Immediate effects of lumacaftor/ivacaftor administration on lung function in patients with severe cystic fibrosis lung disease.

Safety-data for lumacaftor/ivacaftor (LUM/IVA) combination therapy in patients with severe lung disease (percent predicted forced expiratory volume in 1s [ppFEV] <40) remain limited. We report immediate post-dose respiratory-related adverse events in 12 patients with severe cystic fibrosis (CF) lung disease (median [IQR] ppFEV: 34 [31-36]) prescribed LUM/IVA. All patients experienced a decline in ppFEV from baseline at 2-hours (median [IQR] relative change: -19 [-21 to -11]%, p<0.001) that persisted at 24-hours but recovered in most patients at 1-month. No pre- and post-differences in bronchodilator response were observed. Ten (83.3%) patients reported non-severe respiratory-related adverse events within 24-hours of LUM/IVA initiation. At 1-month, eight (67%) patients had persistent symptoms and six (50%) were treated for a pulmonary exacerbation. Our results highlight that LUM/IVA respiratory-related adverse events are common in patients with a ppFEV<40. We recommend close assessment of adverse events. Further studies are required to evaluate the efficacy of LUM/IVA in patients with severe lung disease.