A Study of AZD0486 in Subjects With B-Cell Non-Hodgkin Lymphoma

Inclusion Criteria: * Biopsy proven B-NHL, including DLBCL, HGBL, or FL. * Relapsed/refractory cohorts: In order to be eligible subjects must have received at least 2 prior lines of therapy and not be candidates for treatment regimens known to provide clinical benefit in B-NHL. CAR T-naive subjects are allowed if they have declined, are considered ineligible for, or do not have timely access to CAR T cell therapies. * 1L FL cohorts: Subject has biopsy-proven FL Grade 1-3a per WHO 2016 classification, Stage II-IV, FL International Prognostic Index 2-5 that has not been treated with prior systemic lymphoma-directed therapy and requires initiation of treatment based on GELF criteria. Radiation to localized disease prior to study entry is allowed if \>14 days from first dose. * All Cohorts: Subject has an Eastern Cooperative Oncology Group (ECOG) Performance Status of ≤ 2. * Subject must have adequate liver, bone marrow and kidney function (eGFR ≥ 50 mL/min). * Subject must have locally confirmed CD19 positivity (must be documented after time of progression from last CD19-targeted therapy, if received) * Subject must have at least 1 measurable disease site * Subject must have ANC \>/= 1000/mm3, platelets \>/= 50,000 mm3, hemoglobin \>/= 8.0 g/dL. Transfusion and/or growth factor are allowed but counts must be stable for at least 72 hours afterwards prior to screening * Subject must have a total bilirubin \<1.5x ULN, AST/ALT \< 3xULN Exclusion Criteria: * Subject has been diagnosed with or treated for another malignancy whose natural history or treatment may interfere with the safety or efficacy assessment of the investigational regimen. * Subject has active central nervous system (CNS) involvement by their B-NHL. --Subjects may be eligible with a distant history of CNS involvement that has been adequately treated with no evidence of recurrence within last 6 months from screening. * Subject has a history of leukemic presentation of their B-NHL (\>5,000 circulating lymphoma cells/uL in the peripheral blood). * Subject has history or presence of clinically significant CNS pathology * Subject has CNS involvement from active or history of autoimmune disease. * Subject received CD19 CAR T therapy within 3 months prior to first dose. * Subject experienced Grade ≥ 3 cytokine release syndrome (CRS) following prior T-cell engager (TCE) or CAR T-cell therapy. * Subject experienced Grade ≥ 2 neurotoxicity/immune effector cell-associated neurotoxicity syndrome (ICANS) following prior TCE or CAR T-cell therapy. * Subject has received a peripheral autologous stem cell transplant (SCT) within 12 weeks, or an allogeneic SCT within 1 year of the first dose of study drug treatment or has received an SCT and requires ongoing immunosuppressive therapy. * Subjects with human immunodeficiency virus (HIV) infection, or subjects with chronic or active infection with hepatitis B virus (HBV) or hepatitis C virus (HCV). HIV-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial. Subjects with chronic HBV may be enrolled if the HBV viral load is undetectable on suppressive therapy, or if the subject has a documented cure. Subjects with HCV who have a documented cure may be enrolled. * Subject has a history of major cardiac abnormalities. * If female, subject must not be pregnant or breastfeeding.