Part 1, Dose Escalation, is comprised of 3 dosing cohorts of 6 subjects each. Acalabrutinib dosing is fixed in all cohorts at 100 mg PO twice daily (BID). In addition to acalabrutinib, subjects in Cohort 1 will receive ACP-319, 25 mg BID; Cohort 2 will receive ACP-319, 50 mg BID: and Cohort 3 will receive ACP-319 100 mg BID. The maximum tolerated dose (MTD) of the study treatment combination will be determined by assessing dose-related toxicities (DLTs) for each cohort at the end of Cycle 1 prior to dose escalation. If there are greater than or equal to 2 DLTs in a cohort, dose escalation will not occur and the MTD will be the highest daily dose for which less than 33% of the subjects in that cohort experienced DLTs in Cycle 1.
Part 2, Dose Expansion, includes 12 subjects per histology, dosing at the MTD for the combination of acalabrutinib and ACP-319 established in Part 1. Subjects will continue dosing until disease progression or unacceptable drug-related toxicity.
