Safety and Clinical Effects of a Muse Cell-Based Product in Patients With Amyotrophic Lateral Sclerosis: Results of a Phase 2 Clinical Trial

Amyotrophic lateral sclerosis (ALS) is characterized by progressive loss of motor neurons. Multilineage-differentiating stress-enduring (Muse) cells are unique endogenous stem cells that show therapeutic effects on motor function in ALS mouse models. We conducted a single-center open phase II clinical trial to evaluate the safety and clinical effects of repeated intravenous injections of an allogenic Muse cell-based product, CL2020, in patients with ALS. Five patients with ALS received CL2020 intravenously once a month for a total of six doses. The primary endpoints were safety and tolerability, and the secondary endpoint was the rate of change in the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) score. In addition, serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), sphingosine-1-phosphate (S1P), cerebrospinal fluid chitotriosidase-1 (CHIT-1), and neurofilament light chain (NfL) levels were evaluated. The CL2020 treatment was highly tolerated without serious side effects. The ALSFRS-R score change trended upward at 12 months post-CL2020 treatment compared with that at 3 months pre-administration, but the difference was not statistically significant. Among five patients diagnosed with ALS, three exhibited a decrease in the rate of ALSFRS-R score change, one demonstrated an increase, and another showed no change. In addition, the patients’ serum IL-6 and TNF-α levels and cerebrospinal fluid CHIT-1 and NfL levels increased for up to 6 months post-treatment; however, their serum S1P levels continuously decreased over 12 months. These findings indicate a favorable safety profile of CL2020 therapy. In the near future, a double-blind study of a larger number of ALS patients should be conducted to confirm the efficacy of ALS treatment with CL2020.