Sonoporation for disrupting the pancreatic cancer microenvironment to enhance chemotherapy delivery and improve outcomes

TPS777

Background: Pancreatic ductal adenocarcinoma (PDAC) is 3% of cancers diagnosed in the United States and it is the fourth leading cause of cancer-related deaths. Hence, there is a considerable clinical need to develop innovative strategies for effective drug delivery and treatment. Sonoporation is a novel method that can enhance the therapeutic efficacy of co-administered chemotherapy by localized contrast-enhanced ultrasound imaging (CEUS) of gas-filled microbubbles (ultrasound contrast agent UCA), which temporarily changes tumor vascular microenvironment by increasing angiogenic vessel leakage through microstreaming, shockwaves and the activation of various intracellular signaling responses. Our Phase I clinical trial of sonoporation in 10 PDAC patients treated with Gemcitabine demonstrated no additional toxicity and an increase in median survival compared to 63 historical controls (8.9 vs 17.6 months; p = 0.011). Animal studies investigated 4 commercial UCAs under 2 different acoustic regimes and established the optimal UCA (Sonazoid, GE Healthcare, Oslo, Norway) as well as acoustic settings for sonoporation of PDAC. Methods: This Phase II clinical trial aims to improve standard of care (SoC) chemotherapy treatment by adding sonoporation (i.e., augmenting the SoC treatment with CEUS and microbubbles). Two sites (one in USA and one in Norway) will enroll 120 subjects with PDAC stage III or IIV prior to starting SoC chemotherapy. Exclusion criteria include known allergies to the UCA. The primary objective is to evaluate the safety and therapeutic efficacy of sonoporation on PDAC SoC treatment based on local progression-free and overall survival. Two groups: SoC chemotherapy or SoC chemotherapy followed by sonoporation. The optimal CEUS and microbubble conditions will be applied to a single PDAC tumor imaged by ultrasound. Treatment delivered day of SoC chemotherapeutic treatment for PDAC when the concentration of drugs is maximum. Gehan-Breslow-Wilcoxon test and Log-rank test will be used to compare survival. All clinical variables (e.g., concomitant imaging results, blood tests, etc.) will also be compared between groups with and without sonoporation. Clinical trial information: NCT04821284 .

Formulation and characterisation of drug-loaded antibubbles for image-guided and ultrasound-triggered drug delivery

The aim of this study was to develop high load-capacity antibubbles that can be visualized using diagnostic ultrasound and the encapsulated drug can be released and delivered using clinically translatable ultrasound. The antibubbles were developed by optimising a silica nanoparticle stabilised double emulsion template. We produced an emulsion with a mean size diameter of 4.23 ± 1.63 µm where 38.9 ± 3.1% of the droplets contained a one or more cores. Following conversion to antibubbles, the mean size decreased to 2.96 ± 1.94 µm where 99% of antibubbles were <10 µm. The antibubbles had a peak attenuation of 4.8 dB/cm at 3.0 MHz at a concentration of 200 × 10³ particles/mL and showed distinct attenuation spikes at frequencies between 5.5 and 13.5 MHz. No increase in subharmonic response was observed for the antibubbles in contrast to SonoVue®. High-speed imaging revealed that antibubbles can release their cores at MIs of 0.6. In vivo imaging indicated that the antibubbles have a long half-life of 68.49 s vs. 40.02 s for SonoVue®. The antibubbles could be visualised using diagnostic ultrasound and could be disrupted at MIs of ≥0.6. The in vitro drug delivery results showed that antibubbles can significantly improve drug delivery (p < 0.0001) and deliver the drug within the antibubbles. In conclusion antibubbles are a viable concept for ultrasound guided drug delivery.