Vedolizumab, Anti-CD25 Antibody, Rapid Reduction of Glucocorticoids for SR-aGVHD With Gastrointestinal Involvement

Sample size: According to Simon optimal two-stage design, P0=60%, P1=80%, α=0.05, β=0.2, a sample size of 45 was chosen. Objects: Adults ages 18-65 diagnosed with grade 3-4 SR-aGVHD with lower gastrointestinal involvement. Design Participants with grade 3-4 SR-aGVHD with lower gastrointestinal involvement(progression after 3 days or lack of improvement after 5 days of 1-2 mg/kg/d systemic steroids) receive combined therapy of vedolizumab and anti-CD25 monoclonal antibody, with methylprednisolone terminated in 7-10 days. Vedolizumab is given 300mg, day 1/15/43, and then once every 8 weeks until gastrointestinal GVHD reaches grade 1 (1 episodes for minimum). Basiliximab is given 20mg twice a week for week 1, and then once a week until GVHD of the participants reaches grade 2(3 episodes for minimum). If basiliximab is not available, it can be replaced by recombinant humanized anti-CD25 monoclonal antibody injection, 50mg once with the same frequency. Methylprednisolone is reduced to 1mg/kg/d at day 1 and is aborted in 7-10 days. If chronic GVHD or overlap syndrome is considered later during treatment, steroids (ie. methylprednisolone 0.5mg/kg/d) can be administered again. Intravenous cyclosporine or tacrolimus is given and plasma concentration is monitored in a safe and effective range. Best supportive treatment is given, including broad-spectrum anti-infection, nutrition support, and blood transfusion. The investigators access the efficacy and safety of second-line therapy once a week from day 14 until complete remission is received. Then the investigators access the hematological disease status, aGVHD, cGVHD, infection state once a month.