Tobias Prasse and Christoph P. Hofstetter
Richard G. Fessler, Reza Ehsanian, Charles Y. Liu, Gary K. Steinberg, Linda Jones, Jane S. Lebkowski, Edward D. Wirth III, and Stephen L. McKenna
The primary objective of this study was to evaluate the safety of 3 escalating doses of oligodendrocyte progenitor cells (LCTOPC1; previously known as GRNOPC1 and AST-OPC1) administered at a single time point between 21 and 42 days postinjury to participants with subacute cervical spinal cord injuries (SCIs). The secondary objective was to evaluate changes in neurological function following administration of LCTOPC1.
This study was designed as an open-label, dose-escalation, multicenter clinical trial. Twenty-five participants with C4–7 American Spinal Injury Association Impairment Scale grade A or B injuries received a single dose of either 2 × 106, 1 × 107, or 2 × 107 LCTOPC1 delivered via intraparenchymal injection into the spinal cord at the site of injury using a custom-designed syringe positioning device. Low-dose tacrolimus was administered until day 60. Outcome measures included adverse event (AE) monitoring and neurological function as measured by the International Standards for Neurological Classification of Spinal Cord Injury.
All 25 participants experienced at least one AE, with a total of 534 AEs (32 study-related vs 502 study-unrelated anticipated complications of SCI) reported at the completion of 1-year follow-up. There were 29 serious AEs reported. Two grade 3 serious AEs (CSF leak in one participant and a bacterial infection in another) were considered related to the injection procedure and to immunosuppression with tacrolimus, respectively. The CSF leakage resolved with sequelae, including self-limited altered mental status, and the infection resolved with antibiotic therapy. For all participants, MRI scans demonstrated no evidence of an enlarging mass, spinal cord damage related to the injection procedure, inflammatory lesions in the spinal cord, or masses in the ventricular system. At 1-year follow-up, 21/22 (96%) of the intention-to-treat group recovered one or more levels of neurological function on at least one side of their body, and 7/22 (32%) recovered two or more levels of neurological function on at least one side of their body.
LCTOPC1 can be safely administered to participants in the subacute period after cervical SCI. The injection procedure, low-dose temporary immunosuppression regimen, and LCTOPC1 were well tolerated. The safety and neurological function data support further investigation to determine the efficacy of LCTOPC1 in the treatment of SCI.
Clinical trial registration no.: NCT02302157 (ClinicalTrials.gov)
Stephen L. McKenna, Reza Ehsanian, Charles Y. Liu, Gary K. Steinberg, Linda Jones, Jane S. Lebkowski, Edward Wirth III, and Richard G. Fessler
The purpose of this study was to evaluate the safety of oligodendrocyte progenitor cells (LCTOPC1) derived from human pluripotent stem cells administered between 7 and 14 days postinjury to patients with T3 to T11 neurologically complete spinal cord injury (SCI). The rationale for this first-in-human trial was based on evidence that administration of LCTOPC1 supports survival and potential repair of key cellular components and architecture at the SCI site.
This study was a multisite, open-label, single-arm interventional clinical trial. Participants (n = 5) received a single intraparenchymal injection of 2 × 106 LCTOPC1 caudal to the epicenter of injury using a syringe positioning device. Immunosuppression with tacrolimus was administered for a total of 60 days. Participants were followed with annual in-person examinations and MRI for 5 years at the time of this report and will be followed with annual telephone questionnaires for 6 to 15 years postinjection. The primary endpoint was safety, as measured by the frequency and severity of adverse events related to the LCTOPC1 injection, the injection procedure, and/or the concomitant immunosuppression administered. The secondary endpoint was neurological function as measured by sensory scores and lower-extremity motor scores as measured by the International Standards for Neurological Classification of Spinal Cord Injury examinations.
No unanticipated serious adverse events related to LCTOPC1 have been reported with 98% follow-up of participants (49 of 50 annual visits) through the first 10 years of the clinical trial. There was no evidence of neurological decline, enlarging masses, further spinal cord damage, or syrinx formation. MRI results during the long-term follow-up period in patients administered LCTOPC1 cells showed that 80% of patients demonstrated T2 signal changes consistent with the formation of a tissue matrix at the injury site.
This study provides crucial first-in-human safety data supporting the pursuit of future human embryonic stem cell–derived therapies. While we cannot exclude the possibility of future adverse events, the experience in this trial provides evidence that this cell type can be well tolerated by patients, with an event-free period of up to 10 years. Based on the safety profile of LCTOPC1 obtained in this study, a cervical dose escalation trial was initiated (NCT02302157).