The study will be conducted in three parts. Part 1 is a dose escalation phase to determine the maximum tolerated dose (MTD) of INCB040093, a PI3Kδ inhibitor, or a tolerated, pharmacologically active dose; Part 2 will evaluate the combination of INCB040093 and itacitinib (INCB039110), a JAK1 inhibitor, to determine the MTD of the combination or a tolerated dose that produces substantial pharmacologic inhibition of both targets; Part 3 will further evaluate the chosen doses of INCB040093 alone and in combination with itacitinib (INCB039110) in subjects with relapsed/refractory B-cell malignancies.