Tocilizumab for the management of immune mediated adverse events secondary to PD-1 blockade

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.