Safety and Efficacy of ABX-101 in Participants Aged 18 to 50 Years of Age With Moderate to Severe Traumatic Brain Injury

The purpose of this study is to investigate the clinical improvement measured by the Glasgow Outcome Scale Extended (GOS-E) with ABX-101 compared with Placebo intramuscular injection in participants with moderate to severe TBI.

Study details include:

* The study duration will be up to 180 days per participant.
* The treatment duration will be up to 7 days.
* The visits post-treatment will be on day 30 and day 180 of the study.

Number of Participants:

A maximum of 45 participants will be enrolled into the study and randomized to each treatment arm in a ratio of 1:1:1. i.e., fifteen participants per arm.

Study Arms and Duration:

Participants will be screened, enrolled and receive the assigned treatment within 12 hours of the primary TBI insult. Enrolled participants will be stratified 1:1 (in each arm) by GCS score (GCS 4-8 in one group and GCS 9 - 12 in the other). The treatment period, which involves 6 hourly, i.e., quarter in die (QID), ABX-101 (1 mg OR 2 mg) intramuscular injections, is seven days. Enrolled participant will continue with the in-hospital standard of care, as decided by the external treating physician, and will be followed up by the study team on days 30 and days 180. The ABX-101 1 mg and 2 mg arm will be enrolled simultaneously.

Eligibility Criteria:
Inclusion Criteria:

* Written informed consent from patient, patient's legal guardian or legal representative, or deferred consent procedure, according to local requirements
* 18 - 50 years of age, inclusive
* Expected to survive more than 24 hours after admission
* Clearly defined time of injury no more than 12 hours before administration of study drug/placebo

  o Subjects stratified 1:1 (in each arm) by treatment administered 0-12 hrs
* TBI with Glasgow Coma Score (GCS) 4-12 requiring intracranial pressure (ICP) monitoring according to the assessment of the treating physician

  o Subjects stratified 1:1 (in each arm) by GCS 4-8 and GCS 9-12
* Catheter placement (intraventricular or intraparenchymal, only) for monitoring and management of increased ICP
* \[Brain computed tomography (CT) showing intracranial parenchymal abnormality and hemodynamically stable\]

Exclusion Criteria:

* Penetrating head injury (e.g. missile, stab wound)
* Concurrent, but not pre-existing, spinal cord injury
* Not expected to survive more than 24 hours after admission
* Pregnant, or a positive pregnancy test
* Coma due to an exclusive epidural hematoma (lucid interval and absence of structural brain damage on CT scan)
* Patient pupils are unresponsive (dilation) in both eyes
* The subject has a neurodegenerative disease or other neurological disorder including dementia, Parkinson's disease, multiple sclerosis, seizure disorder, or brain tumors.
* Coma suspected to be primarily due to other causes than head injury (e.g. drug overdose intoxication, drowning/near drowning
* Known or CT scan evidence of pre-existing major cerebral damage
* Any severe concomitant condition (cancer; hematologic, renal, hepatic, coronary disease; major psychiatric disorder; alcohol or drug abuse), that can be ascertained at admission
* Known to have received an experimental drug within 4 weeks prior to current injury
* Patients who cannot be monitored with regard to their recovery (GOS-E and QOLIBRI)