Sandoz v Biogen for the use of Natalizumab in MS….What do you go for?….Well we heard last week that neuros on the pharma payroll tend to go with the people giving the lolly. But the companies also do stuff to support the use of their drugs and on of them is JC virus testing. This is done because it is a risk factor for PML which can be a fatal consequence of taking natalizumab. The companies have two different assays and what is evident is that the Sandoz assay is more likely to detect previous infection than the Biogen assay. This is perhaps problematic because the go, no-go calls on natalizumab use or cessation is based on results from the biogen assay….This could therefore mean a change from or lack of start onto the Sandoz product.
There have been papers surfacing from most places that us natalizumab
Chisari CG, Crimì P, Spampinato G, Ferraro E, Alecci A, Lo Fermo S, Cimino V, Zappia M, Patti F. Threshold-Dependent Discordance Between STRATIFY JCV
and IMMUNOWELL Assays in Relapsing Multiple Sclerosis. Neurol Ther. 2026 Apr 10. doi: 10.1007/s40120-026-00937-9.
Introduction: Anti-JC virus (JCV) antibody testing is central to progressive multifocal leukoencephalopathy (PML) risk stratification in patients treated with natalizumab. While STRATIFY JCV is the historical reference assay, IMMUNOWELL is increasingly used in the context of biosimilar adoption. We aimed to determine whether inter-assay discordance reflects true biological divergence (Eh?) or threshold-dependent (Think this is the obvious answer) interpretative effects within clinically relevant PML risk categories.
Methods: In this single-center observational study, 250 consecutive patients with relapsing multiple sclerosis (RMS) underwent same-day paired STRATIFY and IMMUNOWELL testing. Agreement was evaluated under two interpretative frameworks: (i) manufacturer-defined analytical cutoffs and (ii) clinically adopted PML risk-based thresholds. Quantitative comparability was assessed using Pearson correlation and Bland-Altman analysis.
Results: Using analytical cutoffs, concordance was 78.0% (κ = 0.55), with discordance predominantly in borderline index ranges (Yep this is what every one else is or has already reported) . When applying clinically adopted risk thresholds, concordance increased to 93.2% (κ = 0.73). Index values correlated strongly (r = 0.922; p < 0.0001)…… analysis showed minimal …..wider deviations confined largely to low-to-intermediate index values rather than high-risk profiles.
Conclusions: Inter-assay discordance between STRATIFY and IMMUNOWELL is largely threshold-driven (Duh telliing us what we already knew) and substantially attenuated when applying clinically meaningful PML risk categories. These findings support practical interchangeability for routine monitoring in the biosimilar era, while underscoring the need for cautious interpretation of borderline results (So what do we do there?. This is what we need insight on and this is where Sandoz need to come to the party to tell people what to do. However, it shows the risk of copying somones summary of product characteritis, which give advice of what to do, when you are basing the outcome on a different assay. At worse it means that people will move away from your product because the neuros are encouraged to switch if condition x is reached. This is because the more sensitive assay is likely to detect X. However I wonder what happens when someone is not switched when X is reached and then they get PML..Will the neuro face legal action….Maybe another reason to stick with the original that made the rules).
COI: multiple as I had non-financial dealing with both companies, but none really
Source: multiple-sclerosis-research.org