Research conducted by Toulmonde et al. revealed that the majority of soft-tissue sarcomas (STS) and gastrointestinal stromal tumors (GIST) resistant to PD-1 blockade exhibited a substantial infiltration of M2 TAMs, which were found to express IDO (Toulmonde and Italiano, 2018). The gene discussed is IDO1; the disease is gastrointestinal stromal tumor.