Oxygen Biotherapeutics, Inc. (“OBI”) (NASDAQ: OXBT), is a development stage biomedical company currently focused on developing its perfluorocarbon-based intravenous oxygen carrier, Oxycyte ®, as a treatment for traumatic brain injury (TBI), stroke and other conditions where critical tissues are oxygen starved. Oxycyte is currently in Phase IIb clinical trials for TBI in Israel and Switzerland; however, the FDA has requested studies to explore the safety profile of Oxycyte with respect to immunocompetency as well as transient decreases in platelet numbers. The company announced today that with the successful completion of four important preclinical studies assessing Oxycyte’s potential effects on the immune system, OBI has moved several steps closer to addressing the questions posed by the FDA and demonstrating a favorable benefit to risk ratio for the product. These studies were funded as part of a $2.07 million cost reimbursement grant from the U.S. Army.
The use of any drug that lowers the body’s resistance to infection must be considered carefully, especially in the long-term hospitalization setting. A recent study reported in the journal, Clinical Microbiology and Infection, found that in TBI patients, the most common infection encountered is ventilator-associated pneumonia, followed by surgical site infections, urinary tract infections, pneumonia, catheter-associated bacteremias / blood stream infections and meningitis [Kourbeti, et al., Clin. Micrbiol. Infect., 19, 359-364, 2012]. Earlier this year, OBI obtained FDA buy-in for a series of studies designed to examine Oxycyte’s potential impact on immune function.
In experiments that used the Influenza virus to assess the overall health of the immune system, Oxycyte had only subtle effects on antibody production and did not adversely impact clearance of this common lung infection. Similarly, in a separate study examining the early phase response of the immune system, Oxycyte did not interfere with the efficient clearance of a Streptococcal pneumonia infection from the lung. Many TBI patients will experience as a result of being intubated one or more bouts of pneumonia; therefore, these results are important in that they provide evidence suggesting that Oxycyte does not compromise the patient’s ability to fight this infection often seen in the ICU. An additional experiment requested specifically by the FDA demonstrated that Oxycyte did not interfere with the ability of macrophages to identify and engulf bacteria and, thus, should have minimal effect on that clearance mechanism, which is associated with many common bacterial infections.
A fourth study was developed to test the potential immunomodulatory effects of Oxycyte in a Listeria model of systemic bacterial infection. This gram positive bacterium is extremely pathogenic and, if not controlled quickly, can progress to sepsis under conditions of immunosuppression. In our study, the administration of Oxycyte immediately prior to an injection of Listeria directly into the circulation resulted in a marked decrease in the animal’s ability to fend off this infection. It is important to note, however, that Listeria is not a bacterium commonly associated with TBI patients and was used in this study simply as a tool to assess immune function. Moreover, any blood stream infection occurring in a hospitalized patient will be treated aggressively regardless of what therapy that patient has received.