Tocilizumab In The Treatment Of Steroid Refractory Graft Versus Host Disease: A Single Institutional Experience

Acute graft-versus-host-disease (aGVHD) is a frequent and often lethal complication of allogeneic hematopoeitic stem cell transplant (allo HSCT) despite current prophylactic regimen. It is fueled by the release of pro-inflammatory cytokines such as interleukin-6 (IL-6), leading to damage of host tissues. Front-line treatment with glucocorticoids provide 30-40% complete response. Tocilizumab is a humanized anti-IL-6 receptor (IL-6R) monoclonal antibody that binds to both soluble and membrane-expressed IL-6R, inhibiting IL-6–mediated proinflammatory activity. A case report and a recent small series (8 patients) with steroid refractory GVHD(SR GVHD) showed encouraging single agent activity of tocilizumab(Gergis et al, 2010; Drobyski et al, 2011). We report our experience on 9 patients who had SR aGVHD and received tocilizumab therapy.

Tocilizumabwas administered intravenously at a dose of 8 mg/kg every 2 to 3 weeks. aGVHD grading and responses were based on consensus criteria (Przepiorka et al, 1995). Patients were monitored for toxicities and infections.

The median age at transplant was 48 years (range 25-61). Four patients had double cord allo HSCT, 2 had matched related, 2 unrelated (with one 9/10 matched) and 1 haploidentical after a failed cord HSCT. Six patients had received myeloablative and 3 reduced intensity allo HSCT. All but one patient received tacrolimus and methotrexate for aGVHD prophylaxis, and all were in complete remission of their underlying disease at time of aGVHD. Table 1 includes responses and outcomes to tocilizumab therapy. All patients had GI involvement and 6 patients had two organs involved. Median aGVHD grade was 3 (range 3-4). The median time from first aGVHD onset to tocilizumab administration was 44 days (range 14-176). The median number of infusions was 2(1-6). There were no allergic or infusion-related events. Two patients (22%) had a complete response (CR), and two had mixed responses with CR in one organ, but no response in another. Only one of nine patients survived. Six patients (67%) died from aGVHD and its complications, one from CMV and one from septic shock. The median survival from start of tocilizumab was 26 days (range 13-759).

While the few tocilizumab treated patients with SR aGVHD reported in the literature have experienced a high response rate of 67%(CR and PR), our limited experience showed a less impressive 22% CR. Although tocilizumab has some activity in the treatment of SR aGVHD, it may not be significantly better than other available agents.

Off Label Use: There is currently no standard of practice of steroid-refractory GVHD, every treatment option besides steroids are considered off-label. However, there is evidence to support its use. Tocilizumab Tocilizumab is a humanized anti–IL-6 receptor (anti–IL-6R) monoclonal antibody that binds both soluble and membrane-expressed IL-6R, inhibiting IL-6–mediated proinflammatory activity. In this study, we report our experience with the administration of tocilizumab, an anti-interleukin 6 receptor antibody, in the treatment of steroid refractory GVHD.