The time-to-first attack of acute exacerbation during systematic immunosuppression for chronic GVHD (n=78): The probability of free from first, second, and third episode of acute exacerbation of chronic GVHD at 2 years was estimated as 23.4±5.3%, 53.6±6.6%, and 75.1±6.4%, respectively (A), GVHD-specific survival between the group with or without acute exacerbation during systematic immunosuppression for chronic GVHD (B)