In Phase A, participants will receive diverse doses and schedules of oral ABBV-744 tablet to detect Risk-free dosing program. Additional individuals will be enrolled on the determined monotherapy dosign regimen. In Section B, participants will obtain oral ruxolitinib and ABBV-744 are going to be offered as "incorporate-on" therapy. In Section https://abbv-744-for-small-cell-l13467.csublogs.com/38788364/what-does-new-advancements-in-brd4-inhibition-therapy-abbv-744-mean