DHODH and neoplasm: Our in silico observation that the pyrimidine synthesis pathway is upregulated in myeloid progenitors in tumor-bearing mice, combined with prior reports demonstrating that inhibiting pyrimidine synthesis by targeting DHODH induces differentiation of immortalized and leukemic myeloid progenitors (45), provided a strong rationale for testing whether a DHODH inhibitor such as BRQ would suppress MDSC biogenesis.