Conference Coverage

GFAP may complement NfL as MS biomarker


 

FROM ECTRIMS 2022

Neurofilament light chain (NfL) is a biomarker for both disease progression and treatment response in multiple sclerosis (MS), but the search continues for additional biomarkers to distinguish between disease activity and progression.

At a session of the annual meeting of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS), researchers presented evidence that serum glial fibrillary acid protein (GFAP) could be a useful complement to NfL in MS, although it is not ready for the clinic. Acceptance of NfL wasn’t universal, either.

Patients with MS follow wide-ranging disease courses, and disability arises due to two partially independent mechanisms, according to Stephanie Meier, who presented results suggests from a study of two cohorts. “Firstly, the acute disease activity leading to relapse associated worsening or RAW (relapse-associated worsening), and secondly the chronic deterioration of neurologic functions leading to progression independent of relapse activity,” said Ms. Meier, a PhD student at University of Basel, Switzerland.

GFAP and NfL may be complementary biomarkers

NfL is a structural protein of neurons, while GFAP is a structure protein of astrocytes. NfL therefore reflects neuronal damage, while GFAP is an indicator of astrogliosis and astrocytic damage. GFAP has been shown to be increased in progressive MS and has been applied in traumatic brain injury and neuromyelitis optica spectrum disorder, according to Ms. Meier.

Her group examined data from two cohorts with “extreme” phenotypes. One cohort included 169 patients with stable MS and 184 with worsening disease progression but no sign of relapses. The other was a focal inflammation cohort that comprised paired samples from 66 patients: One sample from an active time point characterized by a relapse or at least one contrast-enhancing lesion (CEL) detected in the previous 30 days, and one remission sample when there was no relapse in the past year and no CEL in the previous 6 months.

The focal inflammation cohort demonstrated an association between raised NfL levels, with a 53% increase in predicted serum NfL during the active state after a multivariate analysis (P < .0001). GFAP values, on the other hand, were nearly identical.

In the progression cohort, there was more total yearly brain loss in the worsening group (0.42% vs. 0.14%; P = .0005). Baseline GFAP predicted gray matter atrophy (–0.24% per year, P < .0001) but NfL did not. The reverse was true for white matter atrophy, with NfL being predictive (–0.26% per year; P < .0001) but not GFAP.

“The use of biomarkers such as NfL and GFAP could be useful to understand the MS disease course by detecting disease activity that is not usually measurable with standard methods,” said Ms. Meier.

“We found that NfL was strongly associated with acute inflammation and prognosticated white matter volume loss, while GFAP has a potential as a prognostic biomarker for disease worsening, including progression independent of relapse activity, and baseline GFAP also prognosticated gray matter volume loss. From this we can conclude that serum GFAP is a promising biomarker reflecting progression in MS and it is complementary to NfL, as NfL is more strongly associated with acute inflammatory activity,” said Ms. Meier.

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