Background: Immune checkpoint inhibitors are poised to revolutionize the management of a growing number of malignancies. Unfortunately, the management of steroid-refractory immune mediated adverse events is based on a paucity of randomized data and limited to single center experiences. Our initial experience with the IL-6 receptor antagonist tocilizumab showed clinical improvement in a wide variety of irAEs. As a result, we adopted the use of tocilizumab for the management of steroid refractory irAEs.
Methods: The character and clinical course of irAEs were abstracted from the medical record and analyzed. The dose of tocilizumab was 4 mg/kg given IV over one hour. C-reactive protein was drawn at first nivolumab infusion and at q two weeks (and with irAEs) thereafter. Clinical improvement was defined as either: documentation of resolution of symptoms or hospital discharge within seven days.
Results: Of the initial 87 patients that were treated with nivolumab, 34 required tocilizumab (39.1%). All patients were on corticosteroids. The majority (88.2%) were lung cancer patients. The index grade 3/4 irAE was pneumonitis in 35.3%, serum sickness/SIRS in 35.3%, cerebritis in 14.7% and one case each of hypophysitis, colitis, pancreatitis, hepatitis and immune mediated coagulopathy. Median time between first nivolumab and initiation of tocilizumab was 76 days (range 1-429). There was a statistically significant increase in C-reactive protein from a median of 23 mg/L (range 0.1-238.5) at baseline to 109.3 mg/L (21.5-350.4) at the time of index irAE, followed by a decrease to 19.2 mg/L (0.25-149) after tocilizumab ( p < 0.00001). Clinical improvement was noted in 27/34 patients (79.4%). Some patients (52.9%) required a single dose, while 38.2% required two, 8.8% required three and 1 patient required four doses. Twenty-seven doses were given in the inpatient setting (49.1%). Median time to discharge was four days (range 1-27). Seventy-four percent of patients were discharged home. For the 53 doses of tocilizumab that were delivered when infliximab was an option, there was a cost savings of $141,048.72 (WAC) during the 18 month study period.
Conclusions: Tocilizumab may be a therapeutic option for the management of steroid refractory irAEs secondary to immune checkpoint blockade. However, randomized trials are needed to better elucidate the relative efficacy and safety of these agents.
Keywords: C-reactive protein; Immune checkpoint inhibitors; Immune mediated adverse events; nivolumab; tocilizumab.