Introduction: Neuroblastoma is the most frequent pediatric extracranial solid tumor being responsible for 8-10% of all childhood malignancies. Patient outcome is still a major issue due to neuroblastoma’s heterogeneity and complex tumor biology.^1,2 Nanotechnology has been widely studied in cancer treatment with the aim of improving the therapeutic index of chemotherapeutic drugs.³ Among them, etoposide is a podophyllotoxin derivative given to neuroblastoma patients that often presents acute and late toxicities.⁴ In this study we have designed and characterized etoposide-loaded lipid nanoparticles (ETP-LN) with the aim of improving therapeutics in neuroblastoma management.

Methods: ETP-LN were prepared by the hot homogenization followed by ultrasonication method which does not involve the use of any organic solvent.⁵ Nanoparticles physiochemical properties were characterized (size, homogeneity, surface charge) by dynamic light scattering and drug loading was evaluated by UV-vis and UHPLC-UV methods. Cell viability studies (MTS assay) were performed in multiple human neuroblastoma cell lines: SK-N-BE (2), SK-N-BE(2)C and NGP-A (MYCN-amplified cells) and SH-SY5Y, CHLA-90, NBL-S and SK-N-SH (MCYN-non-amplified cells).

Results: Optimized ETP-LN showed a mean particle diameter of 105 ± 3.29 nm with a PDI value of 0.19±0.01, indicating homogenous particle distribution. The surface charge presented a negative zeta potential value of -19.9 ± 4.24 mV. UHPLC-UV showed better reproducibility than the UV-vis method. Nevertheless, both techniques indicated a similar drug loading (4.26 ± 0.18 µg/mg and 4.58 ± 0.60 µg/mg, respectively), corresponding to an encapsulation efficiency of 86.8 + 4.16 %. Preliminary in vitro cell-based cytotoxicity assay revealed that ETP-LN displayed similar IC₅₀ values in the studied cell lines when compared to the free drug, indicating that the encapsulation process did not affect etoposide’s antitumor efficacy.

Conclusions: ETP-LN were successfully developed and characterized. Further experiments in vitro and in vivo will be performed to evaluate the therapeutic potential of ETP-LN in neuroblastoma.

References:

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3. Rodríguez-Nogales, C., Gonzaíez-Ferna, Y., Aldaz, A., Couvreur, P. & Blanco-Prieto, M. J. Nanomedicines for Pediatric Cancers. (2018).
4. Relling, M. V. et al. Etoposide and antimetabolite pharmacology in patients who develop secondary acute myeloid leukemia. Leukemia 12, 346–352 (1998).
5. González-Fernández, Y., Brown, H. K., Patiño-García, A., Heymann, D. & Blanco-Prieto, M. J. Oral administration of edelfosine encapsulated lipid nanoparticles causes regression of lung metastases in pre-clinical models of osteosarcoma. Cancer Lett. 430, 193–200 (2018).