Six Month Freedom from Treatment Failure is an Important Endpoint for Acute Graft-Versus-Host Disease Clinical Trials

We studied the ASBMT 6 month (m) freedom from treatment failure (FFTF) as a predictor of survival for patients with acute graft-versus-host disease (aGVHD) requiring treatment. Adult patients undergoing allogeneic hematopoietic cell transplant (HCT) from February 2007 to March 2009 who were enrolled in a prospective biomarker clinical trial and developed aGVHD requiring systemic corticosteroids by day +100 were included (N=44). Six month FFTF was defined per ASBMT guidelines [absence of death, malignancy relapse/progression, or systemic immunosuppression change within 6 months of starting steroids and before chronic GVHD development]. aGVHD was treated with systemic corticosteroids in 44 patients. Day 28 response after steroid initiation (CR+VGPR+PR) occurred in 38 (87%) patients, but only 28 (64%) HCT recipients met the 6 m FFTF endpoint. Day 28 response predicted 6 m FFTF. Achieving 6 m FFTF was associated with improved 2 year (y) overall survival (OS) [81% vs. 48%, P= 0.03)] and decreased 2 y non-relapse mortality [8% vs. 49% (P= 0.01)]. In multivariate analysis, 6 m FFTF continued to predict improved OS (HR, 0.27; P=0.03). The 6 m FFTF endpoint measures fixed outcomes, predicts long-term therapeutic success, and could be less prone to measurement error than aGVHD clinical response at day 28.