Neutralizing antibodies in multiple sclerosis patients on weekly intramuscular Avonex and biosimilar interferon beta-1a (CinnoVex): comparing results of measurements in two different laboratories.

The appearance of neutralizing antibodies (NAbs) has significant clinical and regulatory consequences for interferons in patients with multiple sclerosis (MS). In a double blind, randomized clinical trial, 84 patients with relapsing remitting MS were enrolled in a 24month study period. Patients were randomly assigned into two groups receiving 30mcg weekly intramuscular injections of either Avonex® (Biogen Idec, USA; 42 patients) or CinnoVex® (CinnaGen Co, Iran; 42 patients). NAb titer was drawn for all patients every 6months and assayed using cytopathic effect assay (CPE) method in Tehran, Iran. To validate the measure done in the Iranian lab, 45 sera with adequate volume and proper storing condition were selected and sent to be rechecked using luciferase reporter gene assay (LA) method for verification in 2 phases in Vancouver, Canada. The cut-off point of 20 TRU was considered for positivity. The two labs found the same three samples to be positive (2 samples from patients received Avonex and 1 received CinnoVex) and 42 to be negative. They had the following values using the Kawade formula as recommended by international standards; 2238, 89 and 302 (TRu/ml) using CPE assay versus 2464, 290 and 169 (TRu/ml) using LA method. As similar results were obtained from CinnoVex or Avonex in our study, we suggest that both medications will have a similar immunogenetic profile.