Preclinical activity of brincidofovir in Peripheral T-cell and NK/T-cell Lymphoma

Results: BCV demonstrated potent anti-tumor activity in vitro across the majority of cell-lines regardless of EBV positivity, with IC50 values within clinically-achievable human plasma concentrations (2 µg/ml) in 17/25 (68.0%) T/NK-NHL and in 13/19 (68.4%) BCL. In vivo treatment via intraperitoneal BCV (IP, 40mg/kg, 2X per week) significantly inhibited tumor growth in all xenograft models when compared to vehicle control.

Notably, RNAseq analysis demonstrated BCV downregulated MYC and MYC-target pathways in T/NK-NHL models. Further mechanistic studies showed that BCV evoked S-phase cell cycle arrest, replication stress, DNA damage and apoptosis, while also triggering STING pathway-mediated interferon responses, PD-L1 expression and immunogenic cell death. In the syngeneic EL4-C57BL/6 model, BCV in combination with anti-PD1 significantly inhibited tumor growth and triggered an immune reaction characterized by highest scores for adaptive immune response, cytokines/chemokines & receptors, cytotoxic cells, dendritic cells, NK CD56dim cells and neutrophils (NanoString Immunology Panel).