Abstract 311: Ponatinib loaded leukocyte-based nanoparticles for osteosarcoma treatment in sarcosphere tumor model

Osteosarcoma (OS) is the most common pediatric bone tumor with a worldwide incidence of 3.4 cases per million people annually. Unfortunately, current treatments are still not sufficient to eradicate OS, due to its ability to resist the upfront standard chemotherapy. Therefore, it is essential to identify and effectively deliver novel therapeutic regimens. Multi-tyrosine kinase inhibitors have been explored as new therapeutics for different sarcomas. Among many, Ponatinib (Pon) demonstrated very potent anti-tumor activity, however, it received a black box warning from the FDA due to significant cardiovascular side effects. Recently, our lab developed novel biomimetic nanoparticles (NPs) called Leukosomes (Leuko) capable of encapsulating and effectively releasing Pon. These NPs are synthesized from activated leukocytes, maintaining leukocytes9 tropism towards inflamed endothelium. Leveraging on this technology, we aim to validate the therapeutic potential of Leuko in 3D OS tumor model (sarcospheres) and their ability to target primary murine OS model while concomitantly reducing the detrimental side effects. Given its biological relevance and ability to better recapitulate the tumor structure, a 3D tumor model was chosen to reproduce key properties, such as diffusion limitations and the cellular network of solid tumors that have significant impacts on cancer drug efficacy.In the sarcospheres model, we observed efficient penetration and internalization of NPs in both, murine (RF379, 577) and human PDX derived (PDX94, pPDX202) OS cell lines, where Leuko exhibited a 20% increase in targeting vs the control Liposome (Lipo). This difference was not detected in the control 2D model. Moreover, our data demonstrated a 2-fold increase in the Leuko cytotoxic effect in 3D compared to 2D systems. Murine OS cell viability was 20% lower in sarcospheres after treatment with the IC50 for Pon. In addition, NPs induced complete inhibition of murine sarcosphere formation in the extreme limiting dilution assay (ELDA). These findings were also confirmed using the PDX derived OS cell lines. Subsequently, an in vivo intratibial syngeneic orthotopic mouse model was utilized to determine the targeting and biodistribution of the NPs. Leuko showed an increased targeting and penetration in the tumor 1 and 3h post NPs injection as anticipated by the 3D in vitro studies. By exploiting the inflammatory conditions within the tumor, which increases the Leuko accumulation, these preliminary results advocate the translational potential of this innovative formulation as a new targeted drug delivery approach for OS. This promising platform could improve the clinical therapeutic approaches and lead to improved outcomes and reduced side effects for OS patients. Citation Format: Federica Giordano, Stefania Lenna, Riccardo Rampado, April Ewing, Gherardo Baudo, Matteo Massaro, Assaf Zinger, Enrica De Rosa, Jason T Yustein, Francesca Taraballi. Ponatinib loaded leukocyte-based nanoparticles for osteosarcoma treatment in sarcosphere tumor model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 311.