Fig. 5: CDK9i exhibits cytotoxic synergy with IR in HGG.

Colony focus assay images (left) and quantification (right) of HGG cultures treated with 4 nM AZD4573 (a), 6 nM NVP-2 (b), or 700 nM atuveciclib (c), IR, or in combination. Quantitative comparisons reflect p value of two-tailed Student’s t-test, mean ± SEM of n = 3 biologically independent replicates. d. Clonogenic survival for HGG cultures treated with IR alone or combination with 2 nM AZD4573, n = 3 biologically independent replicates. e. SU-DIPG4 clonogenic survival treated in combination with IR alone or in combination with 6 nM NVP-2, 700 nM atuveciclib (Atuv), or 15 nM zotiraciclib (ZTR), n = 3 biologically independent replicates. f. Brain tumor initiating cell fraction as identified by ALDH expression before and after combinatorial AZD4573 + IR treatment, n = 2 biologically independent replicates. g. Neurosphere formation efficacy (left) and relative stem cell frequency (right) by extreme limiting dilution assay following treatment with 4 nM AZD4573, IR, or combination. Comparisons reflect p value of pairwise one-sided Chi-square test for stem cell frequencies, data reflect single experiment per cell line with replicates per density in Source Data file. h. Neurosphere formation efficacy and relative stem cell frequency by extreme limiting dilution assay following CDK9 shRNA transduction compared to non-targeting control. Insert reflects p value of pairwise one-sided Chi-square test, data reflect single experiment per cell line with replicates per density in Source Data file. i. Viability of HSJD-DIPG007 cells following 4 Gy IR and ±4 nM AZD4573 treatment. Cells were modified to overexpress either WT CDK9 or D167N catalytic-inactive mutant. Quantitative comparisons reflect p value of two-tailed Student’s t-test of n = 6 biologically independent replicates, box plots display interquartile range, median, and whisker (minimum to maximum). Source data are provided as a Source Data file.