CCL2 and neoplasm: For instance, secreted circulating factors such as IL6, IL-1Ra, and CCL2 have been found to initially increase in patients after PD-1 pathway inhibition and correlate with tumor stabilization/shrinkage, as measured by objective response rates (ORR) (Feng et al, 2020; Li et al, 2023; Lu et al, 2019b; Murakami et al, 2016; Naqash et al, 2018; Okiyama and Tanaka, 2017; Schoenfeld et al, 2019; Yamazaki et al, 2017).