Phase 1/2a Dose Escalation Study in Participants With CLL, SLL, or NHL

This is an open-label, Phase 1/2a, multi-dose, multi-center trial of orally administered cerdulatinib assessing safety, tolerability, and pharmacokinetic (PK) parameters conducted in 2 phases: * Phase 1: Dose-escalation portion, during which participants will be enrolled to receive a single-agent cerdulatinib at their assigned dose level starting at 15 milligrams (mg) once daily (QD), administered in increasing doses until the maximum tolerated dose (MTD)/maximum administered dose (MAD) is identified. * Phase 2a: Consisting of planned cohorts based on cancer type. The participants will receive single agent cerdulatinib at a starting dose of 35, 30, or 20 mg twice daily (BID) for 28-day cycles except for one of the cohorts, the participants will receive cerdulatinib plus intravenous (IV) rituximab at 375 mg/square meter (m\^2) for 28-day cycles.