Fig. 1: Regorafenib reduces neuroblastoma cell viability and xenograft tumour growth.

a Neuroblastoma cell lines (SK-N-AS, SK-N-SH, SK-N-BE(2), IMR-32, NGP, CHP-212, CHP-134 and SJ-NB-10) were treated with increasing concentrations of regorafenib for 72 h, and cell viability was measured using MTT assays. Mean average values from triplicate experiments were then plotted against regorafenib dose levels. b IC₅₀ values were calculated using curve-fit equations for each tested neuroblastoma cell line. c Images of untreated and treated neuroblastoma cells were taken at regular intervals, and representative images of untreated and treated neuroblastoma cells after 72 h are shown. d Mice with orthotopic adrenal SK-N-SH neuroblastoma xenograft tumours were treated with vehicle (n = 4) or regorafenib (n = 5). Tumour development and growth were monitored twice per week, and tumour volume was estimated using luminescent signal intensity (in p/s/cm²/sr). The arrow represents the start of regorafenib treatment, and changes in signal intensity were plotted over time (p = 0.10). e Tumours were harvested after 14 days of treatment, and representative final images for harvested tumours from untreated control and regorafenib-treated mice are shown. f Tumour weights from harvested tumours were obtained, and the average values were calculated, with significance determined by Student’s t test (p < 0.05).