About the INTREPID-2566 Study

INTREPID-2566 is a research study to assess the safety of an investigational drug – NNZ-2566. A second purpose of the study is to assess the drug’s effectiveness to reduce the effects of brain injury and improve recovery in patients with TBI. The study will find out if NNZ-2566 given with standard medical care is safe and works better than standard medical care alone. We have completed enrollment in this study.

Who was included in the Study?

Doctors assessed patients who presented to the emergency room at one of the participating hospitals with a TBI. Patients were entered into the study if they:

  • Are between 16 and 75 years of age
  • Have a blunt closed head injury (i.e. nothing entering the brain);
  • The doctors determine that the severity of the TBI is moderate or severe;
  • Do not have other serious injuries and have not lost too much blood;
  • Are able to read and write English;
  • Are not pregnant.

What happened on the Study?

Everyone who was entered into the study received the same standard medical care as any other patient treated at the hospital for TBI. Study patients also received either NNZ-2566 in normal saline or normal saline alone (called a placebo) delivered into their vein by intravenous (IV) infusion.

Whichever of these two infusions the patient received was determined by chance, like flipping a coin or rolling dice. This is called random assignment, and no one knew which of the drugs the patient received However, they had a 2 in 3 (66.6%) chance of getting the NNZ-2566 drug. The most common side-effects reported during previous studies that may have been related to NNZ-2566 were:

  • Infusion site reactions such as bruising and irritation of the vein (27% of patients)
  • Mild headache (11% of patients)
  • Dizziness (7% of patients)
  • Back pain (4% of patients)
  • Bruising or irritation at the blood sampling site (4% of patients)
  • Sleepiness (3%)
  • Nausea (3%)
  • Mild changes in heart rhythm or ECG (< 3% of patients)

Less frequently reported side effects that may have been related to NNZ-2566, occurring in less than 3% of study patients, were palpitations, nosebleed, decreased appetite, irritation or swelling in throat (sore throat), flu-like symptoms, fainting, nausea, lack of energy, sleepiness, numbness around the drug infusion site, abdominal pain, rash, itchy skin, diarrhea, sweating, muscular pain, low blood pressure, and reversible changes in a blood laboratory tests (raised amylase, related to the digestive system and raised ALT, a liver function test).

Where was the Intrepid-2566 study conducted?

The INTREPID-2566 study was conducted at up to 30 centers in the United States. The following hospitals recruited subjects under the EFIC protocol for this study:

In the United States

  • Arrowhead Regional Medical Center, Colton, CA.
  • UC Davis Medical Center, Sacramento, CA.
  • Detroit Receiving Hospital, Detroit, MI.
  • Sinai-Grace Hospital, Detroit, MI.
  • University of Pittsburgh Medical Center, Pittsburgh, PA.
  • The Queens Medical Center, Honolulu, HI.

When can I find out my treatment assignment if I participated in the study?

 The point of contact for information about your treatment assigment will be your enrolling hospital. They will be in contact with you by mail within 12-16 weeks of the announcement of the study results. 

Where can I find out more about the study results?

The study data was reviewed by medical experts and the military. The Intrepid-2566 study did show that the study medicine was safe but we were not able to prove that it made people better. There may have been a number of reasons why this happened. It may have been related to how badly people were injured or if they were injured in places other than their brain. We did find that people treated with the study medicine performed better on one of the tests that measures memory, language skills and attention. It’s not clear why people treated with the study medicine did better on this test but not the other tests that we used.  Further review is underway to help us understand the results and how future studies should be designed.  The study did establish the value of a specialized blood test called a biomarker that can be used to understand severity and predict outcome in brain injury. 

The detailed results of the trial will be published within the next year.  An overview of the trial will be presented at the 6th Annual Traumatic Brain Injury Conference on 12 May 2016 in Washington D.C.

We want to express our sincere thanks to all of the study participants and their families. Only with continued research can we improve the treatment for patients with brain injury.


The INTREPID-2566 study is sponsored by Neuren Pharmaceuticals and funded in part by grants from the US Army Medical Research and Materiel Command.