M. Allsberry1, A. Brewer3, C. Simpson1, T. Molley2, H. Sonowal1, R. White1 1University Of California – San Diego, Surgery, San Diego, CA, USA 2OxyLo Bio, San Diego, CA, USA 3Baylor University, Waco, TX, USA
Introduction:
A key conserved feature across most solid tumors is aberrant metabolism and vascularization, leading to dysregulation of oxygen levels and cellular glycolysis. Currently, multiple strategies to control tumor oxygenation are being tested to improve responses to standard-of care therapies. HypoxyCaps are microscale gas-modulating capsules, which can provide spatiotemporal control over oxygen tension both in vitro and in vivo (Fig. A). We hypothesized that local reduction in glucose and oxygen in the tumor microenvironment will lead to higher levels of cell death, paving the way for combination with chemotherapy, ablation, and/or embolization for several solid tumors.
Methods:
HypoxyCaps were fabricated using a water-in-oil emulsion system, where liquid gelatin preloaded with glucose oxidase (GOx) was added dropwise under agitation. The oil was subsequently cooled down to harden the gelatin, and the particles were then washed and coated with polymerized dopamine. The effect of HypoxyCaps on cell viability in vitro was analyzed using a colorimetric cell viability assay. A panel of human (PANC-1 and 79E), murine (KPC46 and KPC4580) pancreatic cancer cells and human (HepG2 and Hep3B) hepatocellular carcinoma cells were analyzed. Cells were trypsinized and sparsely seeded onto 96-well plates in 200 µl media (Fig. A). After 24 h, serial dilutions of HypoxyCaps in media were added to the cells, and viability was assessed at 48 h. Percentage viability was calculated compared to vehicle-treated control. Mean ± standard error of mean (SEM) data from 3 independent experiments are shown.
Results:
A concentration-dependent effect on cell viability was observed after 48 h of incubation with HypoxyCaps in all 6 cell lines tested. A 1:100 dilution of 100 U of GOx enzyme containing HypoxyCaps led to 80-90 % decrease in cell viability in all cell lines, with differentially (greater) effects seen in KPC46 and Hep3B cell lines (Fig. C, D). In vivo testing of safety and efficacy of HypoxyCaps in murine syngeneic and xenograft models as well as mechanistic studies are ongoing.
Conclusion:
In this study, HypoxyCaps were highly effective at inhibiting proliferation of pancreatic and hepatocellular carcinoma cells in vitro. This successful perturbation of local tumor oxygen and glucose levels, with subsequent cancer cell death, provides significant scope for synergy with existing systemic or locoregional therapies. HypoxyCaps have previously been shown to be stable, with observed enzymatic activity, for over a week in vivo. Future studies are aimed at combining HypoxyCaps with approved therapeutic drugs in animal models of pancreatic and hepatocellular carcinoma.