Targeted proteomics upon Tofersen identifies candidate response markers for SOD1-linked amyotrophic lateral sclerosis

Tofersen is the first effective and approved therapy for familial ALS caused by pathogenic variants in the SOD1 gene. Following treatment with tofersen, neurofilaments in patients CSF and serum display a faster response than clinical parameters, underlining their importance as a biomarker for treatment response in clinical trials. This evidence led us to hypothesize that this novel treatment might represent an opportunity to identify additional therapy-responsive biomarkers for ALS. We chose the commercial NUcleic acid Linked Immuno-Sandwich Assay (NULISA), to investigate a predefined panel of 120 neural, glial and inflammatory markers in CSF and serum samples longitudinally collected from SOD1-ALS patients at baseline and three months after tofersen treatment. We identified a set of proteins (beyond pNfH and NfL) whose levels differed between SOD1-ALS and the matched control group and that were responsive to treatment with tofersen, including Amyloid beta 40;42, NPY and UCHL1. Even though our results warrant validation in larger cohorts and longer follow-up time, they may pave the way for a panel of responsive proteins solidifying biomarker endpoints in clinical trials. ### Competing Interest Statement SP has received speaker fees from Amylyx, Biogen, ITF-Pharma, Roche, and Zambon, and served on advisory boards for Amylyx, Biogen, Roche, Zambon, and ITF Pharma, and has participated as an investigator on clinical trials on ALS sponsored by Alexion Pharmaceuticals, AL-S Pharma, Amylyx, Apellis Pharmaceuticals, Biogen, Cytokinetics, Corcept Therapeutics, Ferrer, Sanofi, Orion Pharma, and Orphazyme. FS reports honoraria for advisory boards of Alnylam, Amylax and Alexion. ZU has received honoraria and grants from Biogen as a consultant. MV received travel expenses and non-financial support from ITF Pharma outside the submitted work. DB owns stocks from IONIS Pharmaceuticals. The other authors report no competing interests. ### Clinical Trial tofersen early access program ### Funding Statement This study was funded by the Deutsche Gesellschaft fur Muskelkranke (DGM) project Ca2/1, the Deutsche Forschungsgemeinschaft (DFG; German Research Foundation) through SFB 1506 - Project A01 and the Alamar Neurology Grant to AC ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Biosampling of serum and CSF was conducted via participation in the MND-NET cohort study, for which informed consent was obtained. The study was approved by the local ethics committee of Ulm University (application number 19/12). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authortofersen under the early access program