This phase I/II trial is trying to understand how much targeted therapy is required and if it is safe to use for the treatment of B-cell lymphoma that have got worse, not responded or come back on prior treatmentsA Phase 1/2, Open-Label, Dose-Escalation Trial of GEN3013 in Patients With Relapsed, Progressive or Refractory B-Cell Lymphoma

Exclusion

Main Exclusion Criteria - All Parts

• Primary central nervous system (CNS) lymphoma or CNS involvement by lymphoma at screening
• Known past or current malignancy other than inclusion diagnosis
• AST, and/or ALT >3 × upper limit of normal
• Total bilirubin >1.5 × upper limit of normal, unless bilirubin rise is due to Gilbert's syndrome or of non-hepatic origin
• Estimated CrCl <45 mL/min
• Known clinically significant cardiovascular disease
• Ongoing active bacterial, viral, fungal, mycobacterial, parasitic, or other infection requiring systemic treatment (excluding prophylactic treatment). Past COVID-19 infection may be a risk factor
• Confirmed history or current autoimmune disease or other diseases resulting in permanent immunosuppression or requiring permanent immunosuppressive therapy
• Seizure disorder requiring therapy (such as steroids or anti-epileptics)
• Any prior therapy with an investigational bispecific antibody targeting CD3 and CD20
• Prior treatment with chimeric antigen receptor T-cell (CAR-T) therapy within 30 days prior to first epcoritamab administration
• Eligible for curative intensive salvage therapy followed by high dose chemotherapy with HSCT rescue
• Autologous HSCT within 100 days prior to first epcoritamab administration, or any prior allogeneic HSCT or solid organ transplantation
• Active hepatitis B (DNA PCR-positive) or hepatitis C (RNA PCR-positive infection). Subjects with evidence of prior HBV but who are PCR-negative are permitted in
• Known human immunodeficiency virus (HIV) infection
• Exposed to live or live attenuated vaccine within 4 weeks prior to signing ICF
• Pregnancy or breast feeding
• Patient is known or suspected of not being able to comply with the study protocol or has any condition for which, participation would not be in the best interest of the patient
• Contraindication to all uric acid lowering agents

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.