Fig. 4: Combination treatment induces tumour regression and suppresses the relapse in vivo.
a,b Induction of apoptosis by the combination of ALK inhibitors and the Nutlin-3 derivative RG7112 in ALK-driven neuroblastoma cells. NB39-nu cells (a) and NB1 cells (b) were treated with the indicated combinations of the ALK inhibitors and RG7112 for 48 h and subjected to a CytoTox GLO assay. The data are shown as mean ± SD (n = 3). These experiments were repeated at least three times. c Scheme used for the in vivo experiments. NB1 cells were injected subcutaneously into nude mice and drugs were orally administrated for 14 days every day after tumour formation (>90 mm3). Tumour volumes were measured three times a week. d, e Suppression of tumour growth by combination treatment with alectinib and RG7112. The relative tumour volumes are shown in graph (d). The data show the mean ± SEM *p < 0.05. The incidence of tumour regression (relative tumour volume at day 14 was lower than day 0) are summarised in e. f Detection of increased apoptosis in tumour sections from animals treated with the combination of alectinib and RG7112, as assayed by immuno-staining using an anti-cleaved caspase 3 antibody. For comparison, haematoxylin–eosin staining of the tumour sections are shown on the left. The scale bar indicates 100 µm. g Prevention of tumour relapse by combination treatment with alectinib and RG7112. The relative tumour volumes after ceasing oral administration of drugs are shown in the graph. The data shown are the mean ± SEM *p < 0.05 (Wilcoxon rank-sum test)
