Pseudoprogression in Previously Treated Patients with Non-Small Cell Lung Cancer Who Received Nivolumab Monotherapy.

Introduction: Nivolumab is effective in the treatment of previously treated patients with advanced NSCLC. However, its radiological evaluation is challenging because of atypical patterns of response such as pseudoprogression. We examined the characteristics and outcomes of previously treated patients with NSCLC who were treated with nivolumab and experienced development of pseudoprogression.
Methods: We conducted a 15-center retrospective cohort study of previously treated patients with advanced NSCLC who received nivolumab monotherapy. For the patients who showed pseudoprogression, we defined progression-free survival 1 (PFS1) as the time to Response Evaluation Criteria in Solid Tumors-defined first progressive disease and progression-free survival 2 (PFS2) as the time to Response Evaluation Criteria in Solid Tumors-defined second progressive disease or death.
Results: Among the 542 patients included, 20% and 53% showed a typical response and progression, respectively. Of the 14 (3%) patients who showed pseudoprogression, most (n = 10) showed a response within 3 months of nivolumab treatment. The median PFS1 and PFS2 were 1.0 and 7.3 months, respectively. The median PFS2 was significantly shorter in the patients who showed pseudoprogression than the PFS of the patients with a typical response (p < 0.001). In contrast, patients showing pseudoprogression had significantly longer overall survival than did patients showing typical progression (p = 0.001).
Conclusions: Pseudoprogression was uncommon, and the duration of response in patients who showed pseudoprogression was shorter than that in patients who showed a typical response. However, the survival benefit of pseudoprogression was markedly better than that of typical progression. Further research is required to elucidate the characteristics of and mechanisms underlying pseudoprogression.
(Copyright © 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.)