Open-label, dose-escalation study in subjects with previously treated B-cell malignancies to find maximum tolerated dose (MTD) or pharmacologic active dose of a PI3Kδ inhibitor, INCB050465, as monotherapy and in combination with: itacitinib (INCB039110), a JAK1 inhibitor; rituximab; and rituximab, ifosfamide, carboplatin, and etoposide. INCB050465 inhibits PI3Kδ, a protein involved in growth and survival of B-cell cancer cells.