Phase IIb Study of MP4OX in Traumatic Hemorrhagic Shock Patients

Overview

MP4OX is a novel oxygen therapeutic agent being developed as an ischemic rescue therapy to enhance perfusion and oxygenation of tissues at risk during hemorrhagic shock. MP4OX is a pegylated hemoglobin-based colloid. Due to its molecular size and unique oxygen dissociation characteristics, MP4OX targets delivery of oxygen to ischemic tissues. This study will evaluate the safety and efficacy of MP4OX treatment in trauma patients suffering from lactic acidosis due to severe hemorrhagic shock. The study hypothesis is that MP4OX will reverse the lactic acidosis by enhancing perfusion and oxygenation of ischemic tissues and thereby prevent and reduce the duration of organ failure and improve outcome in these patients.

Acute traumatic injury, including both blunt and penetrating injury, is often associated with severe uncontrolled bleeding which can lead to hemorrhagic shock. During shock, inadequate blood flow results in local ischemia and tissue hypoxia (insufficient oxygenation) of critical organs, which can be detected by an increase in serum lactate levels in these trauma victims. Despite optimal care, more than 10% of trauma victims who reach hospital alive will die, and many will suffer from organ failure. Death and significant, persistent morbidity are consequences of trauma, and traumatic injuries are associated with lost productivity, reduced quality of life, and direct costs to patients and health care systems worldwide. The primary treatment of trauma is to support ventilation and oxygenation, limit blood loss, and maintain cardiovascular function so that organs are perfused. The patient's airway may be intubated to allow oxygenated airflow to the lungs. Mechanical ventilation is used if the patient cannot maintain oxygenation and carbon dioxide elimination. Damage-control surgery is used to limit blood loss and to intentionally delay definitive repair until the patient can better tolerate procedures. Blood transfusions are provided to maintain the oxygen-carrying capacity of the circulation. Platelets and coagulation factors are infused to correct any coagulopathy from dilution of blood and consumption of clotting factors. Vasopressor and inotropic agents may be used to support low cardiac output or blood pressure. Renal replacement therapy may be instituted if kidney failure occurs. Despite optimal care, organ dysfunction is present in many patients. Hypoperfusion and anaerobic metabolism of organs and tissues can be detected by the presence of lactic acidosis. Current therapy is aimed at supporting failing organs, but an agent that accelerates the repayment of an oxygen debt and prevents or shortens the duration of organ failure is sought. Blood transfusion improves circulation of oxygen-carrying red blood cells but is insufficient if lactic acidosis is present, even when the hemoglobin level has been restored. Studies in critically ill intensive care patients have demonstrated that elevated initial and 24-hour lactate levels are significantly correlated with mortality, and prolonged elevation of blood lactate levels after trauma has been correlated with increased organ failure and mortality. Support for the efficacy of MP4OX in resuscitation of severe hemorrhage shock comes from several preclinical studies in hamster, rat, and swine. Using a swine model of uncontrolled hemorrhage and resuscitation, survival was greater and restoration of hemodynamics and acid-base status were improved with MP4OX relative to equivalent volume of crystalloid, pentastarch, or unmodified hemoglobin. Administration of MP4OX improved 24-hour survival, stabilized cardiac output and arterial pressure at nearly normal levels, and reduced lactate more effectively than control fluids. Importantly, these benefits of MP4OX were observed with or without co-administration of autologous blood, suggesting that blood alone is not sufficient to achieve resuscitation, and that the effects of MP4OX are additional to those of blood. Additional support comes from a recently completed phase IIa trauma study in 51 patients with lactic acidosis due to severe hemorrhage. MP4OX treatment was associated with a more rapid and sustained reduction of high lactate levels, and a greater proportion of MP4OX-treated patients who normalized lactate by four hours after dosing. There was also a trend toward shorter median hospital stay and a greater proportion of MP4OX-treated patients being discharged from hospital alive by Day 28. These phase IIa results suggest improved oxygen delivery and utilization by ischemic tissues in the MP4OX-treated patients, based on the reversal of lactic acidosis, and support the positive results from the preclinical models of hemorrhagic shock resuscitation.