Pentostatin therapy for steroid-refractory acute graft versus host disease: identifying those who may benefit.

We report outcomes of 60 patients with steroid-refractory (SR)-aGVHD treated with pentostatin. Almost half (47%) of patients had grade 4 GVHD-22% had stage 3-4 liver GVHD and 51% had stage 3-4 lower gastrointestinal tract (LGI) GVHD. Patients received a median of 3 courses (range, 1-9) of pentostatin. Day 28 overall response rate (ORR) was 33% (n = 20) (complete response 18% (n = 11), partial response 15% (n = 9)). Non-relapse mortality was 72% (95% confidence interval (CI) 61-84%) and overall survival (OS) was 21% (95% CI 12-32%) at 18 months. On univariate analysis, age >60 years (HR 1.9, 95% CI 1.01-3.7, p = 0.045) and presence of liver GVHD (HR 1.9, 95% CI 1.9, 95% CI 1.5-3.3, p = 0.03) were significant predictors of poor OS while patients with LGI GVHD had superior OS than those without (HR 0.4, 95% CI 0.2-0.8, p = 0.01). On stratified analysis, patients <60 years with isolated LGI GVHD had the best outcomes with an ORR of 48% and OS of 42% at 18 months. Among older patients, OS was 14% in those with isolated LGI aGVHD and 0% in others. Pentostatin remains a viable treatment option for SR-aGVHD, especially in patients 60 years or younger with isolated LGI involvement.