Transient Asymptomatic Pulmonary Opacities Occurring during Osimertinib Treatment

Introduction: Osimertinib is an EGFR inhibitor licensed for the treatment of EGFR-mutant, T790M-positive NSCLC. Previously unreported, frequent transient asymptomatic pulmonary opacities were noted in patients during osimertinib therapy at the University of Colorado. Methods: Computed tomography imaging and clinical notes on patients with NSCLC who had been treated with osimertinib at the University of Colorado were retrospectively reviewed. Results: Transient asymptomatic pulmonary opacities developed in seven of 20 patients (35%) while they were receiving osimertinib. The radiological patterns seen included ground glass opacities with or without nodular consolidation. The median time to development of the first lesion was 8.7 weeks (range 1.6-43 weeks), the median time to resolution during continued osimertinib was 6 weeks (range 1-11 weeks). Conclusions: Transient asymptomatic pulmonary opacities may be a previously unrecognized, benign feature associated with osimertinib therapy that may be mistaken for isolated pulmonary progression or the beginning of more severe pneumonitis. If new-onset pulmonary lesions, especially those associated with ground-glass appearances, are asymptomatic and localized and there is no evidence of disease progression elsewhere, it may be reasonable to continue treatment with osimertinib and monitor the lesions for resolution. (C) 2016 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.