Study design. The first row of boxes shows the dose escalation cohort (n = 31) and the 4 dose-limiting toxicities of duvelisib (1 at 15 mg BID, 1 at 75 mg BID, and 2 at 100 mg BID). The MTD was found to be 75 mg BID. The lower 2 boxes represent the expansion cohorts (1 at 25 mg BID and 1 at 75 mg BID).