O28 - Synergistic In Vivo Therapy Using Bioengineered microRNA and Chemotherapy for High-Risk Neuroblastoma

Introduction: : Neuroblastoma is the most common extracranial solid tumor in children under the age of five, accounting for 15% of pediatric cancer deaths. High-risk neuroblastoma (HRNB) is particularly aggressive and difficult to treat, with overall survival rates of 50% despite intensive multimodal therapies. MicroRNAs (miRs), small non-coding RNAs, have emerged as important players in cancer biology. Aberrant expression of specific miRNAs has been linked to tumor initiation, progression, and resistance to therapy in neuroblastoma and other cancers. These discoveries have sparked interest in developing miRNA-based therapies. In this study, we evaluated a novel combination strategy integrating bioengineered miR therapy and conventional chemotherapeutics to improve treatment outcomes in HRNB. Using both in vitro cell assays and in vivo models, we investigated whether co-delivery of therapeutic miRNAs alongside chemotherapy could enhance anti-tumor efficacy when compared to high-dose chemotherapy alone.

Materials and

Methods: : Bioengineered miR-124-3p fused to human tRNA-glycine scaffold (miR-124) was used throughout. The combined effects of miR-124 and cisplatin chemotherapy were evaluated in vitro using MTT assay across four high-risk neuroblastoma (HRNB) cell lines: Be(2)-c, SK-N-SH, SH-SY5Y, and NB1643. Based on observed in vitro efficacy, two cell lines—Be(2)-c and SK-N-SH—were selected for in vivo studies. Each was injected subcutaneously (2 × 10⁶ cells/injection) into the right flank of NOD-scid-gamma (NSG) mice. Once tumors reached the target size, mice received intratumoral injections of miR-124 in combination with intravenous cisplatin (10mg/kg). Control groups included saline-treated mice and mice treated with cisplatin alone at two different dosages: 10 mg/kg and 20 mg/kg. Tumor growth was monitored until the study endpoint at which time mice were euthanized and necropsy performed. Blood serum analysis was also performed at study endpoint to assess for treatment toxicity.

Results, Conclusions, and Discussions:: In vitro, HRNB cell lines treated with miR-124 and cisplatin showed a significantly greater reduction in cell viability, compared to cisplatin treatment only across all concentrations. In vivo subcutaneous models of both Be(2)-c (Fig. 1A) and SK-N-SH (Fig. 1B) HRNB models showed that the combination therapy with miR-124 and cisplatin led to a marked reduction in tumor size, surpassing the efficacy of both low dose cisplatin (10mg/kg) and high dose (20mg/kg) alone, while not exhibiting any systematic toxicity. Notably, two-thirds of SK-N-SH tumors demonstrated complete tumor regression after combination therapy. In conclusion, in both in vitro and in vivo HRNB models, the combination of miR-124 and cisplatin demonstrated significantly enhanced therapeutic efficacy and suggests the potential for reducing the required chemotherapy dosage, which is particularly valuable in pediatric oncology. These promising results support the need for further investigation into miRNA-based combination therapies as a therapeutic strategy for children with HRNB.

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