High-risk neuroblastoma is an aggressive and invasive paediatric malignancy, with few actionable somatic mutations. As such, intense multi-agent chemotherapy remains the standard-of-care. We previously demonstrated that patient-specific modelling of chemotherapy-induced apoptotic signalling can stratify neuroblastoma patient cohorts and provide robust biomarkers of patient survival (Fey et al., 2015, Science Signaling). However, there is little understanding of the combined mechanism of action induced by the multi-agent chemotherapy regimens used in the clinic.
Here we have applied a network-wide, systems level approach to identify drug-specific apoptotic signalling axes which we have used to identify and define the emergence of synergy between relevant chemotherapy drug combinations. Firstly, a functional genomics screen was performed on a high content cellomics platform with a siRNA library of 200 apoptotic genes with current standard-of-care chemotherapy and preclinical drugs. Multi-dimensional analysis of this dataset elegantly demonstrated that synergy between any two chemotherapy drugs is proportional to the magnitude of divergence in apoptotic signalling between individual drugs.
The key drug-specific apoptotic signalling nodes underlying this synergy were validated using genetically incorporated fluorescent biosensors, endogenously tagging and multiplexed IF. These tools allowed us to perform high-throughput kinetic live cell analysis at the single cell resolution. Optimised drug combinations were further validated in vivo using matched PDXs of treatment naïve and relapsed tumours.
Collectively, our data has demonstrated that synergistic combinations emerge from the differential utilization of apoptotic signaling pathways by each single agent, regardless of the direct molecular target of each drug. This is contrary to the current dogma of utilising drugs with different molecular targets in combination chemotherapy. This research will therefore inform the development of precision medicine approaches with the aim to improve patient outcomes for high-risk neuroblastoma.