Immune Checkpoint Inhibitor Trials Over the Last Decade: They Are A-Changing

Abstract

Background: Immune checkpoint inhibitor (ICI) therapy has transformed cancer treatment. However, due to a lack of comprehensive data about their characteristics, it is challenging for stakeholders to keep track of this rapidly evolving field. Methods: Here, we analyzed the characteristics of ICI trials registered on ClinicalTrials.gov between 2007 and 2017. A total of 25,907 interventional oncology studies were included. Findings: Although ICI trials accounted for only a minority (1317, 5.1%), the number of ICI trials has exploded, from 3 to 534 trials per year. Compared with other oncological trials (n = 23,590), ICI trials were more likely to be early-phase trials (phase 0 - 2, 88.0% vs. 82.1%). The proportion of trials funded by non-industry sources significantly increased from 31.9% in 2007-2015 to 62.1% in 2015-2017. At the same time, the proportion of ICI trials with a sample size of >100 patients decreased from 35.3% to 10.7% and that of trials involving multiple regions (≥2) decreased dramatically from 28.6% to 2.5%. Most ICI trials excluded patients infected with hepatitis or human immunodeficiency viruses, and this exclusion becomes more common in recent trials. An ICI was combined with other treatment modalities in 77.7% of trials, but there was significant heterogeneity in the strategy of combinations. Interpretation: Although trials evaluating ICIs exploded in the last decade, large or inter-region trials have become less common in recent years. Future investigation of ICIs in cancer patients with virus infection and the interaction between ICIs and other treatments are warranted. Funding: Guangdong Science and Technology Department, Ministry of education of the People's Republic of China, and the Natural Science Foundation of Guang Dong Province. Declaration of Interest: The authors declare that they have no conflict of interest.