index (PASI)?of at least 75% from baseline at two weeks following the 12-week treatment period. Other treatment responses included the proportion of subjects who achieved a scoring of 'almost clear' or 'clear' by Physician Global Assessment (PGA) and the proportion of subjects with a reduction in PASI of at least 50% from baseline two weeks after the 12-week treatment period.

In both studies, onset of response to Amevive treatment (at least a 50% reduction of baseline PASI) began 60 days after the start of therapy. In Study 1, the median duration of response (75% or greater reduction in PASI) was 3.5 months for Amevive treated patients and 1 month for placebo-treated patients. In Study 2, the median duration of response was approximately 2 months for both groups. A majority of the subjects had responded to either Amevive or placebo maintained a 50% or greater reduction in PASI through the 3-month observation period. In both studies, an additional 11% (42/367) and 7% (12/166) of subjects treated with Amevive, respectively, achieved a 75% reduction from baseline PASI score at one or more visits after the first 2 weeks of the follow-up period.

Side Effects

Adverse events associated with the use of Amevive may include (but are not limited to) the following:

  • Serious Infections
  • Malignancies
  • Lymphopenia
  • Sore throat
  • Dizziness
  • Cough
  • Nausea
  • Itching
  • Muscle Aches
  • Chills
  • Injection Site Pain
  • Injection Site Inflammation
  • Accidental injury

 

Mechanism of Action

Amevive (alefacept) is an immunosuppressive dimeric fusion protein that consists of the extracellular CD2-binding portion of the human leukocyte function antigen-3 (LFA-3) linked to the Fc (hinge, CH2 and CH3 domains) portion of human IgG1. Alefacept is produced by recombinant DNA technology in a Chinese Hamster Ovary (CHO) mammalian cell expression system.

Amevive interferes with lymphocyte activation by specifically binding to the lymphocyte antigen, CD2, and inhibiting LFA-3/CD2 interaction. Activation of T lymphocytes involving the interaction between LFA-3 on antigen-presenting cells and CD2 on T lymphocytes plays a role in the pathophysiology of chronic plaque psoriasis. The majority of T lymphocytes in psoriatic lesions are of the memory effector phenotype characterized by the presence of the CD45RO marker? express activation markers (e.g., CD25, CD69) and release inflammatory cytokines, such as interferon y.

Amevive also causes a reduction in subsets of CD2+ T lymphocytes (primarily CD45RO+), presumably by bridging between CD2 on target lymphocytes and immunoglobulin Fc receptors on cytotoxic cells, such as natural killer cells. Treatment with Amevive results in a reduction in circulating total CD4+ and CD8+ T lymphocyte counts. CD2 is also expressed at low levels on the surface of natural killer cells and certain bone marrow B-lymphocytes.

Literature References

Bos JD, Hagenaars C, Das PK, et al. Predominance of 'memory' T cells (CD4+, CDw29+) over 'na飗e' T cells (CD4+, CD45R+) in both normal and diseased human skin. Arch Dermatol Res 1989; 281:24-30.

Ellis C, Krueger GG. Treatment of chronic plaque psoriasis by selective targeting of memory effector T lymphocytes. N Engl J Med 2001; 345:248-255.

Fredriksson T, Pettersson U. Severe psoriasis--oral therapy with a new retinoid. Dermatologica 1978; 157:238-244.

Additional Information

For additional information regarding Amevive or psoriasis, please contact The Amevive Information Site




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