Long-Term Follow Up in Anti-Contactin-1 Autoimmune Nodopathy.

Objective: To analyze long-term clinical and biomarker features of anti-contactin-1 (CNTN1) autoimmune nodopathy (AN).

Methods: Patients with anti-CNTN1 autoimmune nodopathy detected in our laboratory from which clinical information was available were included. Clinical features and treatment response were retrospectively collected. Autoantibody, serum neurofilament light chain (sNfL), and serum CNTN1 levels (sCNTN1) were analyzed at baseline and follow up.

Results: A total of 31 patients were included. Patients presented with progressive sensory motor neuropathy (76.7%) with proximal (74.2%) and distal involvement (87.1%), ataxia (71.4%), and severe disability (median INCAT at nadir of 8). A total of 11 patients (35%) showed kidney involvement. Most patients (97%) received intravenous immunoglobulin, but only 1 achieved remission with intravenous immunoglobulin. A total of 22 patients (71%) received corticosteroids, and 3 of them (14%) did not need further treatments. Rituximab was effective in 21 of 22 patients (95.5%), with most of them (72%) receiving a single course. Four patients (12.9%) relapsed after a median follow up of 25 months after effective treatment (12-48 months). Anti-CNTN1 titers correlated with clinical scales at sampling and were negative after treatment in all patients, but 1 (20/21). sNfL levels were significantly higher and sCNTN1 significantly lower in anti-CNTN1 patients than in healthy controls (sNfL: 135.9 pg/ml vs 7.48 pg/ml, sCNTN1: 25.03 pg/ml vs 22,186 pg/ml, p < 0.0001). Both sNfL and sCNTN1 returned to normal levels after successful treatment.

Interpretation: Patients with anti-CNTN1 autoimmune nodopathy have a characteristic clinical profile. Clinical and immunological relapses are infrequent after successful treatment, suggesting that continuous treatment is unnecessary. Anti-CNTN1 antibodies, sNfL, and sCNTN1 levels are useful to monitor disease status in these patients. ANN NEUROL 2024.