STAT3 and neoplasm: They collectively adopt different mechanisms for MDSCs inhibition: (i) deactivation (PDE5, histone deacetylase, NO inhibitors, Arginase inhibitors, ROS inhibitors, STAT3 inhibitors) (ii) inhibition of recruitment at the site of tumor (CCR5 antagonist, CCL2 inhibitor) (iii) differentiation (ATRA, Vitamin A, D3) (iv) Regulation of myelopoiesis and depletion (Tyrosine kinase inhibitors, cytotoxic agents, anti Hsp90) (107, 114, 115).