PARPi potentiates TMZ therapy in conventional GBM cell lines on serum-supplemented medium. A) Viability of T98 and U373 cell lines treated at the indicated doses with TMZ and PARPi. Viability is indicated as a measure of ATP conversion into luminescence. Lines above columns indicate significance between two conditions with a p-value <0.05. If monotherapy with TMZ is significant when compared to non-treated controls, the significance of combination therapy when compared to non-treated controls is related and therefore not defined as such in the figure. B) Viability as a measure of confluence per well as measured by microscopy. Read out is performed at 5 days post treatment. C) Microscopic images of U373 and T98. From left to right the PARPi dosage increases from 0 to 10 uM. Lower panel depicts combination therapy with TMZ at indicated dosages. Note the differential effect of PARPi monotherapy between T98 and U373. D) Combination Index (CI) plotted against Fraction affected (Fa) for T98 and U373. PARPi with TMZ combination therapy is synergistic in T98 but not in U373. CI < 1 demonstrates synergistic interaction of combination therapy with TMZ and PARPi at the indicated Fa. CI > 1 demonstrates antagonistic effect of combination therapy at the indicated Fa.