Development of rational drug combinations. (A) CDI of different drug combinations with adavosertib across 4 mTCL cell lines. CDIs of adavosertib (WEE1i) with 5-azacitidine (demethylating agent), cisplatin (platinum), etoposide (topoisomerase inhibitor), olaparib (PARP inhibitor), everolimus (mTOR inhibitor), duvelisib (PI3K inhibitor), and ruxolitinib (JAK1/2 inhibitor) were calculated after 24-hour treatment. CDI values are mean values of 3 independent experiments. (B) Impact of JAK1/2 inhibition on STAT3/5 phosphorylation. Western blot data of 4 cell lines after treatment with 5 μM ruxolitinib for 24 hours. (C) Response to WEE1/JAK inhibitor combination treatment and genetic JAK/STAT signaling background of TCL cell lines. Treatment combination of the WEE1i adavosertib and JAK1/2 inhibitor (JAK1) ruxolitinib of 11 TCL cell lines showed a wide range of CDIs and an increased occurrence of activating JAK/STAT signaling alterations (single-nucleotide variants, fusions, or copy number gains), resulting in constitutive STAT3 (Tyr705) and STAT5 (Tyr694/699) phosphorylation in cells with lower CDI values. (D) Cell lines holding activating alterations of JAK1, JAK2 or JAK3 or phosphorylation of STAT3 demonstrated significantly lower CDI values than cell lines without such alterations. Significance was calculated using an unpaired 2-tailed t test. CDI values represent mean values of at least 3 independent experiments. ∗P ≤ .05, ∗∗P ≤ .01.