Lipophilic Poly(beta-amino ester)/poly(lactic-co-glycolic acid) blends for co-delivery of small molecules and proteins to enable locoregional combination therapy of hepatocellular carcinoma

Introduction:: Introduction: Hepatocellular carcinoma (HCC) accounts for 90% of all cases of primary liver cancers. Trans-arterial chemoembolization (TACE) is the standard of care for a subset of HCC patients that are classified as intermediate stage. In spite of the fact that TACE offers the opportunity for intra-tumoral treatment of intermediate HCC, the cargo for TACE, however, has not changed significantly over the past 20 years. Patient outcomes have not dramatically improved and 5-year survival is < 20%. Entinostat, a class I HDACi, increases tumor necrosis while rendering carcinoma cells more amendable to immune cell-mediated killing(1), in part by upregulating major histocompatibility complex I and antigen presentation. Interleukin-12 (IL-12) is a cytokine for cancer immunotherapy, converting the poorly inflamed tumor microenvironment into a functionally inflamed immune hub(2). We demonstrate that new formulations of microparticles composed of biodegradable polymer blends of anionic poly(lactic-co-glycolic acid) (PLGA) and cationic lipophilic poly(beta-amino ester) (PBAE) enable co-delivery of small molecule Entinostat and IL-12 to orthotopic HCC tumors.

Materials and Methods:: Materials and Methods: Lipophilic PBAE was synthesized by Michael Addition. Entinostat loaded polymeric microparticles were synthesized using single emulsion techniques by emulsification of the mix of poly (lactic-co-glycolic acid) (PLGA) solution in dichloromethane and PBAE in DMSO, in PVA solution. Entinostat was loaded into the microparticles by mixing the Entinostat with polymer blends before emulsification. Mouse recombinant IL-12 was adsorbed to the microparticles by mixing the IL-12 with the microparticles. Hepa-1,6 cancer cells were implanted to right lobes of C57BL/6 mice and microparticles were injected intratumorally. The tumor sizes were measured with a caliper at the beginning and end point of the treatment.

Results, Conclusions, and Discussions:: Results and Discussion: We synthesized microparticles composed of new PLGA and PBAE blends with the capability of loading small molecule drugs and proteins at a higher efficiency compared with previous PLGA/PBAE formulations. The bioengineered biodegradable microparticles enabled the delivery of Entinostat and IL-12 to orthotopic HCC tumors synergically via intratumorally injections. The PLGA/PBAE blends microparticles successfully inhibited the growth of orthotopic HCC in the 14 days treatment period.

Conclusions: A new microparticle formulation composed of a new PBAE and PLGA was developed to enable co-delivery of small molecule HDACi Entinostat and immunomodulatory cytokine IL-12. The new microparticles achieved high loading of Entinostat and IL-12 and enabled inhibition of orthotopic HCC growth.


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References (Optional): : References: (1) Hicks, K. C. et al. Clin. Cancer Res. 2020. (2) Schmudde, M. et al. Cancer Lett. 2008.