Just came across another study that recommends all patients who have started on the interferons be tested for NABs.
Neurology. 2005 Jul 12;65(1):33-9. Epub 2005 May 11. Related Articles, Links
Appearance and disappearance of neutralizing antibodies during interferon-beta therapy.
Sorensen PS, Koch-Henriksen N, Ross C, Clemmesen KM, Bendtzen K; Danish Multiple Sclerosis Study Group.
Copenhagen MS Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark. email@example.com
BACKGROUND: Neutralizing antibodies (NABs) occur frequently in patients receiving interferon (IFN)-beta for multiple sclerosis (MS), but it is unclear whether occurrence of NABs is predictive for the persistence of NABs during continued IFN-beta therapy. METHODS: The authors used an antiviral neutralization bioassay to measure NABs blindly from 6 months up to 78 months in patients with MS who were followed for at least 24 months during treatment with IFN-beta. Patients were classified into three groups: 1) persistently NAB-negative patients, defined as patients without any positive samples at any time; 2) definitely NAB-positive patients, defined as patients who had at least two consecutive positive samples; and 3) patients with fluctuating NAB-positive and NAB-negative samples. RESULTS: A total of 455 patients were included in the study. Overall, 52.3% of the patients were persistently NAB-negative, 40.9% became definitely NAB-positive, and the remaining 6.8% were fluctuating. More patients treated with IFN-beta-1a (Avonex) remained NAB-negative (p < 0.0001), whereas there was no difference between IFN-beta-1b (Betaferon) and IFN-beta-1a (Rebif). Patients who have remained NAB-negative during the first 24 months of therapy rarely developed NABs. On the contrary, the majority of patients, who had been NAB-positive from 12 through 30 months after start of therapy, remained NAB-positive. CONCLUSIONS: NABs should be measured in all patients treated with IFN-beta. If patients have been persistently NAB-negative for 24 months, measurements can be discontinued. Patients who have been NAB-positive for a period of 18 months or more usually remain NAB-positive for a long time.