Cell Therapy for Chronic TBI: Interim Analysis of the Randomized Controlled STEMTRA Trial

OBJECTIVE: To determine whether chronic motor deficits secondary to traumatic brain injury (TBI) can be improved by implantation of allogeneic modified bone marrow–derived mesenchymal stromal/stem cells (SB623). METHODS: This 6-month interim analysis of the 1-year double-blind, randomized, surgical sham–controlled, phase 2 Stem Cell Therapy for Traumatic Brain Injury (STEMTRA) trial (NCT02416492) evaluated safety and efficacy of the stereotactic intracranial implantation of SB623 in patients with stable chronic motor deficits secondary to TBI. Patients in this multicenter trial (n = 63) underwent randomization in a 1:1:1:1 ratio to 2.5 × 10(6), 5.0 × 10(6), or 10 × 10(6) SB623 cells or control. Safety was assessed in patients who underwent surgery (n = 61), and efficacy was assessed in the modified intent-to-treat population of randomized patients who underwent surgery (n = 61; SB623 = 46, control = 15). RESULTS: The primary efficacy endpoint of significant improvement from baseline of Fugl-Meyer Motor Scale score at 6 months for SB623-treated patients was achieved. SB623-treated patients improved by (least square [LS] mean) 8.3 (standard error 1.4) vs 2.3 (standard error 2.5) for control at 6 months, the LS mean difference was 6.0 (95% confidence interval 0.3–11.8, p = 0.040). Secondary efficacy endpoints improved from baseline but were not statistically significant vs control at 6 months. There were no dose-limiting toxicities or deaths, and 100% of SB623-treated patients experienced treatment-emergent adverse events vs 93.3% of control patients (p = 0.25). CONCLUSIONS: SB623 cell implantation appeared to be safe and well tolerated, and patients implanted with SB623 experienced significant improvement from baseline motor status at 6 months compared to controls. CLINICALTRIALS.GOV IDENTIFIER: NCT02416492. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that implantation of SB623 was well tolerated and associated with improvement in motor status.