Sustained-hepatic arterial infusion of oxaliplatin: pharmacokinetic advantages over hepatic arterial infusion using a preclinical animal tumour model.

Hepatic arterial infusion (HAI) of oxaliplatin allows greater liver tumour drug exposure compared to systemic infusion. However, the therapeutic index of HAI oxaliplatin remains poor. Using Pickering emulsion technology, we developed a platform able to provide sustained releases of oxaliplatin. The goal of this study was to evaluate the pharmacokinetic advantages of sustained-HAI oxaliplatin over HAI using a preclinical animal tumour model. Injections of 0.6 mg oxaliplatin in 20 min were selectively done in left hepatic arteries of 20 rabbits bearing a VX2 liver tumour in the middle left-lobe, using HAI (n = 10) or sustained-HAI (n = 10). In each group, half of the rabbits were sacrificed at 24 h and half at 72 h. Mass spectrometry was used to quantify drug pharmacokinetics in blood and oxaliplatin concentrations in tumour tissues, right- and middle left-liver lobes, spleen and lung. Compared to HAI, sustained-HAI of oxaliplatin resulted in lower plasmatic peak (Cmax: 275 ± 41 vs. 416 ± 133 ng/mL, p = 0.02) and higher concentration in the tumour at 24 h (2118 ± 2107 vs. 210 ± 93 ng/g, p = 0.008). After HAI, oxaliplatin concentration in tumours was significantly higher than in lung at 24 h (p = 0.03) but no other difference was found between oxaliplatin concentrations in tumours and in liver lobes, spleen or lung, neither at 24 h nor at 72 h. On the opposite, sustained-HAI resulted in higher concentrations of oxaliplatin in tumour compared to oxaliplatin concentrations in the middle left lobe (163 ± 86 ng/g at 24 h, p = 0.01, and 90 ± 15 ng/g at 72 h, p = 0.04), right lobe (174 ± 112 ng/g at 24 h, p = 0.01, and 112 ± 35 ng/g, p = 0.04 at 72 h), spleen (142 ± 21 ng/g at 24 h, p = 0.01, and 98 ± 12 ng/g at 72 h, p = 0.04), and lung (85 ± 11 ng/g at 24 h, p = 0.01, and 52 ± 4 ng/g at 72 h, p = 0.03). Sustained-HAI improves the therapeutic index of HAI oxaliplatin and offers a great potential for patients suffering from unresectable colorectal liver metastases or hepatocellular carcinoma.

Pickering emulsions with ethiodized oil and nanoparticles for slow release of intratumoral anti-CTLA4 immune checkpoint antibodies.

BACKGROUND: Intratumorous immunotherapy for cancer is currently thriving. The aim of such local strategy is to improve the therapeutic index of these treatments, for higher on-target/on-tumor activity and less on-target/off-tumor adverse events. Strategies allowing for slow release of anti-CTLA4 in the tumor microenvironment could improve their clinical efficacy.The purpose of the study was to develop a radiopaque delivery platform to improve the targeting and exposure of intratumorous anti-CTLA4 antibodies for cancer immunotherapy. METHODS: Pickering emulsions of anti-CTLA4 antibodies were formulated with radiopaque ethiodized oil and poly-lactic-co-glycolic acid (PLGA) nanoparticles. We characterized the microscopic aspect and stability of such emulsions using Turbiscan. We monitored the release of anti-CTLA4 over time from these emulsions and evaluated their structure using mass spectrometry. We then tested the functionality of the released antibodies by preforming ex vivo competitive binding assays. Finally, we assessed the in vivo efficacy of intratumorous anti-CTLA4 Pickering emulsions. RESULTS: Pickering emulsions of ethiodized oil and PLGA nanoparticles (PEEPs) resulted in a radiopaque water-in-oil emulsion with average internal phase droplet size of 42±5 µm at day 7. Confocal microscopy showed that anti-CTLA4 antibodies were effectively encapsulated by ethiodized oil with PLGA nanoparticles located at the interface between the aqueous and the oily phase. Turbiscan analysis showed that emulsions were stable with continuous and progressive release of anti-CTLA4 antibodies reaching 70% at 3 weeks. Structural and functional analysis of the released antibodies did not show significant differences with native anti-CTLA4 antibodies. Finally, intratumorous anti-CTLA4 PEEPs were able to eradicate tumors and cure mice in a syngeneic immunocompetent preclinical tumor model. CONCLUSION: Pickering emulsions of ethiodized oil and PLGA is an innovative radiopaque delivery platform that does not alter the functionality of anti-CTLA4 immune checkpoint antibodies. Beyond local anti-CTLA4 applications, these emulsions might be used with other therapeutic molecules for optimal intratumorous or intra-arterial delivery of novel cancer immunotherapies.

Biodegradable Pickering emulsions of Lipiodol for liver trans-arterial chemo-embolization.

Water-in-oil (W/O) Lipiodol emulsions remain the preferable choice for local delivery of chemotherapy in the treatment of hepatocellular carcinoma. However, their low stability severely hampers their efficiency. Here, remarkably stable W/O Lipiodol emulsion stabilized by biodegradable particles was developed thanks to Pickering technology. The addition of poly(lactide-co-glycolide) nanoparticles (NPs) into the aqueous-phase of the formulation led to W/O Pickering emulsion by a simple emulsification process through two connected syringes. Influence of nanoparticles concentration and water/oil ratio on emulsion stability and droplet size were studied. All formulated Pickering emulsions were W/O type, stable for at least one month and water droplets size could be tuned by controlling nanoparticle concentration from 24 µm at 25 mg/mL to 69 µm at 5 mg/mL. The potential of these emulsions to efficiently encapsulate chemotherapy was studied through the internalization of doxorubicin (DOX) into the aqueous phase with a water/oil ratio of 1/3 as recommended by the medical community. Loaded-doxorubicin was released from conventional emulsion within a few hours whereas doxorubicin from stable Pickering emulsion took up to 10 days to be completely released. In addition, in vitro cell viability evaluations performed on the components of the emulsion and the Pickering emulsion have shown no significant toxicity up to relatively high concentrations of NPs (3 mg/mL) on two different cell lines: HUVEC and HepG2. STATEMENT OF SIGNIFICANCE: We present an original experimental research in the field of nanotechnology for biomedical applications. In particular, we have formulated, thanks to Pickering technology, a new therapeutic emulsion stabilized with biodegradable PLGA nanoparticles. As far as we know, this is the first therapeutic Pickering emulsion reported in the literature for hepatocellular carcinoma. Such a new emulsion allows to easily prepare a predictable and stable lipiodolized emulsion having all the required characteristics for optimum tumor uptake. As demonstrated throughout our manuscript, emulsions stabilized with these nanoparticles have the advantage of being biodegradable, biocompatible and less toxic compared to usual emulsions stabilized with synthetic surfactants. These findings demonstrate the plausibility of the use of Pickering emulsions for chemoembolization as a therapeutic agent in extended release formulations.

Pickering-Emulsion for Liver Trans-Arterial Chemo-Embolization with Oxaliplatin.

PURPOSE: Biodegradable polylactic-co-glycolic acid (PLGA) nanoparticles can adsorb at the water/oil interface to stabilize the emulsion (forming Pickering-emulsion). The purpose of this study was to compare the release profiles of oxaliplatin from Pickering-emulsion and Lipiodol-emulsion. MATERIALS/METHODS: Pickering-emulsions and Lipiodol-emulsions were both formulated with oxaliplatin (5 mg/mL) and Lipiodol (water/oil ratio: 1/3). For Pickering-emulsion only, PLGA nanoparticles (15 mg/mL) were dissolved into oxaliplatin before formulation. In vitro release of oxaliplatin from both emulsions was evaluated. Then, oxaliplatin was selectively injected into left hepatic arteries of 18 rabbits bearing VX2 liver tumors using either 0.5 mL Pickering-emulsion (n = 10) or 0.5 mL Lipiodol-emulsion (n = 8). In each group, half of the rabbits were killed at 1 h and half at 24 h. Mass spectrometry was used to quantify drug pharmacokinetics in blood and resulting tissue (tumors, right, and left livers) oxaliplatin concentrations. RESULTS: Pickering-emulsion demonstrated a slow oxaliplatin release compared to Lipiodol-emulsion (1.5 ± 0.2 vs. 12.0 ± 6% at 1 h and 15.8 ± 3.0 vs. 85.3 ± 3.3% at 24 h) during in vitro comparison studies. For animal model studies, the plasmatic peak (Cmax) and the area under the curve (AUC) were significantly lower with Pickering-emulsion compared to Lipiodol-emulsion (Cmax = 0.49 ± 0.14 vs. 1.08 ± 0.41 ng/mL, p = 0.01 and AUC = 19.8 ± 5.9 vs. 31.8 ± 14.9, p = 0.03). This resulted in significantly lower oxaliplatin concentrations in tissues at 1 h with Pickering-emulsion but higher ratio between tumor and left liver at 24 h (43.4 vs. 14.5, p = 0.04). CONCLUSION: Slow release of oxaliplatin from Pickering-emulsion results in a significant decrease in systemic drug exposure and higher ratio between tumor and left liver oxaliplatin concentration at 24 h.