GZMA and neoplasm: We further evaluated other genomic-pathologic features associated with immune cell abundance such as tumor purity [21], total mutation burden, CYT activity score (i.e., the geometric mean of the expression of PRF1 and GZMA) [22], TCR richness (i.e., the number of T-cell clones with unique TCRs) [18], expression-based estimates of immune cells and stromal cells [23], and expression levels of immune checkpoints of PD-L1 and CTLA-4, as shown in Figure 2a.