Tumoral oxygenation and biodistribution of Lonidamine oxygen microbubbles following localized ultrasound-triggered delivery.

Prior work has shown that microbubble-assisted delivery of oxygen improves tumor oxygenation and radiosensitivity, albeit over a limited duration. Lonidamine (LND) has been investigated because of its ability to stimulate glycolysis, lactate production, inhibit mitochondrial respiration, and inhibit oxygen consumption rates in tumors but suffers from poor bioavailability. The goal of this work was to characterize LND-loaded oxygen microbubbles and assess their ability to oxygenate a human head and neck squamous cell carcinoma (HNSCC) tumor model, while also assessing LND biodistribution. In tumors treated with surfactant-shelled microbubbles with oxygen core (SE61O) and ultrasound, pO levels increased to a peak 19.5 ± 9.7 mmHg, 50 s after injection and returning to baseline after 120 s. In comparison, in tumors treated with SE61O/LND and ultrasound, pO levels showed a peak increase of 29.0 ± 8.3 mmHg, which was achieved 70 s after injection returning to baseline after 300 s (p < 0.001). The co-delivery of OandLNDvia SE61 also showed an improvement of LND biodistribution in both plasma and tumor tissues (p < 0.001). In summary, ultrasound-sensitive microbubbles loaded with O and LND provided prolonged oxygenation relative to oxygenated microbubbles alone, as well as provided an ability to locally deliver LND, making them more appropriate for clinical translation.