Characterizing immune-mediated adverse events with durvalumab in patients with unresectable stage III NSCLC: A post-hoc analysis of the PACIFIC trial

Abstract

Introduction Immune-mediated adverse events (imAEs), including all-cause immune-mediated pneumonitis, were reported in approximately 25% of patients in the placebo-controlled, phase III PACIFIC trial of durvalumab monotherapy (for up to 12 months) in patients with unresectable, stage III NSCLC and no disease progression after concurrent chemoradiotherapy; only 3.4% of patients experienced grade 3/4 imAEs. With broad application of the PACIFIC regimen (consolidation durvalumab after chemoradiotherapy), now standard-of-care in this setting, there is a need to better characterize the occurrence of imAEs with this regimen. Methods We performed descriptive, post-hoc, exploratory analyses to characterize the occurrence of imAEs (pneumonitis and non-pneumonitis) in PACIFIC in terms of: incidence, severity, and timing; clinical management and outcomes; and associations between the occurrence of imAEs and (1) all-cause AEs and (2) baseline patient, disease, and treatment characteristics. Results Any-grade immune-mediated pneumonitis (9.4%) and non-pneumonitis imAEs (10.7%) occurred infrequently and were more common with durvalumab versus placebo. Grade 3/4 immune-mediated pneumonitis (1.9%) and non-pneumonitis imAEs (1.7%) were uncommon with durvalumab, as were fatal imAEs (0.8%; all pneumonitis). The most common non-pneumonitis imAEs with durvalumab were thyroid disorders, dermatitis/rash, and diarrhea/colitis. Dermatitis/rash had the shortest time to onset (from durvalumab initiation), followed by pneumonitis; dermatitis/rash had the longest time to resolution, followed by thyroid disorders. Most patients with immune-mediated pneumonitis (78.4%) and non-pneumonitis imAEs (56.3%) had these events occur ≤ 3 months after initiating durvalumab. ImAEs were well managed with administration of systemic corticosteroids, administration of endocrine replacement therapy, and interruption/discontinuation of durvalumab. Time elapsed from completion of prior radiotherapy to trial randomization (<14 vs. ≥ 14 days) did not impact either incidence or severity of imAEs. Durvalumab had a manageable safety profile broadly irrespective of whether patients experienced imAEs. Conclusion The risk of imAEs should not deter use of the PACIFIC regimen in eligible patients, as these events are generally well managed through appropriate clinical intervention.