A Study to Evaluate Adverse Events of Subcutaneous (SC) Epcoritamab Administered in the Outpatient Setting in Adult Participants With Relapsed or Refractory Diffuse Large B-Cell Lymphoma and Classic Follicular Lymphoma

Inclusion Criteria:

• Life expectancy >3 months on standard of care (SOC) treatment.

• Meets the following disease activity criteria:

-- Relapsed or Refractory (R/R) Diffuse Large B-Cell Lymphoma (DLBCL):

• Documented CD20+ mature B-cell neoplasm according to the the 5th edition ofWorld Health Organization (WHO) classification of Haematolymphoid Tumours,based on most recent representative pathology report;

• Diffuse large B-cell lymphoma, not otherwise specified (NOS) (de novo ortransformed from follicular lymphoma (FL) or Marginal Zone Lymphoma [MZL]);

• High-grade B-cell Lymphoma including "double-hit" or "triple-hit" DLBCL (technically classified in WHO 2022 or 2016 as high-grade B-cell lymphoma [HGBCL], with MYC and BCL2 and/or BCL6 translocations).

• Follicular large B-cell lymphoma (FLBL, formerly FL grade 3B);

• Relapsed or refractory disease and previously treated with at least 1 priorsystemic antineoplastic therapies including at least 1 anti-CD20 monoclonalantibody-containing therapy; Note: Relapsed disease is defined as disease thatpreviously responded to therapy but progressed >= 6 months after completion oftherapy. Refractory disease is defined as disease that either progressed duringtherapy, failed to achieve an objective response to prior therapy, orprogressed within 6 months after completion of therapy (including maintenancetherapy).

• Either failed prior autologous hematopoietic stem cell transplantation (HSCT),or ineligible for autologous HSCT including but not limited to age, EasternCooperative Oncology Group (ECOG) performance status, participant decision,comorbidities and/or insufficient response to prior treatment.

• R/R Follicular Lymphoma:

• Documented CD20+ mature B-cell neoplasm according to the 5th edition of WHOclassification of Haematolymphoid Tumours, based on representative pathologyreport; --- Classic FL (cFL) (previously FL grade 1, 2, or 3a) without clinical orpathological evidence of transformation;

• Relapsed or refractory disease and previously treated with at least 2 priorlines of systemic antineoplastic therapies including at least 1 anti-CD20monoclonal antibody containing therapy; Note: Relapsed disease is defined asdisease that previously responded to therapy but progressed >= 6 months aftercompletion of therapy. Refractory disease is defined as disease that eitherprogressed during therapy, failed to achieve an objective response to priortherapy, or progressed within 6 months after completion of therapy (includingmaintenance therapy).

• Previously treated with an alkylating agent or lenalidomide;

• Relapsed or refractory to the last prior line therapy. Previous lymphomatherapy is defined as 1 of the following: At least 2 months of single-agenttherapy, at least 2 consecutive cycles of combination therapy, autologous HSCT,immunomodulatory therapy, or radioimmunotherapy.

• Has at least one target lesion defined as:

• >= 1 measurable nodal lesion (long axis > 1.5 cm) and/or >= 1 measurableextranodal lesion (long axis > 1.0 cm) on CT (or MRI) AND

• FDG PET scan demonstrating positive lesion(s) compatible with CT (or MRI)defined anatomical tumor sites.

• Must have ECOG performance status 0 - 2.

• Must have acceptable organ (renal, liver, and hematologic) function within thescreening period prior to the first dose of study drug:

• Absolute neutrophil count (ANC) >= 1.0 × 10^9/L (growth factor support allowedin case of bone marrow involvement, but participant must have not receivedgrowth factor within 14 days prior to screening lab collection);

• Hemoglobin >= 8.0 g/dL (RBC transfusions permitted, but participants must nothave received blood transfusions within 7 days prior to Screening labcollection);

• Platelet count >= 75 × 10^9/L, or >= 50 × 10^9/L in the presence of bone marrowinvolvement or splenomegaly (platelet transfusions are permitted, butparticipants must not have received blood transfusions within 7 days prior toScreening lab collection);

• International normalized ratio (INR) (or Prothrombin Time [PT]) and aPTT <= 1.5 × upper limit of normal (ULN), unless receiving anticoagulation

• Serum aspartate aminotransferase (AST) and serum alanine aminotransferase (ALT) <= 3.0 × upper limit of normal (ULN); unless due to hepatic involvement ofdisease or non-hepatic origin. For participants with hepatic involvement ofdisease, serum AST and serum ALT <= 5.0 × ULN

• Direct bilirubin <= 2 × ULN;

• Estimated creatine clearance (CrCl) as calculated by Cockcroft-Gault Formula >= 45 mL/min, or estimated glomerular filtration rate (eGFR) as calculated byModification of Diet in Renal Disease [MDRD] equation >= 45 mL/min;

• Lymphocyte count < 5 × 10^9/L.

Exclusion Criteria:

• Have a primary central nervous system (CNS) lymphoma or known CNS involvement bylymphoma including leptomeningeal disease, at screening as confirmed by magneticresonance imaging (MRI)/computed tomography (CT) scan (brain) and, if clinicallyindicated, by lumbar puncture.

• Uncontrolled Human Immunodeficiency Virus (HIV) infection. HIV viral load that isundetectable and controlled with medication for at least 1 year prior to enrollmentis allowed. Note: If participant has no history of HIV infection, HIV testing doesnot need to be conducted at screening unless it is required per local guidelines orinstitutional standards.