タイサブリ
2013年1月16日、Natalizumab (Tysabri; タイサブリ) が多発性硬化症の first-line therapyとして FDAと European Medicines Agencyに申請されました。
Biogen, Elan seek okay for first-line Tysabri use in MS
LONDON | Wed Jan 16, 2013 5:12am EST
(Reuters) – Biogen Idec and Elan have filed for approval to sell their drug Tysabri as a first-line treatment for multiple sclerosis, a move that could boost sales of the drug.
Demand for Tysabri has been curtailed due to concerns over its association with a potentially fatal infection known as progressive multifocal leukoencephalopathy, or PML, which is caused by the JC virus.
Now, however, there is a test for the virus to predict if patients are at risk of developing PML, opening the possibility that Tysabri could be used more widely and at an earlier stage of treatment.
Biogen and Elan said on Wednesday they had submitted applications to the U.S. Food and Drug Administration and the European Medicines Agency seeking approval for first-line use in patients with relapsing forms of multiple sclerosis (MS) who have tested negative for antibodies to the JC virus.
The JC virus is generally harmless, but in people with weakened immune systems, such as those using immune system-suppressing drugs like Tysabri, it can lead to an increased chance of developing PML.
Tysabri use is currently limited to between 10 and 12 percent of treated MS patients, due to the risk of PML, and analysts said the hoped-for wider approval would improve uptake and send a positive signal to doctors.
Berenberg analysts said Tysabri’s share of the MS market could increase to about 15 percent by 2015, representing sales of $2.9 billion, while today’s share price for Elan implied peak sales of only some $2 billion.
Tysabri was briefly pulled from the market over PML concerns – but it was considered to be so effective, compared with other available treatments, that MS patients argued the risk was worth taking and demanded its return.
Health regulators bowed to the pressure and allowed the drug’s relaunch with restrictions.
“A first-line approval would allow people with MS access to a highly efficacious treatment earlier in the course of the disease, potentially leading to better outcomes,” said Alfred Sandrock, Biogen’s chief medical officer.
“This is an important consideration for people with MS who may want or need more efficacy.”
Both the U.S. and European regulators are expected to decide on the applications for first-line use later this year.
(Reporting by Ben Hirschler; Editing by Louise Heavens)
タイサブリは、AFFIRM trialや SENTINEL tiralなどで高い有効性が示されている薬剤です。一方で稀ながら進行性多巣性白質脳症 (PML) の副作用が指摘されています。PMLは免疫抑制による JC virusの増殖が原因で起こる疾患です (AIDS及び免疫抑制剤使用により発症した患者をそれぞれ担当したことがあります)。
これらのジレンマを解決するため、JC virusを検査して陰性であれば、タイサブリを第一選択薬として使っても良いのではないかというのは自然な考え方だと思います。JC virusが検出限界以下のコピー数だった患者さんが、薬の使用のせいでウイルスが増殖して PMLを発症することがあるかどうかの知見は未知数だと思いますが、現実的には meritと riskを天秤にかけて判断されるべきことでしょう。
なお、日本では 2010年2月から治験がされています。国内においても、多発性硬化症の治療選択肢は今後どんどん増えていきそうです。
(参考)
下記のサイトに、多発性硬化症の新薬が紹介されています。多発性硬化症については、様々な新薬が登場し混乱しそうですが、すっきりと纏められています。
Themocracy