LAUSR

other day for 6 doses. This was followed by a maintenance dose of 120 mg/kg IV weekly for seven weeks in responding patients. Four patients received AAT as the first therapy option after demonstrating steroid-refractory GVHD, while three patients received it as a subsequent line of treatment. The median interval between initial acute GVHD diagnosis and administration of AAT was 36 days (range 5–124 days). No adverse events related to AAT were seen. Among the seven treated patients, three had a PR at day 28; however, there were no CRs (Table 1). Six patients were evaluable for 3-month GVHD-F/A-IST-free endpoint, and none had a sustained response to AAT. One (non-evaluable) patient with PR is currently 6 weeks post therapy initiation. Four patients died due to GVHD-related complications with a median time to death post GVHD diagnosis of 138 days (Range 83–217). Over the last 2 years, several novel agents have demonstrated promise for steroid-refractory GI GVHD, however no agent has been shown to be efficacious in a randomized controlled trial. Patients with steroid-refractory GVHD often do not respond to second-line therapies, and even when they do respond, they frequently experience a flare in their disease requiring subsequent therapy as was seen in our experience with AAT. To assess durability of responses, we utilized an alternative endpoint, GVHD-F/A-IST-free, at 3 months to assess the number of patients who were still responding and free from additional therapies targeting GVHD. In the study by Mercondes et al. 33% of patients had a CR to AAT, and all patients received the drug as second line. In contrast, three out of the 7 patients in our study received AAT beyond second line and none of our patients achieved a CR with this agent alone. Additionally, all patients in our series had overall grade IIIIV disease at presentation compared to 16% (n52) in the previous study, which could be a possible reason for discrepant suboptimal activity seen in our series. It is possible the up-front application of AAT in GVHD management before steroid-refractory disease is establishment might be more beneficial. A multi-center trial evaluating AAT’s use prior to development of steroid-refractory disease is currently underway (NCT02956122), and hopefully will clarify role of this agent as frontline therapy of acute GI GVHD.