Table 1 Inclusion and exclusion criteria for patient enrollment

Inclusion criteria

Age < 18 years

Receiving allo-HSCT within a year before enrollment

Signs and symptoms of BoS (dyspnea on exertion, dry cough, wheezing, pneumothorax, pneumomediastinum, and subcutaneous emphysema) [17]

Evidence of air trapping or small airway involvement in HRCT

Definite diagnosis of end-stage, steroid-refractory BoS, according to the modified NIH criteria [17]*:

 First, the FEV1/FVC or SVC must be less than 0.7 or the 5th percentile of predicted (with appropriate adjustments for pediatric or elderly individuals)

 Second, FEV1 must be less than 75% of the predicted value, with at least a 10% decline over less than 2 years

 Third, respiratory tract infections must be ruled out

 Fourth, there must be evidence of either air trapping in expiratory CT scans, or air trapping in pulmonary function tests (RV more than 120% of the predicted values or RV/TLC increased more than 90% confidence interval), or small airway thickening or bronchiectasis in HRCT

Exclusion criteria

BoS caused by any etiology other than allo-HSCT

Evidence of relapsed or progressive underlying malignant disorder

Evidence of viral, bacterial, or fungal pneumonia

HLA-haploidentical or T-cell-depleted transplantation

Known history of allergy or adverse drug reactions