Subjects must satisfy the following criteria to be enrolled in the study: 1. Subject is e"18 years of age at the time of signing the informed consent form (ICF). 2. Subject must understand and voluntarily sign an ICF prior to any study-related assessments/procedures being conducted. 3. Subject is willing and able to adhere to the study visit schedule and other protocol requirements. 4. Subject has a history of NHL (including DLBCL, FL, MCL, and PCNSL) with relapsed or refractory disease according to one of the following definitions: a. For R/R DLBCL (not otherwise specified, [NOS]): following at least 2 prior lines of therapy (eg, have received first-line combination chemotherapy regimen containing rituximab, anthracycline, an alkylating agent, and steroids and have received at least one additional (second line/salvage) treatment) OR have failed at least one prior line of standard therapy and are not eligible for SCT -ð Subjects with only one prior line of standard therapy must be ineligible for autologous SCT at the time of enrollment. Documentation of SCT ineligibility is required and acceptable reasons include: -ð Comorbidity, defined as any condition including laboratory abnormalities or clinical symptoms such as cardiac insufficiency and severe pulmonary diseases that place the subject at an unacceptable risk if he/she underwent SCT -ð Subject declined SCT -ð Physician considered the subject s disease could not be adequately treated by autologous SCT for possible reasons such as active disease following salvage therapy (ie. chemo-insensitive disease) -ð Insufficient CD34 cell collection. b. For R/R DLBCL (transformed lymphoma): following chemotherapy for lower grade lymphoma and at least one standard treatment regimen for DLBCL c. For R/R FL: following at least 2 prior lines of therapy and meet treatment criteria at the time of enrollment based on investigator s assessment (eg, according to Groupe d Etude des Lymphomes Folliculaires [GELF] criteria [NCCN, 2018]) d. For R/R MCL in Part B: following at least 2 prior lines of therapy. Subject must have progressed on or been refractory to at least one BTK inhibitor containing regimen (eg, ibrutinib or acalabrutinib) e. For R/R PCNSL in Part B: following at least 2 prior lines of therapy. In addition, subjects with PCNSL must meet the following criteria: ·ð Their neurological symptoms are stable (subjects taking glucocorticoids must be on a stable dose for 7 days prior to Day 1). 5. Subjects must have measurable disease: a. Bi-dimensionally measurable disease on cross sectional imaging by computed tomography (CT) or magnetic resonance imaging (MRI) with at least one lesion > 1.5 cm in the transverse diameter, as defined by the Lugano classification of NHL(Cheson, 2014) -ð Measurable disease cannot be previously irradiated b. PCNSL subjects in Part B must have disease that is objectively measurable by International Workshop to Standardize Baseline Evaluation and Response Criteria in Primary CNS Lymphoma (Abrey, 2005), cerebrospinal fluid (CSF) cytology (in case of leptomeningeal only disease), or vitreal aspiration cytology and/or retinal photographs (in case of ocular lymphoma if clinically indicated). 6. Subject consents to retrieve formalin-fixed paraffin-embedded (FFPE) archival tumor tissue, either in tumor blocks or sectioned/mounted specimens, if collected within the last year and if using in place of the Screening biopsy for PD in Part A. 7. For subjects participating in Part A, subject consents to and has tumor accessible for tumor biopsy or FNA at Screening and FNA in Cycle 1, for Part B, subject consents to and has tumor accessible for paired tumor biopsies during Screening and Cycle 1 (as described in Section 6.6 and Section 6.2.10). 8. Subject has an Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2. 9. Subjects must have the following laboratory values: a. Absolute neutrophil count (ANC) e" 1.5 x 109/L without growth factor support for 7 days (14 days if pegfilgastrim) b. Hemoglobin (Hgb) e" 8 g/dL c. Platelets (plt) e" 75 x 109/L without transfusion for 7 days d. Aspartate aminotransferase / serum glutamic oxaloacetic transaminase (AST/SGOT) and alanine aminotransferase / serum glutamate pyruvic transaminase (ALT/SGPT) d" 2.5 x upper limit of normal (ULN) e. Serum bilirubin d" 1.5 x ULN except in cases of Gilberts Syndrome, then d" 2.0x ULN f. Estimated serum creatinine clearance of e" 60 mL/min using the Cockcroft-Gault equation or directly determined from the 24-hour urine collection method g. International normalized ratio (INR) < 1.5 x ULN and partial thromboplastin time (aPTT) < 1.5 x ULN 10. Subjects must agree not to donate blood while receiving CC-99282, during dose interruptions and for at least 28 days following the last dose of CC-99282. 11. Females of childbearing potential (FCBP) must (Appendix I): a. Either commit to true abstinence from heterosexual contact (which must be reviewed on a monthly basis and source documented) or agree to use, and be able to comply with, at least 2 effective contraceptive methods (oral, injectable, or implantable hormonal contraceptive, tubal ligation, intra-uterine device, barrier contraceptive with spermicide, or vasectomized partner), one of which must be barrier, from signing the ICF, at least 28 days before starting CC-99282, throughout the study, and for up to 28 days following the last dose of CC-99282 and up to one year following the last dose of rituximab, and b. Have 2 negative pregnancy tests as verified by the Investigator prior to starting CC-99282: -ð a negative serum pregnancy test (sensitivity of at least 25 mIU/mL) at Screening (between 10 to 14 days prior to Cycle 1 Day 1) -ð a negative serum or urine pregnancy test (Investigator s discretion) within 24 hours prior to Cycle 1 Day 1 of study treatment (note that the Screening serum pregnancy test can be used as the test prior to Day 1 study treatment if it is performed within the prior 24 hours). c. Avoid conceiving for 28 days after the last dose of CC-99282. d. Agree to ongoing pregnancy testing during the course of the study, and after the end of study treatment. This applies even if the subject practices true abstinence* from heterosexual contact. e. Agree to refrain from donating ova while on CC-99282 for 30 days after its discontinuation. f. Agree to abstain from breastfeeding or providing breast milk while on CC-99282 and for 28 days after its discontinuation. 12. Males must practice true abstinence* (which must be reviewed on a monthly basis) or agree to use a condom (a latex condom is recommended) during sexual contact with a pregnant female or a FCBP and will avoid conceiving from the date of signing the ICF, while participating in the study, during dose interruptions, and for at least 90 days following CC-99282 discontinuation, even if he has undergone a successful vasectomy. a. Males must agree to refrain from donating semen or sperm while on CC-99282 and for 90 days after its discontinuation.

The presence of any of the following will exclude a subject from enrollment: 1. Subject has any significant medical condition, laboratory abnormality, or psychiatric illness that would prevent the subject from participating in the study. 2. Subject has any condition including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study. 3. Subject has any condition that confounds the ability to interpret data from the study. 4. Subject has life expectancy d" 2 months. 5. Subjects who have aggressive lymphoma relapse requiring immediate cytoreductive therapy to avoid potential life-threatening consequences (eg, due to tumor location). 6. Subject has received prior systemic anti-cancer treatment (approved or investigational) d" 5 half-lives or 4 weeks prior to starting CC-99282, whichever is shorter. 7. Subject has received prior CAR-T or other T-cell targeting treatment (approved or investigational) d" 4 weeks prior to starting CC-99282. 8. Subject has received prior therapy with CRBN-modulating drug (eg, lenalidomide, avadomide/CC-122, pomalidomide) d" 4 weeks prior to starting CC-99282. 9. Subject is a pregnant or nursing female or intends to become pregnant during participation in the study. 10. Subject has symptomatic CNS involvement of disease (does not apply to PCNSL subjects in Part B). 11. Persistent diarrhea or malabsorption e" Grade 2 National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE), despite medical management 12. Peripheral neuropathy e" NCI CTCAE Grade 2. 13. Subject is on chronic systemic immunosuppressive therapy or corticosteroids (eg, prednisone or equivalent not to exceed 10 mg per day within the last 14 days) or subjects with clinically significant graft-versus-host disease (GVHD). a. Stable use of inhaled corticosteroids is allowed b. The use of topical steroids for ongoing skin or ocular GVHD is permitted c. In Part B, PCNSL subjects taking glucocorticoids are allowed but must be on a stable dose for 7 days prior to Cycle 1 Day 1 14. Subject has impaired cardiac function or clinically significant cardiac diseases, including any of the following: a. Left ventricular ejection fraction (LVEF) < 45% as determined by multigated acquisition scan (MUGA) or echocardiogram (ECHO) b. Complete left bundle branch or bifascicular block c. Congenital long QT syndrome d. Persistent or clinically meaningful ventricular arrhythmias e. QTcF e" 470 msec on Screening electrocardiogram (ECG, mean of triplicate recordings) f. Unstable angina pectoris or myocardial infarction d" 3 months prior to starting 15. Subject had prior autologous SCT d" 3 months prior to starting CC-99282 and any treatment-related toxicity is unresolved (grade > 1). 16. Subject had prior allogeneic SCT with either standard or reduced intensity conditioning d" 6 months prior to starting CC-99282 and any treatment-related toxicity is unresolved (grade > 1). 17. Subject had major surgery d" 2 weeks prior to starting CC-99282. Subjects must have recovered from any clinically significant effects of recent surgery 18. Prior radiotherapy within one month prior to starting study drug. 19. Subject has known human immunodeficiency virus (HIV) infection. 20. Subject has known chronic active hepatitis B or C virus (HBV/HCV) infection. 21. Subject has a history of concurrent second cancers requiring active, ongoing systemic treatment. 22. Concurrent administration of strong CYP3A4/5 modulators (see Section 8.2)