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Tysabri (natalizumab): Drug Safety Communication - New Risk Factor for Progressive Multifocal Leukoencephalopathy (PML)
AUDIENCE: Neurology, Gastroenterology
FDA notified healthcare profesisonals that testing positive for anti-JC virus (JCV) antibodies has been identified as a risk factor for progressive multifocal leukoencephalopathy (PML). PML is a rare but serious brain infection associated with use of Tysabri (natalizumab) for the treatment of multiple sclerosis (MS) or Crohn's disease.
A patient's anti-JCV antibody status may be determined using an anti-JCV antibody detection test that has been analytically and clinically validated, and has been ordered by a healthcare professional. The Stratify JCV Antibody ELISA test2 was cleared by FDA on January 20, 2012. Testing positive for anti-JCV antibodies means that a person has been exposed to JCV in the past.
BACKGROUND: Tysabri (natalizumab) is in a class of medications called immunomodulators. It works by stopping certain cells of the immune system from causing damage to the body. Tysabri is approved for the treatment of relapsing forms of multiple sclerosis since November 2004 and for the treatment of moderately to severely active Crohn's disease since January 2008.
RECOMMENDATION: The risks and benefits of continuing treatment with Tysabri should be carefully considered in patients who are found to be anti-JCV antibody positive and have one or more of the other known risk factors for PML. Patients with all three known risk factors have an estimated risk of PML of 11/1,000 users. See the Drug Safety Communication Data Summary section for additional information.
The following risk factors have been identified that increase the chance of Tysabri-treated patients developing PML:
the presence of anti-JCV antibodies, which reflects prior exposure to JCV
treatment with Tysabri for a significant period of time (longer than 2 years)
treatment with certain medicines that can weaken a patient’s immune system (immunosuppressants such as mitoxantrone, azathioprine, methotrexate, cyclophosphamide, and mycophenolate mofetil) before receiving Tysabri.
Healthcare professionals and patients are encouraged to report adverse events or side effects related to the use of these products to the FDA's MedWatch Safety Information and Adverse Event Reporting Program:
* Complete and submit the report Online: www.fda.gov/MedWatch/report.htm
* Download form or call 1-800-332-1088 to request a reporting form, then complete and return to the address on the pre-addressed form, or submit by fax to 1-800-FDA-0178
Read the MedWatch safety alert, including links to tht eFDA Drug Safety Communication and News Release, at:
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHuma...
FDA提醒醫療人員， 陽性的anti-JC virus (JCV)抗體已被證實為progressive multifocal leukoencephalopathy (PML)的危險因子，PML是種罕見但嚴重的腦部感染，與使用Tysabri (natalizumab)治療多發性硬化症(multiple sclerosis, MS)或庫隆氏症(Crohn's disease)相關。
在2012年1月20日，FDA核准JCV抗體的ELISA檢測，醫療人員可以用此檢測病人是否擁有anti-JCV抗體，如果檢測結果為陽性代表此人以前曾暴露於JCV。
Tysabri是一種免疫調節劑，作用為抑制免疫系統的特定細胞對身體的傷害。Tysabri於2004年11月被核准為治療復發性的多發性硬化症，而2008年1月時，另被核准可治療中重度的庫隆氏症。
建議若病人為anti-JCV抗體陽性或有其他PML危險因子，應審慎評估使用Tysabri的利與弊。病人如果同時存在3個危險因子，則發生PML的機率為11/1000。PML的危險因子如下：
* 檢測anti-JCV抗體為陽性。
* 使用Tysabri超過2年。
* 使用Tysabri前有使用其他免疫抑制劑，如mitoxantrone、azathioprine、methotrexate、cyclophosphamide及mycophenolate mofetil。
其他詳細資訊請見FDA網站上Drug Safety Communication。
相關訊息與連結請參考FDA網址：
http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm288602.htm
[Posted 01/20/2012]
資料來源：美國FDA之藥物安全警訊
資料提供：台大醫院藥劑部
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資料來源：藥師週刊（第1762期）
