Nano ZSA-51D

Nano ZSA-51D is a systemically administered immunotherapy candidate consisting of a novel non-nucleotide STING (Stimulator of Interferon Genes) agonist dimer, ZSA-51D, encapsulated within albumin nanoparticles. Developed by researchers at the University of Michigan, this formulation is designed to overcome the limitations of traditional STING agonists by improving systemic delivery and targeting. The nanoparticle formulation specifically accumulates in the bone marrow, where it is absorbed by neutrophils. This leads to the activation of the STING pathway in these cells, triggering their infiltration into the tumor microenvironment. Once inside the tumor, the activated neutrophils enhance antigen presentation via MHC class I and promote the proliferation and activation of T cells. Preclinical studies presented at AACR 2025 demonstrated that Nano ZSA-51D, particularly when combined with anti-PD-1 therapy, achieves complete remission in colon cancer models and robust anti-cancer effects in pancreatic cancer models.