Supplementary Figure 1. ITPP increases O2 dissociation from hemoglobin. Supplementary Figure 2. Impact of ITPP on tumor burden, hypoxia and survival in the CT- 26/BALB model. Supplementary Figure 3. Impact of ITPP on metabolic and immune parameters in the CT- 26/BALB model at day 17. Supplementary Figure 4. Impact of ITPP on malignant tumor phenotype in the CT-26/BALB model at day 17. Supplementary Figure 5. Impact of oxygen levels and ITPP on cancer cells in vitro. One day after seeding MC-38 and CT-26 cells at hypoxia, cells were exposed or not to normoxia (A-C), or exposed to ITPP or saline (D-F) for 24h. Supplementary Figure 6. Impact of ITPP on tumor vasculature in the MC-38/B6 model at day 17. Supplementary Figure 7. Impact of ITPP on tumor vasculature in the CT-26/BALB model at day 17. Supplementary Figure 8. Long-term impact of ITPP on hypoxic response and tumor vasculature in the CT-26/BALB model.
ARTICLE ABSTRACT
Purpose: Tumor hypoxia activates hypoxia-inducible factors (Hifs), which induce a range of malignant changes including vascular abnormalities. Here, we determine whether inhibition of the hypoxic tumor response through myo-inositol trispyrophosphate (ITPP), a compound with antihypoxic properties, is able to cause prolonged vascular normalization that can be exploited to improve standard-of-care treatment.Experimental Design: We tested ITPP on two syngeneic orthotopic mouse models of lethal colorectal cancer liver metastasis. Tumors were monitored by MRI and analyzed for the hypoxic response and their malignant potential. A Hif activator and in vitro assays were used to define the working mode of ITPP. Hypoxic response and vasculature were re-evaluated 4 weeks after treatment. Finally, we determined survival following ITPP monotherapy, FOLFOX monotherapy, FOLFOX plus Vegf antibody, and FOLFOX plus ITPP, both overlapping and sequential.Results: ITPP reduced tumor load, efficiently inhibited the hypoxic response, and improved survival. These effects were lost when mice were pretreated with a Hif activator. Its immediate effects on the hypoxic response, including an apparent normalization of tumor vasculature, persisted for at least 4 weeks after treatment cessation. Compared with FOLFOX alone, Vegf antibody combined with FOLFOX prolonged survival by <30%, whereas ITPP combined with FOLFOX extended survival by >140%, regardless of whether FOLFOX was given in overlap or after ITPP exposure.Conclusions: Our findings reveal a truly antihypoxic mechanism for ITPP and demonstrate the capacity of this nontoxic compound to potentiate the efficacy of existing anticancer treatment in a way amenable to clinical translation. Clin Cancer Res; 22(23); 5887–97. ©2016 AACR.
