INDIVIDUAL TEST 106
Natalizumab
Indication
Natalizumab (Tysabri) anti-drug antibodies (ADA) has been found in 4.5 to 14.1% of natalizumab-treated multiple sclerosis (MS) patients. High levels of antibody titers indicate a risk for persistent natalizumab ADA which is associated with a negative effect on the response to treatment.
Method
Sampling of serum at Cmin when the drug concentration is at its lowest, and the test is performed with RIA (radioimmunoassay). Results are reported as AU/mL. Antidrug antibodies (ADA) against natalizumab between 11-20 AU/mL are considered detectable, above 20 AU/mL can be quantified.
Interpretation
In the event of a positive sample it is recommended to collect a new sample within 4-8 weeks to verify the positivity and if the patient is persistent positive. Treatment with natalizumab should be continued until the follow up test is confirmed positive or negative, unless hypersensitivity noted. If the verification test is positive, treatment should be discontinued.
References
Lundkvist et al. Characterization of anti-natalizumab antibodies in multiple sclerosis patients. Mult Scler. 2013 May;19(6):757-64
Vennegoor et al. Clinical relevance of serum natalizumab concentration and anti-natalizumab antibodies in multiple sclerosis. Mult Scler. 2013 Apr;19(5):593-600.
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ENSKILD ANALYS 106
Natalizumab
Indikation
Natalizumab (Tysabri) anti-läkemedelsantikroppar (anti-drug antibodies, ADA) har hittats i 4,5-14,1% av natalizumab-behandlade multipel skleros (MS) patienter. Höga nivåer av antikroppstitrar indikerar risk för att natalizumab ADA blir kvarstående vilket associeras med en negativ effekt på behandlingssvar.
Metod
Serumprovet tas vid Cmin då läkemedelskoncentrationen är som lägst och analyseras med RIA (radioimmunoassay)
Resultatet anges som AU/mL. ADA mot natalizumab mellan 11-20 AU/mL kan detekteras, över 20 AU/mL kan kvantifieras.
Tolkning
Vid positivt prov rekommenderas ett nytt prov inom 4-8 veckor för att verifiera positiviteten och om patienten är persistent positiv. Behandlingen med natalizumab bör fortsättas tills uppföljande prov har bekräftats positivt eller negativt, såvida ingen överkänslighet noterats. Om även det verifierande provet är positivt bör behandlingen avslutas.
Referenser
- Lundkvist et al. Characterization of anti-natalizumab antibodies in multiple sclerosis patients. Mult Scler. 2013 May;19(6):757-64
- Vennegoor et al. Clinical relevance of serum natalizumab concentration and anti-natalizumab antibodies in multiple sclerosis. Mult Scler. 2013 Apr;19(5):593-600.