PDCD1 and neoplasm: For immune-checkpoint inhibitors (ICIs) that target the programmed cell death 1 (PD-1) pathway, early cytokine changes (e.g., IL6, IL8) in patients after treatment can correlate with initial responses (Sanmamed et al, 2017; Tsukamoto et al, 2018a) or adverse events (Naqash et al, 2018), but less is known about whether tumor-specific secretory profile changes can be a cause or a consequence of acquired resistance (Bridge et al, 2018; Madden et al, 2020).