DLT was defined as any of the following toxicities, possibly or probably related to cerdulatinib, and clinically significant (in the judgement of Investigator): -Febrile neutropenia (absolute neutrophil count <1000/microliter [μL] and temperature ≥38.5°Celcius). -Grade 4 neutropenia for >5 days. -Grade 4 thrombocytopenia with or without bleeding. -Grade 3 thrombocytopenia with bleeding. -Grade 4 anemia, unexplained by underlying disease. -Grade 3 or greater nausea, vomiting, or diarrhea if persistent despite optimal antiemetic or anti-diarrheal therapy. -Grade 3 or greater increase in transaminases lasting >5 days. -Grade 3 or greater fatigue persisting >7 days in absence of any other underlying cause. -Any other Grade 3 or greater non-hematologic toxicity (except fatigue as noted above) considered clinically significant by Investigator. -Toxicity of any grade resulting in dose delay of >7 days. -Toxicity resulting in study drug discontinuation prior to completion of Cycle 1.

The Safety Analysis Population included participants who received at least 1 dose of study drug. Only data from participants in Phase 1 cohorts (arms) were applicable and evaluated for this Outcome Measure. Evaluable participants for this Outcome Measure must have received 80% of doses in Cycle 1 or withdrawn from study drug due to drug-related toxicity.

CR included: -Via a positron emission tomography (PET)/computed tomography (CT) scan, score of 1 (no uptake above background), 2 (uptake of <mediastinum), or 3 (uptake of >mediastinum but <liver) for lymph nodes and extralymphatic sites; no new lesions; and no evidence of fluorodeoxyglucose (FDG)-avid disease in bone marrow. -Via CT scan, target nodes/nodal masses regressed to <1.5 centimeters (cm) in longest transverse diameter of a lesion (LDi); no extralymphatic sites of disease; organ enlargement has regressed to normal; and bone marrow was normal by morphology and if indeterminate, immunohistochemistry was negative.

PR included: -Via a PET/CT scan, score of 4 (uptake of moderately >liver) or 5 (uptake markedly higher than liver and/or new lesions) with reduced uptake compared with baseline and residual masses of any size. -Via CT scan, >50% decrease in the sum of the product of perpendicular diameters for multiple lesions of up to 6 target measurable nodes and extranodal sites.

The Efficacy Analysis Population included all participants who took at least 1 dose of study drug and had at least 1 post-baseline Investigator response assessment. Only the cohorts (arms) with participants with FL or with PTCL were applicable and evaluated for this Outcome Measure. Here, 'Number of participants analyzed' signifies participants evaluable for this outcome measure.

CR included: -Via a PET/CT scan, score of 1 (no uptake above background), 2 (uptake of <mediastinum), or 3 (uptake of >mediastinum but <liver) for lymph nodes and extralymphatic sites; no new lesions; and no evidence of FDG-avid disease in bone marrow. -Via CT scan, target nodes/nodal masses regressed to <1.5 cm in LDi; no extralymphatic sites of disease; organ enlargement has regressed to normal; and bone marrow was normal by morphology and if indeterminate, immunohistochemistry was negative.

PR included: -Via a PET/CT scan, a score of 4 (uptake of moderately >liver) or 5 (uptake markedly higher than liver and/or new lesions) with reduced uptake compared with baseline and residual masses of any size. -Via CT scan, >50% decrease in the sum of the product of perpendicular diameters for multiple lesion of up to 6 target measurable nodes and extranodal sites.

The Safety Analysis Population included participants who received at least 1 dose of study drug. Only data from participants in Phase 1 cohorts (arms) were applicable and evaluated for this Outcome Measure.

Clinical benefit was defined as achieving stable disease (SD) or better, as assessed by the Investigator. SD included: -Via a PET/CT scan, a score of 4 (uptake of moderately >liver) or 5 (uptake markedly higher than liver and/or new lesions) with no significant change in FDG uptake from baseline at interim or end of treatment; no new lesions; and no change from baseline in bone marrow. -Via CT scan, <50% decrease from baseline in sum of products of the greatest perpendicular diameters (SPD) of up to 6 dominant, measurable nodes and extranodal sites; no increase consistent with progression in nonmeasured lesions or organ enlargement; and no new lesions.

The Safety Analysis Population included participants who received at least 1 dose of study drug. Only data from participants in Phase 1 cohorts (arms) were applicable and evaluated for this Outcome Measure.

An AE is any untoward medical occurrence, which may or may not have a causal relationship to the study drug, including: unfavorable and unintended sign, symptom, or disease temporally associated with the use of the study drug; any newly occurring event or exacerbation of previous condition (for example, increase in severity or frequency) since the administration of study drug; recurrence of an intermittent medical condition not present at baseline; any deterioration in a laboratory value or other clinical test that is associated with symptoms or leads to a change in study treatment or concomitant treatment or discontinuation from study drug; and AEs related to a study intervention. An SAE is an AE that is fatal, is life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, or a congenital anomaly/birth defect.

The Safety Analysis Population included participants who received at least 1 dose of study drug.

The Pharmacokinetic Analysis Population consisted of all participants who received the requisite treatments and have data at the required timepoints. Only data from participants in Phase 1 cohorts (arms) were applicable and evaluated for this Outcome Measure. Here, 'Number of participants analyzed' signifies participants evaluable for this outcome measure and 'Number Analyzed' signifies participants evaluable at specified timepoints.

PFS=(first documentation of disease progression [DP] or death [whichever occurred first]-study drug first dose date+1)/30.4375 in months. PFS right censored for 1 of these conditions: 1) no baseline disease assessments; 2) starting new anticancer therapy before documented DP/death; 3) DP/death immediately after >6 months since last disease assessment (or >12 months if after last cycle); & alive without documented DP. 95% confidence interval estimated using Brookmeyer method. DP included: -Via a PET/CT scan, score of 4 (uptake of moderately >liver) or 5 (uptake markedly higher than liver and/or new lesions) with uptake increase in intensity, new FDG-avid foci, & no nonmeasured lesions. -Via CT, abnormal individual node/lesion with significant LDi or shortest axis perpendicular to LDi increase; prior splenomegaly, >50% splenic length increase; if no prior splenomegaly, ≥2 cm splenic length increase; new or recurrent splenomegaly; new/clear progression of preexisting nonmeasured lesions.

The Efficacy Analysis Population included all participants who took at least 1 dose of study drug and had at least 1 post-baseline Investigator response assessment. Only the cohorts (arms) with participants with FL or with PTCL were applicable and evaluated for this Outcome Measure. Here, 'Number of participants analyzed' signifies participants evaluable for this outcome measure.

Clinical benefit was defined as achieving SD or better, as assessed by the Investigator. SD included: -Via a PET/CT scan, a score of 4 (uptake of moderately >liver) or 5 (uptake markedly higher than liver and/or new lesions) with no significant change in FDG uptake from baseline at interim or end of treatment; no new lesions; and no change from baseline in bone marrow. -Via CT scan, <50% decrease from baseline in sum of products of the greatest perpendicular diameters (SPD) of up to 6 dominant, measurable nodes and extranodal sites; no increase consistent with progression in nonmeasured lesions or organ enlargement; and no new lesions.

The Efficacy Analysis Population included all participants who took at least 1 dose of study drug and had at least 1 post-baseline Investigator response assessment. Only the cohorts (arms) with participants with FL or with PTCL were applicable and evaluated for this Outcome Measure. Here, 'Number of participants analyzed' signifies participants evaluable for this outcome measure.

DMR was defined as achieving a ≥50% decrease from baseline in the SPD of the target nodal and extranodal lesions. SPD at a visit was considered missing if any target lesion was not evaluated.

The Efficacy Analysis Population included all participants who took at least 1 dose of study drug and had at least 1 post-baseline Investigator response assessment. Only the cohorts (arms) with participants with FL or with PTCL were applicable and evaluated for this Outcome Measure. Here, 'Number of participants analyzed' signifies participants evaluable for this outcome measure.