Comparative Analysis of Durable Responses on Immune Checkpoint Inhibitors Versus Other Systemic Therapies: A Pooled Analysis of Phase III Trials

PURPOSE Immune checkpoint inhibitors (ICIs) have been demonstrated to improve overall survival (OS) in several tumor types. Durable responses have been reported with these agents in patients with melanoma and lung cancer. We aimed to quantify the proportion of patients who experience durable responses on ICIs and to compare it with other drug classes. PATIENTS AND METHODS We retrieved published phase III randomized trials that included at least one ICI arm in the recurrent and/or metastatic setting. A durable response to treatment was defined as a progression-free survival that exceeded three times the median progression-free survival of the whole population. The proportion of patients who experienced an OS that exceeded two times the median OS of the whole patient population also was estimated. RESULTS Nineteen studies involving 11,640 patients treated in 42 treatment arms (26 ICI and 16 non-ICI arms) were included. The mean proportion of patients who experienced a durable response was 2.3 times higher in those treated with an ICI compared with those treated in the control arms (25% v 11%). Durable responses were more frequent in patients treated with anti-PD-1/PD-L1 agents than in patients treated with anti-CTLA-4 agents (28% v 18%). The mean proportion of patients who had an OS that exceeded two times the median OS was also higher in those treated with ICIs than in those treated in the control arms (30% v 23%). In multivariable analysis, the effects of treatment with anti-PD-1/PD-L1 agents and of first-line treatment were statistically associated with a higher mean proportion of durable responses. CONCLUSION Durable responses were more frequent in patients treated with ICIs, although they also occurred in patients treated with other drug classes. (C) 2019 by American Society of Clinical Oncology