PDCD1 and neoplasm: Multiple protein biomarkers of response or resistance to classic chemotherapy drugs were identified: PD-1 positive tumor infiltrating lymphocytes in 25% (2/8), low ERCC1 (cisplatin sensitivity [23] in 83% (10/12), high TOPO1 (irinotecan sensitivity [24] in 63% [12/19], high TUBB3 (vincristine resistance [25] in 93% [13/14] (Fig 2F), and high MRP1 (multidrug resistance) in 100% (6/6).