Treatment of Macrophage Activation Syndrome (MAS) With Anakinra

Macrophage activation syndrome (MAS) is a disorder whereby the immune system generates very high levels of substances (cytokines) that promote inflammation to the extent dysfunction occurs in multiple organ systems which if unchecked, is frequently fatal to the affected individual. This can occur in the setting of a number of different immune system disorders including, systemic lupus, systemic-onset juvenile arthritis, and adult-onset Still's disease. MAS can also occur in response to infection with certain viruses such as Epstein-Barr virus (EBV) and malignancies involving lymphocytes.

Because of the high fatality of MAS (>50%), a number of different treatments have been tried to manage this disorder, including use of high-dose steroids, immune suppressants such as cyclosporine, and cytotoxic chemotherapy treatments (etoposide) with variable success and/or severe complications of immune suppression (as may occur with etoposide). A number of recent case reports and case series have reported success using cytokine-blocking therapies such as anakinra in the treatment of MAS that is associated with systemic-onset juvenile idiopathic arthritis and adult Still's disease. Anakinra is a bio-engineered form of the naturally occurring interleukin-1 receptor antagonist (IL-1ra), that blocks the action of interleukin-1, one of the cytokines that is expressed and present in very high amounts in patients who have MAS. Anakinra/Il-1ra is an attractive treatment for patients presenting with clinical features of MAS because it has a relatively short half-life and is easy to administer by subcutaneous injection. In previous trials of its use in patients with clinical features of bacterial sepsis (fever, elevated heart rate, low/falling blood pressure) , it was shown that anakinra does not have a harmful effect but also did not appear to have any benefit with repect to the defined primary outcome of improved survival. However, a recent re-analysis of the data accumulated in these same previous sepsis trials (for which the primary defined outcome was survival) indicates that survival was actually increased in the subgroup of sepsis patients with features of MAS (ferritin elevations in excess of 2,000 ng/ml, signs of coagulopathy, and liver enzyme elevations) who were randomized to receive anakinra compared to the subgroup of sepsis patients with features of MAS who were randomized to receive placebo.

Previous doses of anakinra up to 3500 mg/day over 72 hours that were employed in the trials of adult patients with sepsis were noted to be well tolerated without increased adverse outcomes compared to patients randomized to placebo. Recent case reports have shown that doses up to 100 mg every 6 hours were efficacious and well tolerated in children with systemic onset juvenile arthritis complicated by refractory macrophage activation syndrome.

This study will be the first controlled study to confirm whether anakinra at dose of 10 mg/kg/day to a maximum of dose of 200 mg/day divided every 12 hours (for children ≤40 kg) or 5 mg/kg/day up to a maximum dose of 400 mg/day divided every 6 hours (children > 40 kg and adults) does not result in increased mortality or infection complications when administered in addition to current UAB standard of care treatment (corticosteroids) to children and adults hospitalized with suspected macrophage activation syndrome.