Flash Talk & E-Poster - Virtual Presentation 33rd Lorne Cancer Conference 2021

MicroRNA-based therapeutics for the treatment of high-risk neuroblastoma  (#23)

Holly Holliday 1 , Eoin Dodson 2 , Iva Nikolic 3 , Niantao Deng 1 , Kaylene Simpson 3 , Alvin Kamili 4 , Madeleine Wheatley 4 , Joshua Mccarroll 4 , Pieter Mestdagh 5 , Glenn Marshall 4 , Jamie Fletcher 4 , Alex Swarbrick 1
  1. Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
  2. The Australian Proteome Anaysis Facility, Sydney, NSW, Australia
  3. Victorian Centre for Functional Genomics, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
  4. Children's Cancer Institute, Lowy Cancer Research Centre, UNSW, Sydney, NSW, Australia
  5. UGent, Belgium

Background

Neuroblastoma is a deadly childhood cancer arising in the developing sympathetic nervous system. High-risk patients are currently treated with intensive multi-layered chemotherapy which is not always curative and leaves surviving patients with life-long side effects. miRNA-based drugs represent an exciting new class of cancer therapeutic.

 

Aims

We aim to screen and validate miRNAs that sensitise neuroblastoma cells to chemotherapy in vitro, dissect their mechanism, and test candidate therapeutic miRNAs in pre-clinical models of high-risk neuroblastoma.

 

Methods

An extensive functional genomic screen of >1200 miRNA mimics was conducted in neuroblastoma cell lines to discover miRNAs with therapeutic potential. This was performed in combination with low doses (IC30) of doxorubicin and vincristine chemotherapies. Selected candidates are tested in the COG-N-519 patient-derived xenograft (PDX) model, originating from a patient with high-risk disease. Star-POEGMA nanoparticles are used to deliver candidate miRNAs in combination with chemotherapy. Mechanistic experiments assess miRNA uptake and their impact on gene expression, and therapeutic experiments are used to monitor the impact on tumour growth and survival.

 

Results

Three miRNAs (miR-99b-5p, miR-380-3p and miR-485-3p) had potent synthetic lethal interaction with doxorubicin in vitro, specifically in models of high-risk disease. Analysis of a clinical cohort revealed that these miRNAs are possible tumour suppressors as they undergo recurrent copy number loss, and low expression predicts poor outcome. Encouragingly, miR-99b-5p could be effectively delivered (40-fold overexpression) to PDX tumours. RNA-seq analysis revealed downregulation of neuroblastoma dependency genes LIN28B and PHOX2B in miR-99b-5p-treated tumours and luciferase reporter assays demonstrated that PHOX2B is a direct target of miR-99b-5p.

 

Conclusions

We have identified novel chemosensitising miRNAs specific to high-risk neuroblastoma that can be administered in vivo to drive favourable gene expression changes, including downregulation of LIN28B and PHOX2B, which are notoriously difficult to target with small molecules. If effective in longer term preclinical studies, we predict that restoring the function of tumour suppressive miRNAs represents an attractive new therapeutic strategy for the treatment of neuroblastoma patients.