Fig. 4: p53-dependent and tumor-selective synergy of B02 with standard RB chemotherapy.

a Combination Index (CI) vs. effect (Fa) plots for two RB cell lines treated with the indicated two-drug combos of B02, topotecan (TPT), and etoposide (ETO). Turquoise and pink data points show B02 + TPT and B02 + ETO combos, respectively. The gray area delineates potent synergistic combos (CI < 0.7 and Fa > 0.7), and the green dotted line CI = 1; detailed growth inhibition curves, PARP westerns, and quantification curves are shown in Fig. S15A, B. b, c RB1021 cells were transduced with control or p53 sgRNA lentivirus, selected in puromycin, then drug-treated as indicated. Cell number (trypan blue, (b)) and apoptosis (PARP cleavage, (c)) were assessed on day 3 (n = 3, mean ± SD, *p < 0.05, **p < 0.01, ***p < 0.001 ordinary one-way ANOVA, Tukey’s multiple comparisons test; representative PARP western in Fig. S16A). d RPC or Y79 tumor cells were treated with the indicated single drugs or combo #5 from (a), and apoptosis quantified on day 3 (PARP cleavage, n = 2, mean ± range; representative PARP western in Fig. S16G). e Timeline to assess IVT B02 and/or TPT in three orthotopic RB xenograft models. f Based on day 7 data from Fig. S17A, B and plotted as dose response in Fig. S17C, subEC50 doses of B02 and TPT were selected (indicated in columns 2 and 3 of the table below the growth curves) and tested alone or together on the three indicated xenograft models (mean ± SD, *p < 0.05 two-way ANOVA, Sidak’s multiple comparisons test). DRI and CI are also indicated on the table. g Representative images of the radiance signals for the three RB tumors treated as indicated after 7 days are shown.